subtopic 6.2 Climate Change - causes and impacts
The current cycle of global warming is changing the rhythms of climate that all living things have come to rely upon. What will we do to slow this warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the face of the Earth as we know it—coasts, forests, farms, and snow-capped mountains—hangs in the balance.
In this unit you will evaluate the role of greenhouse gases, the effects of rising global temperatures and the arguments associated with global warming. This issue involves the international community working together to research and reduce the effects of global warming.
This unit is a minimum of 3 SL hours.
In this unit you will evaluate the role of greenhouse gases, the effects of rising global temperatures and the arguments associated with global warming. This issue involves the international community working together to research and reduce the effects of global warming.
This unit is a minimum of 3 SL hours.
Guiding Questions:
- To what extent has climate change occurred due to anthropogenic causes?
- How do differing perspectives play a role in responding to the challenges of climate change?
Understanding
6.2.1 Climate describes the typical conditions that result from physical processes in the atmosphere
- Explain how climate differs from weather.
- List two physical processes that impact climate.
Climate refers to the long-term patterns of temperature, humidity, wind, and precipitation in a given region. It describes the average weather conditions over a period of at least 30 years.
Climate is influenced by physical processes such as the Earth’s rotation, the angle of the sun, and interactions between the atmosphere and oceans.
Climate is influenced by physical processes such as the Earth’s rotation, the angle of the sun, and interactions between the atmosphere and oceans.
The main factors that impact climate in any given area are seasonal variations in temperature and precipitation. These variations are caused by the tilt of the Earth's axis, which affects the intensity and duration of sunlight received at different latitudes.
Climate is distinct from weather, which refers to short-term atmospheric conditions. While weather can change daily, climate refers to long-term patterns.
Microclimates may exist within larger climate zones due to factors such as altitude, proximity to bodies of water, and urban development, which can influence localized temperature and humidity.
Difference is TIMESCALE!
Temperature and precipitation are two indicators often used on climate graphs to represent climate. In many areas of the world, these factors will indicate their seasons.
Climate as a System:
- Inputs:
- Solar radiation: The primary input of energy to Earth’s climate system. Solar radiation heats the Earth's surface, drives atmospheric circulation, and powers the hydrological cycle.
- Greenhouse gases (GHGs): Inputs such as CO2, methane, and water vapor trap heat in the atmosphere, contributing to the greenhouse effect.
- Volcanic emissions: Particles and gases released from volcanic eruptions can reflect solar radiation back into space, temporarily cooling the Earth.
- Outputs:
- Infrared radiation: After absorbing solar energy, the Earth radiates heat (infrared radiation) back into space. However, greenhouse gases can absorb some of this outgoing heat, leading to warming.
- Latent heat: Energy released or absorbed during phase changes of water (e.g., evaporation and condensation) is an output from the Earth's surface to the atmosphere.
- Storages:
- Atmosphere: Acts as a storage of heat, water vapor, and greenhouse gases. The atmosphere stores energy and distributes it across the planet.
- Oceans: Oceans store large amounts of heat and carbon dioxide. They act as a heat sink, buffering the planet from rapid changes in temperature.
- Ice and snow: Glaciers, ice sheets, and polar ice caps store freshwater and affect the Earth’s albedo (reflectivity), which in turn influences how much solar energy is absorbed or reflected.
- Flows:
- Energy flows: Solar energy flows from the Sun to the Earth's surface and is redistributed by ocean currents and wind patterns. Some energy is absorbed by the atmosphere and surface, while some is reflected back into space.
- Water flows: Water moves through the climate system in the form of precipitation, evaporation, and runoff. These flows are part of the hydrological cycle, a crucial component of climate dynamics.
- Transfers:
- Wind and ocean currents: Energy is transferred across the planet by wind and ocean currents, which redistribute heat from the equator toward the poles.
- Evaporation and precipitation: Water is transferred from the Earth's surface to the atmosphere through evaporation and returns to the surface as precipitation, affecting temperature and humidity.
- Transformations:
- Radiative transformations: Solar energy is transformed into thermal energy (heat) when it reaches the Earth's surface, warming the land, oceans, and atmosphere.
- Photosynthesis: Solar energy is transformed into chemical energy by plants during photosynthesis, removing CO2 from the atmosphere and storing carbon in plant biomass.
- Cloud formation: Water vapor condenses into liquid water during cloud formation, transforming latent heat into sensible heat, which impacts local temperature.
Activity: Create a climate system diagram showing inputs, outputs, storages, flows, and transformations. Label each part and explain how they interact.
6.2.2 Anthropogenic carbon dioxide emissions have caused concentrations of atmospheric carbon dioxide to rise significantly. The global rate of emission has accelerated, particularly since 1950.
- Define anthropogenic CO2 emissions.
- Explain the link between the Industrial Revolution and the rise in atmospheric CO2 levels.
- Describe how the global rate of CO2 emissions has changed since the 1950s and the factors contributing to this change.
Anthropogenic carbon dioxide (CO2) emissions are the result of human activities, such as the burning of fossil fuels (coal, oil, and natural gas), deforestation, and industrial processes. The Industrial Revolution, which began in the late 18th century in Europe, marked a significant turning point in human history, as the widespread use of coal-powered machines led to a rapid increase in CO2 emissions.
CO2 concentrations in the atmosphere remained relatively stable for thousands of years before the Industrial Revolution. Since then, emissions have risen sharply, with the rate of increase accelerating particularly from the mid-20th century (around 1950) due to the global spread of industrialization, urbanization, and population growth. By the mid-20th century, the world saw a dramatic rise in fossil fuel consumption for electricity, transportation, and industry, leading to an unprecedented rise in atmospheric CO2 levels.Additional Information:
Atmospheric CO2 concentrations have increased from around 280 parts per million (ppm) before the Industrial Revolution to over 400 ppm today, a level not seen in millions of years. This sharp rise in CO2 is a primary driver of the enhanced greenhouse effect, which is causing global temperatures to rise. The impacts of increased CO2 emissions are global, with climate change now affecting weather patterns, causing sea-level rise, and increasing the frequency of extreme weather events such as heatwaves, droughts, and hurricanes.
CO2 concentrations in the atmosphere remained relatively stable for thousands of years before the Industrial Revolution. Since then, emissions have risen sharply, with the rate of increase accelerating particularly from the mid-20th century (around 1950) due to the global spread of industrialization, urbanization, and population growth. By the mid-20th century, the world saw a dramatic rise in fossil fuel consumption for electricity, transportation, and industry, leading to an unprecedented rise in atmospheric CO2 levels.Additional Information:
Atmospheric CO2 concentrations have increased from around 280 parts per million (ppm) before the Industrial Revolution to over 400 ppm today, a level not seen in millions of years. This sharp rise in CO2 is a primary driver of the enhanced greenhouse effect, which is causing global temperatures to rise. The impacts of increased CO2 emissions are global, with climate change now affecting weather patterns, causing sea-level rise, and increasing the frequency of extreme weather events such as heatwaves, droughts, and hurricanes.
Below is the graph of global temperatures and the level of carbon dioxide in the atmosphere from 1880 to present, courtesy of the National Climatic Data Center (NCDC). NCDC has a more complete discussion of this graph along with other interesting material on their Global Climate Change Indicators page. A more in-depth discussion of computing global temperatures can be found on their Global Surface Temperature Anomalies page
Activity: Create a graph showing the trend of global CO2 emissions since 1750. Use data to highlight key periods of growth (e.g., post-1950 industrialization).
6.2.3 Analysis of ice cores, tree rings and deposited sediments provide data that indicates a positive correlation between the concentration of carbon dioxide in the atmosphere and global temperatures.
- Define proxy data and give two examples.
- Explain how ice cores can provide information about historical CO2 concentrations.
- Describe the relationship between CO2 levels and temperature as shown in proxy data from ice cores.
Insights about the role of carbon dioxide in global warming are not new. In the 1800s, scientists first proposed the possibility of the greenhouse effect and the link with carbon dioxide
Ice cores, extracted from ice sheets in places like Antarctica and Greenland, contain layers of snow that fell thousands to hundreds of thousands of years ago. These layers trap small air bubbles that provide a direct record of ancient atmospheric conditions.
By analyzing the gases trapped in these bubbles, scientists can reconstruct past CO2 and methane levels and compare them with current levels, showing how human activity has dramatically increased greenhouse gases since the Industrial Revolution.
Tree rings are another form of proxy data, providing information about annual climate conditions. Wider rings indicate wetter or warmer years, while narrower rings suggest cooler or drier years.
Pollen analysis from sediment cores can also help scientists understand past ecosystems, showing how plant species responded to climate changes in different periods.
Ancient sediments buried beneath the ocean floor, deposited during the last ice age, offer key insights into past ocean oxygen levels and their connection to atmospheric carbon dioxide during that era. By studying these sediments, scientists gain an additional approach to understanding historical climate changes.
Application of skills: Research global temperature records since 1850 using data from sources like NASA, NOAA, or the HadCRUT dataset.
- Create a graph that shows the long-term trend of global average temperature from 1850 to the present.
- Mark key historical events on the graph, such as the Industrial Revolution, major volcanic eruptions (e.g., Mount Pinatubo, Krakatoa), and the rise of fossil fuel consumption.
- What trends are visible in the temperature data? How has the rate of warming changed over time?
- What periods saw significant increases in temperature, and what might explain these changes?
- Add CO2 concentration data to your graph and analyze the correlation between rising CO2 levels and global temperature increase. What does this tell you about the relationship between greenhouse gas emissions and temperature?
6.2.4 The greenhouse effect has been enhanced by anthropogenic emissions of GHGs. This has led to global warming and, therefore, climate change.
- List the three major anthropogenic greenhouse gases and their sources.
- Explain why methane is a more potent greenhouse gas than carbon dioxide, despite its lower concentration.
- Describe the role of anthropogenic greenhouse gases in the enhanced greenhouse effect.
Human activities have intensified the greenhouse effect by releasing large amounts of greenhouse gases (GHGs) into the atmosphere. This has contributed to global warming and, consequently, climate change. Significant emissions of carbon dioxide, methane, and nitrous oxide, along with smaller amounts of other GHGs, are the primary contributors
Anthropogenic greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), are primarily responsible for the enhanced greenhouse effect that drives global warming.
CO2 is released from burning fossil fuels for energy, deforestation, and industrial processes. Methane is released during the production and transport of fossil fuels and from agricultural activities (e.g., livestock).
These gases trap heat in the atmosphere, warming the planet. Methane, though less abundant than CO2, has a global warming potential 25 times greater over a 100-year period.:
Anthropogenic greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), are primarily responsible for the enhanced greenhouse effect that drives global warming.
CO2 is released from burning fossil fuels for energy, deforestation, and industrial processes. Methane is released during the production and transport of fossil fuels and from agricultural activities (e.g., livestock).
These gases trap heat in the atmosphere, warming the planet. Methane, though less abundant than CO2, has a global warming potential 25 times greater over a 100-year period.:
- Nitrous oxide, often overlooked, is a potent GHG released from fertilizers in agriculture.
- Reducing emissions of these gases is essential for limiting global temperature rise.
Although a 1.5°C temperature rise may seem minor, it is sufficient to disrupt our stable climate system, posing risks to human agriculture and societal structures. As the climate becomes less predictable, crop failures could increase, and densely populated regions may become uninhabitable.
6.2.5 Climate change impacts ecosystems at a variety of scales, from local to global and affects the resilience of ecosystems and leads to biome shifts.
- Define ecosystem resilience and explain how biodiversity contributes to it.
- Outline the local impacts of climate change on coral reef ecosystems.
- Describe the potential global impacts of sea-level rise on coastal habitats.
- Explain how changes in ocean circulation can affect marine productivity and climate.
- List three factors that affect the resilience of an ecosystem in the face of climate change.
Climate change is already having profound impacts on ecosystems at local, regional, and global scales. These impacts alter the resilience of ecosystems, leading to shifts in biomes and changes in species composition, productivity, and biodiversity. The changes can be felt locally, with specific ecosystems like coral reefs and deserts, and globally, through processes like sea-level rise and changes in ocean circulation.
Local Ecological Impacts:
- Biome Shifts:
- Biomes, or large ecological regions such as deserts, rainforests, or tundra, are sensitive to changes in temperature and precipitation. As climate patterns change, biomes may shift geographically, moving to higher altitudes or latitudes to remain within their ideal climate conditions.
- For example, tundra ecosystems may be replaced by boreal forests as warming temperatures allow trees to grow further north, while savannas may expand into previously forested areas as those regions become drier.
- Species Adaptation and Evolution:
- Some species are already undergoing rapid adaptation in response to changing environmental conditions. For example, organisms in warming environments may evolve shorter lifecycles or shift their migration patterns.
- Evolutionary responses may include changes in size, breeding season, or behavior. However, not all species can adapt fast enough, leading to local extinctions or range reductions.
- Productivity and Biodiversity:
- Local ecosystems may experience changes in natural productivity (the rate at which plants and animals produce biomass). In some areas, warming temperatures and increased CO2 levels may enhance plant growth and lead to greater productivity. However, extreme heat or changes in precipitation can reduce productivity in other areas, leading to desertification.
- Biodiversity is also under threat. Coral bleaching, driven by warmer sea temperatures, reduces biodiversity in reef ecosystems. Similarly, forest ecosystems impacted by drought and fire can experience declines in species richness.
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- Ecosystem Resilience and Tipping Points:
- The resilience of an ecosystem refers to its ability to recover from disturbances. Ecosystems with higher biodiversity are generally more resilient because they have more species performing overlapping roles (functional redundancy).
- Ecosystem tipping points occur when a system undergoes a sudden and irreversible shift to a new state. For example, coral reefs that undergo repeated bleaching events may reach a tipping point where recovery is no longer possible, transforming them into algal-dominated systems with significantly reduced biodiversity.
- Local Examples:
- Coral Bleaching: Rising ocean temperatures stress coral ecosystems, causing them to expel the algae (zooxanthellae) that live within their tissues. Without these algae, corals lose their color and their primary source of nutrients, leading to coral death and a collapse in the biodiversity supported by reefs.
- Desertification: In areas where precipitation declines due to climate change, drylands expand, turning once productive land into desert. This reduces local biodiversity and negatively impacts agriculture, leading to food and water shortages for human populations.
Projected change in marine biomass. Simulated global biomass changes of (a,b,c) surface phytoplankton, (d,e,f) zooplankton, (g,h,i) animals and (j,k,l) seafloor benthos. In (a,d,g,j), the multi-model mean (solid lines) and very likely range (envelope) over 2000–2100 relative to 1995–2014, for SSP1-2.6 and SSP5-8.5. Spatial patterns of simulated change by 2090–2099 are calculated relative to 1995–2014 for (b,e,h,k) SSP1-2.6 and (c,f,i,l) SSP5-8.5. Confidence intervals can be affected by the number of models available for the Coupled Model Intercomparison Project 6 (CMIP6) scenarios and for different variables. Only one model was available for panel (j), so no confidence interval is calculated. For panels (a–f), the ensemble projections of global changes in phytoplankton and zooplankton biomasses updated based on Kwiatkowski et al. (2019) include, under SSP1-2.6 and SSP5-8.5, respectively, a total of nine and ten CMIP6 Earth system models (ESMs). For panels (b,c,e,f), unhatched areas represent regions where at least 80% of models agree on the sign of biomass anomaly. For panels (g,h,i), the ensemble projections of global changes in total animal biomass updated based on Tittensor et al. (2021) include six to nine published global fisheries and marine ecosystem models from the Fisheries and Marine Ecosystem Model Intercomparison Project (Tittensor et al., 2018; Tittensor et al., 2021), forced with standardised outputs from two CMIP6 ESMs. For panels (j,k,l), globally integrated changes in total seafloor biomass have been updated based on Yool et al. (2017) with one benthic model (Kelly-Gerreyn et al., 2014) forced with the CMIP6 ESM UKESM-1.
Global Ecological Impacts:
- Changes in Ocean Circulation:
- Ocean circulation patterns, such as the Atlantic Meridional Overturning Circulation (AMOC), are critical for redistributing heat and nutrients across the planet. Climate change is altering these patterns, potentially leading to a slowdown in the Gulf Stream and other currents. This could have widespread impacts, such as more severe winters in Europe and changes in marine ecosystems, where upwelling zones that bring nutrient-rich waters to the surface may become less productive
- Sea-Level Rise:
- Global warming is causing polar ice sheets and glaciers to melt, contributing to sea-level rise. Higher sea levels threaten coastal ecosystems, leading to the loss of critical habitats such as mangroves, salt marshes, and estuaries, which serve as breeding grounds for many marine species.
- Saltwater intrusion into freshwater systems also disrupts ecosystems and human communities that rely on freshwater for drinking and agriculture.
Seasonal (3-month) sea level estimates from Church and White (2011) (light blue line) and University of Hawaii Fast Delivery sea level data (dark blue). The values are shown as change in sea level in millimeters compared to the 1993-2008 average. NOAA Climate.gov image based on analysis and data from Philip Thompson, University of Hawaii Sea Level Center.
- Monsoon Rains:
- Monsoon patterns in regions like South Asia are expected to become more unpredictable due to climate change. The intensity and timing of monsoons, which are critical for agriculture, could be altered, leading to either flooding from increased rainfall or droughts from reduced or delayed rains. Both scenarios have devastating consequences for ecosystems that rely on regular rainfall patterns to thrive.
- Tropical Cyclones:
- Tropical cyclones (hurricanes, typhoons) are becoming more intense due to warmer sea surface temperatures. These storms can cause widespread destruction to coastal ecosystems, damaging coral reefs, mangroves, and coastal wetlands. The frequency of category 4 and 5 storms (the most severe) is projected to increase, bringing stronger winds, heavier rainfall, and more significant storm surges.
Global Examples:
- Polar Ice Melt and Ocean Currents: Melting Arctic sea ice is contributing to changes in ocean circulation patterns, which could slow down or disrupt the thermohaline circulation. This may lead to drastic regional changes in climate and ocean productivity.
- Sea-Level Rise and Coastal Habitats: Rising seas are threatening biodiversity in coastal ecosystems, including mangrove forests and salt marshes, which protect coastlines from storm surges and serve as nurseries for many fish species.
Factors Affecting Ecosystem Resilience:
- Biodiversity: Ecosystems with greater biodiversity are more resilient because multiple species can fill similar ecological roles. This redundancy ensures that the ecosystem can maintain function even if some species are lost.
- Ecosystem Health: Healthy ecosystems with intact food webs, nutrient cycling, and habitat connectivity are more likely to withstand and recover from climate-related stress.
- Human Activity: Ecosystems already stressed by human activities such as pollution, deforestation, and habitat fragmentation are less resilient to climate change. Human intervention, like building seawalls or artificial reefs, may be necessary to restore ecosystem resilience in some cases.
Activity: Draw a table with three columns:
- Benefits of Global Warming
- Problems of Global Warming
- Areas Affected by Rising Sea Levels
- Research and fill in the table with real-world examples, evidence, and data. For each column:
- Benefits of Global Warming: Consider possible advantages such as extended growing seasons in colder regions or new shipping routes in the Arctic.
- Problems of Global Warming: Focus on issues such as increased frequency of extreme weather events, health impacts, economic disruptions, etc.
- Areas Affected by Rising Sea Levels: Identify coastal cities, island nations, and low-lying areas at risk of being submerged or affected by coastal erosion, flooding, and saltwater intrusion.
Application of skills: Investigate climate graphs for different global locations. Atmospheric and oceanic CO2 levels in long-term graphs provide evidence for anthropogenic global warming and ocean acidification. Use databases to explore the impact of temperature change on a specific ecosystem, for example, coral reefs or forests.
Data sources:
Data sources:
- NASA's Climate Change website
A range of data and interactives showing impacts on ocean warming, ice sheets, and sea levels. - Our World in Data - Climate Change Impacts Data Explorer
Overlaps with data provided on the NASA site. - NASA's Sea Level Projection Tool
Map and data of sea level rise projections based on different temperature scenarios, based on the Intergovernmental Panel on Climate Change's Sixth Assessment Report (2021). Data is available for many coastal locations around the world. - Audubon Society
Interactive content on climate scenarios, habitat loss, and threats to bird species. - US National Oceanographic and Atmospheric Administration
Data on carbon dioxide atmospheric concentration levels, carbon dioxide ocean levels, and pH levels over time in three locations. - Global Forest Watch
Article on forest loss due to fire, with links and embedded graphs with data related to forest fires. - World Resource Watch Climate Dashboard
Includes mapping and data of climate impacts, including projections of future coral reef bleaching.
6.2.6 Climate change has an impact on (human) societies at a variety of scales and socio-economic conditions. This impacts the resilience of societies.
- Define societal resilience in the context of climate change.
- Describe two impacts of climate change on water supply in vulnerable regions.
- Explain how climate change is affecting global food security and crop yields.
- Outline how economic resources contribute to the resilience of a society facing climate change.
- List three factors that can either enhance or weaken the resilience of a society to climate change.
Climate change is affecting human societies in profound ways, with impacts varying based on geographic location, economic status, and the level of development. The consequences are felt at local, regional, and global levels, influencing key areas such as health, water supply, agriculture, and infrastructure. These changes challenge the resilience of societies, which is the ability to adapt, recover, and maintain functionality in the face of climate-related disruptions.
Societies that are less economically developed or more geographically vulnerable often bear the brunt of these impacts, even though they may contribute less to the causes of climate change. Conversely, wealthier and more developed nations may have greater capacity to adapt and build resilience, though they are not immune to the impacts.
Societies that are less economically developed or more geographically vulnerable often bear the brunt of these impacts, even though they may contribute less to the causes of climate change. Conversely, wealthier and more developed nations may have greater capacity to adapt and build resilience, though they are not immune to the impacts.
Climate Change Impacts on Societies:
- Health:
- Heatwaves: Rising global temperatures increase the frequency, intensity, and duration of heatwaves, which are particularly dangerous for vulnerable populations such as the elderly, young children, and people with pre-existing health conditions. Heat-related illnesses, including heatstroke and cardiovascular complications, are becoming more common, especially in urban areas where the urban heat island effect amplifies temperature extremes.
- Vector-borne diseases: Warmer temperatures and altered precipitation patterns expand the habitats of disease vectors such as mosquitoes, ticks, and fleas. Diseases like malaria, dengue fever, and Lyme disease are spreading to new areas, putting millions more people at risk, especially in regions with weak healthcare systems.
- Respiratory issues: Increased levels of air pollution, such as ground-level ozone and particulate matter, exacerbated by climate change, lead to a rise in respiratory illnesses like asthma, chronic bronchitis, and other lung diseases.
- Water Supply:
- Water scarcity: Climate change is altering global precipitation patterns, leading to droughts in some regions and flooding in others. Areas that depend on glacier melt or regular rainfall are experiencing water shortages, threatening drinking water supplies, irrigation, and sanitation.
- Changes in freshwater availability: The melting of glaciers and snowpacks, which provide freshwater to billions of people in regions like the Himalayas, the Andes, and parts of North America, is accelerating. As these water sources shrink, communities are increasingly vulnerable to water shortages, particularly during the dry season.
- Increased competition for water: As water becomes scarcer, competition between agricultural, industrial, and domestic users intensifies, potentially leading to conflict, especially in transboundary water systems where rivers and lakes cross national borders.
- Agriculture:
- Crop yields: Changes in temperature, rainfall, and the frequency of extreme weather events are having a direct impact on crop productivity. Droughts, floods, and heatwaves can destroy crops, reducing yields and threatening food security. In some regions, pest populations are also expanding due to warmer conditions, further jeopardizing crops.
- Food security: As global food production becomes more uncertain, food prices may rise, increasing the risk of hunger and malnutrition, especially in developing countries. The loss of agricultural productivity can also lead to displacement and migration, as people seek better opportunities elsewhere.
- Changes in growing seasons: Climate change is shifting growing seasons, particularly in temperate regions where warmer temperatures allow for longer growing periods. However, in tropical and semi-arid regions, growing seasons may shorten or become less predictable, reducing agricultural output.
- Infrastructure:
- Extreme weather damage: Hurricanes, floods, and storm surges are becoming more intense due to climate change, posing severe risks to infrastructure. Coastal cities are particularly vulnerable to rising sea levels and storm surges, which can damage roads, bridges, ports, and buildings.
- Energy infrastructure: Rising temperatures can stress energy systems, particularly electricity grids that rely on air conditioning during heatwaves. Hydroelectric power is also threatened by reduced water availability in regions dependent on river flows or glacial melt for energy generation.
- Transportation disruptions: Floods, landslides, and extreme storms can damage critical transportation infrastructure such as roads, railways, and airports, disrupting supply chains and leading to economic losses. Coastal infrastructure is especially at risk from sea-level rise and storm surges.
- Economic and Social Impacts:
- Migration and displacement: Climate change is increasingly contributing to the displacement of people. Climate refugees are forced to leave their homes due to sea-level rise, desertification, and extreme weather events. Low-lying island nations and coastal cities face significant displacement pressures.
- Economic inequality: The economic impacts of climate change are disproportionately felt by poorer communities and countries, which have fewer resources to adapt. This exacerbates global inequality, as wealthier nations can invest in climate resilience while poorer nations struggle to cope with the impacts.
- Conflict: Climate change can exacerbate existing social and political tensions, particularly in regions where resources like water and food are scarce. Competition over these resources may lead to conflict, especially in politically unstable areas.
Factors That Affect the Resilience of Societies:
- Economic Resources:
- Societies with strong economies and access to financial resources are generally more resilient to the impacts of climate change. They can invest in adaptation strategies such as building seawalls, upgrading infrastructure, and developing early warning systems for extreme weather events.
- Insurance: Access to insurance markets can help individuals and businesses recover from climate-related disasters. In many low-income countries, however, insurance is either unavailable or too expensive, increasing vulnerability.
- Technological Innovation:
- Societies that invest in green technologies and renewable energy can reduce their vulnerability to climate change by mitigating emissions and reducing reliance on fossil fuels. Technologies such as drought-resistant crops, solar energy, and desalination plants enhance the resilience of communities.
- Early warning systems and forecasting technologies help societies prepare for extreme weather events, reducing the human and economic toll of disasters.
- Social and Political Stability:
- Socially cohesive societies with strong governance are better able to respond to the challenges of climate change. Effective leadership, public trust in institutions, and the ability to implement adaptive policies contribute to resilience.
- Conversely, societies with political instability or poor governance are more vulnerable, as corruption, weak institutions, and lack of coordinated planning impede adaptation and recovery efforts.
- Environmental Management:
- Societies that prioritize sustainable land use, water management, and biodiversity conservation are more resilient to climate impacts. Healthy ecosystems, such as mangroves, wetlands, and forests, act as natural buffers against climate-related disasters.
- Overexploitation of natural resources, deforestation, and unsustainable agricultural practices, on the other hand, reduce resilience by weakening the natural systems that help absorb climate shocks.
- Community and Cultural Factors:
- Community-level adaptation plays a crucial role in enhancing resilience. Societies with strong local organizations, traditional knowledge systems, and social networks can better mobilize resources and respond to disasters.
- Cultural resilience also affects a society’s ability to adapt to change. Indigenous communities, for example, often possess valuable traditional knowledge about managing natural resources in the face of environmental variability.
Activity: Research how climate change is impacting your local area (e.g., changes in temperature, precipitation, extreme weather events, sea-level rise).
- Focus on how these changes are affecting different aspects of society, including:
- Health (e.g., heatwaves, increased air pollution).
- Water supply (e.g., droughts, floods).
- Agriculture (e.g., crop yields, soil degradation).
- Infrastructure (e.g., damage from storms, rising maintenance costs).
- Create a case study detailing the local impacts, using data and case studies from your region.
- How are local communities adapting to these changes? Are certain communities or socio-economic groups more vulnerable than others?
- Discuss how resilience varies among different socio-economic groups in your area and what factors contribute to or hinder this resilience.
6.2.7 Systems diagrams and models can be used to represent cause and effect of climate change with feedback loops, either positive or negative, and changes in the global energy balance.
- Define a positive feedback loop in the context of climate change.
- Explain how the ice-albedo effect accelerates global warming.
- Outline one negative feedback loop and its role in climate regulation.
- Positive feedback loops are processes that accelerate climate change. For example, as the Arctic warms, permafrost (permanently frozen ground) begins to thaw, releasing methane—a potent greenhouse gas—into the atmosphere. This methane causes further warming, which in turn leads to more permafrost thaw.
- Negative feedback loops act as natural brakes on the climate system. For example, as global temperatures rise, evaporation increases, leading to more cloud formation. These clouds reflect more sunlight back into space, reducing the amount of heat absorbed by the Earth’s surface, potentially slowing the warming process.
The systems diagram below was produced by the UN’s IPCC and does an excellent job of showing the inputs, outputs, and relationships among human activities, climate change processes, climate characteristics, and threats to human populations and ecosystems. I recommend studying it extensively.
Activity: Draw diagrams for different positive feedback loops (e.g., ice-albedo effect, permafrost thawing).
- For each loop, explain how it works and how it accelerates climate change.
6.2.8 Evidence suggests that the Earth has already passed the planetary boundary for climate change.
- Define the concept of radiative forcing and explain its role in climate change.
- Describe how atmospheric carbon dioxide concentrations contribute to exceeding the climate change planetary boundary.
- Explain the consequences of radiative forcing levels greater than 1 and how they affect global temperatures.
- Outline the relationship between the planetary boundary for climate change and the Paris Agreement’s temperature goals.
The planetary boundary for climate change is defined by two key factors:
Atmospheric CO2 Concentrations:
Radiative Forcing:
The Role of the Global Energy Balance:
- Atmospheric carbon dioxide (CO2) concentrations
- Radiative forcing (the balance between the Sun's incoming energy and the outgoing energy from the Earth)
Atmospheric CO2 Concentrations:
- CO2 is the primary greenhouse gas contributing to global warming. Before the Industrial Revolution, atmospheric CO2 levels were around 280 parts per million (ppm). Today, they have surpassed 400 ppm, well beyond the planetary boundary for maintaining climate stability.
- The rise in CO2 concentrations is largely due to human activities such as burning fossil fuels, deforestation, and industrial processes. High CO2 levels intensify the greenhouse effect, trapping more heat in the Earth's atmosphere and leading to a rise in global temperatures.
Radiative Forcing:
- Radiative forcing measures the difference between the energy the Earth receives from the Sun and the energy it radiates back into space. It is expressed in watts per square meter (W/m²).
- Radiative forcing = 1: The Earth's energy input (from the Sun) and output (radiated back into space) are in balance, meaning no net warming or cooling occurs.
- Radiative forcing > 1: More energy is entering the atmosphere than leaving, which leads to global heating. Current radiative forcing levels are estimated to be around 1.6 W/m², largely driven by rising CO2 and other greenhouse gases.
- This imbalance causes global warming and contributes to more frequent extreme weather events, rising sea levels, and other climate-related impacts.
The Role of the Global Energy Balance:
- The global climate system is highly sensitive to changes in energy balance. When radiative forcing is greater than 1, the excess energy is absorbed by the Earth's surface, oceans, and atmosphere, leading to long-term increases in global temperatures.
- This energy imbalance can lead to feedback loops, such as melting ice (which reduces albedo) and ocean heat uptake, further accelerating warming.
Climate change and planetary boundaries, inspired by Rockstrom et al. 1,2 . We use the planetary boundary 1,2 on climate change: a CO 2 concentration of 550 ppm as an objective for 2100 and a concentration of 350 ppm for 2100. The temperature-limited scenario, based on Copenhagen conference, complies with this planetary boundary. The " 2010 " scenario uses as initial point the baseline scenario in 2010. The " 2025 " and " 2035 " scenarios starts respectively in 2025 and in 2035 using the baseline scenario as initial conditions.
Exceeding the Planetary Boundary:
- Exceeding the climate change planetary boundary poses significant risks to global stability. Crossing this boundary leads to irreversible changes to Earth's climate system, including the melting of ice sheets, shifts in ocean circulation, and severe impacts on ecosystems and human societies.
- The goal set by the Paris Agreement is to limit warming to well below 2°C, with efforts to limit the temperature increase to 1.5°C. This is critical to avoid triggering tipping points and maintaining the Earth's climate within a stable boundary.
Published evidence from key scientific reports Here are examples of published evidence supporting these assertions:
Atmospheric CO2 Concentrations and Climate Change
- Evidence from the IPCC (Intergovernmental Panel on Climate Change): The IPCC's Sixth Assessment Report (2021) provides comprehensive evidence on the impact of rising CO2 concentrations. It reports that CO2 concentrations have reached levels not seen in at least 2 million years, with current levels exceeding 400 ppm. The IPCC asserts that human activities are unequivocally responsible for this increase, primarily through fossil fuel combustion and deforestation.
- Key Findings:
- CO2 concentrations have increased by 48% since pre-industrial times, largely due to human activities.
- This rise in CO2 has been directly linked to global temperature increases, with observed warming of approximately 1.1°C since the late 19th century.
- The report warns that unless CO2 emissions are reduced rapidly, global temperatures could exceed 2°C by the end of the century, crossing critical planetary boundaries and leading to potentially catastrophic impacts.
- Source: IPCC, 2021. Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
- Key Findings:
Radiative Forcing and Global Warming
- Evidence from NASA and NOAA (National Oceanic and Atmospheric Administration): Both NASA and NOAA regularly monitor and report on the Earth's radiative forcing. According to their reports, radiative forcing has increased significantly over the last century due to the accumulation of greenhouse gases, with CO2, methane (CH4), and nitrous oxide (N2O) being the main contributors. NASA estimates that current radiative forcing from CO2 alone is approximately 1.68 W/m².
- Key Findings:
- As of recent measurements, radiative forcing is about 2.3 W/m², including all greenhouse gases. This indicates that more energy is being trapped by Earth's atmosphere than is being emitted, leading to continuous warming.
- Climate models predict that if radiative forcing continues to rise at current rates, we will see an additional 0.5°C–1°C of warming by mid-century.
- The increase in radiative forcing correlates with an increase in heat content within the oceans, which act as a buffer but are also warming, contributing to sea-level rise and more extreme weather patterns.
- Source: NASA Global Climate Change – Vital Signs of the Planet: https://climate.nasa.gov
- Key Findings:
Activity Research published scientific evidence from sources like the IPCC reports, Our World In Data, or NASA that suggests the Earth has already passed the planetary boundary for climate change.
- Write a report summarizing key findings, including:
- Evidence of rising CO2 levels and their impact on climate.
- Global temperature trends exceeding safe limits (e.g., 1.5°C or 2°C).
- Changes in ice sheets, sea levels, and extreme weather patterns.
- Include charts or graphs to support your evidence, highlighting how recent data shows that we have exceeded the planetary boundary for CO2 concentrations and radiative forcing.
- How reliable is the evidence that we’ve already passed the planetary boundary? What are the most convincing pieces of data?
- What are the immediate and long-term consequences of exceeding this boundary?
6.2.9 Perspectives on climate change for both individuals and societies are influenced by many factors.
- Outline how political ideologies influence a society’s response to climate change.
- Explain differences in perspectives between developed and developing nations.
- Describe how personal experiences with climate change shape individual actions.
- List two factors that influence individual perspectives on climate change.
Perspectives on climate change vary greatly depending on individual, societal, and global contexts. These perspectives influence how societies and individuals respond to climate change, shaping policies, actions, and levels of engagement. Factors such as economic development, cultural values, political ideologies, education, and geography all play significant roles in determining how climate change is perceived and addressed.
Societal Perspectives:
- Developed Nations: Focus on mitigation through technology and policy, but economic and political concerns can slow action. For example, the U.S. faces debates about jobs in fossil fuel industries versus transitioning to renewable energy.
- Developing Nations: Emphasize adaptation due to more immediate impacts (e.g., droughts, flooding) and often demand climate justice since they contribute less to global emissions. Many argue wealthier countries should bear more responsibility for mitigation.
- Global North vs. Global South: The Global South is more vulnerable and advocates for financial assistance from the Global North, which has greater resources but is often slower to act due to political and economic priorities.
- Indigenous Communities: Often emphasize stewardship and traditional ecological knowledge. Many are highly vulnerable, such as Inuit communities in the Arctic facing rapid sea ice loss.
- Political Ideologies: Responses vary by political systems. Liberal democracies often face fragmented policies due to opposition, while authoritarian regimes may enforce top-down strategies. For example, Germany has ambitious policies, while China balances emissions cuts with coal use for economic growth.
. Individual Perspectives:
- Economic Concerns: Individuals in industries like coal or oil may resist climate policies that threaten their jobs. For example, many U.S. workers in fossil fuel regions oppose green policies for economic reasons.
- Education and Awareness: Higher education levels tend to correlate with greater awareness of climate issues and support for action. In Europe, higher climate literacy has led to widespread public backing for climate policies.
- Geography: Those living in regions directly impacted by climate change, such as coastal cities experiencing sea-level rise, may support stronger action compared to those less affected.
- Political Beliefs: Progressives often view climate change as an urgent issue requiring government intervention, while conservatives may prioritize economic growth and express skepticism about the need for regulation.
- Ethical and Moral Values: Younger generations and environmental activists, like those in Fridays for Future, see climate change as a moral issue and advocate for urgent action to protect future generations.
Societal Resilience and Response:
- Societies' resilience to climate change depends on economic stability, governance, and access to technology and education. Trust in institutions and social cohesion can also shape responses, with more cohesive societies better able to implement climate policies.
hl only
This unit is a minimum of 4 HL hours.
6.2.10 Data collected over time by weather stations, observatories, radar and satellites provides opportunity for the study of climate change and land-use change. Long-term data sets include the recording of temperature and greenhouse gas (GHG) concentrations. Measurements can be both indirect (proxies) and direct. Indirect measurements include isotope measurements taken from ice cores, dendrochronology and pollen taken from peat cores.
- Define direct and indirect climate measurements, providing one example of each.
- Explain how proxy data from ice cores is used to study past climate conditions.
- Describe the role of direct measurements in validating climate models.
- Outline how satellite data contributes to understanding land-use change.
Climate models are complex computer simulations used to predict how the Earth’s climate will change over time. They are based on physical laws (e.g., conservation of energy) and are designed to simulate the interactions between different components of the Earth’s system—such as the atmosphere, oceans, land, and ice.
Long-term climate data provides essential insight into how the Earth’s climate has changed over time. Weather station data gives us detailed records of temperature and precipitation for the past century, while satellite data provides more recent, highly accurate measurements of global temperature, sea levels, and ice cover.
Paleoclimate records, such as ice cores and sediment layers, give scientists a much longer view, allowing them to study natural climate variability over hundreds of thousands of years.
Paleoclimate records, such as ice cores and sediment layers, give scientists a much longer view, allowing them to study natural climate variability over hundreds of thousands of years.
Role in Climate Models:
- Direct measurements validate short-term climate predictions, while indirect (proxy) data provide long-term climate records, extending back thousands of years. This combination is critical for modeling historical climate trends and making future predictions.
Types of Measurements:
- Direct Measurements:
- Real-time data from weather stations, satellites, and observatories that measure temperature, GHG levels (e.g., CO2 at Mauna Loa Observatory), and other atmospheric parameters.
- Indirect Measurements (Proxies):
- Ice cores: Preserve ancient air bubbles, showing past CO2 levels and temperatures.
- Dendrochronology: Tree rings reveal past climate conditions (e.g., growth patterns in warm or cool years).
- Pollen in peat cores: Provides clues about historical vegetation and climate conditions.
- Isotope analysis: Measures isotopic ratios to infer past temperatures and atmospheric conditions.
Applications of Long-Term Data:
- Studying Climate Change: Data from weather stations and proxies reveal trends like rising temperatures and increased GHG levels, confirming unprecedented modern warming.
- Land-Use Change: Satellite data tracks changes like deforestation and urban expansion, showing their impact on climate and ecosystems.
Activity: Use an online climate modeling tool (e.g., EdGCM or Simple Climate Model from NASA) to explore two simple models. Simulate long-term climate changes by inputting different levels of CO2 concentrations and solar radiation.
- After running the simulations, create graphs showing the predicted global temperature and sea level rise for the next 100 years.
- Compare these predictions with historical trends and discuss the potential accuracy of these models in predicting future climate changes.
- What trends are most pronounced in the simulations (e.g., rapid temperature rise, sharp sea-level increases)? How do they compare with historical data?
- How do different variables (e.g., CO2 concentrations, changes in solar radiation) influence the predictions made by the models?
6.2.11 Global climate models manipulate inputs to climate systems to predict possible outputs or outcomes using equations to represent the processes and interactions that drive the Earth’s climate. The validity of the models can be tested via a process known as hindcasting.
- Define hindcasting in the context of climate modeling.
- Explain how hindcasting is used to validate climate models.
- Describe one challenge in using global climate models to predict future climate changes.
Global climate models (GCMs) use mathematical equations to simulate the Earth's climate by processing inputs like solar radiation, GHG concentrations, and land-use changes. These models predict future climate outcomes by representing interactions between the atmosphere, oceans, and land.
How climate models work:
- GCMs divide the Earth into a grid and calculate changes in variables like temperature, humidity, and wind. Models use observational data (both direct and indirect) to simulate past climates and forecast future changes.
Uncertainty in Climate Models:
- Uncertainty arises from factors such as:
- Inputs: Variability in future emissions and land-use changes.
- Proxy data: Indirect measurements (like ice cores) can introduce uncertainty.
- Natural variability: Events like volcanic eruptions or solar activity are hard to predict.
- Feedback loops: Complex processes like ice-albedo or permafrost thawing are difficult to model accurately.
Hindcasting and Model Validation:
- Hindcasting is a crucial method for testing the accuracy of climate models. It involves running the model backward from the present time to simulate past climate conditions and comparing the model’s predictions to actual historical data. If the model can accurately reproduce known climate events from the past (e.g., past temperature trends, glacial periods), it increases confidence in the model’s ability to predict future outcomes.
- For example, if a climate model successfully hindcasts the observed temperature rise of the 20th century, it is likely to provide reliable predictions for future climate scenarios.
- Improving models with hindcasting: Hindcasting not only checks the validity of a model but also helps scientists refine their models by identifying areas where the model may be inaccurate or where assumptions need to be adjusted. This process allows for the continuous improvement of climate forecasts.
Range of Possible Outcomes:
- Because of the uncertainties in both inputs and internal processes, climate models produce a range of possible future outcomes rather than a single definitive prediction. The model outputs often present a range of temperature increases, sea-level rise estimates, or changes in precipitation patterns under different emission scenarios (e.g., high emissions vs. low emissions scenarios). This range reflects the complexities and uncertainties involved in predicting climate change.
Activity: Using a simple climate modeling tool or online resource, try to replicate a hindcasting experiment. Select a historical time period (e.g., 1950–2000) and compare the model’s predictions with actual data (e.g., global temperatures, CO2 levels).
- Create a graph or chart comparing the model’s predictions with the real-world data from the same period.
- How well did the model’s predictions match the actual data? What discrepancies did you notice, and what might have caused them?
- How does hindcasting increase confidence in a climate model’s ability to predict future conditions?
6.2.12 Climate models use different scenarios to predict possible impacts of climate change.
- Define what climate scenarios are and explain their role in climate modeling.
- Outline the differences between high and low-emissions scenarios in terms of sea-level rise.
- Describe how changes in precipitation patterns might affect different regions under high-emissions scenarios.
- Explain why policymakers use climate scenarios to plan for future impacts.
Climate models use a variety of scenarios to explore how different levels of greenhouse gas (GHG) emissions and other factors may affect the Earth’s climate in the future. These scenarios help scientists predict potential outcomes for temperature, precipitation patterns, sea-level rise, and extreme weather events.
Climate Scenarios:
Scenarios are based on assumptions about future emissions, land use, population growth, and energy consumption. The most widely used scenarios come from the IPCC and are known as Representative Concentration Pathways (RCPs) or Shared Socioeconomic Pathways (SSPs):
Scenarios are based on assumptions about future emissions, land use, population growth, and energy consumption. The most widely used scenarios come from the IPCC and are known as Representative Concentration Pathways (RCPs) or Shared Socioeconomic Pathways (SSPs):
- RCP 2.6: A low-emissions scenario that assumes immediate, aggressive action to reduce greenhouse gas emissions, aiming to limit global warming to below 2°C.
- RCP 4.5: A moderate emissions scenario where some mitigation efforts are implemented, leading to a medium level of warming.
- RCP 8.5: A high-emissions scenario where little is done to curb emissions, leading to severe climate impacts and significant warming above 4°C by 2100.
Potential Climate Impacts:
- Sea-Level Rise:
- Different scenarios predict varying levels of sea-level rise depending on the rate of ice melt and thermal expansion of seawater. Under RCP 8.5, sea levels could rise by over 1 meter by 2100, threatening coastal cities and low-lying areas.
- RCP 2.6 predicts a lower rise, around 0.3–0.6 meters, but still poses risks for coastal ecosystems and infrastructure.
- Temperature Changes:
- Climate models predict global temperature increases under all emissions scenarios, with the amount of warming depending on the level of mitigation efforts.
- RCP 8.5 suggests a potential rise of over 4°C by 2100, leading to more frequent heatwaves, while RCP 2.6 limits the rise to around 1.5–2°C, which would still have significant but more manageable impacts.
- Precipitation Patterns:
- Models also predict changes in precipitation patterns, with some regions becoming wetter and others drier.
- Under high-emissions scenarios, areas like the Mediterranean and parts of the U.S. Southwest could experience more severe droughts, while regions like Northern Europe and parts of Asia could see increased flooding due to heavier rainfall.
Using Scenarios in Climate Planning:
- Policymakers use climate scenarios to assess the risks of future climate impacts and plan for adaptation. For example, scenarios predicting sea-level rise inform coastal protection strategies, while temperature predictions help cities prepare for heatwaves and manage water resources.
Activity: Choose an RCP scenario (e.g., RCP 2.6, RCP 4.5, or RCP 8.5) from the IPCC reports.
- Research the predicted outcomes of that scenario for the following:
- Global temperature rise
- Sea-level rise
- Changes in precipitation patterns (e.g., droughts, floods, regional rainfall changes)
- Create a poster summarizing these impacts visually and include:
- A world map highlighting regions most affected by each factor.
- Graphs or charts showing the predicted temperature and sea-level rise by 2100.
- Key bullet points explaining the potential consequences of the scenario.
- Present your poster to the class. How does your chosen RCP compare to others in terms of predicted impacts?
- What regions of the world are likely to experience the most significant changes?
- Add a section to your poster proposing mitigation or adaptation strategies that could help reduce the impacts of the scenario.
6.2.13 Climate models show the Earth may approach a critical threshold with changes to a new equilibrium. Local systems also have thresholds or tipping points.
- Define a tipping point in climate systems and describe how feedback loops contribute.
- Explain the impact of the Antarctic ice sheet reaching a tipping point.
- Outline the effects of a slowdown in the Atlantic thermohaline circulation on climate.
Climate models show that Earth's systems may reach critical thresholds or tipping points, where small changes trigger rapid, often irreversible shifts in the climate system, leading to a new equilibrium. These tipping points, often driven by positive feedback loops, can result in global or local catastrophic changes.
Tipping Points and Positive Feedback Loops:
Tipping Points and Positive Feedback Loops:
- Positive feedback loops amplify changes. For example, melting ice reduces Earth's albedo (reflectivity), leading to further warming and more ice melt, pushing the system past a tipping point.
Examples of Critical Thresholds:
- Melting of the Antarctic Ice Sheets:
- As Antarctic ice melts, warm ocean waters speed up ice loss, potentially causing a tipping point where the ice sheet’s collapse becomes irreversible.
- Impact: This could raise global sea levels by over 1 meter, severely affecting coastal cities and ecosystems.
- Slowing of the Atlantic Thermohaline Circulation (THC):
- Thermohaline circulation distributes heat globally. If it slows, major climate shifts could occur, especially in Europe and North America.
- Impact: Colder winters in Northern Europe, disrupted marine ecosystems, and shifts in global weather patterns.
- Amazon Rainforest–Cerrado Transition (CAT):
- The Amazon is nearing a tipping point where deforestation and warming could turn much of it into a savanna. This would reduce rainfall, accelerate fires, and further deforestation.
- Impact: Major biodiversity loss and the release of vast amounts of carbon dioxide, accelerating global warming.
Our global warming threshold estimates for global ‘core’ and regional ‘impact’ climate tipping elements (a) relative to likely future scenarios given current policies and targets. Bars show the minimum (base, yellow), central (line, red), and maximum (top, dark red) threshold estimates for each tipping element (bold font, global core; regular font, regional impact), with a palaeorecord of Global Mean Surface Temperature (GMST) over the past ~25ky, projections of future climate change (green, SSP1-1.9; yellow, SSP1-2.6; orange, SSP2-4.5; red, SSP3-7.0; purple, SSP5-8.5) from IPCC AR6, the estimated 21st century warming trajectories for current policies (grey horizontal lines shows central estimate, bar height the uncertainty range) as of November 2021, and the Paris Agreement range of 1.5-<2°C (green horizontal lines and shading) shown for context. Adaptation of Figure 2a from Armstrong McKay et al. (2022).
Global and Local Thresholds:
Unanticipated Changes:
- Global tipping points (e.g., ice sheet collapse, THC slowdown) can cause widespread impacts, while local tipping points (e.g., coral reef loss) can disrupt regional ecosystems and economies.
Unanticipated Changes:
- Tipping points can lead to rapid, unexpected changes in climate, which are difficult to reverse once crossed, potentially leading to catastrophic outcomes.
Activity: Research a tipping point in the climate system (e.g., Antarctic ice sheet melt, thermohaline circulation slowdown, Amazon Rainforest dieback).
- Create a timeline that outlines the sequence of events leading to and following the crossing of the tipping point.
- Include the initial conditions (e.g., gradual warming or increased greenhouse gas levels).
- Detail what happens once the tipping point is crossed (e.g., rapid ice melt, disruption of ocean currents, ecosystem collapse).
- Highlight the long-term effects on global or regional climates, ecosystems, and human societies.
- After creating a timeline for a specific tipping point, research whether it could trigger other tipping points (e.g., the melting of the Antarctic ice sheets affecting global sea levels and disrupting thermohaline circulation).
- Why are tipping points so dangerous for the climate system?
- How do positive feedback loops accelerate the process after a tipping point is crossed?
- What can be done to prevent or delay these tipping points?
6.2.14 Individual tipping points of the climate system may interact to create tipping cascades.
- Define what a tipping cascade is and explain how it increases uncertainty in climate predictions.
- Outline the difference between biotic and abiotic tipping points with examples.
- Explain how the interaction between two tipping points can accelerate climate change.
Tipping points are critical thresholds where small changes can cause large, often irreversible shifts in the climate system. When multiple tipping points interact, they can trigger a tipping cascade, where one tipping point accelerates the crossing of others, creating more rapid and unpredictable changes.
Tipping Cascades:
Biotic and Abiotic Tipping Points:
Uncertainty in Climate Predictions:
Tipping Cascades:
- Tipping cascades occur when the crossing of one tipping point increases the likelihood or speed of crossing others. For example, the melting of polar ice can increase global temperatures, accelerating the Amazon Rainforest dieback, which releases more carbon, further warming the planet.
- The interaction between multiple tipping points makes it difficult to predict the exact scale and pace of climate change, increasing uncertainty in climate models.
Biotic and Abiotic Tipping Points:
- Biotic tipping points involve living systems, such as the collapse of forests or the death of coral reefs, which can lead to major ecological changes and feedback loops.
- Abiotic tipping points involve non-living systems, such as ice sheet melting or ocean circulation changes, which can drastically affect global climates.
- Combination tipping points: Some tipping points involve both biotic and abiotic factors. For example, as the permafrost thaws (abiotic), it releases methane (a biotic factor), which accelerates warming and leads to more permafrost thawing.
Uncertainty in Climate Predictions:
- The interaction of multiple tipping points creates complex feedback loops, making it hard to predict how fast or how severely the climate will change. These uncertainties complicate climate models, as tipping points often trigger unexpected domino effects.
Activity: Investigating tipping pointsUsing one or more of the sources below, choose 1–2 systems that scientists are concerned about and research some key facts about them.
- What is the system and what role does it play in the global climate?
- What is causing this system to approach a tipping point?
- What are some potential impacts of passing the tipping points you investigated?
6.2.15 Countries vary in their responsibility for climate change and also in vulnerability, with the least responsible often being the most vulnerable. There are political and economic implications and issues of equity.
- Define climate justice and explain its importance in the context of global climate change.
- Describe the differences in responsibility for climate change between developed and developing nations.
- Explain why some of the least responsible countries are the most vulnerable to climate change.
- Outline the political and economic implications of differing emissions and vulnerability levels among nations.
Countries vary in their responsibility for causing climate change and their vulnerability to its impacts. Often, those least responsible for emissions are the most vulnerable to the negative effects of climate change, raising concerns about climate justice.
Responsibility for Climate Change:
Responsibility for Climate Change:
- Current emissions: Developed nations like the U.S., China, and EU countries contribute the largest share of global greenhouse gas (GHG) emissions today, due to industrial activities, energy consumption, and transportation.
- Cumulative emissions: Since the Industrial Revolution, developed countries have emitted the majority of CO2. For example, the U.S. and European countries have been major historical emitters, contributing significantly to global warming.
- Per capita emissions: Countries with higher standards of living, such as Australia, Qatar, and the U.S., have much higher per capita emissions compared to developing countries.
High income countries like the USA and EU-27 have been able to reduce their territory-based carbon dioxide emissions in part because factory production of many goods they buy and use occurs elsewhere in the world,
Vulnerability to Climate Change:
- Least responsible, most vulnerable: Many of the countries most vulnerable to climate change, like Bangladesh, Pacific island nations, and parts of Sub-Saharan Africa, have contributed very little to global emissions. These nations face significant threats from rising sea levels, extreme weather, and food and water insecurity.
- Developed vs. developing nations: While developed nations have more resources to adapt to climate impacts (e.g., building sea walls, upgrading infrastructure), developing nations often lack the financial and technological capacity to protect themselves from these changes, leaving them disproportionately exposed.
Climate Justice and Equity:
- Climate justice addresses the inequities between countries that have historically benefited from industrialization (and contributed to emissions) and those that suffer most from the consequences. This includes the need for financial support from developed nations to help vulnerable countries adapt to climate change.
- Political and economic implications: The global debate centers around who should pay for climate adaptation and mitigation. Developing countries argue that wealthy nations should take greater responsibility in funding global climate action and reducing emissions, as they have contributed the most to the problem.
Activity: Visit the Our World In Data website and review the data in the section Who Emits the Most CO2
- Use the Our World In Data website to compare the CO2 emissions of developed countries (e.g., U.S., Germany) and developing countries (e.g., India, Brazil).
- Write a report comparing emissions trends, including the reasons for the differences between developed and developing countries.
- What are the key drivers of CO2 emissions in developed versus developing countries? Consider industrial activities, energy use, and transportation.
- How do emission patterns reflect differences in economic development, population growth, and energy sources?
- Propose strategies that both developed and developing countries could use to reduce their CO2 emissions. How would these strategies differ based on each country's economic context?
Key Terms
Ice cores
Tree rings (dendrochronology) Sediment deposits CO2 concentration Glacial cycles Proxy data Biome shifts HL ONLY Tipping points Tipping cascades Climate justice Political implications Economic implications Equity Antarctic ice sheets Thermohaline circulation Amazon Rainforest-Cerrado transition |
Greenhouse gases (GHGs)
Methane (CH4) Nitrous oxide (N2O) Greenhouse effect Carbon dioxide (CO2) Atmospheric composition Climate policy Climate responsibility |
Ice-albedo effect
Permafrost thawing Carbon sinks Methane release Amplification Planetary boundaries Vulnerability Adaptation |
CO2 concentration
Radiative forcing Global energy balance Climate threshold Climate resilience Societal perspectives Emission rates |
Classroom Materials
Subtopic 6.2 Climate Change - Causes and Impacts Presentation.pptx | |
File Size: | 9966 kb |
File Type: | pptx |
Subtopic 6.2 Climate Change—Causes and Impacts Workbook.docx | |
File Size: | 5084 kb |
File Type: | docx |
Climate Feedback Loops
Global Warming Reading
Rising Temps Case Study
Review Common Misconceptions
Climate and Malaria
As Rising Heat Bakes U.S. Cities, The Poor Often Feel It Most article
Global Warming and Agriculture article
Climate Change Data Analysis activity
Climate Change Data Analysis graphs
Global Warming PHET simulation
Global Warming and Hurricanes Data Analysis Activity
Case Studies
- Two detailed examples of the impacts of climate change (whether beneficial/adverse) in different countries, including: changes in water availability, distribution of biomes and crop growing areas, loss of biodiversity and ecosystem services, coastal inundation, ocean acidification, spread of tropical disease, and damage to human health.
- Two detailed examples of contrasting viewpoints on climate change, namely Al Gore, The Stern Report
Correct use of terminology is a key skill in ESS. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
Useful Links
Greenhouse effect - Sumanis
Factors Affecting Global Climate - Nature
Four ways to look at global carbon footprints - an infographic from National Geographic magazine
Common questions about climate change from the United Nations Environment Program (1997)
The Issue of Global warming - This is the above UNEP site converted to a MS Word document for offline viewing.
How reliable are CO2 measurements? - Skeptical Science
Review on the Economics of Climate Change - BBC News
Feedback Effects - BBC News
Climate Change Around The World - BBC
UN Framework Convention on Climate Change - UN
Global Warming Effects Simulation - National Geographic
Investigating carbon offsets - Carbon Footprint
Investigating carbon offsets - Environmental Research WEb
Understanding Global Dimming - NOVA
Global Warming - Take Part
Cause and Effect of Global Warming - S-Cool
Climate Tipping Point Info
In The News
Unequal Impact: The Deep Links Between Racism and Climate Change - BBC, June 2020
Young people are suing governments over climate change - Gold Coast Bulletin, March 2016
Scientists develop CO2 sequestration technique that produces ‘supergreen’ hydrogen fuel - Maybe a way to fulfill growing energy needs and combat global warming at the same time? from LabManager.com
Massive Antarctic Glacier Uncontrollably Retreating, Study Suggests - LiveScience Jan 2014
Acidic oceans dissolving shells of marine organisms - The Register 26 November 2012
Carbon Trading Causes Increase in Greenhouse Gas Emissions - New York Times 8 August 2012.
Scientists Concerned About Effects of Global Warming on Infectious Diseases - Science Daily, 22 May 2007
Polar Ice Loss Quickens, Raising Seas - BBC Science and Environment News 9 March 2011
Penguin and Krill Populations Decline due to Climate Change - Discovery News 11 April 2011
Global carbon emissions reach record, says IEA - BBC Science and Environment News 30 May 2011.
Species flee warming faster than previously thought - BBC Science and Environment News 20 August 2011
Why the warming climate makes animals smaller - New Scientist 23 September 2011
Marine life shifts as temperatures change - New Scientist 24 September 2011
Global Warming: Runaway temperature increase unlikely - Summit County Voice 25 November 2011
China report spells out “grim” climate change risks - Reuters 17 January 2012
Ocean currents and their role in global climate change - The Register 30 January 2012
Plant study flags dangers of a warming world - NewsDaily Science News 2 May 2012
This is a great article about agroforestry in the Sahel - Scientific American 28 January 2011
Indigenous people have much of the knowledge needed to adapt to climate change - Trust.org 24 April 2012
International Mindedness:
- The impacts of the climate change are global and require coordinated international action.
TOK:
- There has been considerable debate about the causes of climate change-does our interpretation of knowledge from the past allow us to reliably predict the future?
Video Clip
Global warming could do more than just melt polar ice. It could change our maps, and displace people from cities and tropical islands
A section from Caution, the 2nd movement of Energy Union. Music by The Creeper and J Dilla. Aims to bring a little clarity as many people still don't accept the reality of manmade climate change. Although no-one fully understands how Earth's climate works, it is may be useful to listen to the solid consensus of reputable scientists and filter out the opposing climate skeptics, many of whom are 'Quacks' with limited credentials and dubious motivations.
This short film/ documentary-esque video asks the contemporary ethical question of: "Given the general scientific consensus that anthropogenic (human induced) climate change is real, are we ethically obliged to take action to stop it?"
How much are human practices contributing to substantial and irreversible changes to the environment? What effect are changes to the climate having in different areas of the planet?
Controversial Danish economist Bjørn Lomborg explains why it's important to question orthodox opinion -- even the widespread fear of global warming.
The biggest problem for the climate change fight isn’t technology – it’s human psychology. Vox takes a look at efforts energy-saving companies are taking to take advantage of human psychology.
Why People Don't Believe in Climate Change