12.3 Future climate scenarios and their potential impacts

Climate scientists use Representative Concentration Pathways to model future greenhouse gas scenarios. These range from strict emission cuts to business-as-usual increases. Each pathway is linked to a specific radiative forcing value, influencing Earth's energy balance.

Climate projections based on these pathways show varying impacts on temperature, precipitation, and sea levels. Higher emission scenarios predict more extreme changes, affecting ecosystems, agriculture, and human health. Scientists emphasize the need for both mitigation and adaptation strategies to address these challenges.

Representative Concentration Pathways and Climate Projections

Representative Concentration Pathways scenarios

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Top images from around the web for Representative Concentration Pathways scenarios

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  Increasingly severe consequences of climate change (GMT 9) — European Environment Agency View original

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  How to mitigate climate change: Key facts from the U.N.'s 2014 report - Journalist's Resource View original

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  Increasingly severe consequences of climate change (GMT 9) — European Environment Agency View original

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  How to mitigate climate change: Key facts from the U.N.'s 2014 report - Journalist's Resource View original

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• Scenarios describing possible future concentrations of greenhouse gases, aerosols, and other climate drivers
  • RCP2.6: Stringent mitigation scenario with emissions peaking around 2020 then declining
  • RCP4.5: Intermediate scenario with emissions peaking around 2040 then declining
  • RCP6.0: Another intermediate scenario with emissions peaking around 2080 then declining
  • RCP8.5: High-emission scenario with emissions continuing to rise throughout the 21st century (business-as-usual)
• Each RCP associated with a specific radiative forcing value in W/m^2 by 2100
  • Radiative forcing: difference between solar energy absorbed by Earth and energy radiated back to space
• RCPs used as input for climate models to project future climate change under different emission scenarios
  • Climate models: mathematical representations of Earth's climate system used to simulate and predict climate behavior (general circulation models, Earth system models)

Projections under RCP scenarios

• Temperature projections:
  • RCP2.6: global average temperature projected to rise by 0.3℃ to 1.7℃ by 2100 compared to 1986-2005
  • RCP8.5: global average temperature projected to rise by 2.6℃ to 4.8℃ by 2100 compared to 1986-2005
• Precipitation projections:
  • Wet regions projected to become wetter and dry regions projected to become drier (intensification of water cycle)
  • Increased intensity and frequency of extreme precipitation events projected under higher emission scenarios (floods, droughts)
• Sea level projections:
  • RCP2.6: global mean sea level projected to rise by 0.26 to 0.55 m by 2100 compared to 1986-2005
  • RCP8.5: global mean sea level projected to rise by 0.45 to 0.82 m by 2100 compared to 1986-2005
  • Sea level rise will not be uniform across regions with some areas experiencing higher increases than others (coastal flooding, erosion)

Impacts and Responses to Future Climate Change

Climate change impacts on systems

• Ecosystems:
  • Shifts in species distribution and phenology due to changes in temperature and precipitation patterns (migration, earlier spring events)
  • Increased risk of extinction for species unable to adapt or migrate (coral reefs, polar bears)
  • Alterations in ecosystem structure and function such as changes in productivity and nutrient cycling (carbon storage, water filtration)
• Agriculture:
  • Changes in crop yields and distribution due to altered temperature and precipitation patterns (longer growing seasons in high-latitudes, reduced yields in low-latitudes)
  • Increased risk of crop failures and reduced food security in some regions (droughts, pests)
  • Potential benefits for some crops in high-latitude regions due to longer growing seasons (wheat, potatoes)
• Human health:
  • Increased heat-related mortality and morbidity particularly in urban areas (heat waves, urban heat islands)
  • Spread of vector-borne diseases into new areas as temperature and precipitation patterns change (malaria, dengue fever)
  • Reduced air quality and increased respiratory health problems due to higher levels of air pollutants and allergens (ozone, pollen)

Mitigation and adaptation strategies

• Mitigation strategies aim to reduce greenhouse gas emissions and limit the magnitude of future climate change
  1. Transitioning to low-carbon energy sources such as renewable energy (solar, wind) and nuclear power
  2. Improving energy efficiency in buildings, transportation, and industry (insulation, fuel-efficient vehicles)
  3. Implementing carbon pricing mechanisms such as carbon taxes or cap-and-trade systems
• Adaptation strategies aim to reduce the vulnerability of natural and human systems to the impacts of climate change
  1. Developing drought-resistant crops (sorghum, millet) and improving water management practices in agriculture (drip irrigation, rainwater harvesting)
  2. Strengthening infrastructure and building resilience to extreme weather events in urban areas (sea walls, green roofs)
  3. Establishing early warning systems and emergency response plans for climate-related hazards (hurricanes, wildfires)
• Mitigation and adaptation strategies are both essential for reducing the risks and impacts of future climate change
  • Mitigation efforts can help limit the magnitude of future climate change reducing the need for adaptation
  • Adaptation measures are necessary to cope with the impacts of climate change that are already occurring or are unavoidable (sea level rise, extreme weather events)