Assembled by Brenda Ekwurzel Slides for Communicating IPCC IPCC Working Group I Summary For Policymakers: The Physical Science Basis Assembled by Brenda Ekwurzel March 2, 2007 www.ucsusa.org

Global and Minnesota Climate Drivers What are the Risks? Opportunities Observed Impacts: Global and Minnesota Why: Climate Drivers Future Impacts: What are the Risks? Future Choices: Opportunities

Projected climate change for the second half of this century depends on the level of future heat-trapping emissions. NASA Photos.com vs Photos.com www.pca.state.mn.us/cleanup/landfills.html Associated Press Union of Concerned Scientists

Global Average Surface Temperature Change relative to 1980-1999 Minnesota is in a region at risk for large consequences from a higher emissions scenario. Future Risks A2 IPCC scenario averaged over 2090–2099 “Warming is expected to be greatest over land and at most high northern latitudes, and least over the Southern [formerly Antarctic] Ocean and parts of the North Atlantic Ocean.” Projected surface temperature changes for the early and late 21st century relative to the period 1980–1999. The panel shows the IPCC Atmosphere-Ocean General Circulation multi-Model average projections for the A2 emissions scenario averaged over decades 2090–2099. The IPCC A2 scenario has continuously increasing population reliant on fossil fuels. Economic development is primarily regionally oriented and per capita economic growth and technological change more fragmented and slower than other storylines. Global Average Surface Temperature Change relative to 1980-1999 °C 1°F 13.5°F Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.

Global Average Surface Temperature Change relative to 1980-1999 Minnesota can avoid experiencing even the lowest emissions scenario projections of the IPCC if the world follows deep reductions targets. Future Risks B1 IPCC scenario averaged over 2090–2099 The panel shows the IPCC Atmosphere-Ocean General Circulation multi-Model average projections for the B1 emissions scenario averaged over decades 2090–2099. The lowest scenario the IPPC chose to evaluate, the “B1” scenario, assumes a mid-century peak in global population, a rapid change toward a service and information economy, and a shift from fossil fuel intensive resources toward clean and resource-efficient technologies. Global Average Surface Temperature Change relative to 1980-1999 °C 1°F 13.5°F Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.

While annual average precipitation levels are unlikely to change, the seasonal distribution is likely to, increasing in winter and decreasing in summer. In all lakes, the duration of summer stratification will increase, adding to the risk of oxygen depletion and formation of deep-water “dead zones” for fish and other organisms.

Global and Minnesota Climate Drivers What are the Risks? Opportunities Observed Impacts: Global and Minnesota Why: Climate Drivers Future Impacts: What are the Risks? We use Minnesota as an example to make this presentation more relevant to local audiences. Please modify as appropriate for your local audiences. Future Choices: Opportunities

Global and Minnesota Climate Drivers What are the Risks? Opportunities Observed Impacts: Global and Minnesota Why?: Climate Drivers Future Impacts: What are the Risks? Future Choices: Opportunities

Great Lakes Region Annual average temperatures are growing warmer. NOAA Winters are getting shorter. The duration of lake ice cover is decreasing as air and water temperatures rise. David Saville, FEMA News Growing evidence suggests that the climate of the Great Lakes region is already changing. Heavy precipitation events, both rain and snow, are becoming more common. Source: Confronting Climate Change in the Great Lakes Region 2005 (UCS and ESA) http://www.ucsusa.org/greatlakes/

Global and Minnesota Climate Drivers What are the Risks? Opportunities Observed Impacts: Global and Minnesota Why: Climate Drivers Future Impacts: What are the Risks? Future Choices: Opportunities

Changes in Heat-trapping Gases from Ice-Core and Modern Data Atmospheric concentrations of carbon dioxide over the last 10,000 years (large panel) and since 1750 (inset panel). Measurements are shown from ice cores (symbols with different colors for different studies) and atmospheric samples (red lines). Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.

Emissions Since the dawn of the industrial era, carbon dioxide and other key heat-trapping gases have increased at a rate that is “very likely to have been unprecedented in more than 10,000 years.” CO2 www.pca.state.mn.us/cleanup/landfills.html CH4 Since the dawn of the industrial age human activities have contributed major heat-trapping gases to the atmosphere. www.epa.gov/nitrousoxide/sources.html N2O Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.

Global Average Surface Temperature The black line represents observed surface temperature changes for the globe (based on temperatures recorded by measuring stations around the world). The blue band represents how the climate would have evolved over the past century in response to natural factors only (according to 19 computer simulations derived from five different climate models); the brown band represents how the climate would have changed in response to both human and natural factors (according to 58 computer simulations derived from 14 different climate models). The overlap of the brown band and black line suggests that human activity very likely caused most of the observed increase since the mid-20th century. Temperature change is plotted relative to the corresponding average for the 1901 to 1950 time period. Source: Climate Change 2007: The Physical Science Basis—Summary for Policymakers. Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.

Human Responsibility for Climate Change The IPCC finds that it is “very likely” that emissions of heat-trapping gases from human activities have caused “most of the observed increase in globally averaged temperatures since the mid-20th century.” Evidence that human activities are the major cause of recent climate change is even stronger than in prior assessments. Source: IPCC Climate Change 2007: The Physical Science Basis—Summary for Policymakers.