Katharine Hayhoe. Katharine Hayhoe. Texas Tech University NATIONAL RESEARCH COUNCIL

Transcription

1 Katharine Hayhoe Texas Tech University Katharine Hayhoe Texas Tech University 1

2 THE TRADITIONAL APPROACH TO EVALUATING CLIMATE CHANGE IMPACTS Emissions Concentrations Temperature Change Impacts Human choices Carbon cycle Climate sensitivity Impacts response

3 Uncertainty (1 to 12 o F at 2090) 20% scientific, 80% scenario

4 A POLICY-RELEVANT APPROACH TO EVALUATING CLIMATE CHANGE IMPACTS Temperature Change 2 o C target

5 A POLICY-RELEVANT APPROACH TO EVALUATING CLIMATE CHANGE IMPACTS Emissions Concentrations Temperature Change Impacts Carbon cycle Climate sensitivity Impacts response

6 HOW CAN WE ACTUALLY DO THAT? How can we actually do that? Emissions Concentrations Temperature Change Impacts Calculate range of atmospheric concentrations and emissions that would achieve a given global mean temperature target Normalize impacts by dividing by global mean temperature

7 SEA ICE Example: Arctic Sea Ice ARCTIC ANNUAL ICE COVER BY YEAR ANNUAL ICE COVER BY GMT -15% per degree in annual average; -25% per degree in September minimum 7

8 Wildfire in the western US (per C WILDFIRE warming) WESTERN UNITED STATES 8

9 FOOD YIELDS Decreases in yield of key food crops per degree C GLOBAL 9

10 HOT SUMMERS GLOBAL 10

11 PRECIPITATION PATTERNS Changes in future rainfall patterns GLOBAL Colored areas: more than 2/3 of models agree 11

12 STREAMFLOW Changes in US streamflow UNITED STATES 12

13 ENERGY DEMAND UNITED STATES

14 IMPACTS BY DEGREE CALIFORNIA

15 15

16 16 And there are also unquantified risks.

17 HOW CAN WE ACTUALLY DO THAT? How can we actually do that? Emissions Concentrations Temperature Change Impacts Calculate range of atmospheric concentrations and emissions that would achieve a given global mean temperature target Normalize impacts by dividing by global mean temperature

18 FROM TEMPERATURE TO CONCENTRATIONS CONCENTRATION RANGE FOR A GIVEN TEMPERATURE TARGET

19 FROM TEMPERATURE TO CONCENTRATIONS GLOBAL MEAN TEMPERATURE RANGE FOR A GIVEN CONCENTRATION

20 2.2 FROM TEMPERATURE TO CONCENTRATIONS PROBABILITY OF AVOIDING A GIVEN TEMPERATURE TARGET

21 FROM EMISSIONS TO TEMPERATURE CUMULATIVE CARBON TARGETS

22 KEY FINDINGS Scientific progress has increased our confidence in how global warming levels of 2, 3, 4, 5 C, or more would affect: Wildfire area Arctic sea ice retreat Crop yields, Streamflow Rainfall patterns Sea level rise

23 KEY FINDINGS This approach presents the latest science within a useful framework, answering questions directly relevant to: Setting a target: What would be the consequences of choosing a 2 o C vs. a 4 o C target? Achieving a target: What cumulative emissions budget would be required to achieve our chosen temperature target?

24 COMMITTEE MEMBERS Committee Members SUSAN SOLOMON (Chair), National Oceanic and Atmospheric Administration, Boulder, CO DAVID BATTISTI, University of Washington, Seattle, WA SCOTT DONEY, Woods Hole Oceanographic Institution, Woods Hole, MA KATHARINE HAYHOE, Texas Tech University, Lubbock, TX ISAAC M. HELD, Geophysical Fluid Dynamics Laboratory, Princeton, NJ DENNIS P. LETTENMAIER, University of Washington, Seattle, WA DAVID LOBELL, Stanford University, Stanford, CA DAMON MATTHEWS, Concordia University, Montreal, Quebec RAYMOND PIERREHUMBERT, University of Chicago, Chicago, IL MARILYN RAPHAEL, University of California, Los Angeles, CA RICHARD RICHELS, Electric Power Research Institute, Inc., Washington, DC TERRY L. ROOT, Stanford University, Stanford, CA KONRAD STEFFEN, University of Colorado, Boulder, CO CLAUDIA TEBALDI, Climate Central, Vancouver, British Columbia GARY W. YOHE, Wesleyan University, Middletown, CT 24