The Science of Climate Change: The Global Picture

The Science of Climate Change:The Global Picture p. 1/24 The Science of Climate Change: The Global Picture Adam Monahan monahana@uvic.ca School of Earth and Ocean Sciences University of Victoria

The Science of Climate Change:The Global Picture p. 2/24 Outline Why do we think the climate is changing?

The Science of Climate Change:The Global Picture p. 2/24 Outline Why do we think the climate is changing? How can we predict future climate changes?

The Science of Climate Change:The Global Picture p. 2/24 Outline Why do we think the climate is changing? How can we predict future climate changes? Where do we think the climate is going?

The Science of Climate Change:The Global Picture p. 3/24 The Greenhouse Effect Figure source: UCAR

Past Climate Changes The Science of Climate Change:The Global Picture p. 4/24

The Science of Climate Change:The Global Picture p. 5/24 The Last Millennium: Temperature Source: IPCC Third Assessment Report

The Science of Climate Change:The Global Picture p. 6/24 The Last Millennium: CO 2 Source: IPCC Third Assessment Report

The Science of Climate Change:The Global Picture p. 7/24 The Recent Past: Temperature Source: IPCC Third Assessment Report

The Recent Past: CO 2 The Science of Climate Change:The Global Picture p. 8/24

The Science of Climate Change:The Global Picture p. 9/24 Recent Wintertime Temperature Trends Source: IPCC Third Assessment Report Warmest Years on Record 1. 1998 2. 2003 3. 2002 4. 2001 5. 1997 6. 1995 7. 1990 8. 1999 9. 2000 10. 1991

What Causes Sea Level Changes? The Science of Climate Change:The Global Picture p. 10/24

Past Sea Level Changes The Science of Climate Change:The Global Picture p. 11/24

The Science of Climate Change:The Global Picture p. 12/24 What is the Climate System? Source: IPCC Third Assessment Report

Modelling the Climate System: What is a GCM? The Science of Climate Change:The Global Picture p. 13/24

The Science of Climate Change:The Global Picture p. 14/24 Modelling the Climate System: Model Evolution Source: IPCC Third Assessment Report

Modelling the Climate System: Past Changes The Science of Climate Change:The Global Picture p. 15/24

The Science of Climate Change:The Global Picture p. 16/24 Radiative Forcing: Estimates and Uncertainties Source: IPCC Third Assessment Report

The Science of Climate Change:The Global Picture p. 17/24 The Scientific Consensus There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities The Intergovernmental Panel on Climate Change, 2001

The Science of Climate Change:The Global Picture p. 18/24 Climate Change Scenarios Source: IPCC Third Assessment Report

The Science of Climate Change:The Global Picture p. 19/24 Temperature Changes: Today vs. 2075 Source: IPCC Third Assessment Report

The Science of Climate Change:The Global Picture p. 20/24 Climate Change: Precipitation Source: IPCC Third Assessment Report

The Science of Climate Change:The Global Picture p. 21/24 Climate Change: Sea Level Source: IPCC Third Assessment Report

Climate Change: Extreme Events The Science of Climate Change:The Global Picture p. 22/24

The Science of Climate Change:The Global Picture p. 23/24 Climate Change: Extreme Events Confidence in observed changes (latter half of the 20th century) Likely Very likely Very likely Likely, over many areas Likely, over many Northern Hemisphere mid- to high latitude land areas Likely, in a few areas Not observed in the few analyses available Insufficient data for assessment Changes in Phenomenon Higher maximum temperatures and more hot days over nearly all land areas Higher minimum temperatures, fewer cold days and frost days over nearly all land areas Reduced diurnal temperature range over most land areas Increase of heat index 8 over land areas More intense precipitation events b Increased summer continental drying and associated risk of drought Increase in tropical cyclone peak wind intensities c Increase in tropical cyclone mean and peak precipitation intensities c Confidence in projected changes (during the 21st century) Very likely Very likely Very likely Very likely, over most areas Very likely, over many areas Likely, over most mid-latitude continental interiors (Lack of consistent projections in other areas) Likely, over some areas Likely, over some areas

The Science of Climate Change:The Global Picture p. 24/24 The Big Picture To our best understanding, human activity is having a measurable impact on Earth s climate system

The Science of Climate Change:The Global Picture p. 24/24 The Big Picture To our best understanding, human activity is having a measurable impact on Earth s climate system These changes will persist for at least 100 years, even if we act now Changes in climate will impact disease geography economic/social structures Kyoto Protocol: small reduction in warming, but enormous symbolic importance