Climate Science Update: Climate physics, change, extremes and variability

1. C-CAIRN Workshop Winnipeg Nov 18, 2003 Henry Hengeveld Meteorological Service of Canada Environment Canada Climate Science Update: Climate physics, change, extremes and variability

2. The IPCC has become the principle source of science advice to policy makers on climate change science 1990 1992 1995 1997 2001 First Report RIO Second Report Kyoto Third Report Increasing Confidence Bonn & Marrakesh Cautious

3. Outgoing Heat Energy Reflected Energy ~31% Incoming Solar Energy Energy Trapped By Greenhouse Gases • CO2 0.028% • CH4 0.0007% • N2O 0.0003% The Atmosphere’s Energy Budget

4. Te equals -19C  Natural greenhouse effect warms the surface by 33C  Estimating the magnitude of the natural Greenhouse Effect Net Incoming Solar Energy Outgoing Heat Energy = (S0 (1-A) R2) (4R2kTe4) where S0 is the solar constant A is average albedo, or reflectivity R is the radius of the earth k is Boltzmann’s constant Te is earth’s apparent temperature (seen from space) However, average global surface T is + 14C

5. Ice cores show evidence of a close relationship between greenhouse gas concentrations and climate

6. 380 360 340 $ 320 $ $ $ $ Highest concentration in last 400,000 years $ $ $ $ $ 300 $ $ $ $ $ $ ! $ $ $ ' $ # ! ! $ ' ' $ ' # $ ' # ! ' ' ' ! ' ! 280 ' ' # ! # ! $ ! $ $ ' # ' ! ' ' $ $ ' ' ' ' ' ' 260 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 CO2 concentrations are now unprecedented in at least the past 400,000 years CO2 Concentration (ppmv)

7. Current NH temperatures are very unusual within at least the past 2000 years Source: IPCC(2001)

8. Physical and Ecological Systems around the world are beginning to change

9. Changes in temperature are unevenly distributed Trends for 1950-98 Degrees C

10. However, the climate system is also influenced by many other complex interactions and feedbacks COMPLEX!

11. Global coupled climate models attempt to simulate climate from ‘first principles’ • CCCma has been involved in climate model development and application since the 1970s.

12. Modelled response to all forcings agrees best with observations (natural only) (natural + human)

13. Projected CO2 emissions for six representative SRES Scenarios Scenarios A1B A1T A1F1 A2 B1 B2 IS92a 25 20 15 10 5 CO2 emissions (GtC/yr) 2000 2020 2040 2060 2080 2100

14. The world will become MUCH, MUCH warmer than during the past millennium

15. Projected temperature changes vary considerably from year to year

16. 3.2C -5% However, site specific projections can vary greatly between models and scenarios used Winnipeg area Projections for summer 2050 SRES + IS92a scenarios Data from CICS Canadian Climate Impacts Scenarios

17. Region NAmer CM3 CM2 SAmer WEur EEur Africa SEAsia -100 -80 -60 -40 -20 0 20 40 60 Change in Cereal Production (Mt/yr) Appropriate selection of scenarios is important, since the magnitude and even sign of impacts can be very scenario dependent

18. Warmer climates offer benefits to Canadians, including: • Warmer growing seasons • Longer growing seasons • Lower heating costs • Shorter snow seasons • Less ice on lakes, rivers and seas • Decrease in some extremes

19. Reasons for concern amplify with time, but also differ in space and time Future generations: Global problem Our lifetime: Developing country problem Now: Increasing vulnerability

20. A small change in average temperature can cause a large change in the frequency of temperature extremes

21. However, the largest change in temperature extremes can occur when both average and variance change

22. Example: A modest increase in mean temperature in Winnipeg could dramatically increase frequency of very hot days

23. Extreme precipitation events are also likely to become more frequent Extreme Precipitation Events (Canada) 95 2090 90 85 2050 80 Size of event (mm) 75 1985 70 65 60 55 50 20 30 40 50 60 10 70 80 Event recurrence time (Years)

24. Central North America Today 60 40 ~2070 Return Period (years) 20 0 10 15 20 25 30 Length of Dry Spell (days) The frequency and severity of droughts are likely to increase in southern Canada

25. Temperature Precipitation Recent Unusual Weather Events in S. B.C: Persistent drought and warm temperatures • Low reservoirs and streamflow • Mountain pine beetle epidemic • Wildfire • Impacts on wide range • of economic sectors

26. Are recent weather extremes due to natural variability or to climate change? • Analyses suggest increases have occurred in some types of weather extremes in some, but not all areas • Individual extreme events occur rarely and hence are difficult to link directly to specific “causes” • However, many of the events are broadly consistent with climate change projections • Hence these events are good examples of what may happen more often in the future

27. Joint statement by Academies of Science from 17 other countries – May 2001 “The work of the…IPCC represents the consensus of the international science community on climate change science. We recognize IPCC as the world’s most reliable source of information…and endorse its method of achieving this consensus.”

28. Most of Annex I (44%) Russian Federation (17%) US and Australia (38%) Near Term Response: Implementing the Kyoto Protocol • To come into effect, 55 countries representing at least 55% of Annex I emissions must ratify • Current status (29/09/03):

29. Temperature will continue to rise for centuries, and sea levels for millennia after CO2 stabilization

30. Some concluding thoughts THANK YOU! • Climate change is for real (it won’t go away!) • Global consequences of future climate change are significant cause for concern • For Canadians, many aspects of warmer temperatures bode well, extremes do not • The regional details are still (and may remain) very uncertain • Need multiple scenarios to study impacts