What we know about global climate change Philip Mote (206) University of Washington

What we know (high confidence) Earth’s climate is changing Humans are involved and the pattern is unlike natural changes Global average temperature is likely to increase °C this century, most land areas more We know this through peer-reviewed research and assessments

Evidence of warming Direct measurements Glaciers receding Ice shelves collapsing Snow declining and streamflow shifting Shifts in ranges and behavior of species

Understanding recent climate history Recent trend: +0.5°C (0.9°F) in 30 yrs Human influence emerges

Larsen B Ice shelf Antarctica January 31, 2002 MODIS data Courtesy NSIDC

February 17

February 23

March 5

Avoiding Dangerous Climate Change : Exeter Feb 2005 Antarctic Peninsula Glacier Acceleration “cork from bottle” analogy Larsen A – x3 increase in flow speed of 2 feed glaciers Larsen B – x2-x6 increase in flow speed of 4 feed glaciers Hektoria glacier lowered by ~40m in 6 mo Glaciers south of collapse region unaffected ~ 0.06mm/y global msl contribution? Work in progress

Satellite temperature trends Fu et al. (2004)

11

Rapid global sea level rise

13 Local evidence of warming

The South Cascade glacier retreated dramatically in the 20th century Courtesy of the USGS glacier group

3.6°F 2.7°F 1.8°F 0.9°F

Puget Sound area

Race Rocks lighthouse, Victoria

As the West warms, winter flows rise and summer flows drop Figure by Iris Stewart, Scripps Inst. of Oceanog. (UC San Diego)

Stewart et al., 2004; Stewart et al., 2005 Spring-pulse dates Centers of Mass By several measures, Western snowfed streamflow has been arriving earlier in the year in recent decades Spring pulse Center time

April 1 snowpack: no decline at high elevations

...but large declines at low elevations

Green daily flow records dating to <1935

Metrics of flow Center date JJAS flow

Center date of annual flow As observed elsewhere, mean inflow to Puget Sound is shifting earlier as the snowpack declines

Causes of climate change

Data from Climate Monitoring and Diagnostics Lab., NOAA. Data prior to 1973 from C. Keeling, Scripps Inst. Oceanogr. Changing atmospheric composition: CO 2 Mauna Loa, Hawaii

Carbon dioxide: up 32%

Natural Climate InfluenceHuman Climate Influence All Climate Influences

Future climate change

21 st century temperature change IPCC (

Climate change commitment: at any point in time, we are committed to additional warming and sea level rise from the radiative forcing already in the system: the brakes work slowly! (Meehl et al., 2005: How much more warming and sea level rise? Science, 307, 1769—1772)

Recent findings and events zOcean acidification zIntensity and destructiveness of tropical cyclones may be increasing (controversial) zUnprecedented 2003 European heat wave may have been accentuated by warming

Hurricane Catarina - first recorded South Atlantic tropical storm, March 2004

Heat-wave deaths in France, August 2003 ( SINERM 2003 )

The 2005 Atlantic hurricane season

Total: 27 (vs 21 in 1933) Total: 13 (vs 12 in 1969)

Conclusions zHuman influence on climate has emerged zWarming and its consequences will continue even after greenhouse gas concentrations are stabilized z