Climate Change and Its Influences On Ecosystems

1. Climate Change and Its Influences On Ecosystems David Gay/NADP and Bob Hall/EPA

2. Two Parts • What exactly is climate change? • Theory • What we know • Impacts on ecosystems

3. So, what is “Climate Change”?

4. First, what is climate? • Definition Average course or conditions of weather at a place, usually over years, as exhibited by • Temperature • Wind velocity • Precipitation (Webster’s) • Prevailing set of weather conditions (temperature, humidity, etc.)

5. Can WE change climate? • Jefferson guessed we could in early 1800’s • Trees in VA • Started making measurements • Urban concrete, no trees • Chemical composition of the atmosphere • Sensible energy vs. latent heating • Albedo changes • Natural changes (ice ages, warm periods) • Changing evaporation/precipitation (trends) • Other patterns (Malenkovitch cycles, el Nino/la Nina) • Cloud cover changes?

6. Definition of Climate Change IPCC usage • Any change in climate over time, whether due to natural variability or from human activity. Alternate • Change of climate, attributed directly or indirectly to human activity, that • Alters composition of global atmosphere and • Is in addition to natural climate variability observed over comparable time periods

7. So? More than just temperature • Precipitation (amount and patterns) • Atmospheric pressure • Humidity • Circulation changes • Number of storms, droughts, freezes, etc. • And more….

8. Average Temperatures, in ◦C

9. Type of Ecosystem, w T and P

10. Water Cycle

11. Radiation Balance“The Greenhouse”

12. Radiation Balance

14. “Effective” Greenhouse Gases Atmospheric Window

15. What do we know? • INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (World Meteorological Organization; UN Env. Program) • http://www.ipcc.ch/

16. Carbon Dioxide Concentration Over Time

17. Quiz • How much has Earth warmed in the last 150 years?

18. Answer ≈ 0.95°C (1.62 °F) since 1850

19. “Diurnal Temperature Range”

20. Temperature Trends, ◦C

21. Changes In…..

22. Sea-Level Rise Total Change = +170 mm or +6.7 inches

23. Trends in Precipitation

24. IPCC Summary of Observations • Global mean surface temperatures have risen • By 0.74°C ± 0.18°C over the last 100 years (1906–2005) • 2005 was one of two warmest years on record • Land regions have warmed at a faster rate than the oceans. • Changes in extremes of temperature are consistent with warming of climate • Widespread reduction in number of frost days in mid-latitude regions, • Increasing number of warm extremes & reducing number of daily cold extremes observed in 70 to 75% of land regions, and • Most marked changes are for cold (lowest 10%, based on 1961–1990) nights, rarer over 1951 to 2003 period.

25. IPCC Summary (cont.) • Sea-surface temperatures warming at all latitudes over all oceans • Urban-heat island effects real but local, have not biased large-scale trends • Average arctic temperatures increased at almost twice global average in past 100 years • Lower-tropospheric temperature increases slightly greater than those at surface between 1958 to 2005

26. IPCC Summary (cont.) • Lower stratospheric temperatures cooling since 1979 • Precipitation has generally increased over land north of 30°N between 1900 to 2005, but downward trends dominate tropics since 1970s • Droughts more common, especially in tropics and subtropics, since 1970s • Changes in large-scale atmospheric circulation apparent

27. Historical Perspective of Temperatures

29. Human Contribution to Climate Change (in one slide) IPCC, 2007

30. Global Climate Models (GCMs) • Physical equations • Lots of computing • Divide the globe into little boxes

32. Further Reading • Intergovernmental Panel on Climate Change (IPCC) • UN organization (Weather Meteorological Office) • http://www.ipcc.ch/ • Summary for the physical science basis • http://ipcc-wg1.ucar.edu/wg1/wg1-report.html

33. The Modeled Future

34. Projections of Surface Temperatures

35. Climate Change and Its Influences On Ecosystems David Gay/NADP and Bob Hall/EPA