What role does the Ocean play in Global Climate Change?

1. What role does the Ocean play in Global Climate Change?

2. The Global Greenhouse

4. How the Greenhouse Effect Works

5. Emission Spectra of Sun and Earth and Absorption Spectra of Atmosphere

6. Interplanetary Comparisons: Venus: Higher concentrations: 400o C Mars: Lower concentrations: -50o C

7. Intergovernmental Panel on Climate Change (IPCC) • Established by the UN and World Meteorological Organization in 1988 • Mission of the IPCC: to assess the scientific, technical, and socio- economic information relevant for the understanding of the risks of human-induced climate change • 2,500 of the world’s leading climate scientists and technical experts contribute to reports • Provides comprehensive and balanced assessments of climate change science, impacts, and adaptation and mitigation options • Extensive peer-review and governmental review ensures scientific credibility and policy relevance

8. Observed Changes in Greenhouse Gas Concentrations

9. Predicted Increases in CO2 Emissions and Concentrations (from IPCC SAR 1995)

10. Global Temperature and Atmospheric CO2 over Geological Time • Current level of CO2 is outside bounds of natural variability • Rate of change of CO2 is also unprecedented • Clear correlation between atmospheric CO2 and temperature over last 160,000 years

11. Observed Changes in Global Mean Temperature (measured and proxy data) *relative to 1961-1990 average

12. IPCC Global Mean Temperature Predictions: • Global average temperature is projected to increase by 1.5 to 5.5° C (2.5 to 10.4° F) from 1990 to 2100 • Projected temperature increases in TAR are greater than those in SAR. • Projected rate of warming is unprecedented for last 10,000 years

13. Predicted Temperature Change in the Context of Last 1000 Years • 1861 to 2000: • Instrumental data • 1000 to 1861: • Proxy data • 2000 to 2100: • Model projections

14. Observed Changes in Spatial Patterns of Land and Sea Surface Temperature Surface temperature change between 20 year mean 1955-1974 and 20 year mean 1975-1994

15. Predicted Changes in Spatial Patterns of Land and Sea Surface Temperature Model-predicted surface temperature change by 2050

16. Atmospheric CO2 and Sea Level Rise

17. IPCC Global Sea Level Rise Predictions: • Global average sea level is projected to rise by 10 to 80 cm (4 to 35 inches) between 1990 and 2100 • Projected rise is slightly lower than the range presented in the SAR. • Sea level will continue to rise for hundreds of years after stabilization of greenhouse gas concentrations

18. Components of Sea Level Rise • Thermal expansion and land ice melt after an initial 1% increase in CO2 • for 70 years • Eventually. most of sea-level rise will be due to thermal expansion of ocean, • not melting of ice

19. Predicted Changes in Annual Precipitation by 2050 The projected change is compared to the present day with a ~1% increase per year in equivalent CO2

20. Increase in Extreme Precipitation Events in the U.S.

21. Number of Billion Dollar Weather Disasters

22. Extreme Weather Events Change in Phenomenon Confidence in projected change* Higher maximum temperatures, more hot days Very likely Higher minimum temperatures, fewer cold days and frost days Very likely Increase of heat index Very likely, over most areas More intense precipitation events Very likely, over many areas Increased summer continental drying & associated risk of drought Likely, over most mid-latitude continental interiors Increase in tropical cyclone peak wind and precipitation intensities Likely, over some areas *Judgmental estimates of confidence by IPCC: very likely - 90-99% chance, likely - 66-90% chance.

23. Impacts of Climate Change on Insurance • Economic losses from catastrophic weather events have increased 10-fold in recent decades • Increasing losses are due in part to socioeconomic factors and in part to climatic factors • Because of expensive coastal development and projection of more extreme events - insurance damages, claims, and costs are likely to increase • Significant challenges in the future if high impact events occur or if catastrophes are closely- spaced

24. IPCC Policy-Makers Summary: • Observations • Human activities are changing the atmospheric concentrations of greenhouse gases. • Extensive and wide-spread evidence that the earth has warmed 0.3 - 0.6° C over the last century; however, this warming has not been uniform. • Global sea level has risen 10 – 20 cm over the last century. • Forecasts • Global average temperature is projected to increase by 1.5 to 5.5° C (2.5 to 10.4° F) from 1990 to 2100 • Global average sea level is projected to rise by 10 to 80 cm (4 to 35 inches) between 1990 and 2100 • Likely to be an increase in extreme weather events

25. IPCC History: Evolution of Our Knowledge • FAR (1990): “The size of the warming is broadly consistent with predictions of climate models, . . . but the unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more.” • SAR (1996): “The balance of evidence suggests a discernible human influence on climate.” • TAR (2001): “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”

26. Unpredictability: What if our models are not complete?

27. Greater warming, lesser warming, but what about cooling?

28. Example: Shutdown of NADW Formation and Collapse of Ocean Thermohaline Circulation?