Greenhouse Gases and Climate Change: Global Changes and Local Impacts

1. Greenhouse Gases and Climate Change:Global Changes and Local Impacts Anthony J. Broccoli Director, Center for Environmental PredictionDepartment of Environmental Sciences Rutgers University New Jersey Clean Air CouncilApril 11, 2007

5. “The unequivocal detection of the enhanced greenhouse effectfrom observations is not likely for a decade or more.” Climate Change – The IPCC Scientific Assessment (1990) “The balance of evidence suggests a discernible human influence on global climate.” Climate Change 1995 – The Second Assessment of the Intergovernmental Panel on Climate Change (IPCC) “Most of the observed warming over the last 50 years islikelyto have been due to the increase in greenhouse gas concentrations.” Climate Change 2000 – The Third Assessment Report of the IPCC “Most of the observed increase in globally averaged temperaturessince the mid-20th century isvery likelydue to theobserved increase in anthropogenic greenhouse gas concentrations.” Climate Change 2007 – The Fourth Assessment Report of the IPCC

6. Future Emissions Scenarios Some scenarios showdecreased emissionsin latter half of 21stcentury Even with aggressivereductions in emissions,CO2 would rise to 2xpreindustrial levels All scenarios showincreasing emissionsduring next severaldecades

7. Red, green, and blue lines represent different emissions scenarios. Height of each colored bar represents variations among different climate models.

8. Potential Climate Change Impacts

10. Sea Level Trends in New Jersey Atlantic City, NJ Source: National Oceanic and Atmospheric Administration NJ sea level rise = global sea level rise + other effects0.4 m/century = 0.16 m/century + 0.24 m/century

11. Why Is Global Sea Level Rising? • Thermal expansion Warmer water is less dense than colder water. • Melting of glaciers and ice caps Water released by the melting of ice on land adds to the volume of the oceans. • Melting and calving of Greenland and Antarctic ice sheets Depends on the ice sheet dynamics (how the ice flows).

12. Why Is Global Sea Level Rising? • Thermal expansion Warmer water is less dense than colder water. • Melting of glaciers and ice caps Water released by the melting of ice on land adds to the volume of the oceans. • Melting and calving of Greenland and Antarctic ice sheets Depends on the ice sheet dynamics (how the ice flows).

13. Why Is Global Sea Level Rising? • Thermal expansion Warmer water is less dense than colder water. • Melting of glaciers and ice caps Water released by the melting of ice on land adds to the volume of the oceans. • Melting and calving of Greenland and Antarctic ice sheets Depends on ice sheet dynamics (how the ice flows).

14. Global mean sea level changes

15. 50% probability of 0.61 m sea level rise by 2100 1% probability of 1.22 m sea level rise by 2100 Effects of Sea Level Rise on the Coastal Environment Land area susceptible to inundation Land area susceptible to coastal flooding (“30-yr flood”) Source: M. D. Beevers, U.S. Climate Change Science Program Workshop, Nov. 2005

16. Effects of Climate Change on Water Resources Floods and Droughts?

17. Warmer↓ MorePrecipitation Warmer↓ MoreEvaporation

18. “Increases in the amount of precipitation are very likely in high-latitudes, while decreases are likely in most subtropical land regions, continuing observed patterns in recent trends.” Relative changes in precipitation (%) for the period 2090–2099, relative to 1980–1999. Stippled areas are where more than 90% of the models agree in the sign of the change.

19. Phenomenon and direction of trend Likelihood that trend occurred in late 20th century (typically post 1960) Likelihood of a human contribution to observed trend Likelihood of future trends based on projections for 21st century using SRES scenarios Warmer and fewer cold days and nights over most land areas Very likely Likely Virtually certain Warmer and more frequent hot days and nights over most land areas Very likely Likely (nights) Virtually certain Warm spells / heat waves. Frequency increases over most land areas Likely More likely than not Very likely Heavy precipitation events. Frequency (or proportion of total rainfall from heavy falls) increases over most areas Likely More likely than not Very likely Area affected by droughts increases Likely in many regions since 1970s More likely than not Likely Intense tropical cyclone activity increases Likely in some regions since 1970 More likely than not Likely Increased incidence of extreme high sea level (excludes tsunamis) Likely More likely than not Likely Detection Attribution Projection

20. Flood Stage

21. More Climate Change in the Pipeline Future emissions Additional “zero-emission” warming (aka “commitment”) Warming to date

22. Managing Climate Change • Leadership: Raise public awareness of the challenges posed by climate change and the need to mitigate and adapt. • Mitigation: Reduce emissions of carbon dioxide and other greenhouse gases. • Adaptation: Increase the resilience of society to climate change. • Knowledge: Develop a better understanding of the details of future climate change.