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

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 is likely to have been due to the increase in greenhouse gas concentrations. Climate Change 2000 – The Third Assessment Report of the IPCC The unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or more. Climate Change – The IPCC Scientific Assessment (1990) Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. Climate Change 2007 – The Fourth Assessment Report of the IPCC

Future Emissions Scenarios All scenarios show increasing emissions during next several decades Some scenarios show decreased emissions in latter half of 21 st century Even with aggressive reductions in emissions, CO 2 would rise to 2x preindustrial levels

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

Potential Climate Change Impacts

Sea Level Trends in New Jersey Source: National Oceanic and Atmospheric Administration Atlantic City, NJ NJ sea level rise= global sea level rise+ other effects 0.4 m/century= 0.16 m/century m/century

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).

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).

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).

Global mean sea level changes

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

Effects of Climate Change on Water Resources Floods and Droughts?

Warmer More Evaporation Warmer More Precipitation

Stippled areas are where more than 90% of the models agree in the sign of the change. Relative changes in precipitation (%) for the period 2090–2099, relative to 1980–1999. 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.

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

Flood Stage

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

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.