Greenhouse Gases and Climate Change Global Changes and

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 unequivocal detection of the enhanced greenhouse effect from 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 is likely to 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 temperatures since the mid-20 th 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 2 x 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 Atlantic City, NJ Source: National Oceanic and Atmospheric Administration NJ sea level rise 0. 4 m/century = global sea level rise + other effects = 0. 16 m/century + 0. 24 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 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 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 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 Land area susceptible to inundation Land area susceptible to coastal flooding (“ 30 -yr flood”) 50% probability of 0. 61 m sea level rise by 2100 1% probability of 1. 22 m sea level rise by 2100 Source: M. D. Beevers, U. S. Climate Change Science Program Workshop, Nov. 2005

Effects of Climate Change on Water Resources Floods and Droughts?

Warmer ↓ More Precipitation Warmer ↓ More Evaporation

“Increases in the amount of precipitation are very likely in highlatitudes, 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.

Detection Attribution Likelihood that trend occurred in late 20 th century (typically post 1960) Likelihood of a human contribution to observed trend Likelihood of future trends based on projections for 21 st 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 1970 s 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 Phenomenon and direction of trend Projection

Flood Stage

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

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.