greenhouse gases and climate change: global changes and local impacts anthony j. broccoli director,...
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Greenhouse Gases and Climate Change:Global Changes and Local Impacts
Anthony J. BroccoliDirector, Center for Environmental Prediction
Department of Environmental SciencesRutgers University
New Jersey Clean Air CouncilApril 11, 2007
“The balance of evidence suggestsa 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 effectfrom observations is not likely for a decade or more.”
Climate Change – The IPCC Scientific Assessment (1990)
“Most of the observed increase in globally averaged temperaturessince 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 ScenariosFuture Emissions Scenarios
All scenarios showincreasing emissionsduring next severaldecades
Some scenarios showdecreased emissionsin latter half of 21st
century
Even with aggressivereductions in emissions,CO2 would rise to 2xpreindustrial levels
Red, green, and blue lines represent different emissions scenarios.
Height of each colored bar represents variations among different climate models.
Potential Climate Change ImpactsPotential 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 + 0.24 m/century
Why Is Global Sea Level Rising?
• Thermal expansionWarmer water is less dense than colder water.
• Melting of glaciers and ice capsWater released by the melting of ice on land adds to the volume of the oceans.
• Melting and calving of Greenland and Antarctic ice sheetsDepends on the ice sheet dynamics (how the ice flows).
Why Is Global Sea Level Rising?
• Thermal expansionWarmer water is less dense than colder water.
• Melting of glaciers and ice capsWater released by the melting of ice on land adds to the volume of the oceans.
• Melting and calving of Greenland and Antarctic ice sheetsDepends on the ice sheet dynamics (how the ice flows).
Why Is Global Sea Level Rising?
• Thermal expansionWarmer water is less dense than colder water.
• Melting of glaciers and ice capsWater released by the melting of ice on land adds to the volume of the oceans.
• Melting and calving of Greenland and Antarctic ice sheetsDepends 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. 2005
Land area susceptible to inundation
Land area susceptible to coastal flooding (“30-yr flood”)
50% probability of 0.61 m sea level rise by 21001% probability of 1.22 m sea level rise by 2100
Effects of Climate Change on Water Resources
Floods and Droughts?
Warmer↓
MoreEvaporation
Warmer↓
MorePrecipitation
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 notLikelyIncreased incidence of extreme high sea level (excludes tsunamis)
Likely More likely than not Likely in some
regions since 1970 Intense tropical cyclone activity increases
Likely More likely than not Likely in many
regions since 1970s Area affected by droughts increases
Very likely More likely than not Likely
Heavy precipitation events. Frequency (or proportion of total rainfall from heavy falls) increases over most areas
Very likely More likely than not Likely Warm spells / heat waves. Frequency increases over most land areas
Virtually certain Likely (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.