advises the United Nations on the Framework Convention on Climate Change
IPCC findings on climate change (1995)
Summary for Policymakers
"Increases in greenhouse gas concentrations since pre-industrial times have led to a positive radiative forcing of climate, tending to warm the surface and produce other changes in climate."
· Many greenhouse gases remain in the atmosphere for a long time (for Carbon dioxide and Nitrous oxide many decades to centuries, hence they affect radiative forcing on long time-scales."
· The atmospheric concentration of greenhouse gases (measured in 1992)
have grown significantly:
· These trends can be attributed largely to human activities, mostly fossil fuel use, land-use change and agriculture.
At any location year-to-year variations in weather can be large, but analyses of meteorological and other data over large areas and over periods of decades or more have provided evidence for some important systematic changes.
· Global mean surface temperature has increased...
· Recent years have been the warmest since 1860...
· Nighttime temperatures over land have generally increased more than daytime temperatures.
· Global sea level has risen . . . over the past 100 years . . . related to the increase in global mean temperature.
· The 1990 to mid-1995 persistent warm-phase of the El Nino-Southern Oscillation was unusual in the context of the last 120 years.
The balance of evidence suggests a discernible human influence on global climate.
· The 20th century global mean temperature is at least as warm as any other century since at least 1400 AD.
· The observed warming trend is unlikely to be entirely natural in origin.
Spencer Weart | Gale Christianson | James Hansen | Contemporary
Fourth Assessment Report, 2-2007
Radiative forcing is the simple measure in Watts per square meter of the perturbation to the energy balance of the Earth's atmosphere. It is a measure of the potential for climate change.
* Approved meaning a "report has been subject to detailed, line-by-line discussion and agreement in a plenary meeting of the relevant IPCC working group." of specialists in the field.
Intergovernmental Panel on Climate Change, UNEP & WMO, Climate Change 1995: The Science of Climate Change, Cambridge, U.K.: The Cambridge University Press, 1996, pp. 3-7.