in Annual Mean Sea Surface Temperature under Four Emissions
In 2001, a report by the Intergovernmental
Panel on Climate Change associated observations of global
warming with increased concentrations of greenhouse gases
in the earths atmosphere. That report, Climate Change
2001, noted that most of the observed warming over the
last 50 years is likely to have been due to the increase in
greenhouse gas concentrations. The report also noted
that carbon dioxide and other gases produced by human activities
would continue to affect the climate system.
In modeling future climates, researchers take into account
the atmospheric concentration of greenhouse gases. These maps
show four possible climate futures for the United Kingdom.
Each scenario assumes a different concentration of carbon
dioxide in the atmosphere. Under the low-emission scenario,
concentrations of carbon dioxide reach about 540 ppm by 2100,
(ppm means parts per million, or parts of carbon dioxide per
million parts of atmosphere sampled). That's nearly twice
the pre-industrial concentration of about 280 ppm. Under the
high-emission scenario, carbon dioxide concentrations reach
920 ppm by 2100.
These scenarios indicate that more carbon dioxide in the atmosphere
leads to greater temperature change. The scenarios also indicate
that climate change will not be uniform.