“Earth is Warming”: The National Academy of Sciences

Earth is warming. Detailed observations of surface temperature assembled
and
analyzed by several different research groups show that the
planet’s average surface
temperature was 1.4 ºF (0.8 ºC) warmer during the first
decade of the 21st century
than during the first decade of the 20th century, with the
most pronounced warming
over the past three decades. These data are corroborated by a
variety of independent
observations that indicate warming in other parts of the
Earth system, including the
cryosphere (snow and ice covered regions), the lower
atmosphere, and the oceans.


Most of the warming over the last several decades can be
attributed to human
activities that release carbon dioxide (CO2) and other
heat-trapping greenhouse gases
(GHGs) into the atmosphere. The burning of fossil
fuels—coal, oil, and natural gas—
for energy is the single largest human driver of climate
change, but agriculture, forest
clearing, and certain industrial activities also make
significant contributions.
 Natural climate variability leads to year-to-year and
decade-to-decade fluctuations in
temperature and other climate variables, as well as
significant regional differences,
but cannot explain or offset the long-term warming trend.

Global warming is closely associated with a broad spectrum of
other climate changes,
such as increases in the frequency of intense rainfall,
decreases in snow cover and sea
ice, more frequent and intense heat waves, rising sea
levels, and widespread ocean
acidification.
 Individually and collectively, these changes pose risks for a
wide range of human and
environmental systems, including freshwater resources, the
coastal environment,
ecosystems, agriculture, fisheries, human health, and
national security, among others.

Human-induced climate change and its impacts will continue for
many decades, and
in some cases for many centuries. The ultimate magnitude of
climate change and the
severity of its impacts depend strongly on the actions that
human societies take to
respond to these risks.

Will read and report back asap.