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The following are some of
the USGCRP's major accomplishments related to Understanding the Earth's
Climate System during Fiscal Year 2001.
Applied climate models to simulate the observed global warming
over the past century, in which the warming occurred primarily in two distinct
20-year periods, from 1925 to 1944 and from 1978 to the present. The results
showed that while the latter warming is primarily attributable to increases
in greenhouse gas (radiative) forcing, the warming of the early 20th century
could have resulted from a combination of human-induced radiative forcing and
an unusually high variability of the coupled ocean-atmosphere system.
Documented that the heat content of the upper 3000 meters of the
Earth's oceans has been increasing since the 1950s. In addition to this warming
trend, there is a decadal signature to the variability in many of the oceans
that requires improved physical understanding.
Showed in two studies, each using a different sophisticated climate
model, that the ocean warming that has been measured over the last half-century
is virtually the same as what would be expected from the observed increase in
greenhouse gases and aerosols in the atmosphere.
Identified an enhanced rate of heating of the Northern Hemisphere
tropical oceans. This rapid warming has contributed to unprecedented coral bleaching
over the past decade.
Began deployment of the Argo array of profiling floats in the
global oceans. This observational system will increase our capabilities to observe
long-term trends in ocean temperatures, currents, and salinity, as well to improve
predictions of the influence of events such as El Niño and La Niña on seasonal
climate.
Carried out the first detailed comparisons of cloud-resolving
model simulations and single column model results with observational data, based
on three years of continuous observations in the Atmospheric Radiation Measurement
Program's Southern Great Plains site. These comparisons give the first detailed
look at how cloud parameterizations in climate models actually perform in real
atmospheric situations.
Made accurate, systematic satellite measurements of solar variability,
now completed through a full 22-year solar cycle, using the ongoing collection
and analysis of data from ACRIMSAT, which was launched in December 1999.
Deployed the Global Lake Drilling System (GLAD 800) to Lake Titicaca
in Bolivia/Peru in an international collaborative research effort to retrieve
a 500,000-year record of atmospheric dynamics and climate in this tropical region.
Recovered an unprecedented record of changing temperature variability
from a Himalayan glacier at an altitude of 23,500 feet, showing the last 50
years were warmer than any other equivalent period in the last 1,000 years.
Submitted to Congress an assessment of climate change titled
Climate
Change Impacts on the United States: The Potential Consequences of Climate Variability
and Change, which was produced by a team of authors operating under the
auspices of the Federal Advisory Committee Act. The assessment includes an overview
of about 150 pages and a foundation volume that is about 600 pages long.
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Research Elements & Cross-cutting Activities
