A new NASA-led study
shows human-caused climate change has made an impact on a wide range of
Earth's natural systems, including permafrost thawing, plants blooming
earlier across Europe, and lakes declining in productivity in Africa.
Cynthia Rosenzweig of NASA's Goddard Institute for Space Science in New
York and scientists at 10 other institutions have linked physical and
biological impacts since 1970 with rises in temperatures during that
period. The study, to be published May 15 in the journal Nature, concludes
human-caused warming is resulting in a broad range of impacts across the
globe.
"This is the first study to link global temperature data sets, climate
model results, and observed changes in a broad range of physical and
biological systems to show the link between humans, climate, and impacts,"
said Rosenzweig, lead author of the study.
Rosenzweig and colleagues also found the link between human-caused
climate change and observed impacts on Earth holds true at the scale of
individual continents, particularly in North America, Europe, and Asia.
To arrive at the link, the authors built and analyzed a database of
more than 29,000 data series pertaining to observed impacts on Earth's
natural systems. The data were collected from about 80 studies, each with
at least 20 years of records between 1970 and 2004.
Observed impacts included changes to physical systems, such as glaciers
shrinking, permafrost melting, and lakes and rivers warming. Biological
systems also were impacted in a variety of ways, such as leaves unfolding
and flowers blooming earlier in the spring, birds arriving earlier during
migration periods, and plant and animal species moving toward Earth's poles
and higher in elevation. In aquatic environments such as oceans, lakes, and
rivers, plankton and fish are shifting from cold-adapted to warm-adapted
communities.
The team conducted a "joint attribution" study. They showed that at the
global scale, about 90 percent of observed changes in diverse physical and
biological systems are consistent with warming. Other driving forces, such
as land use change from forest to agriculture, were ruled out as having
significant influence on the observed impacts.
Next, the scientists conducted statistical tests and found the spatial
patterns of observed impacts closely match temperature trends across the
globe, to a degree beyond what can be attributed to natural variability.
The team concluded observed global-scale impacts are very likely because of
human-caused warming.
"Humans are influencing climate through increasing greenhouse gas
emissions," Rosenzweig said. "The warming is causing impacts on physical
and biological systems that are now attributable at the global scale and in
North America, Europe, and Asia."
On some continents, including Africa, South America, and Australia,
documentation of observed changes in physical and biological systems is
still sparse despite warming trends attributable to human causes. The
authors concluded environmental systems on these continents need additional
research, especially in tropical and subtropical areas where there is a
lack of impact data and published studies.
Source: NASA
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