Earth Impacts Linked To Human-Caused Climate Change
Pastor Dale Morgan
Earth Impacts Linked To Human-Caused Climate Change*
Areas of significant changes to Earth systems observed in North America
over the last 20 years, represented by various symbols, are linked with
areas of rising temperatures, noted in red. Credit: NASA
by Staff Writers
Greenbelt MD (SPX) May 19, 2008
A new NASA-led study shows that human-caused climate change has impacted
a wide range of Earth's natural systems, from permafrost thawing to
plants blooming earlier across Europe to 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, published May 15 in the journal Nature, concludes
that 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 that 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, 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.
Impacts also included changes to biological systems, such as leaves
unfolding and flowers blooming earlier in the spring, birds arriving
earlier during migration periods, and ranges of plant and animal species
moving toward the 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 in which they showed,
first, 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 that the
spatial patterns of observed impacts closely match temperature trends
across the globe, to a degree beyond what can be attributed to natural
variability. So, the team concluded that observed global-scale impacts
are very likely due to human-caused warming.
"Humans are influencing climate through increasing greenhouse gas
emissions and 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," said Rosenzweig.
On other 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 that 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.