NASA Study Links Earth Impacts to Human-Caused Climate Change

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A team of NASA led scientists have completed a study that shows that 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 were able to link physical and biological impacts since 1970 with rises in temperatures during that period.

The study will be published May 15 in the journal Nature and it 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.

The researchers 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.

The study’s 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.

The impacts that were observed included changes to physical systems, such as glaciers shrinking, permafrost melting, and lakes and rivers warming.

In addition, biological systems 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.

A "joint attribution" study was conducted. They showed that at the global scale, about 90 percent of observed changes in diverse physical and biological systems are consistent with warming.

There are other driving forces, such as land use change from forest to agriculture and these were ruled out as having significant influence on the observed impacts.

The researchers then 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.