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May 28, 1997

The Greening of Earth's Northern Latitudes

Color-Coded Plot of Vegetation

A color-coded plot of the change in green vegetation for the months of May through September between 1982 and 1990 for the latitudes north of 27.5 degrees.

Meaning of the color code:

Green refers to regions in which the amount of vegetation increased by up to five percent, pink to regions in which the increase was between five and twenty-five percent, red to regions in which the increase was between twenty-five and fifty-five percent, and orange to regions in which the increase was more than fifty-five percent.

Image Credit: R. B. Myneni, C. D. Keeling, C. J. Tucker, G. Asrar, R. R. Nemani, and NASA/NOAA.

The Earth's northern latitudes are getting greener.

In the above color-coded plot, notice the checkered bands dominated by orange, red, pink, and green that extend from Europe across Russia and Siberia to the Pacific Ocean and thence south into China, and from Alaska in a southeasterly direction to the Great Lakes and easterly to Quebec and Labrador as well as into parts of the US. As the colors indicate, in these bands the growth of trees and other green plants increased anywhere from a few percent to over fifty-five percent between 1982 and 1990.

On the other hand, virtually no increase in vegetation occurred in arid, mountainous, and snow-covered areas, such as in North Africa, in much of the Middle East, Central Asia, the US Southwest, and in Greenland and other regions of the Arctic.

The average increase in green vegetation for all land areas north of 27.5 degrees latitude was ten percent during the nine-year period from 1982 to 1990.

Detailed comparison of the above color-coded plot with the seasonal cycles of atmospheric carbon dioxide levels and surface temperatures, both of which have been rising during the past three decades, suggests the following: The vegetation of the Earth's northern latitudes is actively responding to the rise in atmospheric carbon dioxide levels and surface temperatures. The regions of greatest increase in vegetation lie between latitudes forty-five and seventy degrees north, where marked warming has occurred in the springtime due to an early disappearance of snow. Preliminary analysis of data from 1992 to 1994 indicates that the trends are continuing.

"Our results demonstrate that the Earth's biosphere -- its plants, animals, and life -- is not a passive participant in our planet's environment," said Dr. Ranga Myneni of Boston University, who led the research reported here. "The warming during springtime is particularly significant because of the related decline in snow cover. As a result, spring greening is happening significantly earlier."

The evidence presented by Dr. Myneni and his team is the first direct observation of the Earth's biosphere that shows an increase in green vegetation on such a broad scale and for so long. The evidence is based on analysis of data from the Advanced Very High Resolution Radiometer (AVHRR) instruments aboard the meteorological satellites NOAA-7, -9, and -11. These satellites are part of the Pathfinder program, which is an interagency partnership between the National Oceanic and Atmospheric Administration (NOAA) and NASA in support of global climate change research.

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We obtained the above image and information from NASA press release 97-71 of April 17, 1997.

A copy of the article in which Dr. Myneni and his colleagues describe their research and which was published in the journal Nature (Vol. 386, pages 698-702 and 659-660, April 17, 1997) can be found here

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