The globally comprehensive, multi-discipline study appears in this week's Science magazine. The article states climate changes have provided extra doses of water, heat and sunlight in areas where one or more of those ingredients may have been lacking. Plants flourished in places where climatic conditions previously limited growth.
"Our study proposes climatic changes as the leading cause for the increases in plant growth over the last two decades, with lesser contribution from carbon dioxide fertilization and forest re-growth," said Ramakrishna Nemani, the study's lead author from the University of Montana, Missoula, Mont.
From 1980 to 2000, changes to the global environment have included two of the warmest decades in the instrumental record; three intense El Nievents in 1982-83, 1987-88 and 1997-98; changes in tropical cloudiness and monsoon dynamics; and a 9.3 percent increase in atmospheric carbon dioxide (CO2), which in turn affects man-made influences on climate. All these changes impact plant growth.
Earlier studies by Ranga Myneni, Boston University (BU), and Compton Tucker, NASA's Goddard Space Flight Center (GSFC), Greenbelt, Md., also co-authors of the study, reported increased growing seasons and woody biomass in northern high-latitude forests.
Another co-author, Charles Keeling, Scripps Institution of Oceanography, La Jolla, Calif., cautions no one knows whether these positive impacts are due to short-term climate cycles, or longer-term global climate changes. Also, a 36 percent increase in global population, from 4.45 billion in 1980 to 6.08 billion in 2000, overshadows the increases in plant growth.
Nemani and colleagues constructed a global map of the Net Primary Production (NPP) of plants from climate and satellite data of vegetation greenn
Contact: Krishna Ramanujan
NASA/Goddard Space Flight Center