Global Warming Being Berry Gude to Me, Say da Forest to da Tree

The earth has been getting greener over the past twenty years, with forests growing larger and thicker over most of the globe. A joint Nasa-DOE study concludes that the past twenty years have been good for a greening earth. The illustration above from the report shows greening areas in green, and the few browning areas in brown.

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 Niño events 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.

....Nemani and colleagues constructed a global map of the Net Primary Production (NPP) of plants from climate and satellite data of vegetation greenness and solar radiation absorption. NPP is the difference between the CO2 absorbed by plants during photosynthesis, and CO2 lost by plants during respiration. NPP is the foundation for food, fiber and fuel derived from plants, without which life on Earth could not exist. Humans appropriate approximately 50 percent of global NPP.

NPP globally increased on average by six percent from 1982 to 1999. Ecosystems in tropical zones and in the high latitudes of the Northern Hemisphere accounted for 80 percent of the increase. NPP increased significantly over 25 percent of the global vegetated area, but decreased over seven percent of the area; illustrating how plants respond differently depending on regional climatic conditions.
Climatic changes, over approximately the past 20 years, tended to be in the direction of easing climatic limits to plant growth. In general, in areas where temperatures restricted plant growth, it became warmer; where sunlight was needed, clouds dissipated; and where it was too dry, it rained more. In the Amazon, plant growth was limited by sun blocking cloud cover, but the skies have become less cloudy. In India, where a billion people depend on rain, the monsoon was more dependable in the 1990s than in the 1980s.

Go to the source for more fascinating illustrations, and some great animations. The illustration just above the previous paragraph illustrates percent yearly change in vegetation production, by the color code provided. Hat tip to Fat Knowledge blog.

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. Actually, no one really knows much of anything about the climate, since the type of sophisticated instrumentation by satellite utilised in this study has only been available for a very few decades.

The less than careful use of proxies by "climatologists" in looking back thousands of years, is too imprecise to definitively determine long-term global climate changes--although plenty of people swimming in tens and hundreds of millions of dollars of grant money continue to claim the ability to do so, in order to keep the funding spigots wide open.

In the meantime, the forests and the trees, by and large, are being berry happe!