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 Greening in the North

To determine how climate changes affect vegetation, scientists have developed new ways of measuring plant growth on a global scale.

The more visible sunlight a plant absorbs, the more the plant photosynthesizes, using the energy in light to produce food. The more photosynthesis occurs in a given region, the thicker the plant cover. Using information collected by satellites, scientists can track the changes in the amount of light absorbed by different parts of the earth. When an area absorbs more visible light and less near-infrared light (which is not useful for photosynthesis), researchers know that more vegetation is growing there.

This map shows the persistence of vegetation growth above thirty degrees north latitude. Persistence is scored on a scale of low to high based on how consistently the vegetation in an area increased between 1982 and 1999. Vegetation in this region has been growing more vigorously over the past two decades. The greatest changes have been north of forty degrees north latitude where the length of the growing season has increased by several days.


 glossary glossary terms  

Click for definitions of words used on this page:

correlation
greening hypothesis
photosynthesis

remote sensing

View the full, printable version of the glossary.




Greening in the North

Greening in the North - This map is color-coded to show how vegetation has been increasing in the earth’s northern most regions over the last 20 years. Source: Ranga B. Myneni, Department of Geography, Boston University
 


 questions about the data  

question How much carbon dioxide do forests take out of the atmosphere?

email Email your own questions about these data sets. 

 research connection  

Technology (in this case, satellite imagery) provides scientists with much new data. Knowing how to use these data takes creativity and ingenuity. As the research on greening shows, scientists sometimes have to find innovative ways to combine new information with what has been known for years. No matter how good a researcher’s instruments are, science remains a form of detective work.


 related sites  

Environmental Protection Agency/Forests - An article on the impact of climate change on North America’s forests.

United States Geological Survey/“How Does Climate Change Influence Alaska's Vegetation?” - An article describing how Alaska's vegetation has responded to climate changes over time periods of centuries to millions of years.

U.S. Department of Agriculture Forest Service/A Climate Change Atlas - This interactive site lets you explore how climate change could affect forest cover in the United States.
 

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