This is a look at the 2005 drought in the Amazon. (Courtesy: NASA)

It is easy to see the result of a dry summer on your yard, but can you imagine how reduced rainfall can affect a much larger piece of greenery?

The 2010 drought has left its mark on Amazon forests. A new study has revealed widespread reductions in the greenness caused by last year’s record-breaking drought.

“The greenness levels of Amazonian vegetation — a measure of its health — decreased dramatically over an area more than three and one-half times the size of Texas and did not recover to normal levels, even after the drought ended in late October 2010,” says Liang Xu of Boston University and the study’s lead author.

An international team of scientists have been using more than a decade’s worth of satellite data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measuring Mission (TRMM).

Scientists created maps of vegetation greenness declines from last year’s drought. The authors of the study developed maps of the area to survey the damage, in a sense. Those maps and satellites show the 2010 drought reduced the greenness of approximately 965 thousand square miles of vegetation. That is more than four times the area affected by the last severe drought in 2005.

“The MODIS vegetation greenness data suggest a more widespread, severe and long-lasting impact to Amazonian vegetation than what can be inferred based solely on rainfall data,” says Arindam Samanta, a co-lead author from Atmospheric and Environmental Research Inc. in Lexington, Mass.

The severity of the drought could be seen in records of water levels across the Amazon basin. Those water levels began to drop in August 2010 and hit record low levels in late October. The only time the levels rose was when rainfall showed up in the winter.

This is a look at the 2010 drought in the Amazon. (Courtesy: NASA)

“Last year was the driest year on record based on 109 years of Rio Negro water level data at the Manaus harbor. For comparison, the lowest level during the so-called once-in-a-century drought in 2005, was only eighth lowest,” said Marcos Costa, coauthor from the Federal University in Vicosa, Brazil.

Computer models predict that in a changing climate, with warmer temperatures and altered rainfall patterns, the developing moisture stress could cause some of the rainforests to be replaced by grasslands or woody savannas. This would release the carbon stored in the rotting wood into the atmosphere, which could accelerate global warming.

The United Nations’ Intergovernmental Panel on Climate Change has warned similar droughts could be more frequent in the Amazon region in the future.