U.S. Climate Affected by Vegetation

Changes in Vegetation across the United States Impact of Changing Vegetation Pattern on July Temperatures Changes in Vegetation across the United States

It is not uncommon to find stories in the news about how climate is affected by things like carbon dioxide emissions, aerosols and other pollutants. Global warming has been a major concern for decades. Now, a new study produces more evidence that land surface changes also play a significant role in climate.

The study was conducted by NASA's Earth Science Enterprise. Their goal is to improve prediction of climate and weather using data from satellites orbiting Earth. The study also used data and computer models from NASA and NOAA (National Oceanic and Atmospheric Administration).

The idea is straightforward, changes in landcover - particularly vegetation has impacted regional temperatures and precipitation. The greatest impacts on nature have occurred since the industrial revolution. There has been a tremendous increase in urban sprawl around cities, reducing the amount of vegetation over areas. It has been known for some time that local temperatures are higher around cities than surrounding countryside, however it has only been recently that scientists realized this was having a much broader effect.

One computer model traced the evolution of vegetation distribution pattern over the US for almost 300 years. Comparing this with climate studies over that same time gives insight into how the two are related. From industrial plants to farms, scientists can now study the affect these areas have on climate.

What is interesting is that it's not as simple as grassland versus concrete. As an example, in areas of the Great Plains and Midwest, as farming replaced grasslands - there was significant cooling of more than one degree Fahrenheit. The reason for this is that farmlands has increased evaporation, creating lower temperatures.

A warming effect occurred along the Atlantic coast lands were crops replaced forests. Croplands are less efficient than forests when it comes to transpiration, a daytime process where water evaporates from leaves during photosynthesis and cools the air.

And surprisingly, a slight warming effect was observed across the Southwest where woodlands replaced some deserts.

Vegetation changes also affect precipitation, though to a lesser degree than temperature. The cooling termperatures over the central US, has likely weakened the temperature difference between land and the Gulf of Mexico, where most of the necessary moisture comes from. This slows the northern movement of weather systems resulting in enhanced rainfall across Texas and a reduction in rainfall around Illinois and Indiana.

Most people associate land cover change with deforestation but it is more complex than that. Forest cover in the US has actually increased over the last 100 years, mostly from a decrease in agriculture in the East, and fire suppression in the West. Other type of land cover change is less noticeable but just as significant. More cooling is expected in the Great Plains areas with an increase in large areas being converted into irrigated croplands. Just changing from grasslands to crops makes a difference.

Understanding things which affect climate changes are very important. Such knowledge could be used to mitigate or exacerbate greenhouse warming. Most scientists still believe that greenhouse warming is one of the top threats to Earth.

Constellations

The Solar System