June through September is the dry season for the Amazon Basin
of South America. Yet the basin's dry season may be getting
uncharacteristically wetter, according to NASA's Goddard Space
Flight Center in Maryland.
That's news that could affect all of us, no matter where we
live.
You might say as the Amazon's weather goes, so goes the world's
climate. That's because in many ways, tropical areas like the
Amazon literally drive weather systems around our globe. Because
of the concentration of sun's rays near the equator and the
plentiful ocean moisture, the tropics receive over two thirds of
the world's rainfall.
When it rains, water changes from liquid to vapor and back
again, storing and releasing heat energy in the process. With so
much rainfall in the tropics, that means an incredible amount of
heat is released into the atmosphere. In fact, so much heat is
released that the tropics are our planet's primary source of heat
redistribution.
One way to think of the tropics is like the human heart: Just
as the heart pumps blood to the body to keep organs and tissues
alive, the tropics circulate heat, triggering changes in weather
and nourishing climates around the world.
Because of the basin's location in the tropics, any sort of
weather hiccup from the area could signal serious changes for the
rest of the world like droughts and severe storms. According to
researchers at Goddard, such changes may indeed be on the horizon.
Using data from NASA's Tropical Rainfall Measuring Mission and
military and NOAA satellites, Goddard meteorologists examined a
large, deforested area in the Amazon Basin. The meteorologists
wanted to know if the lack of tree cover is affecting the weather
around the area. Initial indications show that it is.
"In deforested areas, the land heats up faster and reaches
a higher temperature...that enhance the formation of clouds and
ultimately produce more rainfall," said meteorologist Andrew
Negri.
The researchers were quick to caution that the change in
rainfall was most apparent in August, when the Amazon changes from
dry to wet seasons. During that time, weather can be
unpredictable, making it difficult to determine what conditions
are normal.
Negri also pointed out that more research needs to be conducted
in order to tell what's really going on.
"The effects here are rather subtle and appear to be
limited to the dry season. The overall effect of this
deforestation on annual and daily rainfall cycles is probably
small and requires more study," Negri said.
In any case, the changes in the Amazon Basin's weather have
caught the eyes of scientists. NASA researchers and others hope to
develop new computer models to better answer the mystery of the
unseasonable rain.