Tip:
Highlight text to annotate it
X
It's been a well-known problem in carbon cycle research that from an atmospheric point of
view, the tropics, and Amazonia in particular, have not been measured very well at all. So
we really don't know what's going on there.
About ten years ago we started helping build a lab in Brazil so we could make measurements
there. We have four sites that make measurements of carbon dioxide and other greenhouse gases
from the surface to about 45 kilometers above the Amazon forest and these flights take place
every two weeks. And this allows us to calculate the emissions or absorption of carbon dioxide
by the forest that's happening both due to fires and due to other processes as well,
that is, just the growth and decay of plants
And what happened in 2010 and 2011 was 2010 was really a record-setting drought. It was
very widespread, very intense.
And 2011, by contrast, returned to normal, and it was actually a little bit wet by some
measures. And so really what happened was we were given, gifted, a beautiful natural
experiment. In 2010, unsurprisingly because of the drought in some ways, the normal amount
of fires increased by about a factor of two.
They doubled compared to previous years (or 2011).
And then parts of the forests that were not burning were normally a sink of carbon. And
this sink, this net absorption of carbon, shut down. They were neutral.
So in total we had fire emission and no sink. Whereas in 2011, there was no drought, the
fires reduced, and the intact forests returned to absorbing carbon on an annual basis.
Predicting the climate in the future is the big question, of course.
We know with global warming things, in general, are going to get warmer. That's for sure.
What our study is confounding a little bit is the fact that what we saw was a much stronger
response to moisture than to temperature. The big difference between 2010 and 2011 was
the water. There was a lot of soil moisture in 2011, and not a lot of soil moisture in
2010. This really highlights our current uncertainty with climate prediction, that we can't think
of climate prediction solely in terms of temperature.
The big picture issue with the Amazon as we go forward is the fact that the Amazon holds
a lot of carbon. If we start to release all this carbon, this actually will change not
just the local or regional situation but has a global impact.
Because we could add greatly to the total amount of CO2 in the global atmosphere, we
could further change temperatures, change the hydrological cycle...
Two years, the two years have data that we have so far has really given its just a glimpse
so far. So our goal, of course, is to try to extend this out into the future as much
as we can.