New study debunks myths about Amazon rain forests

Mar 11, 2010

A new NASA-funded study has concluded that Amazon rain forests were remarkably unaffected in the face of once-in-a-century drought in 2005, neither dying nor thriving, contrary to a previously published report and claims by the Intergovernmental Panel on Climate Change.

"We found no big differences in the greenness level of these forests between drought and non-drought years, which suggests that these forests may be more tolerant of droughts than we previously thought," said Arindam Samanta, the study's lead author from Boston University.

The comprehensive study published in the current issue of the scientific journal used the latest version of the NASA MODIS satellite data to measure the greenness of these vast pristine forests over the past decade.

A study published in the journal Science in 2007 claimed that these forests actually thrive from drought because of more sunshine under cloud-less skies typical of conditions. The new study found that those results were flawed and not reproducible.

"This new study brings some clarity to our muddled understanding of how these forests, with their rich source of biodiversity, would fare in the future in the face of twin pressures from logging and changing climate," said Boston University Prof. Ranga Myneni, senior author of the new study.

The IPCC is under scrutiny for various data inaccuracies, including its claim - based on a flawed World Wildlife Fund study -- that up to 40% of the Amazonian forests could react drastically and be replaced by savannas from even a slight reduction in rainfall.

"Our results certainly do not indicate such extreme sensitivity to reductions in rainfall," said Sangram Ganguly, an author on the new study, from the Bay Area Environmental Research Institute affiliated with NASA Ames Research Center in California.

"The way that the WWF report calculated this 40% was totally wrong, while [the new] calculations are by far more reliable and correct," said Dr. Jose Marengo, a Brazilian National Institute for Space Research climate scientist and member of the IPCC.

Explore further: NASA sees Hurricane Edouard far from US, but creating rough surf

More information: Samanta, A., S. Ganguly, H. Hashimoto, S. Devadiga, E. Vermote, Y. Knyazikhin, R. R. Nemani, and R. B. Myneni (2010), Amazon forests did not green‐up during the 2005 drought, Geophys. Res. Lett., 37, L05401, doi:10.1029/2009GL042154

Provided by Boston University Medical Center

5 /5 (6 votes)

Related Stories

Scientists Study True Colors of Amazon Rainforests

Mar 15, 2007

Using NASA satellite data, Boston University scientist Ranga Myneni studied the amount and dynamics of green leaf area of Amazon rainforests. The study found a 25 percent increase in leaf area during the dry ...

Amazon carbon sink threatened by drought

Mar 05, 2009

The Amazon is surprisingly sensitive to drought, according to new research conducted throughout the world's largest tropical forest. The 30-year study, published today in Science, provides the first solid evidence that d ...

Climate change may kill the Amazon rainforest

Feb 10, 2009

(PhysOrg.com) -- The dieback of the Amazonian forests caused by climate change is not inevitable but remains a distinct possibility, according to a study led by the Professor of Ecosystem Science at Oxford. ...

Will climate change kill the Amazon?

Mar 28, 2007

One of the most profound predicted impacts of climate change was discussed in a landmark conference at Oriel College by scientists, conservationists and policymakers from Europe and North and South America. ...

Recommended for you

NASA sees Odile soaking Mexico and southwestern US

4 hours ago

Tropical Storm Odile continues to spread moisture and generate strong thunderstorms with heavy rainfall over northern Mexico's mainland and the Baja California as well as the southwestern U.S. NASA's Tropical ...

NASA sees Tropical Storm Polo intensifying

4 hours ago

Tropical storm warnings now issued for a portion of the Southwestern coast of Mexico as Polo continues to strengthen. Infrared imagery from NASA's Aqua satellite showed powerful thunderstorms around the center ...

User comments : 15

Adjust slider to filter visible comments by rank

Display comments: newest first

RJU690
2.6 / 5 (5) Mar 11, 2010
I'm impressed that PHYSorg as a demonstration of their impartiality posted an article which contradicts the dogma of anthropogenic climate change.
RJB26
2 / 5 (4) Mar 12, 2010
yeah its a nice change of pace. i guess reality is starting to sink in around here. usually physorg dutifully goes along with whatever piece of agw hysteria that comes their way.
mary_hinge
4.4 / 5 (7) Mar 12, 2010
After reading the studies and comparing it to Physorgs headline I have to say that this is sloppy work by Physorg.
The Amazon basin is a huge area, you are going to find many differences in soil type, elevation, water table, micro-climates, seasonal changes, bioactivity, flora, fauna etc. Some areas will benefit from drought conditions to the detriment of other species and vice versa with increased precipitation. The stress produced by drought induces many trees to put on a reproductive show, looking deceptively healthy. Prolonged changes in precipitation, wind speed and cloud cover will have major effects on complex biosystems with a general short term (hundreds to thousands of years) reduction in biodiversity.
To lump all of the Amazon basin into one crass headline is very sloppy scientific journalism. No myths are debunked, on the contrary, as should be expected, some parts showed greening, others browning and both in the range shown by the results from both studies.
Loodt
1.7 / 5 (11) Mar 12, 2010
Mary Hinge, I disagree with you.

When it suits the Warmist agenda, all surface temperature records in a region can be reduced to the values of a single cell.

Consider the Grand Canyon, 277 miles long, 10 miles wide and 1 mile deep. The various micro-climates that must exist at that site is remarkable. The difference in temperatures at the valley bottom and the crests must be huge, yet we are happy to let some AGW joker claim that he can reduce this complex area to one temperature reading.

I've been to the Amazon basin, and despite its vast extend and beauty, the complexity of modelling that part of the globe cannot be more difficult than that of the Grand Canyon.

To lump the Grand Canyon into one temperature reading is stretching science further!
yOnsa
4 / 5 (4) Mar 12, 2010
"The way that the WWF report calculated this 40% was totally wrong, while [the new] calculations are by far more reliable and correct," said Dr. Jose


tsk tsk..You just can't trust anything from the World Wrestling Federation.
mary_hinge
4.4 / 5 (7) Mar 12, 2010
What do you disagree with Loodt? Aren't the points I made exactly what you are agreeing with?
You then make an unrelated point about the Grand Canyon. It is possible to have an average temperature for the canyon in much the same way you can have an average temperature for the Earth's surface. The point being discussed was the changes in biodiversity over the Amazon basin and the differences the various microclimates, geology etc. have on this. Life and its adaptations are a lot more complicated and complex than taking average temperatures over a set piece of earth!
I think other readers would appreciate that you and your type actually make the effort to read the background to the stories, and indeed to other contributors, before burdening us with your reflex and increasingly tired arguments.
Thank you
JayK
4.1 / 5 (9) Mar 12, 2010
How many denialists will jump on this article without actually reading it? This is how science works, this doesn't disprove anything about AGW and this is a study backed by some serious data. If you can't discuss the what the article actually says, why would you comment at all? (I'm looking at the Loodt Troll in the corner)
dachpyarvile
1.5 / 5 (8) Mar 12, 2010
While the article and study neither proves nor disproves AGW, what it does show is yet another error of many perpetuated by the IPCC. Peer-reviewed science indeed!

Last year, I wrote that 'climategate' was just the beginning... There is yet more to come...watch for it... :)
Loodt
1.4 / 5 (11) Mar 12, 2010
JayK, haven't you learned to skip a paragraph?

If you see something you don't like, pass over it.

Or are you green with envy because you haven't been to the Amazons yet?

Mary Hinge, I disagree with you, I don't think this article was sloppy.

That's my view, different from yours. Deal with it.
PinkElephant
4.3 / 5 (6) Mar 12, 2010
We found no big differences in the greenness level of these forests between drought and non-drought years
I'm not sure how greenness indicates whether or not a forest is replaced by a savanna. Both would be green, unless and until the drought gets truly epic.

As well, I don't see how greenness measured from above, says anything about growth rates and nutrient flows within a multi-layered evergreen forest. Do the authors expect plants to skimp on chlorophyll just because there's less water available?
dachpyarvile
2 / 5 (4) Mar 12, 2010
I'm not sure how greenness indicates whether or not a forest is replaced by a savanna. Both would be green, unless and until the drought gets truly epic....


Greenness differs between Savannah and Rain Forest. The differences can be picked up by satellites equipped with the proper sensors to do so.
Caliban
3.7 / 5 (3) Mar 13, 2010
"Greeness" in this context may be a misnomer. I have read elsewhere that different types of vegetation can be identified by their thermal(infrared) emissions, with relative accuracy- this principle, as I understand it, is frequently used by law enforcement to locate -from a helicopter or other aircraft- marijuana growing operations in forested areas.

While it's nice to know that a brief drought apparently caused no harm to the extant rainforest, the thing that went unmentioned in the article is: what happens in an extended drought, and how does deforestation affect the overall frequency, duration, and severity of drought, and does this deforestation actually induce and/or enhance drought/cycle?
dachpyarvile
1 / 5 (3) Mar 14, 2010
No, "greenness" is not a misnomer. While it is true that IR can be used along with UV and other ranges in the spectrum, The kinds of plants that grow in savanna actually do have a slightly different shade of green than rain forest trees. This is because of the differences in the amount of green mixed with fractional amounts of other colors that are reflected off the differing kinds of foliage.

As to what an extended drought might do, that is another question. It is a relatively simple matter to sample in various places from soils that are much older and see what the record of the past shows.
lengould100
not rated yet Mar 15, 2010
I'd first like to see a confirmation of the scientific methods use as the basis of the hypothetical conclusion stated in this article. A one-year variation in colour green measured from geostationary orbit? Hmmmm.....
dachpyarvile
1 / 5 (3) Mar 15, 2010
Well, you could read the paper itself. Or, you could obtain the paper, read it, and check over the sources cited. Or, you could contact the lead authors directly:

Arindam Samanta (arindam.sam [at] gmail [dot] com)
Sangram Ganguly (sangramganguly [at] gmail [dot] com)

and grill them over confirmatory evidence for the underlying science in their study using the MODIS project land data.

The satellites involved in compiling and researching MODIS data do not measure a single color for studies like this. Usually, there are at least two or three bands used for varying studies.

By the way, I suggest knowing a bit about what you are talking about before attempting to contact the authors. You do not want to look like a total twit. :)