View from Above
By Alison Hawkes
In 2007, the journal Science published a study that concluded that the severe drought in the Amazon in 2005 actually prompted forests to thrive because more sunshine led to a flourishing of plant growth.
On the other hand was a IPCC-published claim (from the World Wildlife Fund) that only a small drop in rainfall could cause some 40 percent of the Amazonian forests to die off and switch to savanna.
Both of these studies can’t be true. Extreme die-off and plant growth during the same dry conditions? Maybe the drought effects are more granular than what’s presumed. Sounds like a cause for more study.
This week in the Geophysical Research Letters, a group of NASA and other scientists published an answer to this contradiction. Amazon forests did not green-up during the 2005 drought, found that there was neither a significant greening nor a significant dieing off of forests during the 2005 drought. In fact, rainforests may be suprisingly drought-neutral.
Data matters. Previous studies were based on ground observations and NASA satellite imagery. The new NASA-funded study made use of a more sophisticated satellite data set on greenness that filtered out clouds and aerosols (which tend to corrupt data of this sort) and used improved algorithms. It also lengthened the time period of the data set to incorporate eight years.
Only time will tell if this new study reaches closer to the truth. The case highlights how the science behind climate conditions and the impact on the Earth’s systems is a work in progress, with studies rarely proving forever conclusive. Here, new and better tools of measurement, which take time to develop as technology progresses, are necessary to bump the science along.
Rather than seeing contradictory studies as weakness in the scientific process or evidence against climate change (as climate change deniers are doing), it seems better to remain open to ongoing research and welcoming to new evidence (just as the public is on less controversial branches of science … does anyone get upset when medical researchers find new insights into cancer?).
After all, it could be good news if the Amazonian forests are, in fact, resilient to droughts. Studying them more will get us closer to the truth.