Washington: A study on plant productivity that said drought and global warming were killing off plants worldwide is now being questioned by scientists, according to research published.
In the study published in the journal Science last year, researchers Maosheng Zhao and Steven Running of the University of Montana used NASA satellite data to show that productivity declined slightly from 2000-2009.
Those findings contradicted previous studies from the 1980s and 1990s that showed warmer temperatures in some parts of the world were driving longer growing seasons and greater plant growth around the globe.
Having more plants on Earth would be good news because it would help offset greenhouse gas emissions by absorbing more carbon dioxide.
While Running noted at the time that the findings came as "a bit of a surprise," the study raised concerns about global food security, biofuels and our understanding of the carbon
The new questions about the study, published in Science on Thursday, are posed by scientists at Boston University in the United States and the Universities of Vicosa and Campinas in Brazil.
A press release distributed to reporters by Boston University said their study is "refuting earlier alarmist claims that drought has induced a decline in global plant productivity."
Statements included by the researchers describe Zhao and Running`s model as "erratic," "poorly formulated," and showing no "trends that are statistically significant."
However, scientists who were not involved in either paper said this was an excellent example of the scientific process at work, and should not be cast otherwise.
"The Boston University press release -- using the term `alarmist` -- speaks of a university trolling for media as distinct from a university seeking to communicate excellence," Andy Pitman, co-director of the Climate Change Research Centre at the University of New South Wales, said in an email.