There is no doubt that global warming is real and that it is caused by people, two of the US government's top climate researchers said.
There is no doubt about the truth of global warming and it is caused by people, said two top US government climate researchers.
Industrial emissions are the number one factor, they say - unlike other critics, who are already in the minority and claim that global warming may be caused mainly by natural factors.
"There is no doubt that the composition of the atmosphere is changing as a result of human activity, and today greenhouse gases are the largest human impact on the global climate," wrote Thomas Carle, director of the National Oceanic and Atmospheric Administration's National Center for Climate Information, and Kevin Turnbreth, head of the National Center for Climate Analysis for the study of the atmosphere.
"The likely result of this is a higher frequency of heat waves, in the form of extreme precipitation events and associated hazards, namely wildfires, heavy heat loads, changes in vegetation and sea level rise," they added in a commentary article, published in Friday's issue of the journal Science .
Karl and Turnberth estimate that there is a 90% chance that between the years 1990-2100 the average global temperatures will rise by about 3.1 to 8.9 degrees Fahrenheit (1.7 and 4.9 degrees Celsius) following the human influence on the climate.
Such a dramatic warming will further melt the glaciers, which are already crumbling, and cause coastal areas to flood. Many other groups have already shown that the ice in Greenland, the North Pole and Antarctica was melting rapidly.
Karl and Turnberth noted that the levels of carbon dioxide in the atmosphere have increased by 31% since pre-industrial times.
Carbon dioxide is the main greenhouse gas, which causes temperatures to rise by trapping solar energy in the atmosphere.
Emissions of sulfur and soot particles have significant effects as well, though more localized effects, they said.
"In light of what has happened so far and what is planned for the future, further climate change is guaranteed," they wrote. The US has been hesitant to sign international treaties to reduce emissions of substances that cause climate change, but the two experts said that global cooperation is the key to a solution.
"Climate change is truly an international issue, one that may prove to be humanity's greatest challenge," they wrote. "It is unlikely that the matter will be dealt with adequately without international cooperation and actions."
