Study confirms recent global warming trend

Still, the debate over human impact on warming goes unresolved.
WASHINGTON POST
WASHINGTON -- An independent scientific panel largely ratified the findings of a controversial climate study Thursday, saying the past few decades amount to the hottest period in the past 400 years.
But the National Academy of Sciences report on the so-called "hockey stick graph" -- a much discussed chart showing a sudden rise temperatures in the Northern Hemisphere since the Industrial Revolution began -- voiced less confidence about the graph's conclusion that the climate is hotter now than it has been in 1,000 years. As a result, the academy report is not likely to resolve the fierce debate over the extent to which human-generated greenhouse gas emissions are responsible for warming the earth.
New ammunition
The new report provides ammunition to those who say the evidence is overwhelming that industrial activity is transforming the planet by spewing carbon dioxide into the atmosphere, as well as to those who see it as confirmation that significant uncertainty still exists in climate change science.
The 141-page report, written by a dozen prominent scientists, concludes "it can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries." The academy is chartered by Congress to provide the government with advice on scientific issues.