It is all but certain that human activity has caused a steady increase in global temperatures over the past 60 years, leading to warmer oceans and an acceleration in sea-level rise, according to findings in the most recent climate change report by an international panel of scientists.
In a draft summary of the fifth climate assessment since its creation in 1988, the U.N. Intergovernmental Panel on Climate Change warns that continued greenhouse gas emissions “would cause further warming” and induce changes that could “occur in all regions of the globe . . . and include changes in land and ocean, in the water cycle, in the cryosphere, in sea level . . . and in ocean acidification.”
Six years ago, in its last report, the IPCC concluded that there was a 90 percent certainty that human activity was responsible for most of Earth’s warming. The 2013 draft summary increased that certainty to 95 percent.
“Human influence on climate caused more than half of the observed increase in global surface temperature from 1951-2010,” the report said. “There is high confidence that this has warmed the ocean, melted snow and ice, raised global mean sea level, and changed some climate extremes, in the second half of the 20th century.”
The IPCC — composed of hundreds of scientists, including from federal agencies — tracks the impact of global warming on specific regions and species and won a 2007 Nobel Peace Prize along with former vice president Al Gore. The body plans to release its massive final report in four stages over the next year, starting with a meeting next month in Stockholm.
The draft summary, completed in June, was leaked and first reported last weekend by the Reuters news service and later by The New York Times. The Washington Post obtained a copy of the draft Tuesday.
In remarks to the British Broadcasting Corp., a spokesman said that the report is far from complete and that conclusions should not be drawn from it.
“It is guaranteed it will change,” said Jonathan Lynn, spokesman for the IPCC. He said the document was provided to U.N. member governments and has drawn 1,800 comments, many of which will be considered as the assessment is debated and edited.
But the leaked draft mirrors previous assessments in many ways, and asserts that its changed predictions are the result of significant improvements in the way scientists study the rise in temperature and sea levels.
Some say the draft’s predictions are too conservative. The prediction that ocean levels could rise as much as three feet by the end of the century conflicts with those of other scientists who envision even more dire consequences.