A preliminary draft of a report by the U.N's Intergovernmental Panel on Climate Change was leaked to the public earlier this month and now climate change skeptics are arguing it shows evidence of 20 years of global warming overestimation.
Someone involved with the U.N.'s IPCC review process reportedly leaked the draft and made it available for download online. The report shows that each of the four temperature models the U.N. body has published since 1990 has overestimated the rise in temperature on planet Earth. The report wasn't actually supposed to be released until 2014.
“Temperatures have not risen nearly as much as almost all of the climate models predicted,” Roy Spencer, a climatologist at the University of Alabama at Huntsville, told FoxNews.com.
“Their predictions have largely failed, four times in a row... what that means is that it's time for them to re-evaluate,” he added.
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The IPCC graph shows that the midpoints of the various models predicted that the world would warm by between about 0.5 degrees Fahrenheit and 0.9 degrees Fahrenheit between 1990 and 2012. Actual warming was much less than that: 0.28 F, according the data the IPCC cites.
But that doesn’t mean the IPCC models are wrong, others argue.
“It’s important to keep in mind that there are natural short-term variations in global temperature that happen right alongside human-induced warming,” Aaron Huertas, of the Union of Concerned Scientists, told FoxNews.com.
The IPCC’s climate report draft also notes that “the model projections ... do not fully account for natural variability.”
However, skeptics like Spencer caution that the chart from the report doesn't mean global warming is a hoax.
“The IPCC's claim is that they are 90 percent sure that humans have 'contributed to' the observed warming. Hell, even I would agree with that innocuous statement," he said.
The indication, he explained, is that "CO2 is not nearly as strong a climate driver as the IPCC has been assuming."
"This is the possibility they do not allow to be considered, because it would end all of their policy-changing goals,” he said.