Global Warming Hiatus Never Happened?!
The infamous global warming hiatus, during which surface warming on Earth has been markedly slower compared to previous decades, has puzzled scientists and been hailed by climate change skeptics. But now it seems the debate over this phenomenon is over, because it turns out this warming "pause" may have never really happened.
In a study published Thursday in the journal Science, researchers from the NOAA took a fresh look at temperature data and concluded that global warming has not stopped or even slowed in the last 18 years.
According to their calculations, Earth's global average surface temperature has climbed 0.2 of a degree Fahrenheit each decade since 1950. That means contrary to popular belief, warming never plateaued and has continued to climb.
Numerous studies have been done to possibly explain the apparent hiatus, including an assessment by the Intergovernmental Panel on Climate Change (IPCC). Scientists have suggested everything from volcanic eruptions and reduced solar radiation, to the oceans absorbing more heat.
Meanwhile, critics of climate change have embraced the idea of a global warming slowdown, and used it as proof that the burning of fossil fuels and other human activities are not to blame for Earth's rising temperatures.
"The reality is that there is no hiatus," lead author Tom Karl, director of the NOAA's National Centers for Environmental Information in Asheville, NC, told The Associated Press (AP).
One key factor that supports the idea of a hiatus is its alleged start date: 1998. That year saw a significant temperature spike, after which the next 15 years experienced global average temperatures that were high by historical standards, but were somewhat below most scientific predictions that estimated the effects of greenhouse gas emissions.
However, scientists' techniques for measuring global warming are constantly changing, so the NOAA team decided to lead a new analysis using updated global surface temperature data. Karl and his colleagues based their measurements on thousands of land weather stations as well as ships and buoys at sea going back to 1880.
Their results show that temperatures in the 21st century did not plateau, as previously thought. Instead, the rate of warming during the first 15 years of the 21st century is at least as great as that in the last half of the 20th century, suggesting warming is continuing apace.
Of course, despite these findings, some contend that the global warming pause is real.
"I don't find this analysis at all convincing," Judith Curry, a climatologist at Georgia Tech, told the Los Angeles Times. "While I'm sure this latest analysis from NOAA will be regarded as politically useful for the Obama administration, I don't regard it as a particularly useful contribution to our scientific understanding of what is going on."
Even some mainstream scientists rejected the idea.
"It's always good to go back and look at the data as carefully as possible and make sure it's calibrated correctly," noted William Patzert, a climatologist at NASA's Jet Propulsion Laboratory in La Cañada Flintridge. "But the hiatus is history and it was real."
Nonetheless, Karl and the rest of the NOAA team stand by their controversial conclusion. According to these and other results, the authors suggest the warming slowdown was an illusion, an artifact of earlier analyses.
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