A new study suggests the "global warming hiatus" may be a myth, and the rate of warming over the past 15 years has actually been accelerating.
A team of researchers the latest global surface temperature data, and found warming has been taking place at the same rate or faster than it did in the latter half of the 20th century, the National Oceanic and Atmospheric Administration reported.
"Adding in the last two years of global surface temperature data and other improvements in the quality of the observed record provide evidence that contradict the notion of a hiatus in recent global warming trends," said Thomas R. Karl, Director, NOAA's National Centers for Environmental Information. "Our new analysis suggests that the apparent hiatus may have been largely the result of limitations in past datasets, and that the rate of warming over the first 15 years of this century has, in fact, been as fast or faster than that seen over the last half of the 20th century."
The apparent slowdown in the rise in global surface temperatures was addressed in the Intergovernmental Panel on Climate Change's (IPCC) Fifth Assessment Report, which showed the upward global surface trend from 1998 to 2012 was lower than what was seen between 1951 and 2012. Since the report was released, NOAA scientists have made improvements in trend calculations, and the world also saw the hottest year on record in 2014. The new calculations also incorporated sea surface temperature and land surface air temperature datasets and corrected the difference between data collected from buoys and ship-based data.
"In regards to sea surface temperature, scientists have shown that across the board, data collected from buoys are cooler than ship-based data," said Dr. Thomas C. Peterson, principal scientist at NOAA's National Centers for Environmental Information and one of the study's authors. "In order to accurately compare ship measurements and buoy measurements over the long-term, they need to be compatible. Scientists have developed a method to correct the difference between ship and buoy measurements, and we are using this in our trend analysis."
The analysis revealed incomplete spatial coverage among ship measurements led to underestimates of the true global temperature change outlined in the 2013 IPCC report. These new data sets could help fill in these gaps. These findings in combination with the high temperature of 2013 and 214 suggest the warming trend is not substantially lower than what has been reported in the past.
The findings were published in a recent edition of the journal Science.