A study published on June 4 2015 by the National Climatic Data Center at the National Oceanic and Atmospheric Administration (NOAA) found that a UN 2013 report erroneously concluded that there had been a 15-year hiatus in global warming. Turns out, the rate of global warming was measured incorrectly: the hiatus never happened and global warming continues unabated.

Other studies have suggested that several factors such as air pollution, lower solar energy levels and volcanic activity may have slowed down the rate of warming. As the trend did not change, it is now thought that had it not been for those factors, the rate of warming might have actually increased.