 An article published in the American Association for the Advancement of Science (AAAS) "Science" journal in June 2015 by a team led by Thomas R. Karl, director of the NOAA datacenter, reported that these adjustments made very little difference to the temperature record, but the small change in recent years was sufficient to indicate that there had been no hiatus in the period from 1998 to 2014.They used the IPCC definition of the supposed hiatus as a slowdown in rate of temperature increase from 1998 to 2012, compared to the rate from 1951 to 2012, and again found no support for the idea of a "hiatus" or slowdown.Natural climate variability can appear to slow down "surface" warming over short periods, but does not refute long-term climate change trends.