Global warming hiatus
A global warming hiatus, also sometimes referred to as a global warming pause or a global warming slowdown, is a period of relatively little change in globally averaged surface temperatures. In the current episode of global warming many such periods are evident in the surface temperature record, along with robust evidence of the long term warming trend.The exceptionally warm El Niño year of 1998 was an outlier from the continuing temperature trend, and so gave the appearance of a hiatus: by January 2006 assertions had been made that this showed that global warming had stopped. A 2009 study showed that decades without warming were not exceptional, and in 2011 a study showed that if allowances were made for known variability, the rising temperature trend continued unabated. There was increased public interest in 2013 in the run-up to publication of the IPCC Fifth Assessment Report, and despite concerns that a 15-year period was too short to determine a meaningful trend, the IPCC included a section on a hiatus, which it defined as a much smaller increasing linear trend over the 15 years from 1998 to 2012, than over the 60 years from 1951 to 2012. Various studies examined possible causes of the short term slowdown. Even though the overall climate system had continued to accumulate energy due to Earth's positive energy budget, the available temperature readings at the earth's surface indicated slower rates of increase in surface warming than in the prior decade. Since measurements at the top of the atmosphere show that Earth is receiving more energy than it is radiating back into space, the retained energy should be producing warming in at least one of the five parts of Earth's climate system.A July 2015 paper on the updated NOAA dataset cast doubt on the existence of this supposed hiatus, and found no indication of a slowdown. This analysis incorporated the latest corrections for known biases in ocean temperature measurements, and new land temperature data. Scientists working on other datasets welcomed this study, though the view was expressed that the short term warming trend had been slower than in previous periods of the same length.