Warming rate this century “virtually identical” to the 2nd half of 20th century —NOAA
Researchers at National Oceanographic and Atmospheric Administration (NOAA) say new evidence show global surface temperatures did not plateau this century, and that there was no “pause” in global surface warming.
The warming rate this century is “virtually identical” to the 20th century, they report in a new study published by Science.
Abstract: Much study has been devoted to the possible causes of an apparent decrease in the upward trend of global surface temperatures since 1998, a phenomenon that has been dubbed the global warming “hiatus.” Here we present an updated global surface temperature analysis that reveals that global trends are higher than reported by the IPCC, especially in recent decades, and that the central estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a “slowdown” in the increase of global surface temperature.
For 1998–2014, NOAA’s new global trend is 0.106± 0.058°C dec−1, and for 2000–2014 it is 0.116± 0.067°C dec−1, which is similar to the warming over the second half of the 20th century.
However, the Intergovernmental Panel on Climate Change (IPCC) had concluded that global average temperatures increased by about 0.05°C dec−1 between 1998 and 2012, compared to an average of 0.11°C dec−1 between 1951 and 2012.
The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (1) concluded that the global surface temperature “has shown a much smaller increasing linear trend over the past 15 years [1998-2012] than over the past 30 to 60 years.” The more recent trend was “estimated to be around one-third to one-half of the trend over 1951-2012.” The apparent slowdown was termed a “hiatus,” and inspired a suite of physical explanations for its cause, including changes in radiative forcing, deep ocean heat uptake, and atmospheric circulation changes.
In fact, the latest data shows a figure of 0.116°C dec−1 for 2000-2014, compared with 0.113°C dec−1 for 1950-1999.
“Our new analysis now shows the trend over the period 1950-1999, a time widely agreed as having significant anthropogenic global warming, is virtually indistinguishable with the trend over the period 2000-2014.”
Based on NOAA’s latest analysis, therefore, the IPCC’s 2013 statement—that the global surface temperature “has shown a much smaller increasing linear trend over the past 15 years than over the past 30 to 60 years” —is invalid, said the director of NOAA’s National Climatic Data Center (NCDC).
Science DOI: 10.1126/science.aaa5632 –