Nature

2015 Was the Hottest Year on Record, and 2016 Could Beat It

January 21, 2016 | Joanne Kennell

Photo credit: Scientific Visualization Studio/Goddard Space Flight Center

Three years in a row of record breaking temperatures?

Generally, I am all for smashing records, however in this case, it is nothing to be proud of.  The numbers are in and globally-averaged temperatures in 2015 beat the previous record set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius).  Only once before, in 1998, has a new record been greater than the old record by this high of a number.

2015 continues the long-term warming trend that started in the late 19th century according to analyses by scientists at NASA's Goddard Institute for Space Studies (GISS) in New York (GISTEMP).  The National Oceanic and Atmospheric Association (NOAA) agrees with the findings based on their own independent analyses of the data.

“Climate change is the challenge of our generation, and NASA's vital work on this important issue affects every person on Earth,” said NASA Administrator Charles Bolden.  “Today's announcement not only underscores how critical NASA's Earth observation program is, it is a key data point that should make policy makers stand up and take notice — now is the time to act on climate.”

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Most of the warming has occurred in the past 35 years, with 15 of the 16 warmest years on record occurring since 2001 — so every year since 2001.  However, last year was the first time the global average temperatures was one degree or more above the 1880–1899 average.

NASA's analyses used surface temperature measurements from 6,300 weather stations, ship- and buoy-based observations of sea surface temperatures, and measurements from Antarctic research stations.  These measurements were analyzed using an algorithm and the result of these calculations is an estimate of the global average temperature difference from a baseline period of 1951 to 1980.

NOAA scientists used a lot of the same temperature data, but a different baseline period, and different methods to analyze Earth's polar regions and global temperatures.

El Niño or La Niña, which warm or cool the tropical Pacific Ocean, do contribute to short-term variations in global average temperature, and El Niño was in effect for most of 2015.  “2015 was remarkable even in the context of the ongoing El Niño,” said GISS Director Gavin Schmidt.  “Last year's temperatures had an assist from El Niño, but it is the cumulative effect of the long-term trend that has resulted in the record warming that we are seeing.”

However, not every region on the planet experienced record breaking temperatures in 2015 because weather dynamics play a role.  For example, NASA and NOAA found that a mean temperature for the contiguous 48 United States was the second warmest on record.

So what are scientists predicted for 2016?  “It's not unprecedented to have two years in a row of record-breaking temperatures, but in our records, we've never had three years in a row,” Schmidt told Deborah Netburn at the Los Angeles Times.  “If 2016 turns out to be as warm as we anticipate, that would be unprecedented in our record book.”

You can watch the long-term warming trend from 1880-2015 in the video below.

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