Why 2015 Was the Hottest Year on Record

January 21, 2016 10:02 AM

Scientists began monitoring worldwide temperatures since 1880. And in the 136 years since then, no year has clocked in hotter than 2015, according to NOAA scientists.

The record-breaking year was fueled in part by abnormally hot areas that included the western Atlantic Ocean, the eastern Pacific Ocean, the Indian Ocean, Europe, central Asia, southern Africa, Central America, northern South America and the eastern United States. A few areas were abnormally cool, including the northern Atlantic Ocean and parts of Northern Africa and the Middle East.

Globally, land and ocean surfaces measured 1.62°F above the 20th century average. It marked the fourth time since 2000 that average global temperature records have been broken.


Rutgers Global Snow Lab analyzed additional NOAA data and found Northern Hemisphere snow cover in 2015 was 9.5 million square miles, the lowest since 2008. And it continues to be a tale of two polar ice caps, with the Arctic seeing its sixth smallest annual value on record, with the Antarctic sea ice extent the third largest on record.

Other climate anomalies of note in 2015:

  • Hurricane activity was 144% above average in the Pacific but 63% below average in the Atlantic.
  • The U.S. saw the second warmest year and third wettest year on record. May 2015 was the wettest month ever recorded.
  • Flooding in China from May to October affected 7 million people.
  • 2012-15 were the four warmest years on record in Argentina.
  • It was the second warmest year on record in Europe (behind 2014).

NASA also did a separate independent analysis of the climate data. The agency reports Earth’s average surface temperatures have risen 1.8°F since the late 19th century. Fifteen of the 16 warmest years on record have occurred since 2001.

“Climate change is the challenge of our generation, and NASA’s vital work on this important issue affects every person on Earth,” says NASA administrator Charles Bolden. “It is a key data point that should make policy makers stand up and take notice - now is the time to act on climate.”

El Niño conditions contributed to record 2015 temperatures, notes GISS director Gavin Scmidt, adding that other factors such as carbon dioxide emissions were still significant.

"2015 was remarkable even in the context of the ongoing El Niño,” he says. “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.”

For more information, visit http://go.nasa.gov/2015climate.

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Spell Check

Dan Cramer
Blairsburg, IA
1/20/2016 07:50 PM

  Warm temperatures in the northern regions this time of year have to do with the location of the arctic jet stream--not a fraction of a degree of global warmer temperature. If a scientist did not say it was the warmest on record I never would have believed it--we never had a day over 100 all summer. It must have been warmer nights during the winter.

Lincoln, NE
1/20/2016 09:25 PM

  Global temperatures cooler or warmer can have tremendous impact on plant, animal and humans affecting environmental, ecological, social and industrial activities. As humans adapt to those factors of drought, floods, growing season lengths, food production methods will be have to broaden research evaluation and determine adaptive or even alternative practices. Nebraska agriculture has farmers incorporating conservation tillage to conserve water and soil. Cover crops are showing dramatic improvements for soil health, animal life and overall land productivity. Climate seasonal temps, precipitation information is helping ag-producers with management skills to be efficient using water resources of surface and groundwater. Future generations will adapt to climate concerns cold and heat much as grandparents survived without air conditioners, refrigerators and other luxuries.

Carlyle Holman
St. Joe, IN
1/21/2016 06:13 AM

  The world and its scientist need to be worrying more about the current happenings with the different terrorist groups around the world. If we don't get our current problems taken care of soon, Global Warming will be the least of our worries. WAKE UP AMERICA it will be a lot HOTTER where most of the people around the world will go!


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