NASA
Continuing the planet's long-term warming trend, globally averaged
temperatures in 2017 were 1.62 degrees Fahrenheit (0.90 degrees Celsius)
warmer than the 1951 to 1980 mean, according to scientists at NASA’s
Goddard Institute for Space Studies (GISS) in New York. That is second
only to global temperatures in 2016.
In a separate, independent analysis,
scientists at the National Oceanic and Atmospheric Administration
(NOAA) concluded that 2017 was the third-warmest year in their record.
The minor difference in rankings is due to the different methods used by
the two agencies to analyze global temperatures, although over the
long-term the agencies’ records remain in strong agreement. Both
analyses show that the five warmest years on record all have taken place
since 2010.
Because weather station locations and measurement practices change
over time, there are uncertainties in the interpretation of specific
year-to-year global mean temperature differences. Taking this into
account, NASA estimates that 2017’s global mean change is accurate to
within 0.1 degree Fahrenheit, with a 95 percent certainty level.
“Despite colder than average temperatures in any one part of the
world, temperatures over the planet as a whole continue the rapid
warming trend we’ve seen over the last 40 years,” said GISS Director
Gavin Schmidt.
Earth’s long-term warming trend can be seen in this visualization of
NASA’s global temperature record, which shows how the planet’s
temperatures are changing over time, compared to a baseline average from
1951 to 1980. The record is shown as a running five-year average.
Credit: NASA’s Scientific Visualization Studio/Kathryn Mersmann. Download high-definition video here.
The planet’s average surface temperature has risen about 2 degrees
Fahrenheit (a little more than 1 degree Celsius) during the last century
or so, a change driven largely by increased carbon dioxide and other
human-made emissions into the atmosphere. Last year was the third
consecutive year in which global temperatures were more than 1.8 degrees
Fahrenheit (1 degree Celsius) above late nineteenth-century levels.
Phenomena such as El Niño or La Niña, which warm or cool the upper
tropical Pacific Ocean and cause corresponding variations in global wind
and weather patterns, contribute to short-term variations in global
average temperature. A warming El Niño event was in effect for most of
2015 and the first third of 2016. Even without an El Niño event – and
with a La Niña starting in the later months of 2017 – last year’s
temperatures ranked between 2015 and 2016 in NASA’s records.
In an analysis where the effects of the recent El Niño and La Niña
patterns were statistically removed from the record, 2017 would have
been the warmest year on record.
Weather dynamics often affect regional temperatures, so not every
region on Earth experienced similar amounts of warming. NOAA found the
2017 annual mean temperature for the contiguous 48 United States was the
third warmest on record.
Warming trends are strongest in the Arctic regions, where 2017 saw the continued loss of sea ice.
NASA’s temperature analyses incorporate surface temperature
measurements from 6,300 weather stations, ship- and buoy-based
observations of sea surface temperatures, and temperature measurements
from Antarctic research stations.
These raw measurements are analyzed using an algorithm that considers
the varied spacing of temperature stations around the globe and urban
heating effects that could skew the conclusions. These calculations
produce the global average temperature deviations from the baseline
period of 1951 to 1980.
NOAA scientists used much of the same raw temperature data, but with a
different baseline period, and different methods to analyze Earth’s
polar regions and global temperatures.
The full 2017 surface temperature data set and the complete
methodology used to make the temperature calculation are available at:
https://data.giss.nasa.gov/gistemp
GISS is a laboratory within the Earth Sciences Division of NASA’s
Goddard Space Flight Center in Greenbelt, Maryland. The laboratory is
affiliated with Columbia University’s Earth Institute and School of
Engineering and Applied Science in New York.
NASA uses the unique vantage point of space to better understand
Earth as an interconnected system. The agency also uses airborne and
ground-based monitoring, and develops new ways to observe and study
Earth with long-term data records and computer analysis tools to better
see how our planet is changing. NASA shares this knowledge with the
global community and works with institutions in the United States and
around the world that contribute to understanding and protecting our
home planet.
For more information about NASA’s Earth science missions, visit:
https://www.nasa.gov/earth
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