EcoAlert –NASA Scientists Confirm 2016 “Earth’s Hottest in Modern Record” (VIDEO)




Earth's 2016 surface temperatures were the warmest since modern record keeping began in 1880, according to independent analyses by NASA and the National Oceanic and Atmospheric Administration (NOAA). NASA and NOAA released independent analyses of global temperatures that each came to the same conclusion: 2016 is very likely the hottest year on record, followed by 2015 and then 2014.

Globally-averaged temperatures in 2016 were 1.78 degrees Fahrenheit (0.99 degrees Celsius) warmer than the mid-20th century mean. This makes 2016 the third year in a row to set a new record for global average surface temperatures.


"You're seeing warmth throughout the world: higher on land than in the ocean, higher in the Northern Hemisphere than the Southern Hemisphere, higher in the arctic most of all, and patterns that we have grown quite familiar with both in modeling and in observation," Gavin Schmidt, director of NASA's Goddard Institute for Space Studies in New York, said during the conference.


Earth's average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century, a trend seen in this visualization of temperature change from 1880 to 2016, as analyzed by NASA's Goddard Institute for Space Studies. (Credit: NASA/GSFC/Scientific Visualization Studio)

The 2016 temperatures continue a long-term warming trend, according to analyses by scientists at NASA's Goddard Institute for Space Studies (GISS) in New York. NOAA scientists concur with the finding that 2016 was the warmest year on record based on separate, independent analyses of the data.

Derek Arndt, head of NOAA's National Centers for Environmental Information monitoring branch, presented records from groups using six different processes for monitoring global temperature, including the U.K. weather service Met Office, calculations from different academics and raw NOAA data that hasn't been corrected to account for changes in sea temperature measurements. All of these records showed a very similar, striking temperature increase, officials said.

"Especially since the mid-20th century, the analyses, while they have slight differences from year to year, are capturing the same long-term signal," Arndt said during the conference. "These data sets are all singing the same song, even if they're hitting different notes along the way. The pattern is very clear."

To measure global temperatures, NASA uses data from 6,300 weather stations, Antarctic research stations, and ships and buoys that measure sea surface temperature. The agency then analyzes the measurements using an algorithm that takes into account the stations' spacing and other elements that could affect measurements at particular stations, like a nearby urban area, NASA officials said in a statement. The key is weaving that data into a comprehensive picture of the overall temperature and changes.

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. However, even taking this into account, NASA estimates 2016 was the warmest year with greater than 95 percent certainty.

“2016 is remarkably the third record year in a row in this series,” said Schmidt. “We don't expect record years every year, but the ongoing long-term warming trend is clear.”

The planet's average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere.

Most of the warming occurred in the past 35 years, with 16 of the 17 warmest years on record occurring since 2001. Not only was 2016 the warmest year on record, but eight of the 12 months that make up the year — from January through September, with the exception of June — were the warmest on record for those respective months. October, November, and December of 2016 were the second warmest of those months on record — in all three cases, behind records set in 2015.

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. Researchers estimate the direct impact of the natural El Niño warming in the tropical Pacific increased the annual global temperature anomaly for 2016 by 0.2 degrees Fahrenheit (0.12 degrees Celsius).

Weather dynamics often affect regional temperatures, so not every region on Earth experienced record average temperatures last year. For example, both NASA and NOAA found the 2016 annual mean temperature for the contiguous 48 United States was the second warmest on record. In contrast, the Arctic experienced its warmest year ever, consistent with record low sea ice found in that region for most of the year.

The planet's long-term warming trend is seen in this chart of every year's annual temperature cycle from 1880 to the present, compared to the average temperature from 1880 to 2015. Record warm years are listed in the column on the right. (Credit: NASA/Earth Observatory/Joshua Stevens)

NASA's 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. 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 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.

"There's a good reason we don't give an absolute temperature. It turns out the absolute temperature for the whole planet is a harder number to estimate than just the difference from one year to the next," Schmidt said. The researchers gave 57 degrees F (14 degrees C) as NOAA's estimate, but cautioned that this number was much less accurate than the amount of change.

"We can make statements about the differences year by year at the 10ths-, sometimes 100ths-of-degree level, but we don't know the absolute temperature of the planet that well. If you take one number that is not very well known and add it to a number that is very well known, it doesn't suddenly become more accurate," Schmidt added.

The reason researchers can estimate the change so much more accurately than the absolute temperature, they said, is that weather changes correlate strongly between locations, even when the locations themselves are at different temperatures. For instance, a storm system can be 1,000 miles (1,600 kilometers) across, and all the places in its path will follow a similar pattern of temperature change, regardless of their starting points. On a broader scale, temperature changes from month to month also correlate, even if the locations are different.

Calculating the overall changes lets the researchers check data from the different stations against each other for consistency, and requires fewer data points to get a strong estimate, the researchers said. By contrast, absolute temperature depends on the exact locations of stations and features like mountains, forests and cities that might not be covered well by the existing measurements.

"We have to do a lot more statistical interpolation to get the absolute temperature, whereas the anomalous temperature, [which documents] the changes — it's actually much easier," Schmidt said.

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 monitors Earth's vital signs from land, air and space with a fleet of satellites, as well as airborne and ground-based observation campaigns. The agency develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing.

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Image credit: With thanks to Doug Knuth / CC BY-SA 2.0


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