For the third year in a row, Earth’s thermostat broke a new record: 2016 was the warmest year since record-keeping began in 1880.
Two phenomena spurred this global fever. One was climate change. The other was a monster El Niño — a periodic warming of Pacific waters around the equator that goes on to affect climate across the planet. The global average surface temperature last year was 0.94 degree Celsius (1.69 degrees Fahrenheit) higher than the 20th century average of 13.9° C (57° F). That slightly edges out 2015, the previous titleholder, by 0.04 degree C. Eight months during 2016 set new all-time highs. These included July, which was the warmest month ever recorded.
Scientists from the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA) shared the new heat-wave statistics January 18.
This is only the second time that the annual temperature record has been broken three years in a row, Deke Arndt said in a news conference. Ardnt is chief of the monitoring branch at NOAA’s National Centers for Environmental Information in Asheville, N.C. But the previous trio — 1939 through 1941 — don’t rank within the top 30 warmest years on record, he noted.
Last year’s heat helped set other records as well. As of January 17, for instance, the global extent (area) of sea ice is at its smallest point in potentially thousands of years. That is according to two types of data. The first are measurements of sea ice by the National Snow and Ice Data Center, based in Boulder, Colo. The other type are analyses of the historical sea ice coverage over the last few thousand years.
Greenhouse gases released by human activities such as the burning of fossil fuels have cranked up Earth’s thermostat over the past few decades. These gases trap heat that would otherwise escape into space. All 16 years in our current century rank among the 17 warmest on record.
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Fossil fuels aren’t solely to blame for 2016’s sweltering heat, says Kevin Trenberth. He is a climate scientist at the National Center for Atmospheric Research in Boulder, Colo. The 2015–2016 El Niño is among the three strongest on record. The phenomenon raised global temperatures by releasing pent-up heat from the ocean into the atmosphere.
The latest El Niño has ceased. But global warming is continuing. Within a decade or so, 2016’s heat will be par for the course even during non-El Niño years, Trenberth predicts. “The temperature record is like going up a staircase. And now with 2015 and 2016, we’ve seemed to go up another step,” he says. In the near future, some years may be a bit higher or lower than 2016. However, he adds, “I don’t think we’ll ever go back to the values we’ve seen in previous years.”
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annual Adjective for something that happens in every year.
atmosphere The envelope of gases surrounding Earth or another planet.
average (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
climate The weather conditions prevailing in an area in general or over a long period.
climate change Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.
El Niño Extended periods when the surface water around the equator in the eastern and central Pacific warms. Scientists declare the arrival of an El Niño when that water warms by at least 0.4 degree Celsius (0.72 degree Fahrenheit) above average for five or more months in a row. El Niños can bring heavy rainfall and flooding to the West Coast of South America. Meanwhile, Australia and Southeast Asia may face a drought and high risk of wildfires. In North America, scientists have linked the arrival of El Niños to unusual weather events — including ice storms, droughts and mudslides.
fossil fuel Any fuel — such as coal, petroleum (crude oil) or natural gas — that has developed in the Earth over millions of years from the decayed remains of bacteria, plants or animals.
global warming The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity.
greenhouse effect The warming of Earth’s atmosphere due to the buildup of heat-trapping gases, such as carbon dioxide and methane. Scientists refer to these pollutants as greenhouse gases. The greenhouse effect also can occur in smaller environments. For instance, when cars are left in the sun, the incoming sunlight turns to heat, becomes trapped inside and quickly can make the indoor temperature a health risk.
National Aeronautics and Space Administration (or NASA) Created in 1958, this U.S. agency has become a leader in space research and in stimulating public interest in space exploration. It was through NASA that the United States sent people into orbit and ultimately to the moon. It has also sent research craft to study planets and other celestial objects in our solar system.
National Oceanic and Atmospheric Administration (or NOAA) A science agency of the U.S. Department of Commerce. Initially established in 1807 under another name (The Survey of the Coast), this agency focuses on understanding and preserving ocean resources, including fisheries, protecting marine mammals (from seals to whales), studying the seafloor and probing the upper atmosphere.
Pacific The largest of the world’s five oceans. It separates Asia and Australia to the west from North and South America to the east.
phenomenon Something that is surprising or unusual.
sea An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.
thermostat A temperature sensor that allows a system to know when a change — either heating or cooling — is called for.