Climate Change: NASA, NOAA Say 2018 Was 4th-Hottest Year Ever Recorded

Global temperatures fueled by climate change continue to rise, according to two separate analyses of global temperature data released Wednesday. Both NASA and the National Oceanic and Atmospheric Administration (NOAA) determined that 2018 was the fourth warmest year on record. Scientists agree that this warming has largely been driven by increased emissions into the atmosphere of carbon dioxide and other greenhouse gases, byproducts of human activity.

Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, told reporters that the “impacts of long-term global warming are already being felt” through coastal flooding, heat waves, intense precipitation, and ecosystem change. These increasing temperatures also contribute to longer fire seasons and more extreme weather events.

These extreme weather events not only severely impact human lives but also cost the United States billions of dollars. According to NASA and NOAA, there were 14 “billion-dollar disasters” in 2018 — events that caused at least $1 billion in direct losses. In fact, these disasters accounted for $91 billion in direct losses. The western wildfires alone accounted for $24 billion of that total.

Last year’s temperature ranks behind 2016, 2017, and 2015. Collectively these past four years represent the warmest years in the modern record. Specifically, NASA determined that global temperatures in 2018 were 1.5 degrees Fahrenheit warmer than the 1951 to 1980 mean, the period of time that the agency uses as a control for these analyses. NOAA, meanwhile, determined that the 2015, 2016, and 2017 each had a global temperature departure from the average that was more than 1.8 degrees above the 1880 to 1990 average — the period of time that NOAA uses as its own control.

These temperature analyses incorporate surface temperature measurements from thousands of weather stations, ship- and buoy-based observations of sea surface temperatures, and temperature measurements from Antarctic research stations. Both agencies are confident in their results, which they describe as quite “robust.”

Deke Arndt, chief of the monitoring section at NOAA’s National Centers for Environmental Information, told reporters Wednesday that despite the slight variations in temperatures that are seen annually, there is a clear warming pattern that’s been consistent over the past four decades.

Arndt says that the pattern resembles “riding up an escalator up in time, then jumping up and down while you’re on that escalator.” The “jumping” in his analogy are the variations driven by internal processes, such as weather-producing phenomena like El Niño and La Niña. These are, respectively, the warm and cool phases of a recurring climate pattern across the tropical Pacific, which make up a pattern of shifting temperatures. Overall, though, the escalator is still going up.

2018 began with a La Niña episode across the tropical Pacific Oceans, which accounts for why it was slightly cooler than 2017. Schmidt says that if you took away the effects of these episodes, 2018 would have been the third warmest year, over 2017. Because 2019 is starting with mild El Niño conditions, Schmidt predicts that 2019 will be warmer than 2018.

Arndt also notes that one of the emerging themes of the 21st century is that “morning time temperatures are increasing more rapidly than afternoons, and we’ve seen the vast majority of the months play this out.” He explains that this daily variation is part of an overall warming trend.

Globally, the effects of climate change pockmarked the planet in severe anomalies. The United States was plagued by both severe drought and intense precipitation last year, making 2018 the wettest year on record for the country. Heavy rain triggered floods and mudslides across parts of Hawaii, while Asia set a new continental maximum temperature record for March when temperatures in Pakistan reached 113.9 degrees Fahrenheit. Australia had its third warmest year on record, while 2018 was the warmest year on record for much of Europe.

But while these are considered anomalies, the scientists say the events do fit into the overall warming trend they’ve observed. The notable exception, they reveal, is the Arctic — where the rate of warming is happening two to three times faster than it is in the rest of the world. Billions of tons of ice has been lost there, contributing to the planet’s overall sea level rise.

“The impacts of these changes on the global mean are really being felt in the Arctic, much more strongly than say the tropics,” explains Schmidt. “I’m very concerned by what is happening there.”