2019 ended Earth's warmest decade since record-keeping began, scientists say

Show Caption Hide Caption Will temperatures continue to rise in the U.S.? If you think it's hot now, just wait. Heat waves are becoming more frequent globally. But how do we measure heat waves? We explain.

The last decade was the warmest on record, federal climate scientists announced Wednesday, with 2019 becoming the second-warmest year on record.

Global temperature records began more than 140 years ago in 1880. The warmest year recorded was 2016, which was just .07 degrees Fahrenheit warmer than last year.

Scientists from the National Oceanic and Atmospheric Administration and NASA made the announcement at the annual meeting of the American Meteorological Society in Boston.

NASA and NOAA are two keepers of the world's temperature data and independently produce a record of Earth's surface temperatures and changes based on historical observations over oceans and land. The results of this year's report closely parallel at least three other global temperature analyses.

Last year was 1.71 degrees Fahrenheit higher than the average from 1901-2000, the report said. The world’s five warmest years have all occurred since 2015, with nine of the 10 warmest years occurring since 2005. And the planet has now experienced 43 straight years (since 1977) with an above-average global temperature.

Natural environmental changes cannot explain this trend, said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies. It's human causes – including pollution, deforestation and, above all, greenhouse gas emissions – that are contributing to the high temperatures.

"We crossed over into more than 2 degrees Fahrenheit warming territory in 2015 and we are unlikely to go back," Schmidt said. "This shows that what’s happening is persistent, not a fluke due to some weather phenomenon: we know that the long-term trends are being driven by the increasing levels of greenhouse gases in the atmosphere."

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The rising temperatures are causing increases in some extreme events, such as heat waves, wildfires and intense precipitation. And it's costing us big: In 2019, the U.S. saw 14 separate billion-dollar disaster events, accounting for $45 billion in direct losses, the report said.

Alaska had its warmest year on record in 2019, with its annual temperature 6.2 degrees above the 1925-2000 average. The high temps caused wildfires and faster-than-normal seasonal snowmelt, bloating rivers and causing authorities to issue flood warnings. Southeast Alaska sustained record drought intensity.

Alaska is in a part of the world that is experiencing rapid temperature changes, the report said. The Arctic region has warmed slightly more than three times faster than the rest of the world since 1970.

In Australia, human-caused climate change is worsening wildfires that have led to the deaths of 28 people since September, destroyed more than 2,600 homes and burned about 25.5 million acres of land. Climate change has lengthened the fire season, decreased precipitation and increased temperature, according to the Australian Bureau of Meteorology.

Southern Australia, which has sustained the worst damage, has warmed by 2.7 degrees Fahrenheit since 1950, scientists say. And in December, the nation marked its hottest day ever recorded.

"We know that the planet is warming faster than any time during the history of human civilization on this planet," said Katharine Hayhoe, professor of atmospheric science at Texas Tech University.

"Climate change affects our health, our natural resources, the economy and even national security," she said. "Climate change isn’t just a science issue, or an environmental issue: it’s a human issue that matters to all of us living on this planet today, whether we know it or not."

Scientists say it's likely that the coming decade will be even hotter.

"Notwithstanding some sort of major, major geophysical event, it would be almost certain that this (coming) decade would be warmer than the previous – that we would break almost one annual record in the process," said Deke Arndt, chief of the global monitoring branch of NOAA’s National Centers for Environmental Information in Asheville, North Carolina.

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