At a time of climatic anxiety, 2019 was the second warmest year since scientists began taking temperatures in 1880, government scientists announced Wednesday.
The almost record temperatures consolidated the title of the last decade as the warmest in modern human history, according to data from NASA and the National Oceanic and Atmospheric Administration. Each of the last five years was among the five warmest years recorded, NASA said.
The constant increase in terrestrial and ocean temperatures throughout the world has been driven by greenhouse gas emissions since the beginning of the Industrial Revolution.
“The last decade is the warmest,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies in New York, at the annual meeting of the American Meteorological Society in Boston.
“Every decade since the 1960s has been warmer than the previous decade, and not for a small amount,” he added.
This warming trend will probably not slow down in the short term, said Derek Arndt, head of climate monitoring at the NOAA National Environmental Information Centers in Asheville, North Carolina.
“Despite some kind of major, major geophysical event, it would be almost certain that the [coming] the decade will be warmer than the previous one, “he said at the meteorological society meeting. And, he said,” it is almost certain that we will beat at least one annual record. ”
In 2019, the average global surface temperature was 1.71 degrees above the 20th century average of 57 degrees Fahrenheit, according to NOAA measurements. That was only 0.07 of a grade less than the record of 1.78 degrees set in 2016.
NASA set the 2019 global temperature at 1.77 degrees Fahrenheit above the average of 1951 to 1980, within a spit distance of the 2016 record anomaly of 1.83 degrees.
Each agency conducts its own analysis using temperature readings from thousands of terrestrial weather stations worldwide, as well as buoys floating in the oceans. Minor differences in their methods produce slight variations in numbers, but the results are on par when it comes to the pace and direction of global warming.
The last five years were exceptionally warm, with only small differences that were driven by natural variations in weather patterns, the scientists said.
“We have seen very clearly in the long term [with] many decades of temperature observations from around the world that global temperature is rising, “said Noah Diffenbaugh, a climate scientist at Stanford University who was not involved in the analyzes.
Periodic weather patterns can play a small role in raising or lowering temperatures, Schmidt said. For example, 2016 secured the title with a small push from the El Niño warming up.
If the effects of El Niño and La Niña were eliminated, the ranking of the warmest years could change slightly: 2017 would have taken first place, with 2016 degraded to second place and 2019 taking third. But the general warming trend continues without diminishing, Schmidt said.
Diffenbaugh agreed. “The signal of that warming is very strong compared to the fluctuations from year to year and from decade to decade that occur as a result of the variability in the ocean and the atmosphere,” he said.
Earth’s climate has undergone a natural variation on prolonged time scales, but the speed and ferocity of global warming since the 19th century have been anything but natural, the researchers said.
Benjamin Santer, an atmospheric scientist at the Lawrence Livermore National Laboratory, said researchers have done everything possible to discover how various natural phenomena leave their mark on the planet’s climate dynamics.
“And the message of that climatic fingerprint, of pattern analysis, is that nature could not do this,” Santer said. “No combination of natural cycles, changes in the sun’s energy production, recovery from volcanic eruptions, could generate the observed changes.”
The onslaught of global warming at the highest latitudes continued unabated this year, with continued losses of ice mass in Greenland and Antarctica. The Arctic has warmed a little more than three times faster than the rest of the world since 1970, authorities said. The annual extent of sea ice dropped to its second lowest level in both the Arctic (around 3.94 million square miles) and the Antarctic (4.16 million square miles).
Alaska saw its warmest year recorded, with an average annual temperature of 32.2 degrees Fahrenheit. That was 6.2 degrees above the average of 1925-2000, the scientists said.
The rising temperature of the Earth’s surface has probably played a role in the growth of certain extreme weather events, both in number and intensity. For example, scientists say warming has led to drier conditions in some areas, which could make droughts worse or increase the risk of forest fires. Higher temperatures have caused sea levels to rise, making dangerous storms more likely and causing hurricanes to shed more rain.
According to the NOAA National Environmental Information Centers, in 2019 there were 14 climatic and climatic events in the United States with losses that exceeded the $ 1 billion mark. That made it the fifth consecutive year with 10 or more billions of dollars in climate or climate disasters. (Between 1980 and 2019, the average number of such events was 6.5 per year; in the last five years, that figure soared to 13.8).
These natural disasters included floods, severe storms, tropical cyclones and forest fires. The California and Alaska wildfires that burned during the summer and fall of last year caused estimated losses of $ 4.5 billion. Large floods generated $ 20 billion in damage, and severe storms left a bill of almost $ 14 billion in its wake. In total, the 14 events resulted in losses of $ 45 billion and 44 deaths, NOAA found.
Meanwhile, President Trump fulfilled a campaign promise by initiating the formal withdrawal of the United States from the Paris climate agreement. The international agreement aims to reduce greenhouse gas emissions and limit global warming to “well below” 2 degrees Celsius (or 3.6 degrees Fahrenheit) above pre-industrial levels, and aim at a limit of 1.5 degrees Celsius.
Measurements from NASA and NOAA indicate that the limit is fast approaching, Schmidt said.
“It is the first decade that is clearly 1 degree Celsius above the end of the nineteenth century we have had,” he said.
Warming since the 1970s has been relatively linear, Schmidt noted. If that trend continues, Earth could cross the 1.5-degree mark for the first time around 2035, although it could zigzag back and forth above that threshold before ascending steadily forward.
“But, of course, that depends on what we do with the emissions, and we can’t tell you by looking at the past how society will really react to this information,” he said.
The year 2019 ended with large forest fires in eastern Australia, while firefighters continued to fight fires in California. Dueling fire seasons offered an example of how climate change could put pressure on humans’ ability to cope with natural disasters.
As California and Australia are in different hemispheres, their fire seasons have been staggered, allowing them to share firefighting personnel and other resources. But if increasingly hot and dry conditions cause overlap in global fire stations, those resources could become increasingly tense, Diffenbaugh said.
“When weather events fall outside the historical envelope of what our systems are designed, then that is where we really see the most acute pressures,” he said.