The decade that just ended was by far the hottest on Earth yet, ended by the second warmest year on record, two US agencies reported on Wednesday. And scientists said they do not see the end of the way in which man-made climate change continues to break records.
"This is real. This is happening," said Gavin Schmidt, director of NASA's Goddard Institute for Space Studies, at the end of a decade plagued by wildfires, ice melting and extreme weather conditions that researchers have repeatedly linked to human activity.
The years 2010 averaged 58.4 degrees Fahrenheit (14.7 degrees Celsius) worldwide, or 1.4 degrees (0.8 C) above the 20th century average and over one third of a degree (one fifth of a degree C) warmer than the previous decade, which was the warmest on record, according to the National Oceanic and Atmospheric Administration.
The decade had eight of the ten warmest years on record. The only other years in the top 10 were 2005 and 1998.
NASA and NOAA also calculated that 2019 was the second hottest year in 140 years of record keeping. Five other global teams of monitoring scientists agreed, based on temperature readings taken at the Earth's surface, while several satellite-based measurements said it was between the warmest year on record and the third warmest year.
Several scientists have said that the next few years will be even hotter, taking those years off the record books.
"If you think you've heard this story before, you haven't seen anything yet. It will be part of what we see every year until we stabilize greenhouse gases" by burning coal, oil and gas, said Schmidt, who was at the convention. American Meteorological Society in Boston, where it was so hot on the weekend that he ran in shorts and a T-shirt. Boston had its hottest day in January on Sunday, at 74 degrees, 2 degrees hotter than the previous record.
"It is worrying to think that we may be breaking global temperature records in rapid succession," said Georgia Tech climate scientist Kim Cobb. "2020 is starting with a horrible climate, and I fear what the rest of the year will bring to our door."
NASA's Schmidt said overall the earth is now about 1.2 degrees C (almost 2.2 F) warmer since the start of the industrial age, a significant number because in 2015 global leaders adopted a target prevent 1.5 C (2.7 F) from heating since the emergence of large industry in the mid-19th century. He said it shows that the overall goal cannot be achieved. (NOAA and the World Meteorological Organization have reduced warming slightly since the industry started.)
"We have strong human-induced global warming," said Friederike Otto, a climate scientist at the University of Oxford. "What we observe here is exactly what our physical understanding tells us to expect and there is no other explanation."
Other explanations that are based on natural causes – extra heat from the sun, more reflection of sunlight due to volcanic particles in the atmosphere and just random variations in climate – "are too small to explain the long-term trend," Princeton University climate scientist Michael Oppenheimer said.
Scientists said a decade's data is more revealing than year-to-year measurements, where natural variations like El Nino, the periodic warming of the Pacific Ocean, come into play.
"Man-made climate change is responsible for long-term warming – it is responsible for the years 2010 being warmer than the 2000s, which were warmer than the 1990s, etc.," said Andrew Dessler, climate scientist at A&M University of Texas. "But humans are not responsible for why 2016 was hotter than 2015 or why 2019 was hotter than 2018".
NOAA said the global average temperature in 2019 was 58.7 degrees (14.85 C), or just a few hundredths of a degree behind 2016, when the world received extra heat from El Nino. That's 1.71 degrees (0.95 C) above the 20th century average and 2.08 degrees (1.16 C) warmer than the late 19th century.
The past five years have been the warmest five on record, almost 1.7 degrees warmer than the 20th century average, according to NOAA.
The last year the Earth was colder than the 20th century average was in 1976, before the birth of Democratic presidential candidate Pete Buttigieg, French President Emmanuel Macron and Donald Trump Jr.
If you want to know what it means for people and the world, just look at Australia that was hit by a fire, said Schmidt and others.
Global warming is already being observed in hot flashes, ice sheet melting, more fires, stronger storms, flood-inducing rains and accelerated sea level rise, said Hans-Otto Portner, chief of the Intergovernmental Panel's team. Climate Change, which analyzes the impact of climate change.
Renee Salas, a Boston emergency room physician and Harvard professor who studies the health effects of climate change, said that "these temperatures are not just statistics, but have names and stories", mentioning a construction worker and a man elderly without air conditioning that were his patients this summer.
"The planet has a fever," said Salas, "and that's the symptom."
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