More nuance. Same mechanism. Heat trapping gases.
Planet-warming pollution rates exploded after the end of World War II. James Watt’s steam engine launched the Industrial Revolution in 1769. Before that, for thousands of years, humans were clearing forested land for farming, releasing carbon from trees and plants into the atmosphere.
The severity of global warming has long depended on your frame of reference — on what temperature you think was normal for the Earth before humans began changing it. But what year should mark that moment?
That’s what makes a groundbreaking new temperature dataset released by a group of scientists based in the United Kingdom so striking. The datasets used to diagnose the modern history of the planet’s climate — and to proclaim that the world is now very near to 1.5 degrees Celsius (2.7 degrees Fahrenheit) of warming — typically begin with the year 1850.
The new one goes all the way back to 1781.
This extended time frame matters because greenhouse gases in the atmosphere increased 2.5 percent between 1750 and 1850, enough to have caused some warming that the data hasn’t accounted for.
The new temperature record, dubbed GloSAT, helps contribute to the growing sense among scientists that the Earth has warmed more than what calculations based on the 1850 starting year would suggest.
“That 1850 start time is one that’s chosen for essentially practical considerations, given the information that’s available,” said Colin Morice, lead author of the new study and a scientist with the Met Office Hadley Centre in the UK. “For sure, 1850 is not the start of industrialization.”
The new dataset, published in Earth System Science Data by 16 scientists, shows a significantly cooler Earth from the late 1700s through 1849 compared with 1850-1900 — the latter being what scientists have defined as the “preindustrial” baseline period used to assess the planet’s temperature change.
However, not all of the warming between the two early periods can be attributed to human activities, scientists caution.
Among other factors, two very powerful volcanic eruptions in the early 1800s had a marked cooling effect on the Earth. Particles from those eruptions spread around the planet’s stratosphere and blocked some sunlight.
“We know 1815 was Tambora, with well documented impacts,” said Ed Hawkins, a researcher with the National Centre for Atmospheric Science and one of the study’s authors. “The 1808 eruption was nearly as big, but we have no idea where it happened.”
Some of the warming that occurred by the late 19th century is a natural recovery from the cooling effect of these eruptions. But perhaps not only.
The leading climate science authority, the U.N. Intergovermental Panel on Climate Change, concluded in 2021 that there had probably been some human-caused warming between 1750 and 1850, assessing that it was between 0 and 0.2 degrees.
The scientists behind GloSAT come down right in the middle of that range.
Morice and many of the same researchers contributed to a second study, accepted in the journal Environmental Research Letters, which uses the new dataset and climate models to analyze how much additional warming humans may have caused between 1750 and 1850. That study, led by Andrew Ballinger of the University of Edinburgh, determined that 0.09 degrees of warming occurred that was attributable to humans, as opposed to other factors, such as the waning effect of the large volcanic eruptions seen in the early 1800s.
“This period of time is just so interesting, it’s got this large amount of volcanism in it,” said Andrew Schurer, one of that study’s authors and a researcher at the University of Edinburgh in the UK.
Piers Forster, a climate scientist at the University of Leeds in the UK, landed on a similar number using a very different approach in a study last year. Forster used the very strong and simple relationship between the planet’s temperature and how much carbon dioxide is in the atmosphere.
It led him to conclude that the very early rise in carbon dioxide levels would have had a significant effect.
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Meanwhile..
Reuters:
This year is set to be the world’s second or third-warmest on record, potentially surpassed only by 2024’S record-breaking heat, the European Union’s Copernicus Climate Change Service (C3S) said on Tuesday.
The data is the latest from C3S following last month’s COP30 climate summit, where governments failed to agree to substantial new measures to reduce greenhouse gas emissions, reflecting strained geopolitics as the U.S. rolls back its efforts, and some countries seek to weaken CO2-cutting measures.
This year will also likely round out the first three-year period in which the average global temperature exceeded 1.5 degrees Celsius (2.7 degrees Fahrenheit) above the 1850-1900 pre-industrial period, when humans began burning fossil fuels on an industrial scale, C3S said in a monthly bulletin.
“These milestones are not abstract – they reflect the accelerating pace of climate change,” said Samantha Burgess, strategic lead for climate at C3S.
Extreme weather continued to hit regions around the globe this year. Typhoon Kalmaegi killed more than 200 people in the Philippines last month. Spain suffered its worst wildfires for three decades because of weather conditions that scientists confirmed were made more likely by climate change.
Had to look up that temperature spike ~1878: gigunda El Niño.