2° C (3.6°F) - What does it mean?
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In 2015, the 196 nation signatories to the Paris Agreement, committed to keeping the mean rise in global temperatures below 2° C (3.6° F) above pre-industrial levels and preferably limit any increase to 1.5° C (2.7° F). Although there is nothing magical about the 2° figure, it is not a meaningless number.
“…[I]t would be wrong to infer that two degrees was just plucked from thin air, cautions Michael Mann, director of the Penn Center for Science, Sustainability and the Media at the University of Pennsylvania.
‘Clearly there is no absolute threshold,’ he says. ‘It’s more a somewhat objective definition of where we move from ‘bad’ into ‘really bad’ territory. Two degrees Celsius is a reasonable dividing line where we cross into the ‘red’ across all areas of concern.’
‘Well, 1.2°C warming, which is where we are, is too much,’ says Mann. ‘We’re already seeing devastating consequences. So, it’s really a question of just how bad we’re willing to let it get. 1.5°C would be bad, two degrees really bad, and three degrees is perhaps, as I argue in my new book Our Fragile Moment, civilization ending.’
Mann notes that a 2018 Intergovernmental Panel on Climate Change (IPCC) report found that the difference between 1.5°C of warming and two degrees could be devastating.
‘Basically, what it shows is that the additional 0.5°C of warming would likely mean the loss of Arctic sea ice, three times as much extreme heat, far greater levels of extinction and the possible loss of coral reefs across the planet. It would take us even closer to the tipping points for loss of Greenland and West Antarctic Ice Sheets (and the meters of sea level rise that go with it). Pretty stark stuff,’ he says.
Additionally, of course, an average global increase is just that— an average. Some places, such as the Arctic, are warming four times more quickly than the rest of the planet; what may seem like a moderate amount of sea level rise in parts of the United States, could be catastrophic in low-lying Pacific Island states.
For that reason, such states have been at the forefront of emphasizing the importance of limiting warming to 1.5°C. …”
What's the big deal about Earth getting 2° hotter? Kieran Mulvaney, National Geographic, December 1 2023
2024 Temperatures Are on Track for a Record High, Researchers Find*
“This year will almost certainly be the hottest year on record, beating the high set in 2023, researchers announced on Wednesday.
The assessment, by the Copernicus Climate Change Service, the European Union agency that monitors global warming, also forecast that 2024 would be the first calendar year in which global temperatures consistently rose 1.5 degrees Celsius above preindustrial levels. That’s the temperature threshold that countries agreed, in the Paris Agreement, that the planet should avoid crossing. Beyond that amount of warming, scientists say, the Earth will face irreversible damage.
Greenhouse gas emissions from the burning of fossil fuels are dangerously heating up the planet, imperiling biodiversity, increasing sea level rise and drought and making extreme weather events more common and more destructive…
Still, it’s important to note that a single year above 1.5 degrees Celsius does not mean the Paris Agreement target has been missed.
Under the terms of the pact, for that to happen, temperatures would have to stay at or above 1.5 degrees over a 20-year period. Each year has natural variability, so one year that’s warmer or cooler is not as important as the general trend of warming. It’s that signal, the steady crawl of record hot year after record hot year, that has alarmed experts….”
The New York Times, Nov 6, 2024 by Austyn Gaffney
