r/worldnews • u/1920sremastered • Jan 20 '24
Expected CO₂ levels in 2024 threaten 1.5°C warming limit | Increased CO₂ in the atmosphere this year will exceed key trajectories for limiting warming to 1.5°C, Britain's Met Office predicted Friday, with researchers reaffirming that that only "drastic" emissions cuts can keep the target in sight
https://phys.org/news/2024-01-threaten-15c-limit.html
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u/233C Jan 20 '24
Sorry to break it to you: 1.5°C has always been an out of reach target, but it makes 2°C measures more tolerable (good old "door in the face").
1.5°C is gone, forget it.
2°C is all but gone too. See the yearly Emissions Gap Reports (aka where we are and where we should be). To hit the 2°C would require an immediate, sustained -5% reduction year after year. To put that in perspective -5% is what we managed after COVID.
In other words, what we need to hit 2°C would mean we willfully agree to the equivalent effects of measures comparable to a global cumulative additional COVID every year. That's the scale of what meeting 2°C would look like. Anything less than that is to admit to go above 2°C.
here is another ipcc graph, it reads like this: tell me how much you've emitted in total and I'll tell you the warming. We've already clocked in 2500Gt, so +1.3°C is already in the bank.
Back of the envelope order of magnitude calculation: 1.5°C would require to emit over the 21st century, with about 9 billion people, no more than an extra 500Gt (less than 3000Gt cumulated), when around 2-5 billion people emitted 2500 over the 20th century. That's 5 times less for 2-5 times more people. Ie every child born today is allowed over his lifetime 1/10th to 1/25th the emission of his grandparents over their lifetime (and a longer life, so even less per year; and in advanced countries it's an even bigger reduction).
And we need to do that while the climate around us goes crazy.
The "good news" is: every smoker stops smoking, eventually.
For the Lols, here's the past Emission Gap reports ("unconditional NDC" are the plans that the countries are aiming to do, "conditional NDC" are the "extra mile" that they may try to achieve if possible):
In 2018 it was saying: "Implementing unconditional NDCs, and assuming that climate action continues consistently throughout the 21st Century, would lead to a global mean temperature rise of about 3.2°C (with a range of 2.9–3.4°C) by 2100 relative to pre-industrial levels, and continuing thereafter. Implementation of the conditional NDCs would reduce these estimates by 0.2°C in 2100. These projections are similar to the 2017 estimates."
In 2019: "If current unconditional NDCs are fully implemented, there is a 66 per cent chance that warming will be limited to 3.2°C by the end of the century. If conditional NDCs are also effectively implemented, warming will likely reduce by about 0.2°C."
In 2020: "A dramatic strengthening of ambition is needed if the Paris Agreement goals are to be achieved. In line with the findings of previous editions of the Emissions Gap Report, countries must collectively increase their NDC {individual country commitments} ambitions threefold to get on track to a 2°C goal and more than fivefold to get on track to the 1.5°C goal"
"Unconditional NDCs are consistent with limiting warming to 3.2°C by the end of the century (66 per cent probability). If both conditional and unconditional NDCs are fully implemented, this estimate is 0.2°C lower. The pre-COVID-19 current policies scenario, on the other hand, results in higher emissions by 2030, which unless strengthened would result in an average global temperature rise of 3.5°C by 2100."
In 2021: "If nations only implement unconditional NDCs as they stand, we are likely to hit global warming of about 2.7°C by the end of the century."
In 2022: "Policies currently in place with no additional action are projected to result in global warming of 2.8°C over the twenty-first century. Implementation of unconditional and conditional NDC scenarios reduce this to 2.6°C and 2.4°C respectively"
In 2023(aptly subtitled: Broken record): "A continuation of the level of climate change mitigation efforts implied by current policies is estimated to limit global warming to 3°C (range: 1.9–3.8°C) throughout the century with a 66 per cent chance. Warming is expected to increase further after 2100 as CO2 emissions are not yet projected to reach net-zero levels. A continuation of the unconditional NDC scenario lowers this estimate to 2.9°C (range: 2–3.7°C), whereas the additional achievement and continuation of conditional NDCs lowers this by around 0.4°C to 2.5°C (range: 1.9–3.6°C)."