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grundar t1_ittfxiz wrote

Renewables and EVs prevented about 70% of the CO2 emissions increase:
> "The rise in global CO2 emissions this year would be much larger – more than tripling to reach close to 1 billion tonnes – were it not for the major deployments of renewable energy technologies and electric vehicles (EVs) around the world."

Given that renewables have been growing at 25%/yr and EVs at 50%/yr, a 70% reduction is likely to turn into a >100% reduction (i.e., a decrease in emissions) within just a few years.

Note that 2022's rise of 300Mt will leave energy-related emissions about 0.7% below their 2018 peak, as emissions in 2021 were still 500Mt below 2018's level. There's a reasonable chance that will be exceeded in 2023, but also some chance it will not. Either way, it looks like energy-related emissions -- 3/4 of the total -- will end up being basically flat from 2018 to about 2025, and then will enter a permanent decline.

Roughly speaking, then, the world hit peak energy-related emissions about 4 years ago, will continue on its current plateau for another couple years, and then will see ongoing emissions declines. That decline will drive a peak and decline of total emissions as well, which as a result will likely slowly increase until 2025 or so before also declining. Fairly big news.

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IamChuckleseu t1_itueskn wrote

Decrease in emissions is not really possible as of now is it? CO2 is not going anywhere. We would have to start "harvesting" it.

% decrease in emissions is incredibly flawed metric. If you have 1000 imaginary units of CO2 and increase it by 100 then it was increase of 10%. Next year you have 1100. You now increase it by 105. Increase of only 9.5%. So growth slowed down right? Except that not really because 105>100. CO2 grew more than last time, only "slower" relative to total sum.

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grundar t1_itv8gqp wrote

> Decrease in emissions is not really possible as of now is it? CO2 is not going anywhere. We would have to start "harvesting" it.

I think you're confusing a decrease in emissions with a decrease in levels.

CO2 emissions are the amount the world pumps out every year. If we replaced all coal-fired power with non-emitting power, our emissions would fall dramatically.

CO2 levels are the fraction of the atmosphere that is CO2 molecules. If we replaced all coal-fired power with non-emitting power, but kept using gas-fired power and ICE vehicles, CO2 levels would still increase.

CO2 emissions are highly likely to start decreasing this decade. That means CO2 levels will still be increasing, but -- for the first time -- more slowly. That change -- yearly emissions flipping from increasing to decreasing -- is a necessary step towards net zero emissions.

> % decrease in emissions is incredibly flawed metric. If you have 1000 imaginary units of CO2 and increase it by 100 then it was increase of 10%. Next year you have 1100. You now increase it by 105. Increase of only 9.5%. So growth slowed down right?

I think you're confusing a decrease in emissions with a decrease in growth of emissions.

Fundamentally:

  • CO2 levels drive warming.
  • Emissions are the first derivative of CO2 levels.
  • Growth of emissions are the second derivative of CO2 levels.

If you imagine a curve, the second derivative declining and falling below zero is a necessary precondition for the first derivative to decline and fall below zero, which is itself a necessary precondition for the curve to start dropping to lower values.

Growth of emissions is the second derivative; it has been declining for years, and will drop below zero around 2025.
Emissions is the first derivative; it still start declining around 2025, and will drop below zero if/when we reach net zero.
CO2 level is the curve itself; it will not start declining until after net zero.

Clear?

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