Submitted by nastratin t3_120uvpy in Futurology
grundar t1_jdmljf3 wrote
Reply to comment by SpiritualTwo5256 in There Is Still Plenty We Can Do to Slow Climate Change by nastratin
> No tipping points under 4C?
None with a timescale under 200 years, according to this paper published in Science.
If you feel the editors of Science have made an error in publishing that paper, you are free to take it up with them.
> the effect of carbon in the atmosphere is expected to last 200 years.
Sure, but other feedback mechanisms will tend to sequester it, and as a result warming will stop shortly after emissions stop.
The scientific consensus is that stopping emissions is enough to stop warming. The scenarios on p.13-14 of the IPCC report show clearly that warming stops shortly after net zero emissions are reached, and temperatures will decline after a period of net negative emissions (as in SSP1-1.9).
I recognize that some of these findings may be counterintuitive to you, but that just highlights how complex science is and how important it is to pay attention to the experts rather than our gut feelings.
vhutever t1_jdny7ma wrote
Warming WILL NOT STOP when emissions stop. Thus everything you have stated previously about the future is on track to slow emissions cannot be trusted.
grundar t1_jdoib2z wrote
> > The scenarios on p.13-14 of the IPCC report show clearly that warming stops shortly after net zero emissions are reached
>
> Warming WILL NOT STOP when emissions stop.
The climate scientists who wrote the IPCC report appear to disagree with you.
Do you have evidence that they are wrong? Or is that just your feeling on the matter?
vhutever t1_jdoj2dq wrote
Your link is not from the IPCC. It’s from a 2021 article from carbon tracker.org which a financial think tank. The other thing you posted literally does not say once emissions are stopped warming will stop. There is a lag in emissions and warming. You can find the evidence yourself I’m not here to do homework for you.
grundar t1_jdorcv9 wrote
> Your link is not from the IPCC.
The link I directed you to is indeed from the IPCC. I'll repeat it for you with the link included a second time for your convenience:
>> The scientific consensus is that stopping emissions is enough to stop warming. The scenarios on p.13-14 of the IPCC report show clearly that warming stops shortly after net zero emissions are reached
Note the domain: www.ipcc.ch
If you click the link I've given you twice now, you will see that it is indeed the IPCC WGI report, and you will see that the chart on p.13 and table on p.14 demonstrate that warming is indeed predicted to stop (and reverse) after net emissions turn negative for SSP1-1.9.
> a 2021 article from carbon tracker.org which a financial think tank.
You appear to be confused, as the other net zero link I posted goes to carbonbrief.org, and not "carbontracker.org", whatever that is. carbonbrief.org/about-us/ shows that the link I actually gave has a ton of climate and environmental scientists on its staff.
Feel free to head directly to the scientific papers cited in that article if you prefer primary sources; for example this paper from 2008, this paper from 2010, or this paper from 2020 concluding that warming will stop at net zero emissions.
As a point of interest, I'd never heard of "carbontracker.org" before you mentioned it, but I agree with you that it seems like a probable misinformation source.
> You can find the evidence yourself
I have, and I've linked it for you.
snikZero t1_jduqibw wrote
The (b) table doesn't seem to show a reduction in temperatures even under the most optimistic case.
SSP1-1.9 shows the total observed temperature increasing (the lighter part of the bar), something like +0.4°C. The darker part is warming to date.
The two optimistic scenarios describe net zero by 2050, followed by net negative emissions into 2081-2100.
However your general point that warming can still be managed is likely correct.
grundar t1_jdw5bsu wrote
> The (b) table doesn't seem to show a reduction in temperatures even under the most optimistic case.
The (b) table is looking at the change relative to the late 1800s.
For change relative to other periods, look at p.14, Table SPM.1, Scenario SSP1-1.9, Best Estimate:
- Near term (2021-2040): 1.5C
- Mid-term (2041-2060): 1.6C
- Long term (2081-2100): 1.4C
i.e., 0.2C estimated temperature decrease between mid-term and long term intervals.
Note that SSP1-1.9 reaches net zero CO2 in ~2057 (p.13, Figure SPM.4), so the end of the mid-term interval. In other words, 20-40 years of increasingly net negative CO2 emissions are projected to result in 0.2C lower temperatures.
snikZero t1_jdwf4fd wrote
Ah, you are correct. This isn't clear from the table on P13, the 'total warming' note underneath makes that ambiguous.
I would note though that SSP1-2.6 also describes a net zero by 2050 followed by negative emissions, but still sees a temperature increase by 2100.
grundar t1_jdwhh1x wrote
> I would note though that SSP1-2.6 also describes a net zero by 2050
SSP1-2.6 doesn't reach net zero until 2075 (p.13), so it has significant net positive cumulative emissions between 2050 and 2090 (the 2041-2060 and 2081-2100 intervals).
snikZero t1_jdwka51 wrote
I think you're looking at the CO2 output only graph, i suspect perhaps in aggregate they provide net zero for 2050.
In P12 Box SPM.1.1, and P14 note 25 (explicitly), both state net zero for that date.
It's also possible the graph doesn't align to the notes due to an error.
grundar t1_jdx1ggj wrote
> In P12 Box SPM.1.1, and P14 note 25 (explicitly), both state net zero for that date.
I believe you're misreading; from p.12 Box SPM.1.1:
>> "scenarios with very low and low GHG emissions and CO2 emissions declining to net zero around or after 2050, followed by varying levels of net negative CO2 emissions23 (SSP1-1.9 and
SSP1-2.6), as illustrated in Figure SPM.4."
Both are net zero around or after 2050.
Similarly for p.14 Note 25:
>> "SSP1-1.9 and SSP1-2.6 are scenarios that start in 2015 and have very low and low GHG emissions, respectively, and CO2 emissions declining to net zero around or after 2050,
followed by varying levels of net negative CO2 emissions."
Both locations clearly note that the scenario may reach net zero after 2050.
> I think you're looking at the CO2 output only graph, i suspect perhaps in aggregate they provide net zero for 2050.
None of the other GHG graphs reach net zero even by 2100, so net zero GHG emissions always occurs after net zero CO2 emissions.
snikZero t1_jdxqzsf wrote
You make good points. I considered that the increase in aerosols for that projection might have influenced the net-zero date, but I see from the 1900's comparison graphs that they have a lesser relative effect.
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