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Humans have caused 1.5 °C of long-term global warming according to new estimates

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399 points gmays | 6 comments | 17 Nov 24 18:49 UTC | HN request time: 0.602s | source | bottom
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jmyeet ◴[17 Nov 24 19:17 UTC] No.42166284[source]▶
Call me pessimistic but I don't think anything is going to change and a lot of people are going to die due to climate-forced migration.

That being said, it's a difficult topic to discuss rationally. Part of the issue is deciding on what your baseline is. Looking at the last 200 years tells a pretty limited view. Consider around 100,000 years ago when global temperatures were similar [1].

That raises some questions about what caused that spike but, more importantly, what caused it to lower. You can say "an ice age" but what really triggers an ice age?

My point here is that doomsday predictions of Venus-like runaway inflation I think are both unrealistic and unhelpful in actually motivating people about an otherwise very real problem. We really have no idea of the mechanics in place.

But like I say, we're going to do absolutely nothing about it anyway.

[1]: https://www.pbs.org/newshour/science/analysis-is-it-actually...

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1. pavlov ◴[17 Nov 24 19:33 UTC] No.42166419[source]▶
The rate of temperature change happening currently is much greater than anything in the geologic record.

What use it is to ponder about what has triggered an ice age in the past, when that mechanism can’t possibly counteract what’s happening now?

It’s like thinking about starting blood pressure medication when you’re having a heart attack right now.

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2. yobbo ◴[17 Nov 24 19:43 UTC] No.42166505[source]▶
I don't think ice-core measurements give year-by-year resolution good enough to determine this, but it would be interesting to know if someone proved it.
3. jmyeet ◴[17 Nov 24 20:33 UTC] No.42166969[source]▶
That's not true [1]:

> There are twenty-five of these distinct warming-cooling oscillations (Dansgaard 1984) which are now commonly referred to as Dansgaard-Oeschger cycles, or D-O cycles. One of the most surprising findings was that the shifts from cold stadials to the warm interstadial intervals occurred in a matter of decades, with air temperatures over Greenland rapidly warming 8 to 15°C (Huber et al. 2006). Furthermore, the cooling occurred much more gradually, giving these events a saw-tooth shape in climate records from most of the Northern Hemisphere (Figure 1).

The last time I brought this up, someone said (paraphrased) "that's only over Greenland". Yeah, the place they did measurements. Do you really think a change in air temperature of 8-15C over decades is repeatedly localized in just one place?

[1]: https://www.nature.com/scitable/knowledge/library/abrupt-cli...

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4. fwip ◴[17 Nov 24 21:07 UTC] No.42167255[source]▶
Well, the link you cite puts forward 2 hypotheses that could explain localized temperature change in Greenland, and does not mention "maybe this was global temperature change."
5. Timon3 ◴[17 Nov 24 22:27 UTC] No.42167931[source]▶
> Do you really think a change in air temperature of 8-15C over decades is repeatedly localized in just one place?

I don't understand your point. This isn't a question where we have to extrapolate from this one study - you can look at similar measurements done in other places and answer this question once and for all.

Instead, you simply declare the hypothesis wrong, because...? You don't bring up an argument, you just ask whether others really think that.

6. defrost ◴[17 Nov 24 22:45 UTC] No.42168054[source]▶
> Do you really think a change in air temperature of 8-15C over decades is repeatedly localized in just one place?

Sure .. we can see this kind of "stutter" in dynamic environments all the time, vortexes "pulsing" in stream water for example.

The "rapid warming" followed by "slow cooling" pattern speaks to a lower tempreture being the long term natural stable temp. for the local region duringthat much longer period .. but interrupted by a pulsing in the climatic cell stability that routinely brings warmth in from the equatorial zone - likely via water currents, possibly via air currents.

Such things can happen during stable global mean land|sea energy levels as that's literally just an average of the activity of all the cells across the planet.