alt Hacker NewsFWIW my personal assessment is that this acceleration is both real and largely out of our control. Models in the past did not attempt to account for non-anthropogenic carbon emissions, but as we experience further warming, most especially in the Arctic, feedback loops and tipping points mean that this (carbon emissions caused by “natural” processes) are becoming more evident. This is especially sensitive because a large proportion of such emissions are methane, which is a much more powerful greenhouse gas vs CO2, albeit with a much shorter expected effect time once airborne (~12 years). Consider also that warming is not uniform and the polar regions are warming significantly faster (3x) than lower latitudes, making permafrost melting a very significant climate tipping point. The last point I’ll mention is not about non-anthropogenic emissions but rather absorption. The world’s oceans have been a significant absorber of CO2 however that process is sensitive to temperature and is less effective as the planet warms, not to mention acidic ocean waters prevent shell formation, which is a minor but meaningful carbon sink all by itself.
I’m of the opinion that direct air capture is the primary escape hatch we have for not hitting 3 or even 4C warming in the next 100-200 years, which mean major dieoffs in warm latitudes, even for humans, due to exceeding wet bulb limits. Oh and roughly 65M of sea level rise as the planet shifts to a snow/ice-free mode.
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> major dieoffs in warm latitudes, even for humans, due to exceeding wet bulb limits
my extremely pessimistic position is nothing will happen systemically even after the first few such events, and they'll take tens if not hundreds of thousands of lives.
I hope writing this out jinxes it.
Albedo modification (stratospheric aerosols) seems much cheaper than direct air capture, as a stopgap.
Re carbon capture -- we can cut trees and dump them in "carbon storage" places like the bottom of some water bodies where due to lack of oxygen no rotting happens, like peats and e.g. Black Sea.
And grow new trees in their place of course.
Excellent comment. I would only add two points.
I think it's important to mention the effects we're seeing today are caused by the emissions from decades ago.
Second, not sure if the paper in the OP touches this but we've reduced aerosols in the atmosphere. These previously were masking the effects of climate change by cooling the temperature.
> Oh and roughly 65M of sea level rise as the planet shifts to a snow/ice-free mode.
Current rates of sea level rise are still in single digit millimetres per year (https://en.wikipedia.org/wiki/Sea_level_rise), so that would take millennia. If there's even enough ice in the caps to get that far. Pre-historically, vast ice sheets covered broad swaths of regions now considered "temperate" (per the famous XKCD, "Boston [was] buried under almost a mile of ice"); what remains is a tiny portion and it's simply hard to imagine that it could fill the seas to such an extent.
If you have detailed calculations, please feel free to cite them. But my back-of-the-envelope reasoning: NOAA gives an average sea depth (https://oceanservice.noaa.gov/facts/oceandepth.html) of 3,682 meters. You propose that this could increase by nearly 2%. But the density of water only exceeds that of ice by about 9% (via https://en.wikipedia.org/wiki/Ice); the thickness of the https://en.wikipedia.org/wiki/Antarctic_ice_sheet is only about half that average sea depth; and it covers only about 4% of the water-covered area of the planet (14 million km^2 vs. 361 million km^2, per https://en.wikipedia.org/wiki/Earth) which is not even all oceanic.
What about solar shades? Seems like a relatively quick and easy way to regulate solar input. It's nice too because you can quickly remove it if necessary.
Regarding carbon capture, it will take more energy to capture the carbon than we burned putting it up there in the first place. Alan Kay, who actually did some systems work on the environment, explained it to me that the climate system is like an upside down coke bottle. It doesn't take much energy to tip it over, but it takes a lot more to put it back up.
In other words, we shouldn't have tipped it over in the first place. We may not have the energy to put things back to a habitable place.
What if global warming is beneficial to keep the next ice age at bay?
Can't wait until the arctic unwinds and releases massive amounts of methane into the air, then in the hot hell that earth becomes, all the fucking idiots saying "See I told those stupid liberals that the warming process was natural and not from my truck!!!1!1"
> Oh and roughly 65M of sea level rise as the planet shifts to a snow/ice-free mode
65M seems a lot bigger than the 3.6mm/year rise we are seeing today (with +1.5C in warming already happening). Where did you read that we will get 65M of sea level rise with 1.5-2.5C more warming?
> Oh and roughly 65M of sea level rise as the planet shifts to a snow/ice-free mode.
Where is this new figure coming from? It seems about 60X what's being published elsewhere.
> direct air capture is the primary escape hatch
We MUST MUST MUST stop burning things. Stop it.
- We are still mining and burning coal. This is incomprehensible. US, AU, etc Eg: https://www.nacoal.com/our-operations
- We are still subsidizing oil to around $1T/year, not counting oil wars.
Yes it will take some grid and storage upgrades (US) and continue to embrace renewables. It would be cheaper than the oil subsidy.
Otherwise it doesn't make sense to put CO2 into the air with one hand and take it out with another.
No offense, but internet opinions are a dime a dozen -- do you have some special experience / credentials in this area? The arguments you provide are all just the sort of thing that PhD students would study, and incorporate into their models. I'm inclined to believe the experts, but if you _are_ one, and are saying with authority that these effects are missed, that is a much more interesting story.
> I’m of the opinion that direct air capture is the primary escape hatch
Great! That means we dont need to reduce emissions, cuz the magic bullet will just take care of everything. No need to change anything.
Relying on DAC is putting our fate in the hands of a technology we've never deployed beyond some pitifully small pilot projects, and expecting that we're going to be able to deploy that at a larger scale than we've deployed any technology since electricity itself.
We're going to have to resort to geoengineering alright, but it's gonna likely be stratospheric sulfate injection given how cheaply that can be done. Is it ideal? Nope. Better than global warming itself? Time will tell.
> I’m of the opinion that direct air capture is the primary escape hatch we have for not hitting 3 or even 4C warming in the next 100-200 years
Why is it always never 'burn less fossil fuels'.
Anything but the oil company bottom line huh?
> Models in the past did not attempt to account for non-anthropogenic carbon emissions
They're literally mentioned by the first IPCC report already.