This is a nice notion, but ignores the feedback cycles which have already been set in motion - at this point, reducing our emissions to zero may provide little benefit, as as the Arctic and Antarctic thaw, relict methane is being emitted at an alarming rate, wildfires are becoming far more frequent globally, and oceans are no longer functioning terribly well as carbon sinks, further pushing emissions.
I'm not saying we shouldn't try, but I fear we're already past the point of no return for catastrophic climate change.
Realistically, extreme negative emissions are a practical impossibility. Zero emissions are as well.
We still have an opportunity to reduce the extent of the damage. Major climate change is likely inevitable at this point as, realistically, the modest measures taken to date are insufficiently binding to be effective.
I don't think we've past the point of no return, yet, but we will certainly do so at some point given the real cost of taking action appears to grow faster than the political will to take action.
This is a really common kind of comment to this issue, but I think it's extremely short-sighted. At this point, because we're probably well past the point that anything we can practically do is likely to get us to net zero carbon before catastrophe (it's already here, really), we're at a point where we're probably going to need to go extremely negative even once we do get there. We're (ironically) going to need a lot of non-carbon-sourced energy to do that, it seems to me.
We can't just be thinking about what we'll do to stem the tide, we have to keep working on how we're going to push it back.
Reaching zero emissions is just a start. We need to reach strong negative emissions in the next 2-3 decades.
Consider the following points:
1) Climate lag. There is a 40 year delay between emissions and effects on the climate so the effects we are now seeing are from the emissions from the late 70s early 80s. We have emitted more GHG in the last 40 years than between 1850 and 1980. Even if a miracle happened and we reached zero emissions today we have a huge climatic bill ahead of us in the next 40 years.
2) Self sustaining climatic systems commonly called feedbacks. These systems once triggered will keep affecting the climate even if we reach zero emissions. Eg: melting of Arctic ice, permafrost methane, etc.
3) There are currently 405ppm of CO2 in the atmosphere which will remain there for centuries and will keep having an effect on the climate unless we remove it.
From the last IPCC report:
> There is sufficient uptake capacity in the ocean to incorporate 70 to 80% of foreseeable anthropogenic CO2 emissions to the atmosphere, this process takes centuries due to the rate of ocean mixing. As a result, even several centuries after emissions occurred, about a quarter of the increase in concentration caused by these emissions is still present in the atmosphere.
4) It is usually stated that we are at about 1ºC of warming right now, but until recently the cooling effects of aerosols in the atmosphere were not well understood. A recent paper from 2019 showed that it's likely there is a lot more cooling going on and we could already be at about 2ºC of warming. This would mean we are in a much more difficult position than commonly believed.
I'm under the impression that the climate feedback loops have developed too much inertia for us to counter with a technical solution that could reduce or even reverse climate change at this point. Even if the world stopped emitting carbon tomorrow we're still going to coast past the IPCC's recommended limits and straight into the worst-case scenarios before the end of the century.
While I still think it's a worthy cause to reduce and sequester carbon I think we shouldn't be thinking about how to reverse this.
We're going to have to live in a world with reduced fresh-water supplies, a dwindling supply of usable soil, and migrant populations. That's going to require a radical shift in global politics and economics.
I think a big part of our role as engineers will be helping society to adapt to these new conditions. How do we continue to deliver power to cooling systems during record-breaking heat-waves, build nuclear reactors that are safe against the new kinds of natural disasters we're encountering, manage housing and construction to reduce emissions and local heat, etc.
Agreed. We are already beyond the tipping point. Positive feedback loops already kicked in (thawing of Tundra, lower albedo due to glaciers melting, ...). We would need to go carbon negative right away and stay at those levels for years. Or go big about engineering the climate until we carbon levels return to normal levels.
Since we already triggered feedback loops (eg. thawing of permafrost) we probably need to go carbon negative for a while to stop said phenomena. This means over-provisioning our clean energy supply to power CO2 scrubbers or some similar tech.
I fear that, considering how hard is to get the world to agree to net 0 emissions, the negative emissions discussion will probably be a bloodbath.
Even if all humans on the planet went to zero emissions tomorrow it is too late. We are now inside a feedback loop that will push temperature rise to +20c and sea levels up 200m or more within 200 years. Photosynthesis drops off to zero long before then. Geoengineering is the only way we don’t go extinct along with most animals.
That would have been great 20 or 30 years ago. As the article mentions, even if we went zero emission right in this instant, it is unlikely that the feedback loop we have started will stop (some models predict an ice age or a delay as the heat exchange between equator and poles stops)
As I understand it (and I would like to know if this is wrong). Carbon dioxide emissions take 5-10 years for their heating impact to work through into warming.
So even if we could get to net zero today we'd still be in for 5-10 years of worsening impacts.
And we're not even talking about getting to net zero today. Even in the UK where we've exported and reduced emissions a long way net zero by 2035 is seen as a wildly optimistic scenario.
So it seems to me inevitable that we're going to need to do geoengineering. We mustn't let this delay emission reduction but I think at this point we should get to where we're going asap so we can research it properly.
1) We don't have enough time to wait for those solutions to be implemented.
2) Climate lag. We're now only seeing the consequences from the emissions from the 80s. Since then we've emitted a lot more CO2. Not only we need to reach zero emissions asap, as in in the next decade, but we also need to reach strong negative emissions very soon.
Don't get me wrong. I think if all humanity was focused working towards that goal it might be possible to get a shot at this, but I don't see that happening anytime soon.
A positive feedback loop through methane was always the nightmare scenario, and now it seems to be happening.
It's probably too late to stop catastrophic warming simply by cutting emissions. We still need to do so, because it can always get worse, but it's time to look seriously at terraforming as well.
That's a false premise, not to mention incredibly de-motivating and unhelpful. We can slow current trends and dramatically delay the negative impacts of climate change without having to eradicate every last ICE on the planet (to name just one hopelessly radical and unrealistic part of a fantasy world with literally zero carbon emission). And slowing the current trends should be the goal, both because it is sufficient and, perhaps more importantly, because it is plausible.
The problem with this is that once we've reached a "perilous level of global warming", it is quite possible that there is no way back.
The 2 degrees target seems to be already out of reach and everything beyond that gets closer and closer to being unpredictable. Of course no one knows what exactly will happen anyway. But as an example: If the arctic permafrost starts to melt methane gets released into the atmosphere which further accelerates everything [1].
I would not hope on some not-yet-existing or not-yet-usable technologies to fix everything we're messing up now. The "eventually" when finally everyone stops using fossil fuels because other kinds of energy are cheaper might be just too late.
This might be the only solution. At any point in the near future we may learn that our previously-emitted GHGs have locked us into a climate feedback loop that ends with unsurvivable temperature increases (at least, unsurvivable for global civilization.) At that point what's the alternative? (And yes: it is catastrophic that we've put ourselves in a situation where this might be our only hope of surviving, happy to discuss the allocation of blame for that mistake.)
I don't think it's a given we can reverse or even stop climate change. There are many positive feedback loops going on right now.
AFAIK neither the Paris accords or any climate management proposals entertain the idea of stopping climate change.
Edit: positive feedback loops are things like the melting ice caps. Less sunlight is reflected back to space by the white ice which means more is absorbed by the dark sea. This causes the earth to warm and more of the ice caps to melt....
In climate science there is something called the tipping point. This is when mechanisms like positive feedback will make drastic climate change inevitable (with current technology).
When the tipping point will happen is up for debate. IMO the idea that we have already passed the tipping point is also up for debate.
I think the point being made is that mankind is not acting fast enough - we are currently on track for facing a real risk of an irreversible domino effect of heating that we can’t stop. The IPCC reports discuss a range of possibilities - this isn’t guaranteed - but it’s possible.
In an ideal world, we would reach net zero in time to prevent that. This is the only long-term solution. But what if, in a decade or two, every projection says we won’t? Are we to chastise the rest of humanity, say “you could have prevented this the proper way!”, and let the dominos begin to fall?
Geoengineering, if the science is proven, should only act as a last resort to prevent such a domino effect. It would symbolise a profound failure of our species. But surely, if we realise we failed, this risky Hail Mary is better than not acting?
The risks of another massive human intervention into the atmosphere are obvious. Furthermore, geoengineering risks giving many nations an excuse to keep burning fossil fuels. Nobody has the right answers yet and everybody sensible agrees we need to do everything we can to reach net zero first.
While 150+ years of GHG emissions have put us in a terrible situation, reducing emissions or even reaching zero emissions will not solve climate change much like removing your foot from the accelerator would not prevent a car crash.
The current 415ppm of CO2 in the atmosphere will break havoc for centuries to an unknown extent. Self sustaining climatic systems have already been triggered (Arctic ice, methane, etc) and due to climate lag the changes we are seeing in the climate today are from the emissions from about 40 years ago. Bad news is we have emitted more GHG in the last 40 years than the previous 150 years before that.
Finally we don't really know for sure how much warming there is today since the cooling effects of aerosols have been difficult to calculate, and there is some debate whether the preindustrial baseline picked by the IPCC is correct. We could already be at 2ºC of warming today.
For climate change we're not even close to making enough progress. Global CO2 emissions are expected to continue rising for the foreseeable future, so we're not even getting the second derivative right. The chances are close to zero that we'll manage to limit warming to two degrees and imho it's likely that we'll set off some feedback loops (melting permafrost, methane clathrates, albedo changes at the poles, etc.) that will lead to catastrophic warming in the next century.
All of these things are part of net zero (and beyond). The problem is that we may already have kicked off a warming/methane/cloud feedback loop (there are several) and so getting carbon emissions down in the future isn’t going to be enough to fix it. These geoengineering solutions scare the life out of me, but they may (soon) be our only option for surviving this.
I'm not saying we shouldn't try, but I fear we're already past the point of no return for catastrophic climate change.
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