Potential Impacts of Climate Change

by JonahS3 min read22nd May 201344 comments

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Climate Change
Personal Blog

According to a recent press release from UC Berkeley’s School of Law:

Overheated: The Human Cost of Climate Change predicts a grim future for billions of people in this century. It is a factual account of a staggering toll, based on hard data […] “Climate change is the most important problem facing the international community in the 21st century,” Guzman said.

Guzman's view is shared by many.

While I have not read Guzman’s book, I have read GiveWell’s summary of the IPCC, as well as notes on GiveWell’s conversations with climate change experts. Based on these, I’ve come to the tentative conclusion that while climate change is an important issue, it’s unlikely to be the most important issue, though there is uncertainty, owing to poorly understood tail risk

Potential Impacts according to the IPCC 

GiveWell recently wrote up a summary and review of some of the impacts of unmitigated climate change, as described by the Intergovernmental Panel on Climate Change's 2007 Fourth Assessment Report. GiveWell writes:

The report suggests that unmitigated climate change would have extraordinarily negative humanitarian impacts across all of the outcomes we looked at: hunger, water stress, flooding, extreme weather, health, biodiversity, and the economy. Successfully mitigating these negative impacts would carry vast humanitarian benefits. 

When looking at the range of possible futures outlined in the report, the bulk of the variation (in humanitarian terms) comes from variation in the level of assumed economic growth and adaptation, rather than variation in the amount of climate change. Of the outcomes we examined, only biodiversity is expected to be unambiguously worse off in the future as a result of both climate change and economic growth.

The most succinct summary of the expected impact is given by a GDP drop estimate:

Most recently, Stern (2007) took account of a full range of both impacts and possible outcomes. […] Using equity weights to reflect the expectation that a disproportionate share of the climate-change burden will fall on poor regions of the world increased their estimated reduction in equivalent consumption per head to 20%.

Such a drop would be highly undesirable, but far from catastrophic. World GDP has been growing at a rate of ~3%, so this corresponds only to a set-back of ~6 years.  Poor countries are expected to become richer regardless, and because of marginal diminishing utility, such a setback would carry less negative humanitarian impact than such a setback would if it occurred today.

Overly weak assumptions regarding adaptation? 

The IPCC considers what the impacts of climate change will be in 2050; a full 35 years away. My intuition is that over the course of the next 35 years, human society will adapt in such a way that the issues that the IPCC describes will have a smaller negative humanitarian impact than the IPCC suggests. I have not vetted the references given by the IPCC, and may be mistaken about their implicit assumptions, so my remarks should be taken with a grain of salt.  

To explicitly address some of the impacts discussed in the IPCC:

  •  Crop productivity and hunger in Africa — The IPCC projects that in 2050, at least 208 million people will be at risk of hunger even without climate change: only ~ 3x fewer than today. New technologies for the production of starch could make the number much smaller.

  • Floods due to rising sea levels — The IPCC mentions dikes and nourishment as possible adaptive responses, but doesn’t mention the possibility that people will move away from coastal areas as sea levels rise. Individual people and families might move away to avoid flooding. On the time scale of 5 years, people are usually unwilling to move, but over the course of 35 years, it might happen organically. Over time, more cities will be built, and people will migrate to them. Cities are more likely to be built in areas that are not prone to flooding, than in areas that are.

  • Significant loss of species and biodiversity — Over the next 35 years, humans may make a concerted effort to preserve rare species by collecting them and housing them in zoos. (I recognize that this would have to happen well before 35 years elapsed in order to avoid the loss.)

There are also more general relevant considerations:

  • Geoengineering — It may be possible to reverse or halt climate change via geoengineering. Geoengineering carries its own risks, but its potential would seem to be positive in expectation, although the situation is murky.

  • Unpredicted technologies — Technological progress is unpredictable, and it could be that we can develop technologies that mitigate effects such as droughts, even if we can’t see these technologies in advance. There are potential unpredicted technologies that would make climate change worse, such as those that facilitate cheaper extraction of fossil fuel, but on balance, technological progress usually enables humans to solve problems more than to create them.

    Breakthroughs in genetic engineering, artificial intelligence and whole brain emulation could also radically alter human needs themselves.

The IPCC as overly optimistic?

Some people have voiced the concern that the IPCC is overly optimistic in its predictions of climate change impacts. This is corroborated by the recent paper Climate change prediction: Erring on the side of least drama, which reports that historic IPCC predictions of current impacts of climate change have erred on the overcautious side. But given that the IPCC represents a consensus, barring tail risk, it seems unlikely that the IPCC is overly optimistic by a huge margin

Tail risk

The biggest reason to be concerned about climate change is that there’s a small probability that the negative impact could be huge.

There is a danger of permafrost in the Arctic melting and releasing methane, creating a feedback loop where the release of methane, global warming, and the melting of the permafrost reinforce each other. This could increase global temperature by 3.5 degrees Celcius, greatly exacerbating all other impacts of climate change. Even if this doesn’t happen, it could be that climate models are wrong, and that the amount by which the earth temperature will rise is much greater than current models predict.

The potential impacts of a much larger increase in temperature than what the IPCC predicts are less studied. One starting point for reading on this is the 4degrees and beyond international climate conference.


About the author: I worked as a research analyst at GiveWell from April 2012 to May 2013. All views expressed here are my own.

Acknowledgements: Thanks to Nick Beckstead, Vipul Naik and Carl Shulman for helpful suggestions.

To be continued: I'll be writing up a follow up report about the implications of the projected impacts for effective philanthropy.

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"Significant loss of species and biodiversity — Over the next 35 years, humans may make a concerted effort to preserve rare species by collecting them and housing them in zoos. "

The extremely dangerous effects of biodiversity cannot simply be handwaved out like this.

Firstly, this is impossible since the vast majority of species are unknown to science (remember that vertebrates and confierous plants only represent a small fraction of species). Actually obtaining viable samples from the 70,000 vertebrate species, 1,000,000+ invertebrate species, 300,000+ plant species and 100,000,000+ estimated bacterial species would be a herculean task of such magnitude that no one would ever pay for it. Let alone actually obtaining a genetically diverse pool - which would require at least 500 random individuals from each species. Zoos often have to trade individuals with each other and interbreed in order to maintain a genetically viable population.

But all of this is ignoring that we already have a zoo that houses all species and is perfectly capable of supporting all of them in the foreseeable future, and doesn't cost anything to run. The only thing it asks is that we not destroy it.

"Doesn't cost anything to run" is silly. If maintaining the ecoysystem was free, we'd do it because most people prefer there to be one rather than not. Maintaining the ecosystem trades off against all sorts of other things we want, and if we have to give them up to maintain it, that's what it costs to run.

It doesn't cost us anything in that we don't have to give up anything we currently have (provided that we execute the right policies to maintain current levels of prosperity without expanding into nature even more). You're talking about an imagined future cost, and that gets pretty tricky. Who's to say that it doesn't cost us to keep the Milky Way running, since in a billion years we could conquer it all?

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The extremely dangerous effects of biodiversity cannot simply be handwaved out like this.

Why do you say extremely dangerous? The IPCC predicts that climate change will cause the extinction of 20%-30% of species by 2100. This seems bad, but not extremely dangerous.

Firstly, this is impossible since the vast majority of species are unknown to science

I don't have subject matter knowledge, but these seems like good points.

But all of this is ignoring that we already have a zoo that houses all species and is perfectly capable of supporting all of them in the foreseeable future, and doesn't cost anything to run. The only thing it asks is that we not destroy it.

This is easier said than done. Do you have proposals?

I suppose 'extremely dangerous' is subjective, but I'm confident in my usage of the term. It has been demonstrated that relationships between species are held in an extremely delicate balance. Extinction of one species can lead to another, which can lead to the blowing-up of a population of another (because it lost a major predator), which can lead to the extinction of others.

In fact we have been observing such fluctuations in the present. We have seen many species suddenly collapse, while others blow up with devastating results (algae blooms). And this is just with a few percent biodiversity loss, let alone 30%.

But the larger point is that we simply don't know what will happen. The relationships between species are very complex. It's possible that the entire food chain that we depend on will collapse (for example, if pollinating insects went instinct). It's also possible that loss of biodiversity will have little effect on humans. We are extremely ignorant about it - but that's no excuse to continue doing it.

"This is easier said than done. Do you have proposals?"

There have been many proposals where just diverting a few percent of worldwide GDP would eliminate global warming. Among them, adoption of renewables and nuclear power.

On an object level your point seems persuasive, but my prior is still that it's not a big issue, because I haven't seen other people highlight this forcibly before. Are you familiar with some discussion of it?

There have been many proposals where just diverting a few percent of worldwide GDP would eliminate global warming. Among them, adoption of renewables and nuclear power.

I mean actionable proposals for effective altruist types. I support adoption of renewables and nuclear power, but I don't know what I or my friends can do to encourage it in a cost-effective way.

[Edit: I'd add that I think that what you describe falls under the category of "tail risk." I haven't heard this issue discussed, and It would be great if you were to write up a detailed account of your view, with citations.]

Loss of biodiversity has definitely been highlighted frequently, although it is often done without reference to climate change (even though it is acknowledged to be the most important factor in general), because people want to have their opinions heard without getting mired in political debates. But the material is there and can be revealed with a simple google search. I'm hesitant to give you links myself because I'd feel like I'm just cherry-picking the articles I want you to read.

I don't know what I or my friends can do to encourage it in a cost-effective way.

I don't either, aside from the usual cliche of 'spreading awareness' .

There has been a lot of concern about loss of biodiversity and the possible chain effects of collapse to one part of the food chain or another.

It also seems likely that the effects of global warming will be magnified by other effect.s For example, naturally speaking, if the Earth's climate change many animals would normally just migrate north and be fine, but we've broken up huge wilderness areas into many small pieces of "wildlife preserve", often relatively small areas of natural environment surrounded by built-up areas of human habitation.

A lot of scientists have described what is going on now as a mass extinction event, on a scale that's only happened 5 times previously in Earth's history.

As for your other question:

I mean actionable proposals for effective altruist types. I support adoption of renewables and nuclear power, but I don't know what I or my friends can do to encourage it in a cost-effective way.

Well, if you're interested, there are a number of fairly simple things people can can do to reduce their power consumption and the amount of fuel they use in transportation by a few percent. This has other positive effects as well, like reducing air pollution. Not that conservation efforts are going to solve the problem by themselves, but at least they may buy us a little time.

LW poster Tim Tyler wrote an interesting contrarian article on his website about global warming. I'm not really endorsing the main argument, but it had a lot of information I was unfamiliar with before reading.

I had a fairly long running argument with him about this some years back, suffice to say that none of the information he presents is little known among climate scientists, and they don't share his optimism. The "danger" of reglaciation is completely overblown (we've most likely already broken the ice age cycle, having boosted atmospheric CO2 back up to Pleistocene levels,) and even if we did enter a new glaciation period, it would be such a slow process as to pose relatively little danger to our society.

He's operating under a largely naive "warmer is better" model which fails to account for the difficulty ecological systems have in adapting to rapid changes.

suffice to say that none of the information he presents is little known among climate scientists

I was never under the impression that climate scientists didn't know these things. However I'd been reading editorials and popular science articles about climate change for years before I read Tyler's post and still didn't know a lot of the really basic facts Tyler presented. For example, I did not understand the distinction between interglacials and ice ages, or the fact that Earth has usually had zero polar ice throughout its history.

From the pop science articles and editorials I'd been reading, I was really badly informed about the topic--and these are the ways almost everyone learns about climate change issues. Since then I've talked to a many people about this, and most people have known very few of these facts.

He's operating under a largely naive "warmer is better" model which fails to account for the difficulty ecological systems have in adapting to rapid changes.

If you believe rapid changes are bad, that actually is evidence that warmer is better, because warm earth eras are dramatically more stable. Ice ages have dramatic positive feedback cycles, where cooling triggers further cooling and warming triggers further warming. Because of this, there have been repeated "snowball earth" events in which life was driven to near extinction. Regardless of what humans do, these cycles will continue until the ice age ends.

The "danger" of reglaciation is completely overblown (we've most likely already broken the ice age cycle, having boosted atmospheric CO2 back up to Pleistocene levels,) and even if we did enter a new glaciation period, it would be such a slow process as to pose relatively little danger to our society.

I agree with you here. Climate change takes centuries or millennia to produce dramatic changes. That just doesn't seem terribly important in light of exponential economic and technological change that produces dramatic effects orders of magnitude faster.

f you believe rapid changes are bad, that actually is evidence that warmer is better, because warm earth eras are dramatically more stable. Ice ages have dramatic positive feedback cycles, where cooling triggers further cooling and warming triggers further warming.

The warming event we're triggering is itself a much more rapid change than the warming and cooling events which occur during an ice age. Going back to Pleistocene level stability might have advantages in the long run, but a rapid shift to Pleistocene level climate is itself going to be harmful.

I agree with you here. Climate change takes centuries or millennia to produce dramatic changes. That just doesn't seem terribly important in light of exponential economic and technological change that produces dramatic effects orders of magnitude faster.

The largest effects aren't going to show up for centuries or more, but at the present rate, we're looking at quite a large ecological impact within this century.

I certainly wouldn't call climate change the top risk to humanity, or even close to it, but a mass extinction event is going to be a significant quality-of-life issue, even if we're not one of the species lost.

[-][anonymous]8y 0

The "danger" of reglaciation is completely overblown (we've most likely already broken the ice age cycle, having boosted atmospheric CO2 back up to Pleistocene levels,)

Go, anthropocentric warming! Fingers crossed on that one, though - at least until there's a consensus on what causes the glacial cycles and their periodic shifts.

and even if we did enter a new glaciation period, it would be such a slow process as to pose relatively little danger to our society.

All climate change is slow - and not-very threatening to civilization.

The "danger" of reglaciation is completely overblown (we've most likely already broken the ice age cycle, having boosted atmospheric CO2 back up to Pleistocene levels,)

Go, anthropocentric warming! Fingers crossed on that one, though - at least until there's a consensus on what causes the glacial cycles and their periodic shifts.

and even if we did enter a new glaciation period, it would be such a slow process as to pose relatively little danger to our society.

All climate change is slow - and not-very threatening to civilization.

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The "danger" of reglaciation is completely overblown (we've most likely already broken the ice age cycle, having boosted atmospheric CO2 back up to Pleistocene levels,)

Go, anthropocentric warming! Fingers crossed on that one, though - at least until there's a consensus on what causes the glacial cycles and their periodic shifts.

and even if we did enter a new glaciation period, it would be such a slow process as to pose relatively little danger to our society.

All climate change is slow - and not-very threatening to civilization.

none of the information he presents is little known among climate scientists, and they don't share his optimism.

Follow the money. They are funded when they project doom. Thus the IPCC fiasco.

He's operating under a largely naive "warmer is better" model which fails to account for the difficulty ecological systems have in adapting to rapid changes.

Warmer is better - when you're in an ice age. I acknowledge rapid change will cause some problems. However, these are overblown by the media, while the large benefits go largely ignored. It seems like pure doom-bias to me. Eco-apocalypse sells, while "actually, thiings might get better in most places" does not.

And here a reason why reglaciation might be a good thing.

That looks like deathophilia :-(

Even if people think there is enormous value in living long and happy lives, it is still coherent to acknowledge that there might be existences that are not worth living. The facts seem to point towards this being the case for the vast majority of wild animals. I'm just pointing out the obvious conclusion.

Appropriate, since ice-nine is a chemical in Kurt Vonnegut's novel Cat's Cradle which causes all water to freeze, exterminating all life on earth.

If your utility function includes stuff you want to minimize, then you cannot a priori rule out that freezing the world may be the best outcome, as this would depend on empirical circumstances. It seems weird to me why anyone would reject a value judgement based on a conclusion that is a possibility for all value systems (or at least the ones that contain minimization); this would be getting it backwards, I think.

Also note that my initial comment was about reglaciation, which doesn't necessarily imply the extinction of all life on earth. All else being equal, wouldn't it be better to reduce the amount of wild animals, if it is empirically the case that the vast majority of wild animals die shortly after birth in ways that are presumably painful? If your answer is "That looks like deathophilia", then I'm somewhat lost to be honest.

Finally, depending one one's view, there is a relevant difference between death an non-existence. One could think that one poses a problem whereas the other doesn't.

Even if you think animal suffering is bad enough that it would be a good idea to kill them all, reglaciation is just a bizarre way of achieving this. First of all it doesn't actually kill off all animals. Also it would be an amazingly slow and destructive and expensive and... stupid way of killing things.

I wasn't commenting on practical strategies about reducing the number of wild animals. All I was saying is that there are positive consequences of reglaciation and that they might outweigh the negative consequences. Of course, there are probably ways to bring about the positive consequences faster and more effectively while still preventing the negative ones. (Don't interpret too much into my account name here, I didn't even realize how fitting it was to this discussion until you pointed it out.)

All I was saying is that there are positive consequences of reglaciation and that they might outweigh the negative consequences.

Reglaciation precludes many other possibilities, so the opportunity costs must be considered as well.

I notice that the great Matt Ridley puts out a stream of broadly-similar material on his blog these days.

For example, his latest post is subtitled: "Global warming will probably be a net benefit for several decades".

I write little about climate - simply because it is a relatively insignificant issue. It's main significance seems to be due to all the time which is wasted on it - time which could be being put to much better use.

Did you deliberately avoid listing potential benefits because you were worried your article already came across as too positive?

The IPCC already discusses some potential benefits: for example, there's discussion increased water runoff reducing water stress in some parts of the world. My post is intended only as very high level summary, so I didn't do research on potential benefits that are not discussed in the IPCC, but if there are some that seem especially important to you, I'll consider adding them.

This somewhat controversial paper estimates a net 849252 fewer deaths in 2050 due to warming from 6 disease types that they studied.

Last I heard, the increased carbon dioxide was increasing temperature mainly in colder region, increasing crop yields, increasing rain, greening the planet, and had likely pushed back the end of the current inter glacial by tens of thousands of years. The estimated sensitivity to a doubling of atmospheric carbon dioxide has come down, and global temperatures have been essentially flat for a decade.