Friday, September 11, 2015

If We Burned All Our Fossil Fuel

If we burned all the coal, oil and gas that’s left in the ground, we’d melt Antarctica and global sea levels would rise as much as 60 meters (200 feet) over the next ten thousand years. Coastal cities from New York to Shanghai would wind up deep underwater.
(One of multiple news stories reporting on a newly published journal article.)
That sounds scary—if you miss "over the next ten thousand years."

The article the news story is based on is webbed. It gives an estimate of the consequences of burning all of Earth's fossil fuel over the next few centuries. The conclusion is that "Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 m per century during the first millennium." Figure 1d from the article shows a rapid rise, close to forty meters in the first thousand years, gradually tapering off thereafter.

Three meters a century is considerably faster than the current rate of rise—not surprising since it would be driven by a CO2 concentration about eight times the current level. One way of getting a feel for how serious it would be is to convert it into a rate at which coastlines move inward, assuming no diking. The rule of thumb for that is about a hundred meters shift for every meter of rise. So three meters per century of SLR implies coastlines shifting in by about three hundred meters a century, more in some places, less in others, but well short of the catastrophe implied by "coastal cities deep underwater."

Another way of looking at it is in terms of what could be done via diking. The lowest city in the Netherlands, a country with centuries of experience protecting land below sea level, is more than six meters below sea level. With two centuries to do it in, I expect New York or Shanghai could match that.

Another conclusion of the article is that the Antarctic would end up almost ice free, but it is not clear why that would be a bad thing. We are currently in an ice age, defined by the existence of ice on the poles. There have been earlier ice ages, but for most of the history of the Earth, including most of the period with living creatures and even most of the period with mammals, the poles have been free of ice.

Figure 1c shows the estimated effect on average global temperature—an increase over about a thousand years of a little over 10°C relative to the current value, followed by a gradual decrease thereafter. That looks like a much bigger problem than sea level rise—but how big? At the same time that the hotter parts of the Earth were becoming unihabitable, the colder parts—Antarctica and currently frozen parts of the Northern Hemisphere—would be becoming habitable. An accurate calculation of the net result would require more expertise than I have and more effort than I am willing to put into the project, but I can at least try a rough back of the envelope estimate.

Warming due to CO2 tends to be greater in cold times and places than in hot, because water vapor is also a greenhouse gas, the warmer it is the more water vapor is in the air, and the more of one greenhouse gas the less the effect of adding another. I do not know how large the difference would be for warming on the scale I am looking at. To simplify my calculations, I will assume that high temperatures in hot areas go up by five degrees, low temperatures in cold areas by fifteen—readers are welcome to recalculate the numbers with other assumptions.

How high do high temperatures have to be to make a place uninhabitable? India is a very hot place and densely populated. Looking at a list of July high temperatures by city, I observe a high of 36°C in Tamil Nadu and Pondicherry. If that represents the upper bound for habitability, another five degrees would make any city currently above 31° uninhabitable. Counting cities, which is less work than looking up regional areas and adding them, I observe that twenty-four out of fifty-two cities are above that, so my very rough estimate is that the projected warming would make almost half of India uninhabitable by a thousand years hence.

Looking at a list of highest temperatures ever recorded by country, the figure for India is 50.6°. Algeria, Iran, Iraq, Kuwait, Mexico, Pakistan and Saudi Arabia equal or exceed that, and a few other countries come close. If I add up the area of India and all countries whose highest temperature is at least as high, I get a total of about 12.7 million square km. To allow for countries a little cooler than India, take it up to 14 million, then divide in half, since my very rough calculation suggests that only about half of India would become intolerably hot.

Very, very rough estimate: A five degree increase in maximum temperatures would make about seven million square km intolerably hot. What would we get in exchange?

Antarctica and Greenland would be ice free, for a total area of about sixteen million square km. How much of that would be warm enough to be habitable I do not know. Siberia is about thirteen million, Canada about ten million. Parts of both are presently habitable, but large parts are not. Similarly for Sweden, Norway, and Finland.

I conclude, from my very rough estimates, that the total habitable area of the Earth would almost certainly go up, not down. I leave to someone more ambitious the task of a more careful and precise calculation. A lot of people would have to move—but a thousand years is a very long time.

Why does all of this matter, given the difficulty of predicting anything a thousand years, even a hundred years, into the future? It matters because it suggests an upper bound to climate catastrophe, at least slow catastrophe. In the worst case, the long term result would be a physical world not strikingly worse for humans, possibly better, than the present world.
If the changes happened over decades there would be enormous human costs. If they took many centuries, probably not.


Brooks Moses said...

Humans don't need land in great amounts for habitation, though; we need it for agriculture. How much of this land would be suitable for such? It's difficult, and expensive in terms of resources, to grow food plants where there isn't any decent topsoil -- and I would be surprised if there's very much under the Antarctic ice.

David Friedman said...

Your point is relevant for rapid change, but over a period of centuries less so. The real constraint to agriculture is sunlight, since everything else can be recycled.

Attempting to be a Skeptical Thinker said...

Ask a warmist "What then, in your view, is the proper temperature for the planet?" and watch the dumb looks you'll get.

Rolf Andreassen said...

While it's true that large parts of Norway, Sweden, and Finland are uninhabited, I don't think those areas are strictly speaking uninhabitable, any more than the Midwest is. It's just that nobody likes to live so far away from where everyone else lives. It seems like this factor would not change even if the permafrost receded.

David Friedman said...

Rolf: You don't think that if the climate warmed sharply, people would migrate in to fill up some of the now empty territory? We aren't talking about changes over a decade but over centuries.

It seems an odd coincidence that population densities are consistently low in places within the arctic circle.

Anonymous said...

Two reasons people dislike the prospect of Antarctica melting, more generally the prospect of the current ice age ending:
- No more penguins, polar bears, icebergs, snow-capped mountains. There will be a loss of interesting animals and natural environments to visit and read about.
- No more snow in winter. No more snowmen, snow angels, tobogganing, snowball fights, etc. No more skiing, no more snowboarding.

This probably seems like a ridiculous complaint but I honestly think it forms part of people's gut dislike of warming. Cold weather is bad for living in but it makes a great novelty to experience occasionally.

hightide said...

"The rule of thumb for that is about a hundred meters shift for every meter of rise. So three meters per century of SLR implies coastlines shifting in by about three hundred meters a century, more in some places, less in others, but well short of the catastrophe implied by "coastal cities deep underwater.""
This is grossly misleading. In the US, for example, the east coast south of New York City all the way down to Key West offers very low relief, and high building concentrations. Three meters of SLR would, in fact, put coastal cities deep underwater in many locations.

"The real constraint to agriculture is sunlight, since everything else can be recycled."
Water doesn't matter? Topsoil doesn't matter? Fascinating.
Also: My understanding is the taiga and tundra, even when thawed, generally make for really crappy farmland. The land is deeply rutted by freeze/thaw/runoff/freeze cycles, which makes it difficult to farm and difficult to build transport (cf Ice Road Truckers). The soil is also uneven and lousy, having been scraped off by glaciers and then having large irregular deposits (moraines) at the terminus of glaciations. Like the idea of the average sea level rise at the coast, having small mountains of topsoil stand amidst hundreds of square miles of uselessly thing topsoil isn't particularly friendly to farming.

"What then, in your view, is the proper temperature for the planet?"
There is no "proper temperature for the planet." Human civilization developed during a period of stable climate; it is unclear to people who study the planet's systems (as opposed to economics) how well it can adapt to significant changes in climate.

David Friedman said...

As it happens, the source for my rule of thumb gave it specifically for the Atlantic coast of the U.S. To see how deep under water how much of it would be with a three meter rise, take a look at:,138.1640625&z=13&m=3

a page that lets you see the flooding for various levels of rise. Zoom in on New York. A little flooding around the edges, but that's it. Similarly for Miami. A good deal of flooding around Savannah, but most of the city still above water.

hightide said...

"...the source for my rule of thumb...."
Can you share said source?

"Zoom in on New York. A little flooding around the edges, but that's it. Similarly for Miami. A good deal of flooding around Savannah, but most of the city still above water."
It's a nice tool, but does it show you below-ground infrastructure? It does not. Does it include storm surge extents? It does not. Does it give you any indication of dependence on fresh water wells that will turn salt as sea level increases? It does not.

jimbino said...

The tacit assumption in all this global-warming controversy is that we do and should have an interest in having humans around in 1000 years. I have personally reduced my carbon footprint and eliminated any and all concern for the future 1000 years hence by simply not breeding. What do I get for my efforts?--higher taxes.

If many or most others would also put an end to their breeding, we could abandon this frivolous concern about the effects of global warming 1000 years hence and, as a bonus, reduce the human load on the planet that is the chief factor in the putative global warming, conserve millions of other species and increase Lebensraum for all the planet's fauna. We might also find time to concentrate our efforts on reducing hunger, war and misery in our time for billions of real, living persons.

David Friedman said...

My source for the hundred feet/foot rule of thumb was:

Tides, Surges and Mean Sea-Level by David T. Pugh, published by Wiley and Sons.1987, reprinted with corrections in 1996.

Colombo said...

1) Please correct me if I'm wrong. A huge increment in the atmospheric concentration of CO2 could react with H2O in the oceans forming H2CO3, which reacts alkaline minerals yielding carbonate salts, which could precipitate. If all this actually happen in the future, Would more deposits of carbonates be beneficial or detrimental to the development of marine life?

2) What do humans do when there is a surplus of something? I find ice sculpture very appealing. Why we assume that more water will necessarily be a problem? Perhaps then humans would have more fish, and they say that fish is better food than meat. If life gives you lemons...

3) Why there is so much misanthropy and hate towards human ingenuity? I say we should hate bacteria, because it is obvious that bacteria have changed the world far more than capitalism. Some people say that bacteria actually "created" us humans, and, if we are evil, our creators must also be evil.

Colombo said...

@Brook Moses, As technology improves, we may reach a point were food is mostly grow in big buildings, controled with computers. Even in the current deserts such operations could be possible.

And if we can create a good artificial environment for plants and animals, why not a good artificial environment for humans also?

I mention these two things because they seem more feasible than controlling weather. But even that does not seem impossible, even though it seems very difficult. But it may be possible one day. As long as the State controls scientific research, progress will be mostly thwarted.

In my opinion, all the bad things associated with fossil fuels are a caused by bad laws.

The biggest risk for human life is not desertization, climate change or some stupid virus, but Governments, because they create and multiply problems and frustrate solutions.

Tibor said...
This comment has been removed by the author.
Tibor said...

I think a common argument is also that more is going on than simple change in temperature and that for example one result of an increasing average temperature could be a re-routing of the Gulf stream which could lead to much more dramatic (and fast) climate shifts. Also, turning the rainforest in Amazon into a desert (I don't know if an average temperature increase of 5-10 degrees would do that) would supposedly have similarly dramatic effects. I don't know how realistic those claims are, but one should also probably address them.

I also agree that one important reason why some people are alarmed by these predictions is a loss of various species and a general change of the environment they are used to. I believe that the latter is seen as a problem for the same reasons why cultural change by immigration is a fear of other (although sometimes the same) people.

Unknown said...

Hightide wrote: "Three meters of SLR would, in fact, put coastal cities deep underwater in many locations."

Now, I am no oceanographer, but I am familiar with arithmetic and it suggests that a 3-meter sea level rise could, at most, put any presently-above-sea-level city 3 meters below the sea level. That is not, I think, what is generally called the deep underwater.

Richard Ober Hammer said...

David makes points which need more emphasis:
"We are currently in an ice age, defined by the existence of ice on the poles. There have been earlier ice ages, but for most of the history of the Earth, including most of the period with living creatures and even most of the period with mammals, the poles have been free of ice."

If ice ages come periodically, in cycles, I would surmise that Earth is presently in the warming part of such a cycle. How much global warming could be attributed to this extra-human pattern of warming? How much ice-cap loss? How much more warming might we expect before the next peak of warmth between ice ages -- independent of human existence or activity?

Do you know, David, if these questions have been responsibly addressed by any warming alarmists?

David Friedman said...

Ice ages are much longer than that--the current one has been going for two and half million years and there is no obvious reason to think it is ending.

Within an ice age interglacials, relatively warm periods with ice still on the poles, alternate with glaciations (sometimes referred to as "ice ages" in non-technical writing, leading to much confusion). We are currently in an interglacial, the Holocene, which has been running for about twelve thousand years. So if anything one would expect cooling as the current interglacial ends, although it's not clear how soon. An optimistic interpretation of recent climate history is that AGW is extending the length of the Holocene, preventing rather than causing a catastrophe. It doesn't strike me as likely, but I don't think it is impossible.

Richard Ober Hammer said...

Thank you, David. I'm reading Wikipedia on Interglacial, Holocene climatic optimum, and Holocene. That's what I was wondering about. Wikipedia has become wonderful.

It seems to me that people who want to blame a recent warming trend (Which I admit can readily be found if you select data for the purpose of showing a warming trend. Just select an earlier period with a lower temperature.) on human activity should, if they desire scientific credibility, first establish the causes of all the earlier upswings of temperature in this chart, and rule out all those causes as pertains to their recent warming trend.

But my theory holds that these people do not want scientific credibility as much as they want political power to exert more control over human industry. And political power can be gained in a democracy by sounding an urgent alarm while trusting in rational ignorance.

David Friedman said...


The claim, for which I think there is evidence, is that the warming over the past century is unusually fast. Evidence is not proof, of course. We know of localized warming considerably faster in the past. Estimates of global temperature depend on elaborate calculations based on a variety of proxies, so it is hard to be sure how reliable they are.

In my view, which I've argued in past blog posts (do a search on "warming", the weak part of the argument is not the claim that temperatures are trending up due to human activity but the claim that warming can be expected to produce large net negative effects.

Laird said...

This is just one aspect of a point I've long been making: that there has never, to my knowledge, been any serious attempt at doing a proper cost-benefit analysis of the total effects of global warming. Assuming the worst-case scenarios of the alarmists*, what would be the benefits as well as the detriments? You've already pointed out a probable increase in habitable land. There would also be a generally more temperate climate, a good thing. How about the benefits to plant life from the higher atmospheric CO2 levels? There is evidence that plants did extraordinarily well in prior ages when the CO2 level was higher than it is today. I'm sure that there are other benefits, too, all of which need to be considered and balanced against the (alleged) drawbacks. My bet is that, overall, we would be better off with a slightly warmer earth.

In any event, until such a serious effort is undertaken, and a significant net negative result is reasonably firmly established, I have precisely zero interest in wreaking vast harm on our economy and condemning my descendants to penury, merely to satisfy the overblown fears of people who seem to enjoy constantly crying that the sky is falling. To me, that seems too close to "we have to destroy the village to save it." Such people like to claim that they are concerned for "the children." Well, those children will have economic needs too, but somehow that never enters into the discussion.

* Personally, I agree with Mr. Hammer that most such people are less interested in actual science than in enhancing their political power.

Unknown said...

@Laird "there has never, to my knowledge, been any serious attempt at doing a proper cost-benefit analysis of the total effects of global warming."

Well, there was the Stern Review, a report that at 700-pages produced by a large and credentialed staff at least had a chance to be such an attempt. Whether it took that chance remains a subject of some controversy. But check yourself.

David Friedman said...

There are at least three economists I know of who have tried to estimate the net costs—Stern, Tol, and Nordhaus. Stern gets by far the largest negative. You can find my comments on Nordhaus by a search of this blog. Tol published a JEP piece a few years back in which he tried to sum up various people's results. (corrected version)

The conclusion was net positive results for about the first two degrees (relative to pre-industrial temperature), negative thereafter. It has, of course, been criticized.

One point worth mentioning ... . Nordhaus somewhere comments that he doesn't think his estimates past 2050 are worth much, given uncertainty. I believe the major negative terms in everyone's estimates are from after 2050.

Jim Ellison said...

Most things i have read suggest that water vapor is the most important greenhouse gas. It is clearly not affected by human activity. It also has a property that I have not seen discussed: increases in water vapor increase the albedo. That is to say that as water temperatures increase and increase the water content of the atmosphere, clouds also increase which reflect sunlight back into space.
Cloudy days are cooler than sunny days. Cloudy nights are also warmer than clear nights. The global thermostat is much more complex than anything I have read anywhere.

David Friedman said...

Jim: Water vapor is affected by human activity indirectly. The warmer the air, the more water vapor it can hold. So if CO2 warms the air that tends to increase water vapor which gives a further warming--positive feedback.

As you point out, water vapor can also increase the albedo, which results in negative feedback. As best I can tell, we don't have any good theoretical basis for predicting the size of the two effects, which is one reason why climate sensitivity, the increase in temperature due to a doubling of CO2 concentration, can't be determined by theory and has to be estimated from data—with considerable uncertainty.

Polyneophite said...

First, sea level is not the same all around the world, not even close:

Adding half a meter of global average increase to a place with 12 meter tide changes could be absolutely catastrophic.

Why sea level rise is a big deal:

One of the concerns for sea level rise is that it increases the start or launch height for storm surges. When a hurricane comes ashore it lifts the water up under it and brings it inland in a massive surge. Adding hight to this means the water has a far greater reach inland and will flood cities much more often.