Saturday, June 02, 2007

Nuclear December or an Unwarranted Lassitude

Nuclear weapons have a potential for damage and destruction beyond imagining. Concern arose in the 1980s that besides immediate deaths, nuclear exchanges could change the planets albedo resulting in a nuclear winter, a climate that would not support agriculture. In 1990 a study was published, called TTAPS after the authors, Turco, Toon, Ackerman, Pollack, and Sagan, that used climate models to predict multiyear nuclear winters caused by the smoke emitted from burning cities. TTAPS assumed that half of the US/USSR nuclear arsenals would be used. Later, more sophisticated studies implied a nuclear winter autumn. The Wikipedia article is a useful summary of the TTAPS conclusions which were later thought to be overblown.

First 1 to 3 months: 10 to 25 % of soot injected is immediately removed by precipitation, while the rest is transported over the globe in 1 to 2 weeks. SCOPE figures for July smoke injection: 22° C drop in mid-latitudes. 10° C drop in humid climates. 75 % decrease in rainfall in mid-latitudes. Light level reduction of 0 % in low latitudes to 90 % in high smoke injection areas. SCOPE figures for winter smoke injection: Temperature drops of 3° to 4° C. Following 1 to 3 years: 25 to 40 % of injected smoke is stabilised in atmosphere (NCAR). Smoke stabilised for approximately 1 year. Land temperatures of several degrees below normal. Ocean surface temperature drops of 2° to 6° C. Ozone depletion of 50% leading to 200% increase in UV radiation incident on surface.
Toon and Turco have found new collaborators, Robock, Bardeen, Oman, and Stenchikov, and access to better climate models. In addition to the direct effects of a small nuclear exchange
We analyze the likely outcome of a regional nuclear exchange involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal). We find that such an exchange could produce direct fatalities comparable to all of those worldwide in World War II, or to those once estimated for a "counterforce'' nuclear war between the superpowers. Megacities exposed to atmospheric fallout of long-lived radionuclides would likely be abandoned indefinitely, with severe national and international implications
They find that
We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and long-lasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter'' simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes are more long-lasting because the older models did not adequately represent the stratospheric plume rise.
That last sentence is rather misleading. These issues have been dealt with in more detail recently in an article appearing in EOS (pay the damn $20 AGU membership fee already and get access)
Toon et al. [2007b] recently found that a regional war between the smallest current nuclear states involving 100 fifteen-kiloton explosions (the number of weapons likely to exist in the arsenals of new nuclear states; India and Pakistan are estimated to have 110–180 weapons between them) could produce direct fatalities comparable to all of those worldwide in World War II. Robock et al. [2007a] showed that smoke from urban firestorms in such a conflict would produce significant global temperature and precipitation changes, lasting a decade or more, shortening the growing season in the midlatitudes by a month in major agricultural areas, and thus affecting world food supplies. In addition, Robock et al. [2007b] found that although the Cold War and its associated nuclear arms race are over, the remaining American and Russian nuclear arsenals could still produce nuclear winter, threatening the lives of billions of people.

Simulations for this new work were carried out using the latest NASA Goddard Institute for Space Studies climate model, ModelE [Schmidt et al., 2006], the result of decades of NASA investment, and the hard work and dedication of a large number of scientists supported by NASA. Because ModelE is able to simulate the entire troposphere, stratosphere, and mesosphere, from the Earth’s surface up to 80 kilometers, and interactively transports black carbon aerosols in response to solar heating and changing wind circulation, we were able to produce fundamentally new results, showing that the smoke would persist in the atmosphere for more than 10 years, an order of magnitude longer than previously assumed. Robock et al. [2007b] also show that early results suggesting that nuclear autumn instead of nuclear winter would follow a fullscale war [Thompson and Schneider, 1986] were based upon climate models that were not adequate to fully address the problem because they did not have deep enough atmospheres, and could not be run long enough.
If you have the nerve to read the full article, "Nuclear Winter Revisited with a Modern Climate Model and Current Nuclear Arsenals: Still Catastrophic Consequences", it can be found on line and soon to appear in J. Geophys. Res.

UPDATE: Roger Pielke Sr. had a post about this back in December. There is also a powerpoint presentation


Anonymous said...

Hi I've passed this on to which is the best web source for general arms control discussion.

Anonymous said...

You mean Sagan's "biggest blunder" was not a blunder at all?

Oh, my.Imagine that.

Perhaps Sagan was a better scientist than the weapons "technicians" (Teller et al) in the National Academy gave him credit for being (better than them at least).

EliRabett said...

Well, it is pretty hard to be a better scientist than one of the Martians

C W Magee said...

Aren't these the same folks who predicted a climactic catastrophe from the oil fires in Kuwait?

And how would the fuel loads be any different than the peat or forest fires in Indonesia over the past decade?

My "underconstrained overextrapolation" alarm is going off.

I suggest experimental verification. Anyone wanna nominate targets?

EliRabett said...

Where are you?

Anonymous said...

And how would the fuel loads be any different than the peat or forest fires in Indonesia over the past decade?"

The fuel load would be very different because the targets would be cities.

If you don't believe that, perhaps you might burn your own house as an experiment. :)

The people who question nuclear winter always give the example of the the Iraqi oil fires, but they were very different both in extent (amount of soot produced) and nature (in the height in the atmosphere to which the soot is injected) from any significant nuclear exchange.

As the authors of the recent study point out, the aerosols produced by a nuclear exchange are lofted high into the stratosphere -- higher even than volcanic particles (which we know cause cooling).

Dr. Lemming said...

I believe they are modelling fires ignited by the nuclear exchange, and not the transient fireballs themselves.

And here in Canberra we recently conducted a large scale bushfire- housefire comparison test.

My response is here:

Anonymous said...

It's clear what they meant if you read the study. :)

EliRabett said...

Reading the study is always to be recommended before commenting but never as much fun.

C W Magee said...

I agree.

From the accepted paper:
"Turco et al. [1990] showed that the original Turco et al. [1983] results were robust, and described how subsequent work filled in the details of the emissions of smoke, smoke properties, and climate response."

From Turco et al. [1990]:
"(ii) sooty smoke from urban fires is the main contributor to nuclear winter"

I recommend your anonymice reread the classic manuscript "Recommendations for residents of vitreous dwellings vis a vis the manual propulsion of stones". They may find that crow tastes better than cheese.

Anonymous said...

Read Dr. Pry. Rean Lenin. Read Golitsyn. Read Sejna.

Prepare for war or be a traitor.

Anonymous said...

Is this what you mean by "prepare for war", anon 10:33?

“President Bush is rushing to deploy a technology that does not work against a threat that does not exist,” says Joseph Cirincione - senior fellow at the Center for American Progress. “Iran is at least 5 to 10 years away from the capability to build a nuclear weapon and at least that far from having a missile that could hit Europe let alone the US. And anti-missile systems are still nowhere near working despite $150 billion spent since the 1983 Star Wars program started and years of phony tests staged to demonstrate ‘progress’ and ‘success.’”

Thanks, but no thanks. I think we have already had enough crappy faux "preparation" over the past 6 years to last our country a lifetime.

Real defense is based on real science and intelligent decisions, not fantasies coming out of the minds of alcoholic coke-heads like Bush.

Anonymous said...

Preparing for war means putting all utopian idiocy out of one's mind, and looking at the current threat environment as well as the range of threat futures. This latter is informed by an unbiased analysis of motivations and capabilities of both obvious and not so obvious potential adversaries. In other words, what might the other guy try to do?

In the idiotic utopian's fantasy world, the world gets flatter and flatter, peculiarities of tribe and nation are erased, and we all clasp hands and celebrate a beautiful secular globalness informed by "human progress." In the real world, the geopolitical environment oscillates between periods of relative calm and a more globalist sisution, and, periods of war and national economic focus. Since the end of WW2, we have incurred a rather long relative calm period, due to the fact that Western countries are quite frightened of nuclear weapons and other WMD. This has driven an ongoing appeasment, in the grand scheme of things. It cannot last. Furthermore, at some point, anti Western interests will eventually want more than what they now have. The West stands in the way. War will come.

So, to answer the question, what does it mean to prepare for war, here is the one sentence version. To prepare for war is to prepare to win unconditionally when the next world war happens. Who is most likely to achieve that result, given current conditions, the West or those who hate the West?

EliRabett said...

Except that no one wins in a nuclear exchange. As Kruschev said, after a nuclear war the living will envy the dead.