July 28, 2010
Soot Seen As Major Climate Warmer

Cutting soot emissions could cool the planet.

The quickest, best way to slow the rapid melting of Arctic sea ice is to reduce soot emissions from the burning of fossil fuel, wood and dung, according to a new study by Stanford researcher Mark Z. Jacobson.

Since soot is bad for human health soot emissions reduction ought to go the head of the line of methods for cutting global warming. Even people who question the anthropogenic global warming theory should be able to see soot reduction as good public policy.

Only carbon dioxide causes a bigger warming effect.

His analysis shows that soot is second only to carbon dioxide in contributing to global warming. But, he said, climate models to date have mischaracterized the effects of soot in the atmosphere.

Because of that, soot’s contribution to global warming has been ignored in national and international global warming policy legislation, he said.

"Controlling soot may be the only method of significantly slowing Arctic warming within the next two decades," said Jacobson, director of Stanford’s Atmosphere/Energy Program. "We have to start taking its effects into account in planning our mitigation efforts and the sooner we start making changes, the better."

One estimate puts the number who die in the US each year from diesel soot at 21,000 people. Soot boosts the risk of lung cancer, heart disease, and other diseases. Soot elevates blood pressure. So I'm very keen to cut soot emissions.

A reduction in soot emissions would cool the Arctic.

Jacobson found that eliminating soot produced by the burning of fossil fuel and solid biofuel could reduce warming above parts of the Arctic Circle in the next 15 years by up to 1.7 degrees Celsius. For perspective, net warming in the Arctic has been at least 2.5 degrees Celsius during the last century and is expected to warm significantly more in the future if nothing is done.

The most immediate, effective and low-cost way to reduce soot emissions is to put particle traps on vehicles, diesel trucks, buses, and construction equipment. Particle traps filter out soot particles from exhaust fumes.

Soot could be further reduced by converting vehicles to run on clean, renewable electric power.

Biofuels burned by poor people in villages of undeveloped countries kills many more people than fossil fuel soot.

Jacobson found that although fossil fuel soot contributed more to global warming, biofuel-derived soot caused about eight times the number of deaths as fossil fuel soot. Providing electricity to rural developing areas, thereby reducing usage of solid biofuels for home heating and cooking, would have major health benefits, he said.

Short of electrification distribution of inexpensive but highly efficient wood-burning stoves could make a big difference.

Share |      Randall Parker, 2010 July 28 11:15 PM  Climate Pollution

Bruce said at July 29, 2010 9:09 AM:

A major source of soot is diesel. Europe is now 50%+ diesel cars. The next major source of soot is coal.

The other major source is coal.


Thanks to misguided followers of Al Gore, the USA has sent much of its manufacturing to China which is building coal fired plants at the rate of 2 per week.

Suprisingly, gasoline is quite clean compare coal burning cars like the Volt.

CyclemotorEngineer said at July 29, 2010 9:14 AM:

This makes a lot of sense. The residence time of CO2 in the atmosphere has been estimated to be between 77 and 400 years. This means that reductions in our lifetime will only benefit future generations. A tough sell in our short-sighted political system.

Soot, on the other hand must have a relatively short residence time. If true, cutting soot emissions will be like cutting sulfur dioxide. The benefit will be immediate.

Chris T said at July 29, 2010 11:07 AM:

Most new diesel vehicles have soot traps already installed. Unfortunately, their inclusion is fairly recent and a lot of older vehicles (especially semis and buses) still lack them.

This has been one of the more insidious effects of global warming. Environmentalists have become overly focused on CO2 to the exclusion of many other environmental concerns or low hanging fruit that also affects global warming and has other detrimental effects.

JAY said at July 29, 2010 1:28 PM:

Did CO2 stop being the problem when Al Gore got in trouble?

Bruce said at July 29, 2010 3:30 PM:

"Soot traps" or Diesel Particulate Filters seem ... unproven.

"The goal is an 80% reduction in diesel particulate (soot) emissions but the technology's not without problems – AA patrols are already being called to cars with the particulate filter warning light illuminated (indicates a partial blockage)."

"If you ignore the light and keep driving in a relatively slow, stop/start pattern soot loading will continue to build up until around 75% when you can expect to see other dashboard warning lights illuminate too. At this point driving at speed alone will not be sufficient and the car will have to go to a dealer for regeneration. "

"If warnings are still ignored and soot loading continues to increase then the most likely outcome will be a new DPF costing around £1000. "


Looks like a disaster waiting to happen.

biobob said at July 29, 2010 3:52 PM:

unproven assertions implicit in this blog entry:
1) seasonal arctic ice melt is something to be avoided [imo when the arctic ice doesn't melt we have a SERIOUS problem eg an ICE AGE]
2) there is something WRONG with global warming at the rate supposedly measured by UHI contaminated and distorted data eg .6 degrees C for last century
3) global warming is anthropogenic
4) CO2 and soot causes global warming
5) elimination of soot would have any significant effect on arctic or global climate

all these and more are simply hypothetical assertions without the simplest experimental confirmation of hypothesis.

send me another load of WAG bull$hit please

LL said at July 30, 2010 10:20 AM:

I always thought that the best way to produce clean energy and reduce the CO2 produced is not to regulate CO2 but dirty emissions like soot and sulfur etc. Carbon dioxide cap and trade will always be a very theoretical threat to most people. It is an odorless colorless gas that we breath out!

The better route is to regulate things that are a lot more tangible like the black smelly smoke and soot comes out of Smokestacks and tailpipes.
This is a lot more obvious in its harm to us and the planet and would be an easier sell for regulation to reduce it.

The key of course if that the main culprits of Soot are also key producers of CO2. Namely Coal and Oil burning. By regulating soot instead of CO2 it will effectively make Coal and Oil more expensive whether through fines or the use of scrubbers etc., helping to shift the cost equation to help Natural Gas, Nuclear, Solar and Wind.

2 caveats to this is that Natural Gas also produces CO2, but its not as bad as Coal. The second is that BioFuel/BioMass plants would be more expensive with the need to use scrubbers to keep emissions soot free.

Randall Parker said at July 31, 2010 11:00 AM:


I agree with you about regulating the dirty emissions. First off, it improves our health. Second, it raises the cost of coal versus cleaner alternatives. So we'll get more nukes, wind, solar if coal conventional pollutants are more tightly regulated.

Engineer-Poet said at July 31, 2010 3:03 PM:

It would probably take a substantial carbon tax to get technologies like oxy-fuel combustion pushed out there.

Oxy-fuel would be a boon for Britain.  The North Sea production is well past peak, and the country looks to be relying on imported NG for basic needs like electricity.  Oxy-fuel with sequestration kills 2 birds with one stone.  It allows Britain to meet emissions limits while not relying on Russian gas, and it encourages EOR to revive the North Sea for a while and reduce the trade deficit.

Bruce said at July 31, 2010 5:42 PM:

Randall: "So we'll get more nukes, wind, solar if coal conventional pollutants are more tightly regulated."

1) Nukes are doomed. Yucca Mountain is dead. Greens hate nukes. Its dead.

2) Wind and solar are outrageously expensive, therefore the economy is in the UK and USA is doomed.

3) India and China are the future, mostly because green polices are deisnged to kill the "western" economies.

If the green movement wasn't a plan by Chinese Intelligence, it should have been one.

Engineer-Poet said at August 1, 2010 8:54 AM:

The NRC's administrative law judges have ruled that the DOE's attempt to withdraw the application for Yucca Mountain is illegal.  It's not dead yet.

Randall Parker said at August 1, 2010 10:29 AM:


The biggest obstacle in the way of nukes: Cost. Really. Read what the CEOs of companies like Exelon say. They see the cost overruns in Finland and France and the rising cost estimates of some proposed projects and they get cold feet.

The greens are not much of an obstacle since Congress passed legislation that simplifies the approval process. Nuclear's problem is that natural gas and coal are so cheap and nukes that are going to last 60+ years with huge amounts of steel and concrete are so expensive.

Wind's cost isn't outrageous. It is higher than natural gas or coal. But the Production Tax Credit that makes wind competitive is about 2.5 cents/kwh if memory serves. Not a huge increase.

Solar's more expensive. But I keep following First Solar's earnings announcements where they report their latest construction cost and it keeps going down pretty quickly. First Solar's module cost fell from $3 in 2004 to $1 in Feb 2009. Well, as of July 2010 First Solar is now reporting $0.76 per watt. That's a decline of a factor of 4 since 2004.

PV module manufacturing cost was reduced to $0.76/watt, down $0.05 from the prior quarter and 13% year over year. Annual throughput per line was up 6% quarter over quarter to 59.0 MW. This increases announced or operating capacity from 2.1 to 2.2 GW by 2012.

If First Solar keeps that up then installation costs and other pieces of equipment in an installation (e.g. grid tie inverters) will make up most of the cost. Some engineers have posted here telling me that grid tie inverter costs can fall quite a bit.

CyclemotorEngineer said at August 1, 2010 8:39 PM:


You are correct in stating that the residence time of CO2 in the atmosphere is relatively short. However, the residence time of carbon in the ocean is hundreds of years, and this reservoir is connected to the atmosphere. Carbon is sequestered in the form of carbonate rocks, which happens more slowly than readmission to the atmosphere. This leads to an effective atmospheric residence time of between 77 and 400 years. Here is a good, graphical explanation:

The blog you cite is a piece of propaganda, with information selected purely to convince, with no appreciation of nature's complexity or the ambiguity inherent in all human understanding.

Biobob said at August 1, 2010 9:41 PM:


You and your citation reel off carbon cycle numbers as if they were fact. They are estimates - and WAG type estimates at best. Our quantitative understanding of most aspects of carbon cycle processes are RUDIMENTARY at best and the error bars on most listed numbers are oftentimes several orders of magnitude of the estimate. The global carbon cycle is VERY complex and poorly studied in many ways and not likely to become any better than current estimates are anytime soon. Just about the only more or less accurate numbers in such a schema are those for human fossil fuel CO2 generation, and gigatons of CO2 in the atmosphere. The rest are BS.

However, you are wildly inaccurate about ocean carbon sequestration. Eventually, much of oceanic carbon does sequester as carbon containing rock, but first it is sequestered into biotic system, bottom mud, etc. Carbon residence time in the atmosphere is very unlikely to be anywhere near 77 years. Of course, any WAG is as good as another, so guess away and no one can gainsay you !!

Biobob said at August 1, 2010 9:43 PM:

oops = meant Cyclemotor tyvm lol

Nick G said at August 2, 2010 10:51 AM:


The wind Production Tax Credit is 2.1 cents per kWh. It applies for the first 10 years of life, which reduces it's overall average value to investors to about 1.3 cents (based on 7% interest, and 25 year wind farm life).

Nick G said at August 2, 2010 10:53 AM:

That also assumes that the investor doesn't lose 25% more of the value of the PTC converting tax credits to actual cash income, which is likely given the expiration of provisions intended to reduce that problem.

Hong said at August 15, 2010 7:41 AM:

The simple question the alarmists refuse to answer is why CO2 levels usually rise only AFTER global temperature increases. It seriously complicates their religious view of the doctrine of man made climate change. Instead the skeptics receive new versions of the old hateful iterations of warmist propaganda from troll beasts like EP. And Randall, you might want to refrain from offering E-P fire support and have him actually read my responses for a change. lol

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