“If black-carbon emissions from aircraft could be reduced 20-fold, warming [from plane-created vapour trails] would be halted”
Nature (subs. req’d) reports on an analysis presented by Stanford’s Mark Jacobson to the American Geophysical Union’s annual meeting last week:
The first analysis of emissions from commercial airline flights shows that they are responsible for 4-8% of surface global warming since surface air temperature records began in 1850 “” equivalent to a temperature increase of 0.03-0.06 °C overall.
The analysis, by atmospheric scientists at Stanford University in Palo Alto, California, also shows that in the Arctic, aircraft vapour trails produced 15-20% of warming.
This study is yet more strong evidence that we need a high priority global strategy to sharply reduce black carbon:
The results of this analysis are likely to be studied widely as nations attempt to address the impact of commercial aviation on global warming. There are around 35 million commercial airline flights every year. Studies have been conducted in Europe, with airlines coming under increased pressure as European Union leaders consider levying a carbon tax on aircraft emissions. But little research has been conducted on the topic in the United States.
Previous studies have only estimated the impacts of commercial aviation, but this is the first use of actual emissions data “” from 2004 and 2006 “” to calculate warming from such flights….
For the latest study, Jacobson and his team developed a model for aircraft emissions that accounts for atmospheric composition, cloudiness and the physical properties of emissions, particularly of black carbon “” a major part of soot.
In his presentation, Jacobson explained how the model was applied to a nine-year simulation covering 2004 to 2013, after breaking up flight routes into 300-kilometre-square grids for analysis. The model was able to calculate the characteristics of vapour trails based on the actual particulate size of emissions and their evolution over time.
Many previous studies have assumed that the impact of aircraft emissions was the same everywhere. But the new analysis reveals that aircraft emissions increased the fraction of cirrus clouds where vapour trails were most abundant, and actually decreased the cirrus fraction in several locations by increasing the temperatures in the lower atmosphere, reducing the relative humidity in such locations.
If black-carbon emissions from aircraft could be reduced 20-fold, warming would be halted and a slight cooling would occur from plane-created vapour trails, Jacobson says.
The team’s study is being peer reviewed and is expected to be published soon, Jacobson added.
While this will need to be confirmed by other analysis, I don’t think the world can dawdle any further on the addressing black carbon. It seems to me of equal importance to, say, stopping deforestation, and possibly much easier.
Photo credit: A. Magurean/iStockphoto
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How does that square with the finding (fromt the days in Sept 2001 when air traffic in the US was grounded) that contrail-induced clouds kept nights warmer by more than they made days cooler?
time to rethink our flying habits? high speed rail anyone?
Post 9-11 studies supported this… even a PBS documentary. Seems to have been forgotten.
Follow up work suggested that 9/11 work was incorrect:
http://www.flightglobal.com/articles/2009/05/14/326581/european-studies-claim-no-climate-effect-from-911-grounding.html
Is it time, do you think, to begin writing of global and climate HEATING? “Warming” sounds benign, and “change” is manifestly a piece of spin, possibly from the same genius who came up with “pro-life.” You’re in a position to lead the way.
Elise: I’ve contended for a while that referring to it as “warming” (or even “heating”) misrepresents the situation. Sure, the immediate effect of the CO2 is to trap heat, but many of the human impacts, like drought, changes in rainfall patterns, forest fires, rising sea levels, and ocean acidification, are not things lay people immediately connect with heat (and in the case of acidification, they shouldn’t).
“Climate change” is much more accurate, which is likely why we’ve been using that term for decades, even though the deniers will screech and claim (for which, read: lie) that switching from GW to CC is a recent change and an attempt to move the goalposts.
I go even further and usually refer to it “climate chaos”, simply because so many of the effects are poorly understood, and nearly all of them seem to be worse than expected. Also, I think that communicates the appropriate urgency of the situation.
lovelock calls it Global Heating.
But the new analysis reveals that aircraft emissions increased the fraction of cirrus clouds where vapour trails were most abundant, and actually decreased the cirrus fraction in several locations by increasing the temperatures in the lower atmosphere, reducing the relative humidity in such locations.
doesn’t make that much sense to me. Can someone explain?
Have military flights been considered. A few years ago military aircraft were not subject to EPA regulations. I don’t believe that’s changed. It’s obvious to anyone who’s spent time near an airfield that the exhaust is dark from particulates.
Is there a correlation between this soot, especially from polar flights, depositing itself on arctic ice?
Elise: My favorite term is “Global Climatic Disruption.”
If planes cause that much effect, and I have no doubt they do, then future regular shipping across the polar region should also be considered. Ships burn bunker diesel and much soot is produced. A large ship will burn about a gallon of fuel to travel 50 feet. Yes the distance is shorter and overall less fuel is burned however the soot is dissipated much closer to the snow and ice.
Damn that pesky physics. If you want a free lunch it comes back to sustainable energy.
Personal to Joe:
No drops lately, Thank you Joe.
Leif
[JR: I think I know what happened. Let me know about any future drops.]
Joe had it right. “Hell and High Water”
The aviation climate change issues are in addition to matters of health for those on the ground. Studies in Europe show over flights significantly increase the incident of cancer, high blood pressure, strokes and other cardiovascular disease from low frequency noise and pollution. A recent study from Germany suggests governments must asks how many health issues and deaths should be considered as a fair trade for the right of air travel. General aviation continues to add lead to our environment.
Re: ships
We could return to using sailing ships for most international cargo and passenger service. Sailing ships were apparently economical enough to still be used throughout the nineteenth century and into the early twentieth. They continued to improve during that time. With modern materials and engineering they could be even better – they could have computers to control trim, and auxiliary motors for added safety and maneuverability. They’d be a little slower, but we could afford to slow down. The hyper pace of life today is a symptom of the dis-ease that got us into the mess we’re in anyway.
Joe: I lost a lot when you were over seas but assumed extra traffic, time shifts etc. I adjusted.
Again, you run a tidy ship, thank you for all you do and I am glad to see the extra traffic even if some disruption occurs.
Leif
[JR: Thanks. I appreciate your comments.]
Those dark particulates on the ground may attract heat, but the NOVA PBS episode about Global Dimming was pretty clear, with multiple sources, not just the 9/11 study. While suspended in the air, particulates shade the Earth, for better (in the case of masking background global warming) and for the worse (having a negative effect upon crop yields and human health).
It is ironic that, while we clean up traditional air pollution, global warming gets to show its true power. Ive often wondered if this was a factor in the relatively stable climate between the 40′s and 1980 — when the Clean Air Act started having a real impact. Was it also the moment when background warming was allowed to reveal its upward climb because airborne particulate pollution was receding?
And then, what is the balance between dark particulates causing cooling sometimes and warming at others? Its bound to get complicated.
[JR: Black carbon is not the same as sulfate aerosols. I'll try to post on this in January.]
Hi Everyone-
I like to call it climate destabilization, by the way. Seems more descriptive, maybe. Climate chaos also seems like a good choice.
How difficult would it be to reduce black soot from airplane engines? Would oxygenated fuels, like ethanol help?
So many problems, so little time. So much resistance to change. So much power in the hands of an intransigent and perhaps malignant financial elite.
I’m glad you brought this up, Joe, but your statement that contrails and even black soot are comparable to the emissions costs of deforestation is way off.
It’s not only that the 15-20% figure attributable to air soot is concentrated in the Arctic. It’s because forests not only stop emitting CO2 when left alone, when allowed to regenerate the growing sinks have huge significance in righting the ship.
Your tech knowledge is excellent here and in your book, but there is a big hole in the deforestation category. It may be because it is much more complex than exhaust emissions, and solving the problem runs into even more corruption and false reporting. You need help here- I’d suggest assigning a reading list to an intern. Above all, you need to understand what’s going on with North American forests. I hope you read the article I wrote on the subject; if not I’ll send it again.
Shut down air travel… at least non emergency flights. That’s unthinkable to most, but why wouldn’t we do that if we can determine beyond any doubt that the climate is about to turn nasty. Or even if we have doubt, why not put an end to flight based on the finite nature of fossil fuels? What’s the point in all the reckless burning? Air travel is an unnecessary luxury.
Rick: that SHOULD have be done in April/May 2009 to stop the pandemic strain A/H1N1 from spreading over the world. Thousands (or millions pearhaps) of deaths would be avoided whith that measures, and the climate data would have been unvaluable.
But that would mean fight the Turism Industry Lobby, and no authority has had the courage to do that. And thanks to this buch of cowards we have now an Infuenza Pandemic.
They grouded the planes afyer 9-11, but not at the beginning of The Pandemic (and a pandemic strain is far more dangerous than a bunch of terrorists)…
SHAME ON THEM!
OK, Eli was at the aviation section of the AGU. Turns out that most of the aviation influence comes from contrails formed when planes fly through air supersaturated wrt ice. The contrails that form are crystalline ice and they last for a comparatively long time. The solution is to route planes through warmer air.
“But the new analysis reveals… Can someone explain?”
High altitude clouds warm and lower altitude clouds cool. DBB, I’d guess Jacobsen’s “lower atmosphere” reference is that it was surprising to find the “good” clouds are retarded in addition to the expected finding “bad” clouds are encouraged by planes. At least future solar-drones are a superior ice age solution to burning coal.
“And then, what is the balance between dark particulates causing cooling sometimes and warming at others? Its bound to get complicated.”
Nope. Soot darkens ice. IDK if main effect is subsequent melting or the albedo change. Those other particulates have their cooling effect when suspended in atmosphere. Former is carbon-based and latter is sulphur and maybe other element-based. Former (partially?) addressed by air pollution health laws in 1960s or 70s in at least developed world. The latter soon to be addressed. Nice thing is with soot if you stop emitting it, it goes away in weeks vs decades and century long lifetimes of some GHGs. My fave soot solution is fund clean burning stoves so Africans and Asians live longer but I can’t find any data about failed India and successful Chinese programmes in 1980s/90s.
How can boomers be enticed to vacation not using air travel? Not worried about business travellers as both Dems and GOP are corporatist and there won’t be much American biz in the future anyway.
…forget my solar-drone suggestion, doesn’t make sense. Though do need purposeful warming contingencies given we might try to hit the thermometer brakes hard since it seems rich people hate their children or think god hates Earth, or IDK what…
This is all very fascinating stuff. I have been struggling lately to understand how if our CO2 output has continued to increase, the actual “global warming” has decreased over the last decade? Then with the latest attempt to blow up a plane got me thinking…What if our climate change has more to do with air travel than anything else? Seems to me our air travel miles have been a lot lower sense 911 which seems to correlate nicely with the recent global temperature lowering.
To all you science gurus, what is the chance that “high altitude” CO2 emissions has a bigger impact on climate change than ground level CO2 emissions?
#24, Keith: As far as the CO2 is concerned I doubt that there is any difference. However the contrails are known to instigate cloud cover with varying effects both pro and con. Another big positive effect is the black carbon soot that settles on the ice and snow, increasing melt. All these effects have been looked at by scientists and information is available.. Rough accounting has been done and CO2 is the driver at the present. Perhaps eclipsed by methane in a few years.
What about R-12? What has the global effect of the use and dis-use of R-12 been? One thing I do know is we stopped putting it in cars around 1994 to stop the growth of the o-zone hole over Antarctica. But I believe it is also a major green house gas. Are we considering this gas in our calculations of the causes of climate change?