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Asian Air Pollution Warms U.S More than Our GHG Emissions (More futility for U.S. EPA)

By Chip Knappenberger -- June 7, 2012

“The whims of foreign nations, not to mention Mother Nature, can completely offset any climate changes induced by U.S. greenhouse gas emissions reductions…. So, what’s the point of forcing Americans into different energy choices?”

A new study provides evidence that air pollution emanating from Asia will warm the U.S. as much or more than warming from U.S. greenhouse gas (GHG) emissions. The implication? Efforts by the U.S. Environmental Protection Agency (and otherwise) to mitigate anthropogenic climate change is moot.

If the future temperature rise in the U.S. is subject to the whims of Asian environmental and energy policy, then what sense does it make for Americans to have their energy choices regulated by efforts aimed at mitigating future temperature increases across the country—efforts which will have less of an impact on temperatures than the policies enacted across Asia?

Maybe the EPA should reconsider the perceived effectiveness of its greenhouse gas emission regulations—at least when it comes to impacting temperatures across the U.S.

New Study

A new study just published in the scientific journal Geophysical Research Letters is authored by a team led by Haiyan Teng from the National Center for Atmospheric Research, in Boulder, Colorado. The paper is titled “Potential Impacts of Asian Carbon Aerosols on Future US Warming.”

Skipping the details of this climate modeling study and cutting to the chase, here is the abstract of the paper:

This study uses an atmosphere-ocean fully coupled climate model to investigate possible remote impacts of Asian carbonaceous aerosols on US climate change. We took a 21st century mitigation scenario as a reference, and carried out three sets of sensitivity experiments in which the prescribed carbonaceous aerosol concentrations over a selected Asian domain are increased by a factor of two, six, and ten respectively during the period of 2005–2024.

The resulting enhancement of atmospheric solar absorption (only the direct effect of aerosols is included) over Asia induces tropospheric heating anomalies that force large-scale circulation changes which, averaged over the twenty-year period, add as much as an additional 0.4°C warming over the eastern US during winter and over most of the US during summer. Such remote impacts are confirmed by an atmosphere stand-alone experiment with specified heating anomalies over Asia that represent the direct effect of the carbon aerosols.

Usually, when considering the climate impact from carbon aerosol emissions (primarily in the form of black carbon, or soot), the effect is thought to be largely contained to the local or regional scale because the atmospheric lifetime of these particulates is only on the order of a week (before they are rained out). Since Asia lies on the far side of the Pacific Ocean—a distance which requires about a week for air masses to navigate—we usually aren’t overly concerned about the quality of Asian air or the quantity of junk that they emit into it. By the time it gets here, it has largely been naturally scrubbed clean.

But in the Teng et al. study, the authors find that, according to their climate model, the local heating of the atmosphere by the Asian carbon aerosols (which are quite good at absorbing sunlight) can impart changes to the character of the larger-scale atmospheric circulation patterns. And these changes to the broader atmospheric flow produce an effect on the weather patterns in the U.S. and thus induce a change in the climate here characterized by “0.4°C [surface air temperature] warming on average over the eastern US during winter and over almost the entire US during summer” averaged over the 2005–2024 period.

While most of the summer warming doesn’t start to kick in until Asian carbonaceous aerosol emissions are upped in the model to 10 times what they are today, the winter warming over the eastern half of the country is large (several tenths of a °C) even at twice the current rate of Asian emissions.

Now let’s revisit just how much “global warming” that stringent U.S. greenhouse gas emissions reductions may avoid averaged across the country.

In my Master Resource post “Climate Impacts of Waxman-Markey (the IPCC-based arithmetic of no gain)” I calculated that a more than 80% reduction of greenhouse gas emissions in the U.S. by the year 2050 would result in a reduction of global temperatures (from where they otherwise would be) of about 0.05°C. Since the U.S. is projected to warm slightly more than the global average (land warms faster than the oceans), a 0.05°C of global temperature reduction probably amounts to about 0.075°C of temperature “savings” averaged across the U.S., by the year 2050.

Comparing the amount of warming in the U.S. saved by reducing our greenhouse gas emissions by some 80% to the amount of warming added in the U.S. by increases in Asian black carbon (soot) aerosol emissions (at least according to Teng et al.) and there is no clear winner. Which points out the anemic effect that U.S. greenhouse gas reductions will have on the climate of the U.S. and just how easily the whims of foreign nations, not to mention Mother Nature, can completely offset any climate changes induced by our greenhouse gas emissions reductions.

And even if the traditional form of air pollution (e.g., soot) does not increase across Asia (a slim chance of that), greenhouse gases emitted there certainly will. For example, at the current growth rate, new greenhouse gas emissions from China will completely subsume an 80% reduction in U.S. greenhouse gas emission in just over a decade. Once again, pointing out that a reduction in domestic greenhouse gases is for naught, at least when it comes to mitigating climate change.

So, what’s the point, really, of forcing Americans into different energy choices? As I have repeatedly pointed out, nothing we do here (when it comes to greenhouse gas emissions) will make any difference either domestically, or globally, when it comes to influences on the climate. What the powers-that-be behind emissions reduction schemes in the U.S. are hoping for is that 1) it doesn’t hurt us too much, and 2) that China and other large developing nations will follow our lead.

Both outcomes seem dubious at time scales that make a difference.


Teng, H., W. M. M. Washington, G. Branstator, G. A. Meehl, and J.-F. Lamarque, 2012. Potential impact of Asian carbon aerosols on future US warming. Geophysical Research Letters, doi:10.1029/2012GL051723, in press.


  1. Gil  

    The ol’ Tragedy of Commons! If only some countries “go Green” then their sacrifice will lost because of countries that won’t therefore there’s no incentive for anyone to change. China and similar parts of Asia aren’t going to jeopardise their growth by getting into the AGW hysteria. If anything the Chinese are probably only into solar panel technology is sell them to stupid Westerners.


  2. Ed Reid  

    Gil @ 1

    I believe it is actually worse than you suggest. Countries which “go Green” would see their energy costs increase, probably driving their industries to relocate to countries with lower energy costs, such as those in Asia. Those relocations would likely result in ever greater emissions than would otherwise have been the case.

    If there is a need to reduce carbon emissions globally, the developed countries would be far better advised to retain their negotiating leverage, rather than assuming that the developing countries would follow them off the cliff.


  3. Andrew  

    “What’s the point, really, of forcing Americans into different energy choices?”

    What is the point indeed? So far global less-colding hasn’t hurt us. It isn’t likely to in the future.


  4. SusanA  

    Great article. I’ve heard a similar view being expressed here in London (namely that our high PM levels are because of pollution being dumped on us from Paris) – but not backed by a scientific paper. I agree levels of air pollution in developing countries can be a disgrace – it’s something we’ve been trying to highlight recently (http://www.allergycosmos.co.uk/blog/hong-kong-air-pollution/) but I suggest that the US and Europe should try to lead by example and hope Asian nations follow suit and try to get that balancing act between industrial development and clean air (and the health of their citizens) right.


  5. Chip Knappenberger: Asian Air Pollution Warms U.S More than Our GHG Emissions (More futility for U.S. EPA) | JunkScience.com  

    […] MasterResource Share this:PrintEmailMoreStumbleUponTwitterFacebookDiggRedditLike this:LikeBe the first to like this post. This entry was posted in Climate Change and tagged climate models, co2 emissions, dioxycarbophobia, greenhouse gas emissions, PlayStation® climatology, weather superstition. Bookmark the permalink. ← IBD: Alabama Bans U.N. Agenda 21 Sovereignty Surrender […]


  6. Andrew  

    Susan-It’s not that we have Asia air pollution in our air, but that the black carbon from their power plants warms the global-and hence US-climate.

    As for “leading the way”, when it comes to real pollutants, like the black carbon in question, the US (and I assume Europe too) are already “leading the way” and have been for decades. But us showing them the way is not what will make Asian countries reduce their emissions. They need to grow their economies to get over the critical point of the Kuznet Curve:



  7. David Appell  

    Chip, this kind of post is beneath you.

    This direct aerosol warming is *in addition* to GHG warming. The authors make that explicit in their summary:

    “Our experiments with CCSM4 indicate that if Asian
    carbon aerosol concentrations are greatly increased in the
    21st century, the induced large-scale circulation may add
    0.4 C TAS warming on average over the eastern US during
    winter and over almost the entire US during summer. This
    warming is in addition to the anthropogenically-induced
    TAS warming over the same US domain found in the
    CCSM4 RCP4.5 experiment [Meehl et al., 2012], which
    during 2005–2024 is about 0.9 C and 0.7 C in DJF and JJA,
    respectively. Hence the US warming is amplified by roughly
    50% by the remote effects of the enhanced carbon aerosols
    over Asia in the 6x and 10x experiments.”

    CO2 is a well-mixed gas and that the very nature of the problem is that it is global — emissions anywhere cause warming everywhere.


  8. cknappenberger  

    David (#7),

    “emissions anywhere cause warming everywhere.”

    Yep. And according to the Teng et al. study, aerosol emissions in China can cause warming in the U.S. Potentially even more warming in the U.S. than greenhouse gas emissions from the U.S.

    So I am missing your point.



  9. Don Vandervelde  

    Chip, good point! I’ve seen studies showing that the burgeoning forests in N. America result in lower CO2 in the air flowing east off our coast than air impinging on us from the west (Pacific) coast. Do we get a cupla attaboys or waytogos for that? Don V.


  10. David Appell  

    Chip: you can, if you want, pretend you’re too stupid to understand the tragedy of the commons. But, having read other things you’ve written, I’m not going to pretend that you are.

    So the real question is, why do you that?

    [RLB HERE:PLEASE IMPROVE THE TONE AND JUST MAKE YOUR SPECIFIC ARGUMENTS–Chip is a great American and a new father and just might be just as nice a guy as one of your favorite relatives.]


  11. Douglas Hanes  

    Good article Chip. It’s really about the big picture and common sense. In 2009 China released more CO2 than North and South America combined. My guess is now you could also add Africa to the mix. What the US is doing is economic suicide, especially since we know the CO2 radiative heat forcing effect has long been saturated so none of it matters anyway. We could go to CO2 800 and it would have effectively no effect on Global Temperatures.


  12. cknappenberger  


    When did I say that anthropogenic greenhouse gas emissions were leading to a “tragedy?”

    My article was generally about the lack of utility in efforts to limit U.S. GHG emissions to affect US climate. A myriad of other factors, including apparently Chinese aerosol emission (and Chinese GHG emissions) can act to swamp the impacts of (major) homegrown actions.



  13. Guy Trafford  

    I find all the finger pointing interesting. So Asian emissions are worse than the US? I doubt it. Living in the South Pacific I find emissions from the USA equally disturbing (and with less excuses) than Asian emissions


  14. David Appell  

    RLB: I made my point and asked my question: why is Chip Kappenberger pretending he is unaware of tragedy of the commons? His entire argument relies on pretending it doesn’t exist. If you ignore it all kinds of things are possible: why any individual can litter, dump his sewage in the nearest, shoplift, etc. Does he also believe such things are permissible? His exact same argument applies.


  15. Mike  

    The warming impact of black carbon (soot) is of limited duration as black carbon is removed from the atmosphere rather quickly. By contrast, about half of emitted CO2 stays in the atmosphere for centuries.


  16. David Appell  

    Chip, again: Why are you pretending you’re unaware of the tragedy of the commons?

    Do you think only the US should be allowed to emit greenhouse gases?

    If not, who else should — and who shouldn’t?


    • rbradley  


      The ‘tragedy of the commons’ assumes a negative exernality; AGW is a positive externality when feedback effects are not strongly positive. But it is likely that the pluses and minuses are too complex to ever make an unambiguous interpretation.

      Secondly, if you insist that AGW is a market failure, what about government failure” This is what Chip’s post really points at.

      Third, it’s time to stop the futile climate crusade and focus on the ‘incredible bread machine’ of market capitalism for climate insurance as just about any other ‘protection’ for the future. Weath is health.


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