[Vision2020] Answering Global Warming Skeptics: NOAA: Human Pollution Cooling Global Climate, Offsetting Greenhouse Gas Warming 50%

[Ted Moffett]

Human sourced atmospheric pollution is dramatically masking the climate
warming expression of greenhouse gas emissions.  The effect of "global
dimming," as some call it, has been known for decades, with uncertainties in
the science regarding the magnitude of the effect, partly because aerosols
can also warm the climate (black carbon, soot).  But the percentage of the
cooling impact of aerosols is becoming more precisely known, as the NOAA
study referenced (at the bottom) in this post indicates.

Ironically, if all sources of human atmospheric pollution (aerosols) were
stopped, anthropogenic global warming would likely accelerate, in a matter
of decades, even if we also stopped all greenhouse gas emissions.

This is because, while a significant percentage of atmospheric CO2 from
human sources can remain in the atmosphere for a century, even centuries,
according to some climate scientists, continuing to impact climate, human
sourced aerosols would dissipate from the atmosphere in a few years, thus
removing their considerable cooling.  And the climate time lag effect would
remain:

http://www.skepticalscience.com/Climate-time-lag.html
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But a sober realistic analysis of greenhouse gas emissions indicates
globally they are likely to increase in coming decades, despite the upcoming
2009 UN Copenhagen Climate Change Conference, and other attempts to solve
this problem.  The pressures of global economic development and
population expansion will create tremendous demand to increase fossil fuel
use, especially of cheap coal power (often without CCS: carbon capture and
storage), which in India and China alone, the two largest nations (in
population) undergoing rapid economic development, could result in increases
in global greenhouse gas emissions.

Imagine India and China with the same per capita greenhouse gas emission
rate as in the US.  If the US currently emits about 20% of global emissions
(roughly correct), China and India alone at their current population (which
is going to increase) of roughly eight times US population, would then emit
roughly eight times US emissions, or about 160% of current global total
emissions.  India and China simply cannot expand a fossil fuel powered
economy (without CCS) to even 50% of current US per capita emission rate, if
emissions are to be dramatically lowered globally, given other nations will
also struggle with lowering emissions.  This math is not very friendly to
hopes of lowering global emissions in absolute amounts, assuming continued
expansion of India and China's economic industrialization.  The world is
living in climate change denial.

http://www.eia.doe.gov/bookshelf/brochures/greenhouse/Chapter1.htm

>From Energy Information Administration website above:

*What is the Prospect for Future Emissions?*
*
*World carbon dioxide emissions are expected to increase by 1.8 percent
annually between 2004 and 2030 (Figure 5). Much of the increase in these
emissions is expected to occur in the developing world where emerging
economies, such as China and India, fuel economic development with fossil
energy.
---------------------------
However, hope springs eternal, so attempts to lower emissions must
continue.  United Nations Climate Change Conference, Dec.7-18, 2009, website
below:

http://en.cop15.dk/
----------------------------
Some skeptics of the science behind anthropogenic climate warming, have
emphasized that atmospheric temperatures are not increasing or are not
increasing as much as they should, given the claims of the climate
scientists (IPCC, et. al.) who insist the scientific evidence is
overwhelming that human greenhouse gas emissions are altering climate.

But the effect of "global dimming" from aerosols is offsetting 50% (that's
FIFTY PERCENT, I'll put in caps, given the profound significance of this
fact) of the climate warming that would otherwise be expressed from
greenhouse gases, according to the study referenced below from NOAA.  And,
again according to this study, most of the warming of Earth's climate from
greenhouse gases that has not been offset has gone into warming the oceans.

We can assume that if greenhouse gas emissions continue to increase
atmospheric CO2 levels, that either we pollute more to offset the warming
effect, or human sourced aerosols will not offset as high a percentage of
the warming from greenhouse gas emissions.  Indeed, one proposal to offset
greenhouse gas warming is to inject huge amounts of aerosols into the
atmosphere to cool the climate, as a deliberate climate geo-engineering
measure:

http://www.noaanews.noaa.gov/stories2009/20090909_haze.html

>From website above:

The results support the 2007 assessment by the Intergovernmental Panel on
Climate Change (IPCC) that estimated aerosol cooling at 1.2 watts per square
meter. But the new study places that estimate on more solid ground and rules
out the larger cooling effects that were previously thought to be possible.

“The agreement boosts our confidence in both the models and the new
approach,” said Murphy. “Plus, we’ve been able to pin down the amount of
cooling by aerosols better than ever.”

The narrower bounds on aerosol effects will help in predicting climate
change and accounting for climate change to date.

In balancing the budget for the processes perturbing the heating and cooling
of the Earth, Murphy and colleagues found that since 1950, the planet
released about 20 percent of the warming influence of heat-trapping
greenhouse gases to outer space as infrared energy. Volcanic emissions
lingering in the stratosphere offset about 20 percent of the heating by
bouncing solar radiation back to space before it reached the surface.
Cooling from the lower-atmosphere aerosols produced by humans balanced 50
percent of the heating. Only the remaining 10 percent of greenhouse-gas
warming actually went into heating the Earth, and almost all of it went into
the ocean.

The new study tackled what the IPCC has identified as one of the most
uncertain aspects of the human impacts on climate. Aerosols, which can be
either solid or liquid, have complex effects on climate. Sulfate particles
formed from pollution can cool the Earth directly by reflecting sunlight.
Soot from biomass burning absorbs sunlight and warms the Earth. Aerosols can
also affect the formation and properties of clouds, altering their influence
on climate. The net effect of all these direct and indirect factors is a
cooling by aerosols, which has partially offset the warming by greenhouse
gases.

Authors of the study are Daniel M. Murphy, Susan Solomon, Robert W.
Portmann, and Karen H. Rosenlof of NOAA’s Earth System Research Laboratory;
Piers M. Forster of the University Leeds, UK; and Takmeng Wong of the NASA
Langley Research Center.
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Vision2020 Post: Ted Moffett
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