Confronting the Roles of Non-CO2 Pollutants in Global Warming

Aggressively reducing emissions of non-CO2 climate drivers could forestall abrupt climate change for up to 40 years, according to a recent study in the Proceedings of the National Academy of Sciences (2009, DOI 10.1073/pnas.0902568106). Without...

November 18, 2009 | Source: Environmental Science and Technology | by Noreen Parks

CLICK HERE TO TAKE ACTION! Industrial food production is responsible for 40% of current greenhouse gas emissions, but if we transitioned all of the world’s farmland to organic, it would sequester 40% of global greenhouse gas emissions. Methane, mentioned in the article on this page, is the big reason why industrial food production emits greenhouse gas pollution while organic agriculture sequesters it. Industrial agriculture produces methane through the use of synthetic nitrogen fertilizers derived from natural gas and the off-gassing of piles of animal waste produced in factory farms. Organic agriculture avoids methane emissions and sequesters carbon by using composted plant materials and manure instead of chemical fertilizers and keeping animals on pastures that absorb their waste and act as a carbon sink. 
Aggressively reducing emissions of non-CO2 climate drivers could forestall abrupt climate change for up to 40 years, according to a recent study in the

Proceedings of the National Academy of Sciences (
read study

). Without such efforts, even drastic cuts to CO2 emissions will fail to put the brakes on planetary warming soon enough to avoid climate tipping points, the authors warn.

HFCs, black carbon (soot), ground-level ozone, and methane together
represent an estimated 40ˆ’50% of the warming caused by human
activities. €œWe€™re on track for a 2 °C warming that will put us in the
danger zone, and current research shows it€™s coming faster than anticipated,€ says study coauthor Durwood Zaelke of the Institute for Governance and Sustainable Development. €œRestricting CO2 emissions is absolutely critical, but it won€™t be enough. So the question is how quickly we can deliver cooling on the non-CO2 side.€

€œfast-action€ mitigation strategies based on available technologies
would jump-start this effort, the researchers say. One key step would
be to phase down the production and use of HFCs, which are now known to
act as long-lasting greenhouse gases. Use of HFCs has been growing
because of the rising demand for air-conditioning and refrigeration in
developing countries. Current projections indicate that by mid-century
the impact of HFCs on the climate could be approximately 20% of that
from CO2 emissions, if the current trends continue unabated.
€œThe Montreal Protocol (MP) has already delayed climate change by 7ˆ’12
years,€ lead author Mario Molina of the University of California San
Diego noted in a prepared statement. €œWe have to take advantage of the
proven ability of this legally binding treaty to quickly phase down
HFCs.€ North American leaders recently submitted a proposal to start this process for consideration at the MP annual meeting in November.

now ranks as the second or third biggest contributor to climate change.
However, soot€™s short life span offers opportunities for comparatively
quick fixes€”such as particulate filters for vehicles and clean-burning
or solar-powered stoves€”that could yield significant climate savings,
the authors say. Likewise, the means for slashing levels of ozone
precursors such as carbon monoxide and nitrogen oxides are within
reach. Research shows that rigorous enforcement of air-pollution
technologies and regulations could cut these emissions by more than
half, dramatically decreasing tropospheric ozone. €œWe

know how
to curb air pollution; we just need to do it better and faster, and get
the solutions applied in developing countries. We can borrow from and
utilize working international agreements to do this,€ Zaelke emphasizes.

the overall greenhouse contributions of climate drivers reveals only
part of their potential for limiting global warming, Michael MacCracken
of the Climate Institute noted in a recent paper. Also critical are their atmospheric lifetimes, which range from centuries to millennia for CO2
and HFCs and from days to weeks for black carbon. €œSteep, immediate
reductions in soot would eliminate its warming influence over the
entire 21st century,€ he explains. Similarly, swift cutbacks in
emissions of methane and ozone-producing pollutants would yield sharp
and enduring declines in their warming influence.