Climate Change: Contrails

Aircraft Contrails Stoke Warming (Reuters, ):"Aircraft condensation trails criss-crossing the sky may be warming the planet on a normal day more than the carbon dioxide emitted by all planes since the Wright Brothers' first flight in 1903, according to a study in Nature Climate Change." [This is about 0.025 Watts per square meter, according to the IPCC (2007)]

Citation: Ulrike Burkhardt & Bernd Kärcher Global radiative forcing from contrail cirrus. Nature Climate Change 1, 54–58 (2011)

Image from Earth Observatory: "NASA scientists have found that cirrus clouds, formed by contrails from aircraft engine exhaust, are capable of increasing average surface temperatures enough to account for a warming trend in the United States that occurred between 1975 and 1994."
Citation: Minnis, Patrick, J. Kirk Ayers, Rabindra Palikonda, Dung Phan, 2004: Contrails, Cirrus Trends, and Climate. J. Climate, 17, 1671–1685.

"Trends in cirrus coverage and 300-hPa relative humidty (1971-19995) and estimated 1992 linear congtrail coverage. (a) Trends in cirrus coverage for all regions with more than 15yr of data. (b) Subset of (1) for all regions having trends sinifcant at the 90% confidence level according to Student's t test. (c) Estimated linear contrail coverage...Only observations taken from land stations and from ships are used for the land and ocean air traffic regions, respectively. (d) Trends in annual mean NCEP relative humidity at 300 hPa."

Citation: Minnis, Patrick, J. Kirk Ayers, Rabindra Palikonda, Dung Phan, 2004: Contrails, Cirrus Trends, and Climate. J. Climate, 17, 1671–1685.

"In response to the Minnis et al. conclusion, contrail Radiative Forcing (RF) was examined in two global climate modelling studies (Hansen et al., 2005; Ponater et al., 2005). Both studies concluded that the surface temperature response calculated by Minnis et al. (2004) is too large by one to two orders of magnitude. For the Minnis et al. result to be correct, the climate efficacy or climate sensitivity of contrail RF would need to be much greater than that of other larger RF terms, (e.g., CO2). Instead, contrail RF is found to have a smaller efficacy than an equivalent CO2 RF (Hansen et al., 2005; Ponater et al., 2005) (see Section 2.8.5.7), which is consistent with the general ineffectiveness of high clouds in influencing diurnal surface temperatures (Hansen et al., 1995, 2005). " (IPCC 2007)

Ship Pollution

Large ships continue to use old, polluting diesel engines, with disasterous health effects for people living close to the ocean. The EPA's proposed plan would greatly alleviate this largely unregulated source of pollution, which is currently equal to about 120 coal power plants running continuously in our nation's harbors and waterways. (source: President's Cancer Commission report, 2010)

EPA Website on large ship pollution.

Interestingly, ships also affect cloud formation: the soot in their exhaust creates nuclei for water droplets to condense and form clouds: http://earthobservatory.nasa.gov/IOTD/view.php?id=44517

Learning the Shape of Clouds

"learning the shape
of clouds" not
that every moment
has to be extra
ordinary. Kick
some leaves.
The underside
of some rocks
pinecones and
pale
leaflitter on
the dark earth
but some days
there is just a single
dark cricket under
the rock and the
leaves make an empty
rustling.

I'm moving in the
right direction. Except
the fire in my
lower stomach and
the surge at the back
of the brain
and the eyelids
when breathing.
Your own footsteps
on the way back.
Tire tracks gradually
you hear only
the swish
of pants
inside the muffle
of hat and jacket