Dear EarthTalk: Why is it that airplane exhaust is so much worse for the environment than engine emissions on the ground? -- Winona Sharpe, New York, NY
While air travel today accounts for just three percent of worldwide greenhouse gas emissions, the carbon dioxide (CO2) and other pollutants that come out of jet exhaust contribute disproportionately to increasing surface temperatures below because the warming effect is amplified in the upper atmosphere.
The Intergovernmental Panel on Climate Change reports that CO2
The Intergovernmental Panel on Climate Change (IPCC), a scientific intergovernmental body set up by the United Nations (UN) to provide comprehensive scientific assessments of the risk of human-induced climate change, reports that CO2 emitted by jets can survive in the atmosphere for upwards of 100 years, and that its combination with other gas and particulate emissions could have double or four times the warming effect as CO2 emissions alone.
Modern jet engines are not that different from automobile engines—both involve internal combustion and burn fossil fuels. But instead of gasoline or diesel, jet fuel is primarily kerosene, a common home heating fuel used around the world. Just like car engines, jets emit CO2, nitrogen oxides, sulfur oxides and soot.
Beyond their contributions to global warming, airplane emissions can also lead to the formation of acid rain and smog, as well as visibility impairment and crop damage down on the ground. The U.S. Environmental Protection Agency (EPA) reports that aircraft engines contribute about one percent of total U.S. mobile source nitrogen oxide emissions and up to four percent around airports in some areas.
What worries environmentalists is the fact that the number of airline flights is on the rise and is expected to skyrocket by mid-century, meaning that if we don’t get a handle on airplane emissions, our other carbon footprint reduction efforts could be for naught. The U.S. Federal Aviation Administration (FAA) reports that commercial flights grew nine percent from 2002 to 2010 and will rise another 34 percent by 2020.
Jet emissions standards are based on guidelines established under the U.S. Clean Air Act and are set by the International Civil Aviation Organization (ICAO). Current standards were created in 1996 and updated in 2006, but environmental leaders want even stricter limits on greenhouse gas and other emissions.
The IPCC recommends funding more research into aviation's effects on climate to guide the development of aircraft and engine technology, promoting more efficient air traffic operations and expanding the use of regulatory and economic measures to encourage emissions reductions.
In regard to economic measures, the European Union (EU) is leading the way with new rules that assess fees on foreign airlines based on their CO2 emissions. The new system, which would require airlines using an airport in Europe to trade for or purchase permits corresponding to the amount of greenhouse gases they emit, was supposed to go into effect in 2013 but has been postponed due to intense opposition from foreign governments which consider it a barrier to trade. EU officials have threatened to put the plan into effect nonetheless if airlines or their governments can’t agree on new stricter emissions limitations.
CONTACTS: IPCC, www.ipcc.ch; FAA, www.faa.gov; ICAO, www.icao.int.
Dear EarthTalk: What are some tips for keeping my dogs and cats healthy?
-- Kim Newfield, via e-mail
Believe it or not, our pets may be exposed to more harsh chemicals through the course of their day than we are. Researchers at the non-profit Environmental Working Group (EWG) found that pet dogs and cats were contaminated with 48 of 70 industrial chemicals tested, including 43 chemicals at levels higher than those typically found in people.
Pets ingest pollutants and pesticide residues and breathe in an array of
“Just as children ingest pollutants in tap water, play on lawns with pesticide residues or breathe in an array of indoor air contaminants, so do their pets,” reports EWG. Since they develop and age seven or more times faster than children, pets also develop health problems from exposures much faster, EWG adds.
“Average levels of many chemicals were substantially higher in pets than is typical for people, with 2.4 times higher levels of stain- and grease-proof coatings (perfluorochemicals) in dogs, 23 times more fire retardants (PBDEs) in cats, and more than five times the amounts of mercury, compared to average levels in people,” reports the group. Their 2008 study looked at plastics and food packaging chemicals, heavy metals, fire retardants and stain-proofing chemicals in pooled samples of blood and urine from 20 dogs and 37 cats tested at a Virginia veterinary clinic.
“For dogs, blood and urine samples were contaminated with 35 chemicals altogether, including 11 carcinogens, 31 chemicals toxic to the reproductive system, and 24 neurotoxins,” adds EWG. This is particularly alarming given that man’s best friend is known to have much higher cancer rates than humans. A 2008 Texas A&M Veterinary Medical Center study found that dogs have 35 times more skin cancer, four times more breast tumors, eight times more bone cancer, and two times more leukemia per capita as humans. And according to researchers from Purdue University, cancer is the second leading cause of death for dogs, with about one in four canines succumbing to some form of the disease. Meanwhile, hyperthyroidism—a condition which many think is on the rise in felines due to chemical exposures—is already a leading cause of illness for older cats.
In its Pets for the Environment website, EWG lists dozens of ways for pet owners to ensure that dogs and cats are as safe as possible in this dangerous world we inhabit. Among other tips, EWG recommends choosing pet food without chemical preservatives such as BHA, BHT or ethoxyquin, and looking for organic or free-range ingredients rather than by-products. As for drinking water, EWG suggests running tap water through a reverse osmosis filter—either faucet-mounted or pitcher-based—before it goes into a pet’s bowl to remove common contaminants. Also, replacing old bedding or furniture, especially if it has exposed foam, can prevent pets from ingesting fire retardants. From avoiding non-stick pans and garden pesticides to choosing greener kitty litter and decking material, the list of tips goes on.
Taking steps to ensure a safer environment for pets—some 63 percent of U.S. homes have at least one—will mean a safer world for humans, too. EWG concludes that our pets “well may be serving as sentinels for our own health, as they breathe in, ingest or absorb the same chemicals that are in our environments.”
CONTACT: EWG Pets for the Environment, www.ewg.org/PetsfortheEnvironment