Provocative NASA study puts road traffic ahead of power plants as cause of climate change near-term

(Picture of auto traffic from Flickr and photographer Lynac)

A new study from NASA’s Goddard Institute for Space Studies says tailpipe emissions will cause the most global warming over the next decade. Next comes heating homes by burning wood and cow dung in poor countries. Third is methane from cows.

Electric power is further down the list, though it will be the prime source of warming by century’s end, the study predicts. The provocative study, by a team led by NASA’s Nadine Unger, was published this month in the Proceedings of the National Academy of Sciences.

Policy implications
Does this mean we should turn away from fighting the coal industry and focus more on electric cars, high-speed rail and aid to third-world countries? Possibly. We may have a little more time than we thought to shut off coal – as far as global warming is concerned.

But this is just one study. It will need to be confirmed by others.

And the reason behind the findings is troubling. It all has to do with the release of aerosols that block the incoming sunlight and have a temporary cooling effect. Tailpipe emissions don’t have much of those, while coal-fired plants do. Some aerosols, such as sulfates and organic carbon, have a very short-term cooling effect (they are rained down in just a few days), while greenhouse gases stay aloft for decades.

Of course this is a double-edged sword. Aerosols have a known harmful effect on human health and on the environment. That’s why industrialized countries have been phasing them out.

A choice we don’t want to make
Do we have to choose between climate change and our health? Unger says, “no,” that we need to phase out unhealthy aerosols, but that an immediate focus on transportation will give us the biggest bang for our buck in the next decade.

A sound way to proceed is by attacking all sources – tailpipes, burning of wood and dung, cattle-produced methane AND power plants. If we can remove many of the sources of greenhouse gases, we won’t need unhealthy particles in the air to block out the sun.

To read about the study and see graphs go to NASA’s Web site.

See Q&A with Unger. (Caution: Don’t be biased by her picture. She’s a pretty blonde.)

If you want to read the study abstract.

(Sources: NASA, Proceedings of the National Academy of Sciences, fastcompany.com)

Global warming to surge in next 5 years as El Niño and sun add to greenhouse gases' impact -- study

(Temperature chart from the UK's Climate Research Unit. It was uploaded to Flickr by T. Raftery.)


Beware. This coming fall and winter could be unusually warm. And that fast-warming phase is likely to continue for 5 years and be worse than previously forecast, a new study predicts.

A combination of natural forces have masked the full impact of rising CO2 emissions on average global temperatures over the past decade, but now they are entering a new phase where they will work in tandem with greenhouse gases to heat the planet, according to scientists from NASA and the U.S. Naval Research Laboratory.

Relatively stable average world temperatures since 1999 are the result of a downward cycle in sunspots and flares and a period of weak El Niños, the study says.

But now the 11-year cycle of solar activity is about to go on the upswing and El Niño effects in the Pacific Ocean are expected to produce more extreme heat, says the study. This is the first look at the impact of all four factors on global temperatures: human actions (greenhouse gases), El Niño, solar activity and volcanic eruptions.

The hottest year on record was 1998, in part because of a strong El Niño episode. The extreme heat that year led to droughts, flooding, severe heat waves and the death of 16% of the world’s coral.

(By contrast, 1601 was the coldest year of the millennium, following the giant eruption of a Peruvian volcano that spewed ash that blocked out sunlight. Among the results was a famine in Russia that killed one-third its population.)

The researchers are quick to point out that while these natural forces have an impact, they do not negate the importance of the steady rise of CO2 emissions and their baseline effect on temperatures.

While 1998 was the hottest year and the 1990s the warmest decade on record, 13 of the 14 warmest years were between 1995 and 2008, according to the UK’s Climate Research Unit. And 8 of the top 9 came after 2000.

“We're seeing a long-term warming trend driven by human activity, with natural factors affecting the precise shape of that temperature rise," said Judith Lean, one of the authors.

The study is to be published in Geophysical Research Letters.

(Sources: The Guardian, Climate Research Unit, UK’s Met Office and Greenwire)


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