NASA: Road transportation a ‘key driver’ of global warming

Analyzing impact by economic sector rather than chemical species, NASA scientists have determined that motor vehicles are the greatest contributor to atmospheric warming, “now and in the near term.”

In a new study led by Nadine Unger of NASA’s Goddard Institute for Space Studies, researchers used a climate model to analyze how 13 different sectors of the economy will impact global warming from the year 2000 to 2100.

Each part of the economy “emits a unique portfolio of gases and aerosols that affect the climate in different ways and on different timescales,” the researchers write.

The scientists based their calculations on real-world inventories of emissions collected by other scientists around the world. For each sector of the economy, they analyzed the effects of a wide range of chemicals — such as carbon dioxide, nitrous oxide, methane, organic carbon, black carbon, nitrate, sulfate and ozone — on the atmosphere, particularly clouds.

Their findings? Cars, buses, and trucks release plenty of pollutants and greenhouse gases that facilitate global warming, but emit few aerosols that counteract them.

The second biggest impact of global warming: the burning of household biofuels such as wood and manure.

The third: agriculture, in the form of raising livestock, particularly methane-producing cattle.

What’s surprising is that many industries produce chemicals that actually cool the globe, according to the study. The industrial sector releases large amounts of sulfates and other cooling aerosols that actually counteract global warming, and biomass burning — tropical forest fires, deforestation, prairie fires and so forth — emits smoke that blocks solar radiation.

That’s not to say smoke and aerosols are good for your health, by the way. But they do, in fact, cool the globe. Unfortunately, as we eliminate them from the atmosphere, we’re also eliminating their cooling factor.

The bottom line: on-road transportation is both low-hanging fruit and the most impactful change to implement.

By 2050, the study’s authors suggest that electric power generation will overtake road transportation as the biggest promoter of warming.

By 2100, the study’s authors predict that the industrial sector will jump to the third largest contribution to global warming. (It’s now the smallest of all sectors.)

The study was published on Feb. 3 in the Proceedings of the National Academy of Sciences.