Jamais at Open The Future has a post on the second biggest contributor to global warming - "black carbon" - None More Black.
An aerosol known as "black carbon," a primary component in soot, looks to be a key driver of anthropogenic global warming in tropical locations around the world -- most notably, in the Himalayan region.
...new research, by NASA’s William Lau and collaborators, reinforces with detailed numerical analysis what earlier studies suggest: that soot and dust contribute as much (or more) to atmospheric warming in the Himalayas as greenhouse gases. This warming fuels the melting of glaciers and could threaten fresh water resources in a region that is home to more than a billion people.
[...] Nicknamed the “Third Pole”, the region in fact holds the third largest amount of stored water on the planet beyond the North and South Poles. But since the early 1960s, the acreage covered by Himalayan glaciers has declined by over 20 percent. Some Himalayan glaciers are melting so rapidly, some scientists postulate, that they may vanish by mid-century if trends persist. Climatologists have generally blamed the build-up of greenhouse gases for the retreat, but Lau’s work suggests that may not be the complete story.He has produced new evidence suggesting that an “elevated heat pump” process is fueling the loss of ice, driven by airborne dust and soot particles absorbing the sun’s heat and warming the local atmosphere and land surface.
Globally, black carbon looks to be the second most-important warming agent after CO2.
Here's the twist: much of the production of black carbon comes from the combustion of biofuels and diesel, the two leading "greener" fuel technologies.
Aerosols last for months in the atmosphere, as opposed to the decades that greenhouse gases can last. This is good, as it means that policies that reduce the production of black carbon can start showing positive results in a matter of weeks.