23 May '12, 6pm
Man-made Pollution Shifting Topics and Sub-Tropics Poleward
NASA Goddard Photo and Video /CC BY 2.0 We've reported before on how climate change is expanding the tropics and sub-tropical zones towards the poles. Now there's some new research showing how man-made pollution, such as black carbon soot, is contributing to this poleward shift. Think Progress reports on a new study, published in Nature: Black carbon aerosols and tropospheric ozone, both man-made pollutants emitted predominantly in the Northern Hemisphere's low- to mid-latitudes, are most likely pushing the boundary of the tropics further poleward in that hemisphere. This expansion of the tropics has been happening at a rate of 0.7° latitude per decade. As for the potential impact of this, lead author Robert Allen says:
If the tropics are moving poleward, then the sub-tropics will become even drier. If a poleward displacement of the mid-latitude storm tracks also occurs, ...