Earth already committed to 2.4-dgree C rise from climate change
Jeremy Hance, mongabay.com
September 15, 2008
Air pollution masking full impact of global warming
Glaciers in the Bhutan-Himalaya. Glacial lakes have been rapidly forming on the surface of the debris-covered glaciers in this region during the last few decades. Image courtesy of Jeffrey Kargel, USGS/NASA JPL/AGU
Given the dire projections, Ramanathan and Feng warn that time is running out. Unless tough mitigation policies on greenhouse gases are put in place, the authors say the Earth will be locked into a rise of 3°C by 2030. They write that “CO2 mitigation polices are extremely critical if we want to limit further increases in the committed warming.”
Air pollution masking climate change
Ramanathan and Feng also explore a question often raised by skeptics: "Why hasn't the planet yet felt the full force of climate change?" So far, the planet has experienced a mean warming of 0.76°C since the late 1800s.
The scientists conclude that a variety of factors are masking the full effect of climate change; one of the most significant of which is air pollution. Some types of air pollution send aerosols that reflect light like a mirror, brightening the planet and thereby cooling it. The pollutants ability to mask rising temperatures has been estimated at 47 percent. However, as nations clean up their skies, the masking effects of such pollutants disappear causing the Earth to undergo sudden warming. The researchers state that this relationship between dwindling air pollutants and higher temperatures can already be seen in Europe.
Considering the many negative aspects for health and environment of air pollution, the researchers do not recommend that nations should forgo policies that clean-up air pollution. But they say countries and international organizations should be aware of the potential rise in temperature due to such actions.
The authors suggest better models are needed to provide nations with more accurate predications of the relationship between air pollutants and greenhouse gases. “This is not easy and the costs may be substantial for developing such models and the associated observing systems, but,” the scientists conclude, “we do not have much choice.”
V. Ramanathan and Y. Feng (2008). On avoiding dangerous anthropogenic interference withthe climate system: Formidable challenges ahead. PNAS Online Early Edition for the week of September 15-19, 2008.