Solar radiation management geoengineering is more dangerous and expensive than previously thought.

Thursday, April 11, 2013

Solar radiation management geoengineering is more dangerous and expensive than previously thought.

Even though the rate of the Arctic melt continues to 'surprise' scientists,[1] it turns out that the rate of global warming slowed down as "OVER the past 15 years air temperatures at the Earth’s surface have been flat while greenhouse-gas emissions have continued to soar."; so says an article titled “A sensitive matter” on The Economist. [2]

But the slowdown it’s not due to cloud cover and atmospheric aerosols (see excerpt), the premise on which solar radiation management geoengineers base their claims, in fact these may in some cases actually exacerbate warming. [3]

Perhaps the deep ocean, below 700 m, has been storing more heat, [4] the article goes on to wonder.

Many of the “uncertainties” about climate and its forcings are explored here, and in doing so strengthening again one certainty: solar radiation management geoengineering is more dangerous and expensive than previously thought.

Excerpt:

“Begin with aerosols, such as those from sulphates. These stop the atmosphere from warming by reflecting sunlight. Some heat it, too. But on balance aerosols offset the warming impact of carbon dioxide and other greenhouse gases. Most climate models reckon that aerosols cool the atmosphere by about 0.3-0.5°C. If that underestimated aerosols’ effects, perhaps it might explain the lack of recent warming.

Yet it does not. In fact, it may actually be an overestimate. Over the past few years, measurements of aerosols have improved enormously. Detailed data from satellites and balloons suggest their cooling effect is lower (and their warming greater, where that occurs). The leaked assessment from the IPCC (which is still subject to review and revision) suggested that aerosols’ estimated radiative “forcing”—their warming or cooling effect—had changed from minus 1.2 watts per square metre of the Earth’s surface in the 2007 assessment to minus 0.7W/m ² now: ie, less cooling.

One of the commonest and most important aerosols is soot (also known as black carbon). This warms the atmosphere because it absorbs sunlight, as black things do. The most detailed study of soot was published in January and also found more net warming than had previously been thought. It reckoned black carbon had a direct warming effect of around 1.1W/m ². Though indirect effects offset some of this, the effect is still greater than an earlier estimate by the United Nations Environment Programme of 0.3-0.6W/m ²”

References:

[1] Antarctic Warming Rate Surprises Scientists: Today's Pic

http://www.bloomberg.com/news/2012-12-28/antarctic-warming-rate-surprises-scientists-today-s-pic.html

[2] A sensitive matter

The climate may be heating up less in response to greenhouse-gas emissions than was once thought. But that does not mean the problem is going away

Mar 30th 2013 |The Economist

http://www.economist.com/news/science-and-technology/21574461-climate-may-be-heating-up-less-response-greenhouse-gas-emissions

[3] July 2012 Greenland melt extent enhanced by low-level liquid clouds

R. Bennartz, M. D. Shupe, D. D. Turner, V. P. Walden, K. Steffen, C. J. Cox, M. S. Kulie, N. B. Miller & C. Pettersen

http://www.nature.com/nature/journal/v496/n7443/full/nature12002.html

[4] Distinctive climate signals in reanalysis of global ocean heat content†

Magdalena A. Balmaseda1,*, Kevin E. Trenberth2, Erland Källén1