Ed Caryl has become a regular contributor here, and today he presents insights on the causes of glacial melt. Here he discusses how absorption of solar energy by soot and Black Carbon contribute significantly to glacial melting and that CO2 is a minor factor.
Glaciers – The Dark Side. It’s Not the CO2 Carbon
by Ed Caryl
The global warming “hockey stick”, invented by Dr. Michael Mann, has been proven to be a distortion. [i] But if carbon dioxide is not significantly warming the planet, then why are most northern glaciers shrinking?
Since the end of the last ice age 12,000 years ago, glaciers have been receding, dramatically in the first few thousand years of warming when the oceans rose by 120 meters. The remaining glaciers have been receding since the end of the “Little Ice Age” in the early 1800s. This is normal. Compared to an ice age, it is warm.
There is evidence that this retreat has stopped and even slightly reversed in the last ten years for some glaciers; those on Mount Shasta in California are examples. These have increased in mass because of greater snowfall. Glaciers in Alaska, California, Europe, and South Greenland are still receding. Some of the melt of South Greenland is because of the Atlantic Ocean.[ii]
The following temperature plots are of the sea off the west coast of Greenland. For a full resolution, better quality graphic go to the link. The years shown are 1992 to 1999.
and 2000 – 2007:As the above chart shows, the Atlantic Ocean off southern Greenland began warming in the early 1990’s and is only now beginning to cool. This local warming is due to the Atlantic Multi-Decadal Oscillation (AMO), a natural Atlantic cycle with a period of about 70 years described here. But not all of the Greenland melting is due to the warm Atlantic.
Soot and Black Carbon
Glaciers are melting in the Alps, Alaska, Canada, most of the Sierra Nevada in California, and the Himalayas because of the other carbon emission: soot. This is known in the literature as Black Carbon. You can even see the geographic source in the map below, south Asia, China, and Russia. The emission sources are coal burning, bio-fuel (including dung), diesel engines, fuel-wood smoke, forest fires, and other incomplete combustion processes that take place in highly populated areas.
The result is clearly visible in nearly any photo of a melting ice field or glacier. Soot is visible also on Greenland glaciers. See here for a photo from National Geographic (also shown to the left). Note the black stains in the ice field; that is Black Carbon. The soot is deposited on the snow in the winter and spring. As the snow melts, it gets concentrated on the surface as the melt water drains away between the ice crystals. When the melt gets down to smooth ice, the soot concentrates in cracks. The sunlight heats the cracks, widening them.
Clean snow melts slowly because 99 percent of the sunlight is reflected away. Dirty snow or ice melts quite quickly because much more of the sunlight is absorbed as heat by the soot. 10 parts per billion of soot in freshly fallen snow is enough to significantly enhance melting.
Soot on glacial tongues in Northern Bhutan. This NASA photo shown below is from here.
The problem is very acute in places like the Swiss Alps, which are surrounded by industrial nations burning a lot of diesel fuel. Those glaciers are disappearing rapidly. The Alaskan and Canadian glaciers are receding because of soot from China. The problem has been recognized in the Himalayas. There is substantial disagreement (a factor of 200 on how much melt forcing takes place), though, on the extent of the problem. A quote from this document:
Black carbon on snow during spring melt in the Tibetan Plateau, for example, creates forcing rates 200 times higher than was assumed for black carbon on snow in the IPCC Fourth Assessment Report.
Here is a map of worldwide black carbon optical thickness from above, and concentration on the surface:
Source: NASA, Dorothy Koch and James Hansen here.
Note how much carbon is in the high Arctic, compared to that at the equator and further south. NASA admits that soot is part of the melting glacier problem, but downplays its importance. They hedge their bets on the subject.[iii] But some of the analysis views soot as an aerosol, and some of it as soot in freshly fallen snow. Only passing mention is made of concentrated soot resulting from melting.
A recent article states that half of the Arctic warming since 1890 may be due to Black Carbon. If that is true, perhaps some of the world’s warming in the last century is due to black soot, and not CO2. Read here.
Black Carbon is much easier to curb than CO2. The European Union has already put severe restrictions on Black Carbon emissions from diesel engines. In the U.S., the EPA has done the same. The time frame of effectiveness is also much shorter for Black Carbon. Eliminate a source, and the Black Carbon from that source is washed out of the atmosphere in days or just a few weeks. On a glacier, the problem will be much reduced in one snow season.
The problem is that there are many sources, all over the populated world. In Asia, cooking fires are a major source, so supplying and improving cook-stoves should be a priority. Low quality cooking fuel, such as animal dung, should be discouraged. In China, coal-fired power plants produce most of their electricity, and are planned to produce more in the future. China must insure that these plants use the very latest in technology to prevent Black Carbon emissions. In Africa and South America, forest clearing fires are a major source, so preventing rain-forest destruction should be a double priority.
[i] For more on the hockey stick: http://www.john-daly.com/hockey/hockey.htm, The Hockey Stick Illusion by A. W. Montford, here, and many others.
[ii] South West Greenland Ocean Temperature. (2009). In UNEP/GRID-Arendal Maps and Graphics Library. Retrieved 19:53, January 3, 2010 from http://maps.grida.no/go/graphic/south-west-greenland-ocean-temperature.
[iii] See: http://earthobservatory.nasa.gov/IOTD/view.php?id=4082