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May 2009 - Climate Change; Insects and Microbes are Moving North - Part II

In the earlier discussion of Earth's climate [see PR 4/5/09], data and observational studies were presented on how ice cover all over the globe is retreating as a result of Global Warming. Today we will look at other changes that are ongoing in our natural world.

Let's travel to the mountains of the American west where the largest known insect infestation in the history of North America is occurring, right now. From New Mexico north to Montana, and adjacent areas, tens of millions of pine trees are dying. Further north into British Columbia the situation is even more severe.

The culprit is the mountain pine beetle [ New York Times 11/18/08]. These beetles, whose numbers in the past were held in check by temperatures that used to reach 30 to 40 degrees below zero, are now thriving. Temperatures this low have not been seen for decades in the Rockies. Two species of pine, the lodgepole pine and the ponderosa pine, are being particularly hard hit. By 2006 in Wyoming and Colorado alone, according to the U.S. Forest Service, there were 1 million acres of dead trees. In 2007 the number had reached 1.5 million and in 2008 the estimated number was 2 million acres. British Columbia forests have now lost over 33 million acres of pines; an area five times the size of the Adirondack Park! The U.S. Forest Service is already dealing with falling trees in campsite areas and trying to assess the potential for future forest fires because of the increase in wood fuel.

In a report in the Proceedings of the National Academy of Sciences in August 2008, a long term study [30 years] by UC Irvine came to the conclusion that warmer temperatures and longer dry spells have killed thousands of trees and shrubs in a Southern California mountain range. This is the first study to show “directly the impact of climate change on a mountainous ecosystem by physically studying the location of plants”. The study was able to rule out air pollution and fire suppression as the main causes of plant death and that the only thing that could account for the findings “across the entire face of the mountain would be a change in the local climate”.

In addition to trees, humans are also beginning to feel the impact of Global Warming. In mid summer 2007 in Italy, the first outbreak of a tropical disease in modern Europe, was documented [NYTimes12/23/07]. Over 100 people had come down with chikungunya, a viral disease. This is a tropical disease and normally found in and around the Indian Ocean. It took the Italian public health authorities a month to figure out what was going on. It had never been seen in Europe before. The virus is carried by the tiger mosquito which first arrived in Italy 3 years ago and has now been found throughout southern Europe.

In one report [PR 9/29/07] the issue of a tropical disease spike was even closer to home. Six people died from brain infections caused by an amoeba, Naegleria fowleri in three separate states, Arizona. Texas and Florida in 2007. During the previous decade 23 people died according to the Centers for Disease Control and Prevention. It enters the brain through the olfactory nerve while swimming. This is a heat-loving amoeba and as water temperatures go up so do its' numbers according to the CDC.

Dengue fever. A viral disease carried by mosquitoes has a name that almost in and of itself sounds ominous. The United Nations Intergovernmental Panel on Climate Change estimates that several billion people will be at risk of dengue fever in the coming decades as a result of climate change. More rainfall in certain areas, and higher temperatures overall, is accelerating its spread throughout the Americas and other tropical regions worldwide. It is already the world's most widespread vector-borne virus.

Who would think that Canada now has evidence of having a tropical disease? In 2006 a farmer in the prairies died of West Nile virus. Another woman from Toronto said “we didn't even know West Nile virus existed here”. Her husband had died after contracting the disease from a mosquito in their garden. This virus had never been seen before on this continent until 1999. It probably landed at an airport in New York and found the unusually hot, dry summer to its liking. It has now infected over 20,000 people and killed more than 800.

While the movement of these diseases northward is not disputed, scientists are not in full agreement that climate change is the only force driving these actions [Microbe, Vol 3, p317]. Some also cite increased population, lack of access to clean water, air pollution, and extreme poverty as additional factors that may also play a role. Studies are continuing on trying to unravel these disparate factors so that control measures can be developed. Most scientists agree, however, that addressing climate change will be one of the important steps we have to take.

Climate change or “Global weirding” as Tom Friedman says [p.133 in “Hot, Flat and Crowded”] is a very complex issue with many different facets. Future articles will explore 800,000 years of climate information obtained from a 10,000 foot long ice cores from Greenland and Antarctica, the recent ruling by the EPA that six greenhouse gases are responsible for global warming, the reasons why carbon dioxide is a greenhouse gas, the role of man, the rising temperatures of the permafrost, and the northward movement of breeding bird species, among other topics.

The scientific career of Raymond N. Johnson, Ph.D., spanned 30 years in research and development as an organic/analytical chemist; he is currently founder and director of the Institute of Climate Studies USA (www.ICSUSA.org). Climate Science is published the first Sunday of every month.