Deforestation & Climate
Monday, 09 March 2009 Trevor Williams - Originally Published in Green Muze
Deforestation in the Amazon Rainforest. Image: iStockphoto
Deforestation and ClimateThe Amazon Rainforest is still being cut down at an alarming rate. Almost every year there is more news about deforestation but it seems to be over-shadowed by the debate on climate change. In 2005, the Food and Agriculture Organisation (FAO) of the United Nations reported on the state of the world’s forests in their Global Forest Resources Assessment. Their next report is due sometime in 2010 and will likely include even more bad news.
The 2005 report stated that 13 million hectares of forest was destroyed and replaced by agricultural land between 2000-2005. This means that significant carbon absorbing mass was lost on the planet and was replaced by land area that actually generates more greenhouse gases through agricultural processes and fossil fuel based agricultural products.
Reforestation and the natural spread of forests reduced the net area lost to 7.3 million hectares (28,000 square miles, or 45,000 square kilometers). The deforestation took place mostly in South America and Africa whereas forest land area actually increased in China as a result of a government program of reforestation.
Over 283 gigatons of carbon are stored in the world’s forest biomass, and more carbon is stored in the trees, dead wood and forest soil than in the entire atmosphere. With the cutting down of forests, it was estimated that 1.1 gigatons of carbon sequestration was lost annually between 1990-2005. This annual amount is equivalent to 3.67 times 1.1 gigatons (4.04 gigatons) of carbon dioxide because the carbon and oxygen atoms combine and the atomic weight increases.
Mato Grosso in 1992. Image courtesy of NASA Earth Observation.
The worldwide annual carbon dioxide emissions are around 49 gigatons (13.4gigatons of carbon) according to the United Nations Intergovernmental Panel on Climate Change. Half of these emissions stay in the atmosphere; the rest is absorbed into the oceans making them more acidic, destroying corals and sea life, and absorbed into the forests and soils. The carbon absorption in the forest and soil regions decreased in Africa, Asia and South America, but increased in all other regions.
The tropical forests in Western and Central Africa and Central and South America are significant carbon sinks. Reforestation needs to be encouraged in these areas, and worldwide, to help reduce the growth of carbon dioxide in the atmosphere.
The tropical Rainforest locks in up to 15 tons of carbon (55 tons of carbon dioxide) in forest biomass and wood, per hectare, per year. The FAO believes that positive management of the forests, including reforestation, could actually capture up to 15% of fossil fuel carbon emissions over the next 50 years.
Mato Grosso in 2006, more than 540,000 hectares (1.3 million acres) have been cleared for pasture and soy plantations. Image courtesy of NASA Earth Observation.
The trees themselves are 20% carbon by weight and the soil in which they stand is a rich organic mixture that uses carbon to make organic matter. This carbon can be stored for centuries, and currently the forest biomass and soils store more than one 640 gigatons of carbon, which is more than what is found in the atmosphere.
It is essential the tropical forests are protected, and it would be wise for all of humanity to come up with a plan for the industrial nations to actually pay those countries, who are usually some of the poorest, to maintain their forests intact. Not only would the forests be protected for all the future medical discoveries from the plants, as yet undiscovered, but it would be an effective method of slowing down climate change to allow industrial countries to find non-fossil fuel based energy supplies.
According to recent research published by Dr. Simon Lewis, it seems the Rainforest is working overtime in absorbing carbon and the trees are actually growing bigger as a result. "We are receiving a free subsidy from nature," says Dr. Simon Lewis, a Royal Society Research Fellow at the University of Leeds. "Tropical forest trees are absorbing about 18% of the CO2 added to the atmosphere each year from burning fossil fuels, substantially buffering the rate of climate change. We cannot rely on this sink forever. Even if we preserve all remaining tropical forest, these trees will not continue getting bigger indefinitely."
There is much debate about the correct value of a carbon tax to apply to emissions, but if $30 a ton were assumed, then the 1.1gigatons of carbon sequestration lost through deforestation is worth $33billion dollars. If 15tons of carbon is absorbed per hectare per year in the Rainforest, then each hectare is worth $450 for carbon absorption per year. If the forest lives for 100 years then each hectare is worth $45,000 – this is probably worth much more than what the loggers actually make from cutting down the forest and raising cattle or growing soybeans. It seems that $33billion dollars could easily be used by industrialized nations ‘buy’ a lease on tropical Rainforests, and is actually money that benefits all of humanity, the poorest of the world, wild animals and the planet.
The satellite images are from NASA and show Mato Grosso in 1992 and 2006. Red indicates vegetation, the more dense it is, the redder it is shown. Between 2001 and 2004, more than 540,000 hectares (1.3 million acres) in Mato Grosso were cleared for pasture and soy plantations.
Resources
UN Food and Agriculture Organisation
Intergovernmental Panel on Climate Change Summary Report
Measuring Earth’s Biomass
NASA Earth Observatory, Mato Grosso
Trevor Williams is a University of Victoria Mechanical Engineering PhD candidate specialising in renewable energy, power grid modelling and plug-in hybrid electric vehicles. He has a bachelors in Aeronautical Engineering, a Masters in Management Science and over 23 years international experience in the space industry, having worked on Earth observation and telecommunications satellites. He is the author of the Eco Geek blog.
