The Greenhouse Effect: Getting to the Causes
The daily work of trees is to inhale carbon dioxide and exhale oxygen. This simple fact has important repercussions for earth’s atmosphere and its worsening greenhouse effect. Forestry companies like DMI are closely watching what is called ‘the living carbon budget,’ that is, the careful balance of carbon stored and released by vegetation. DMI is doing its part to address the problem by harvesting sustainably.
Carbon budgets are going to shoot through the roof when humans dig up and burn excessive amounts of fossil fuels, carbon in its most condensed form. Some 80% of Canada’s greenhouse gas emissions result from the use of fossil fuels. Ontario and Alberta are the two most offending provinces. In Alberta alone, we unleash about two hundred megatons of carbon dioxide equivalent emissions, twenty-five per cent of which are associated with fossil fuel production.
If oil and gas producers are dominant contributors to greenhouse gases, consumers are equally accountable. At the Kyoto conference on global warming, Canada committed to reducing its greenhouse gas emissions by 6% between 2008 – 2012. Canada’s Environment Minister, Christine Stewart, pledged that the majority of Canada’s reductions would be achieved through domestic action. She was well aware of the data, which shows that about half of the carbon dioxide emissions from the transportation sector come from the 14 million or so vehicles Canadians drive for personal use.
Environment Canada states that the ozone layer is up to 5% thinner than it was a decade ago. The global mean surface of the Earth has increased by 0.3 – 0.6 degrees C over the past 100 years. Estimates are that human activities directly add over five billion tonnes of carbon dioxide to the atmosphere each year. Canada has only one half of a percent of the world’s population, yet it is responsible for around two percent of the world’s greenhouse gas emissions. That means Canada outstrips Brazil, Mexico and Australia.
If the facts are dampening, you can take encouragement from the many energetic responses they’ve spurred. After Kyoto, the government of Alberta set a 14% emission reduction target, and claims that the province “has already reduced emissions by 10%.” Closing a Climate Change Round Table held in Edmonton, Alberta Premier Klein stated that “our government is committed to long-term action on climate change.” While Klein promised that he would establish a Climate Change Central where government and stakeholders would work together, he stressed that this is a matter which every citizen must act on.
Trees act as carbon sinks, absorbing carbon dioxide from the atmosphere. Because world demand for forest products has increased deforestation, it is estimated that about 1 – 1.5 billion tonnes of carbon dioxide that would have been removed from the atmosphere each year by trees, is left to aggravate the greenhouse effect. For DMI, being a responsible global citizen means pursuing ways we can diminish any impact our forestry practices may have on earth’s atmosphere. Operating sustainably – making up for harvested trees with new stands – and recycling wood fibre and energy are some of the ways we are being part of the solution.
It is easy to think of carbon dioxide as the only greenhouse gas. But all of the following are naturally occurring greenhouse gases that become problematic when present in excessive quantities.
Water vapor is produced from natural and human-induced respiration, transpiration, evaporation and combustion of fossil fuels. The amount of water vapor released through evaporation increases as Earth’s surface temperature rises.
Carbon dioxide (CO2) is the most common greenhouse gas released by human activities. Fortunately, the more potent greenhouse gases are released in much smaller amounts. Carbon dioxide is produced from decaying materials, respiration of plant and animal life, and combustion of organic materials and fossil fuels such as natural gas, oil and coal. Carbon dioxide is removed from the atmosphere through photosynthesis and ocean absorption.
Methane (CH4) is produced from decaying matter when there is no oxygen. Primary sources of methane include wetlands, rice paddies, animal digestive processes, fossil fuel extraction, and decaying garbage. Methane is 21 times more potent a greenhouse gas than carbon dioxide. Methane is destroyed primarily through chemical reactions with other gases in the atmosphere.
Nitrous oxide (N2O) is produced naturally from soil and oceans. Humans contribute to nitrous oxide through soil cultivation, the use of nitrogen fertilizers, production of nylon and the burning of organic material and fossil fuels. It is roughly 310 times more potent a greenhouse gas than CO2.
Halocarbons are chemical compounds, produced by humans, that contain members of the halogen family (bromine, chlorine and fluorine) and carbon. They are some of the most potent greenhouse gases. Most are used in refrigeration and fire suppression.