Reduce emissions of coal: The best way to reduce global warming

The combustion of fossil fuels, in particular coal, oil and the gas, are responsible for approximately 80% of the increase in the carbon dioxide emissions since the industrial era. A study by NASA suggests focusing efforts on reducing emissions from coal. A solution presented as the most realistic to limit the concentration of greenhouse gases in the atmosphere below dangerous levels.

A team of researchers from NASA has developed a series of scenarios that consider different outlook for the exploitation of fossil resources in the world. What emerges is a scenario described as realistic, which would limit the presence of carbon dioxide below levels that scientists consider to be dangerous for climate.

To determine how and when oil production reaches its highest level is a question long debated. It is therefore difficult to anticipate the level of future emissions, and to accurately estimate the impact of combustion on the climate, scientists warn.

To better understand how emissions might change in future Pushka Kharecha, NASA and James Hansen of the Goddard Institute for Space Studies, discussed a range of scenarios of fossil fuel consumption.

This research, published last summer in the American Union's Global Biogeochemical Cycles, shows that the increase of CO2 emissions from fossil fuel can be contained below dangerous levels, provided that emissions from coal are reduced to nil at the global level, and in the coming decades.

"This is the first document of the scientific literature that explicitly combines the two key issues relating to both the world's oil production and the impact of men on climate change is" Karecha explains.

The study builds on recent research, which define a level of concentration of carbon dioxide in the atmosphere which would be dangerous to pass. This threshold is 450 parts per million (ppm). Is a concentration of 61% higher than pre-industrial 280 ppm, but only 17% above the current level of 385 ppm.

The two scientists have developed 5 scenarios covering the period 1850-2100. Each scenario reflects a different estimate of the peak of global oil production, depending on the size of reserves, recoverability and technology.

The first scenario takes into account a lack of restriction of emissions of fossil fuel and prolong the trend, with an annual growth in emissions of 2%, until half of each reservoir has been recovered. Follows a decrease of 2% per year.

In this scenario, the concentration of carbon dioxide in the atmosphere will be more than double compared to pre-industrial, exceeding the 450 ppm in 2035. Even taking into account an assumption of low fossil fuel reserves, the level is exceeded in fateful 2050.

The second scenario considers a reduction in emissions from coal, first by developed countries from 2013, and in developing countries a decade later. Emissions from coal-fired power would be phased out by 2050. The other three scenarios reflect this assumption, but the matching of different situations of use and supply of oil. One case considers the possibility of a decline in the peak production of 21 years, in 2037. Another considers the implications of an overstatement of reserves, or the addition of a tax on emissions would make the oil too expensive to extract. The last scenario, finally, replaces the concept of peak by a "plateau" extending from 2020 to 2040.

4 of these scenarios lead to levels of CO2 concentration exceeding 450 ppm at different dates, but all had their concentration levels fall below this level at the latest around 2080. Two scenarios help to keep the level below 450 ppm.

From each of these assumptions, the team of researchers used a mathematical model, called the Bern carbon cycle model, to convert carbon dioxide emissions of each scenario in concentration in the atmosphere.

Karecha comments on the results obtained: "Because coal is much more abundant than oil and gas, reducing coal emissions is absolutely essential to avoid 'dangerous' climate change, with a concentration of carbon dioxide in excess of its 450 ppm. "

"The limitation strategy that we advocate a gradual elimination of CO2 emissions from coal in the coming decades is achievable given the current technologies available or in the short term," he says.

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