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Dear Pablo: I've heard that we don't have enough remaining fossil fuels available to burn in order to reach the carbon dioxide concentrations that the IPCC scientists are predicting. What would happen to the concentration of CO2 in the atmosphere and the global average temperature if we were to burn all remaining fossil fuels? Do you think IPCC scientists are overstating the problem to get us to act more quickly?This question is difficult to answer, partially because the estimated amounts of remaining fossil fuels (oil, coal, and natural gas) are hard to determine. For geopolitical reasons, many countries,--particularly OPEC countries--overestimated their oil reserves and many have increased or kept those reserves constant, even without any evidence of new discoveries. Some recent reports on coal reserves claim that the amount of remaining coal is also far less than previously believed.
Fossil Fuels Reserves: Peak OilThis entire article could be written about the geopolitics of oil reserves, but let's just go with an accepted number. Don Paul, former CTO of Chevron, said in one 2007 speech that the earth once had about 3 trillion barrels of oil and that we had used about 1.1 trillion. In fact, many scholars believe we are near global peak production levels; this correlates to the theory that oil resources are roughly half gone, according to the work of M. King Hubbert. Simply put, about 1.1 trillion barrels of oil remain to be extracted, and about 800 billion barrels of oil are inaccessible.
Fossil Fuels Reserves: CoalUntil recently, researchers believed that coal was far more abundant. But now some experts are saying that we'll reach peak production as early as 2025. Based on the rate at which China is building coal-fired power plants, this should not be a surprise. According to one source, there are 479 billion tons of anthracite and bituminous coal, 272 billion tons of sub-bituminous coal and 158 billion tons of lignite remaining, as of 2002.
Fossil Fuels Reserves: Natural GasAccording to the Oil & Gas Journal there are 6,182 trillion cubic feet of natural gas remaining. At current rates, this will last us about 60 years, but those rates will taper off as natural gas prices climb with a falling supply. And once everyone realizes that the sun provides free energy, we may not need to extract it at all.
What Happens If We Burn All Remaining Fossil Fuels?To recap, there are 1.1 trillion barrels of oil, 909 billion tons of coal, and 6,182 trillion cubic feet of natural gas remaining. I would strongly caution against trying to burn it all at once, but let's just see what it would do to our planet. When burned, a barrel of oil will turn into 475 kg of carbon dioxide. 1.1 trillion barrels would turn into 525 billion metric tons of CO2. One ton of coal will turn into 2.68 tons of carbon dioxide, so 909 billion tons of coal will turn into 2,600 billion metric tons. Finally, 1 cubic foot of natural gas turns into 0.12 pounds of carbon dioxide, so 6,182 trillion cubic feet of natural gas turns into 337 billion metric tons of CO2. So, burning all remaining fossil fuel would put 3,462 billion metric tons of carbon dioxide into the atmosphere. Currently we are putting about 17.5 billion metric tons into the atmosphere per year.
So Is the IPCC Assessment on Global Climate Change Wrong?Before the industrial revolution, atmospheric CO2 levels were at about 275 parts per million. Since then, we have added about 1,039 billion tons of carbon dioxide to the atmosphere, bringing the concentration up to 390 ppm. If we were to assume that our addition of CO2 to the atmosphere is perfectly correlated to concentrations, the burning of all remaining fossil fuels would increase atmospheric concentrations to 660 ppm. Of course our assumption is a big one. In addition to carbon dioxide emissions from combustion, we also have to worry about the leakage of methane from pipelines, nitrous oxide emissions from fertilized fields, and even releases of a gas used in manufacturing plasma televisions. All of these substances have an even greater effect than CO2 does--methane, for example, is 23 times more potent, and some gases are even 26,000 times worse! In addition to the direct anthropogenic (human-caused) emissions, we also now have to worry about indirect emissions from thawing permafrost, and the decreasing amount of forests that absorb CO2.
The IPCC projects global average temperatures at a concentration of 650 ppm to be 3.6 degrees Celsius. While this might sound comfortable--especially if you've been looking out the window at icicles for months--keep in mind that the difference between a global ice age and the pre-industrial average temperature is also just a few degrees. We have taken the planet's temperature in the other direction, the consequences of which are still not completely known. The back-of-the-envelope calculations above fall in the middle of IPCC projections for future CO2 concentrations, some of which are as high as 1,000 ppm. If forests continue to be slashed and burned and if the seas diminish their ability to absorb CO2, we could actually get there. Still, there are people out there that dispute the findings of the IPCC.
What do you think?
Ask Pablo is a weekly column that aims to answer your pressing eco-quandries. Want to ask Pablo a question? Simply email pablo(at)treehugger(dot)com. Wondering why Pablo's qualified to answer? As the Vice President of Greenhouse Gas Management at ClimateCHECK, he helps major corporations measure and manage their greenhouse gas emissions.
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The Ultimate Race: Peak Oil vs. Gobal Warming
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Further Resources on Fossil Fuels and Climate Change
How Much Oil and Gas is Left
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