While delegates at the Durban Climate Summit discuss the advantages and disadvantages of delaying a global agreement on greenhouse gas emissions into the atmosphere, the latest study shows that CO2 emissions are higher than ever. At the Summit, many of the world’s nations would like to see global warming limited to 1.5C (2.7F) while an important bloc of countries, including the European Economic Community (EEC) are prepared to accept a more conservative global 2C (3.6F) rise. 2C is the level at which irreparable damage is expected to result in the climate system. Already, with about 0.8C rise in temperature since the preindustrial era, we are seeing enhanced warming locally in the Arctic, above and beyond the 2C figure.
Increases in CO2 Emissions
This new study, by Dr. Glen Peters et al., published in Nature Climate Change on 4 Dec 2011, shows that fossil fuel emissions increased by 5.9% in 2010 and by 49% in the last 20 years. The Kyoto Protocol, due to expire at the end of 2012, commits countries to reduce emissions to 1990 levels by the end of 2012. Clearly, this will not occur, with fossil fuel emissions projected to increase by another 3% in 2011. This rate of increase is 3 times the rate which was in place at the time the Kyoto Protocol was being negotiated, although for the 1980s, the emission rates increased at 2% per year.
Sources of CO2 Emissions
Emissions from fossil fuel burning were 8.7 billion tonnes (1 tonne = 2205 lbs approx.) in 2010. About 0.4 billion tonnes came from cement production, and another 0.9 billion tonnes were emitted from the land, including from deforestation. Half of the total emissions were retained in the atmosphere, raising the level of CO2 to 389.6 ppmv. The other half of the emissions were absorbed by the land and oceans. The CO2 in the ocean has an acidification effect on the oceans, leading to further environmental degradation there. The CO2 absorbed by the land would have gone into growth of the biosphere.
One of the authors of the study, Prof. Corinne Le Quéré, the director of the Tyndall Centre for Climate Change Research at the University of East Anglia, UK comments, “Global CO2 emissions since 2000 are tracking the high end of the projections used by the Intergovernmental Panel on Climate Change, which far exceed two degrees warming by 2100. Yet governments have pledged to keep warming below two degrees…..”
Economic Influences on CO2 Emissions
Some countries have performed better than others, in the area of carbon-emission-reduction. For example, the 2010 UK emissions were 20% above 1990 levels, but this still falls far short of the requirements of the Kyoto Protocol. Over the period since 1970, the Nature study shows that annual emissions are correlated with global economic conditions. There was a stabilization or even a reduction in emissions after the oil crises (1973 and 1979), collapse of the former Soviet Union (1989), the Asian financial crisis (1997), and the Global Financial Crisis (2008). A few years after these events, however, the growth in emissions rate resumed its increase.
As lead author Glen Peters, of the Centre for International climate and Environmental Research in Norway also commented, “Many saw the global financial crisis as an opportunity to move the economy from persistent and high emissions growth, but the return to emissions growth in 2010 suggests the opportunity was not exploited.”
As a result of the increased emissions, the greenhouse effect was larger than ever in 2010.
Cumulative Emissions of CO2 and the 2C Limit
Previous studies have shown that the long-term future warming is primarily constrained by cumulative emissions of CO2 (for example, Mathews et al., 2009). Estimates also indicate that about 50% of the amount allowed, for the amount to remain below the 2C limit, has already been emitted (Allen et al., 2008). Studies have explored how emissions changes can be structured in the future to stay below target. In particular, Friedlingstein et al. (2011) conclude that a 90% eventual reduction in emissions rates is needed. At the latest, reductions need to start within the next two decades.
To keep below the target, the atmospheric emissions need to be less than about 1 trillion tonnes. At current emission rates, the 2C limiting concentration will be reached by about 2043. After that, emissions would need (implausibly) to be zero, to stay within the 1 trillion tonne limit. Amongst many plausible scenarios, Prof. Le Quere told Decoded Science that “global emissions need to peak by 2020 and decrease by 3% per year afterwards to keep the most likely warming to two degrees.”
New Technology Needed to Reduce Carbon Dioxide in the Atmosphere?
Delaying a climate change agreement until 2020, which is the position sought by major countries in the 2011 UN Climate Summit, would lock the world into the need for severe emissions reductions. Moreover, Friedlingstein et al. show that if the climate sensitivity to greenhouse gases is stronger than typically predicted by climate models, negative emissions would need to be implemented in the next decade. That is, technology needs to be developed so that CO2 is removed from the atmosphere, to compensate for the emission from fossil fuel burning and other sources.
Allen, M. et al. Warming caused by cumulative carbon emissions towards the trillionth tonne. (2009). Nature 458, 1163-1166. Accessed December 3, 2011.
Friedlingstein et al. Long-term climate implications of twenty-first century options for carbon dioxide emission mitigation. (2011). Nature Climate Change, 1, 457–461. Accessed December 3, 2011.
Matthews, D.H., et al. The proportionality of global warming to cumulative carbon emissions. (2009). Nature, 459, 829-832. Accessed December 3, 2011.
Peters, G.P., Marland, G., Le Quéré, C., Boden, T., Canadell, J.G. and Raupach, M.R. Rapid growth in CO2 emissions after the 2008-2009 global financial crisis. (2011). Nature Climate Change. Accessed December 4, 2011.
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