At COP16 in Copenhagen two years ago, negotiators had proposals on the table that essentially found a 2° C increase in temperature acceptable. To put this into perspective, for January through October, 2011, the global combined sea and land surface air temperature was 0.4 °C ± 0.1°C above the 1961-1990 annual average according to the World Meteorological Organization. The 1961-1990 range is the current international standard period for the calculation of climate averages even though that average is higher than a century ago. When a 2° C increase in temperature is put into various models, it becomes apparent that the predicted associated sea level rise from this amount of global warming could lead to the demise of several small island nations. Thus, the slogan at COP16 quickly became 1.5 to stay alive.
The United Nations Advisory Group on Greenhouse Gases in 1986 reported that warming “beyond 1°C may elicit rapid, unpredictable and non-linear responses that could lead to extensive ecosystem damage.” Yes, the U.N. had groups working on climate change 25 years ago. (And those of us in academe think change comes slowly!) But then again, the Swedish chemist Svante Arrhenius predicted that warming (albeit without the other complex aspects of climate change) would occur back in 1896. The cause? The release of carbon dioxide into the atmosphere from the burning of coal. Arrhenius' greenhouse law, not surprisingly, was met with criticism. Some things never change. Like contemporary atmospheric scientists (most notably Stephen Schneider and James Hansen), Arrhenius published a book aimed at the general population on the topic of climate change. Translated to English, the title was Worlds in the Making. Arrhenius predicted that the extent of warming would be sufficient to prevent future ice ages, that weather in many parts of the world would be more pleasant (remember, he was from Sweden), and that warmer climates were needed to grow sufficient food to feed the rapidly increasing population! The world population at the time was about 1.7 billion.
But I digress. Because of the growing calls for climate justice for all people including the poor and marginalized, discussions in Cancun at COP16 both recognized the need for deep cuts in greenhouse gas (GHG) emissions in order to limit global average temperature increases to 2° C, but the Parties also agreed to consider targets that would keep warming to 1.5° or lower. This would require developed countries (those with the largest carbon footprints) to adopt targets with at least 25 to 40% below 1990 levels by 2020. The Parties agreed to consider a more ambitious target of greater than 40% reductions at COP18. The 2020 timeline is important given the U.S. latest position that any significant agreement to mandate GHG emissions is not likely until 2020. Ironically, many poorer countries have goals of being carbon neutral by 2020-2021! (For example see http://www.guardian.co.uk/environment/2011/nov/07/developing-countries-climate-action?intcmp=239 and http://www.npr.org/templates/story/story.php?storyId=19141333).
For the first time at this meeting, I heard reference to how much “carbon space” is left in the atmosphere (about 1000 gigatons or Gt). According to Martin Khor of the South Centre, at current rates of emissions, it is predicted that we will exhaust this space within 15 to 20 years. I should also point out that all of the models with “business as usual” (current GHG emission levels and rates of increase of emissions) predict that we are headed for much higher global average temperature increases (4 to 9° C). According to the United Nations Environment Program (UNEP), climate pollution must be about 12 Gt lower per year by 2020 to have a reasonable chance of keeping warming below 2° C and about 14 Gt lower to keep temperature rise below 1.5° C. At COP15, developing countries pledged more than 5 Gt worth of reductions – with finance, technology, and capacity building support from developed nations. Developed countries have offered less than 4 Gt of reductions and there are many loopholes in the accounting measures. (A short article on this topic can be found at http://www.iol.co.za/business/international/greenhouse-gas-goals-need-to-double-by-2020-un-1.1187115). It is this difference between what is on the negotiation table (at least prior Durban) and what the science says that is referred to as the “mitigation gap” or the “Gigaton gap”.
But with a population that continues to grow and has higher demands for resources including energy and meat (i.e. livestock and, therefore, methane), with Canada announcing that it will pull out of the Kyoto Protocol, and with the United States indicating that they won’t or can’t agree to significant cuts at this point (and prefer 2005 as a base year and expect China to make major concessions), I suspect that this mitigation gap will widen rather than shrink.