At every round of international climate negotiations global leaders agree upon that collective commitments should be in line with the 2°C target, the generally-recognized temperature rise limit to stay under by the end of this century in order to avoid catastrophic effects of climate change.
The 2°C target was recalled also during the latest climate talks in Lima, where countries set the first basic elements of a new global climate deal expected to be agreed in Paris in December this year.
The 2° target is not an easy one and is incompatible with the unabated use of all current fossil fuels reserves, according to a study recently published in Nature. Scientists calculated that a substantial share of current global oil (33-35%), gas (49-52%) and coal (82-88%) reserves should remain unused from 2010 to 2050 in order to have a reasonable chance of keeping warming below the threshold.
In addition, the study shows how the “unburnable” resources are distributed among countries and regions, as summarized in the map below published by Carbon Brief.
The authors of the study concluded that “policymakers’ instincts to exploit rapidly and completely their territorial fossil fuels are, in aggregate, inconsistent with their commitments to this temperature limits”.
According to the study, all fossil resources located within the Arctic Circle should be classified as “unburnable” and any increase in unconventional oil production is “incommensurate” under the 2°C constraint. Scientists said that “the utilization of unconventional gas resources is considerably higher than unconventional oil”, but only if the indicated amount of coal reserves (around 80% globally, 819-887 Gt) are not exploited.
Another key conclusion highlighted in the article regards the role of CCS technology. The study presents the results under two different scenarios: one assuming a “widespread deployment of CCS from 2025 onwards” and the other in which technologies providing carbon sequestration are unavailable. The study finds a relative small contribution of CCS in allowing a more intense use of fossil fuels: “the reserves of coal that can be burned are only six percentage points higher when CCS is allowed, with the utilization of gas and oil increasing by an even smaller fraction (around two percentage points)”, the authors wrote. “Because of the expense of CCS, its relatively late date of introduction (2025), and the assumed maximum rate at which it can be built, CCS has a relatively modest effect on the overall levels of fossil fuel that can be produced before 2050 in a 2°C scenario”.
The regional distribution provided by this study raises new elements regarding the efforts needed to limit temperature rise and climate change impacts. Another recent article (published in Nature Climate Change, in December 2014) showed the regional implications of post-2020 climate policies, assessing the timing and amount of greenhouse gas emissions that each of the world’s major economies could produce under different scenarios.
(Image: Lignite mine of Garzweiler, Germany. Photo credit: Bert Kaufmann/Flickr)