At the end of COP21, the world welcomed the ambitious goal that the Paris Accord set for governments around the world, to contain global warming to 2°C by 2100. Five years later, it seems clear that too little has been done by the signatory states to meet this program. A recent simulation of the cost-benefit ratio on different scenarios shows that this objective is nevertheless the most interesting financially. When saving the planet becomes profitable, are there still reasons to wait?
In 2015, the Americans Burke, Hsiang and Miguel calculated the average impact of global warming on a country’s economic growth. Upon reading these results, a team of researchers from the Potsdam Institute for Climate Impact Research had the idea of comparing these figures with those of the costs of mitigating climate change, based on the temperature targets to be achieved by the year 2100. Contrary to all expectations, limiting global warming to 2°C would be statistically the most cost-effective scenario observed. Anders Levermann, Nicole Glanemann, and Sven N. Willner have therefore given their study an evocative title: “Paris Climate Agreement passes the cost-benefit test.”
A long-overdue transition
Five years ago, the adoption of the Paris Agreement set this ambitious goal of containing global warming “well below 2°C above pre-industrial levels” by 2100. More than a vague promise, the agreement requires each signatory state to communicate an action plan to achieve this objective, called the Nationally Determined Contributions or NDCs (which can be seen on the World Resources Institute website).
Unfortunately, the latest report of the Universal Ecological Fund estimates that at least 130 nations (out of a total of 196) have not committed themselves sufficiently to contribute adequately to the 50% global reduction in CO2 emissions required in 2030 to contain warming to 1.5°C. Among them are four of the five biggest polluters, releasing more greenhouse gases than the other 191. Moreover, most of the promises announced are far from being fulfilled. China, for example, at the top of the podium with 26.8% of total emissions, had announced a reduction of 60 to 65% between 2005 and 2030. However, from 2005 to 2018, an increase of 80% has been observed, and it does not seem to be about to stop.
According to the 2019 report of the UNEP, the United Nations Environment Programme, countries should triple their ambitions if they want to reach the 2°C target, and at least fivefold if they want to reach the 1.5°C target. The report also underlines that in view of the time lag between political decision-making and an effective reduction in CO2 emissions, waiting longer to strengthen national commitments would prevent the gap from being closed by 2030. According to analyses by the Climate Action Tracker (CAT), if the signatory states respect their current commitments, warming will still reach 2.8°C by the end of the century. At a press conference on the sidelines of COP25, Climate Analytics and the New Climate Institute, the two scientific bodies behind the CAT, called on governments to adopt more stringent targets. So far only Chile, Mongolia, Suriname and the Marshall Islands have proposed a new draft program.
The cost of inaction
The UNEP is clear in its report: if truly effective action had been taken as early as 2010, emissions could have been reduced by 0.7% per year, in order to reach 2°C in 2100. Now that ten years have gone by without seeing any real change in dynamics, figures are closer to 3% per year. Waiting any longer without reacting would mean future reductions so substantial that they would have a strong impact on the global economy and endanger food security. The report acknowledges that a massive transition would face many economic, political and technical barriers. However, it highlights our increasingly clear understanding of the possible synergies between economic growth and climate action, the growing number of political commitments in this area, and the steady decline in the price of technologies that would help green our economies. All these developments contribute to making this challenge increasingly achievable.
In 2017, we reached a global temperature increase of one degree compared to the pre-industrial period, with a current increase of about 0.2°C per decade, according to IPCC figures. The risks to which global warming exposes us are no longer a secret to anyone: an increase in the frequency and scale of extreme climatic events, the disappearance of many species, rising water levels and acidification of the oceans, along with a reduction in the yield of cereal crops and their nutritional quality, which will fatally amplify socio-economic differences.
The Postdam Institute team points out in their study that their estimate focuses on the impact of global warming on GDP. The costs do not consider the non-monetary losses in human lives and biodiversity, which adds to the toll. In light of this study, limiting warming to at least 2°C by the end of the century appears to be both the most human and cost-effective scenario. The reasons for waiting longer are becoming increasingly rare and are becoming less and less valid every day.