Why should the planet's temperature not rise more than 2 ° C?

Why should the planet's temperature not rise more than 2 ° C?

Currently, more than 185 countries of the United Nations Framework Convention on Climate Change (UNFCCC) have submitted their National Determined Contributions (INDC), through which they made voluntary commitments to reduce their emissions of greenhouse gases (GHG), cause of climate change.

However, the announcements are not enough to face global warming, as reflected in the report published in October 2015 by the UNFCCC, which analyzes the contributions of 146 countries, and realizes that the sum of these commitments would lead the planet to a 2.7 ° C average temperature increase compared to pre-industrial levels. If these contributions are not implemented, the effect could be 4, 5 or even more degrees of warming.

According to Dr. Rubén Mario Caffera, academic head of the Amigos del Viento Association and member of the Latin American Climate Action Network (CANLA), the future outlook for the planet is even more bleak. He explains that: "Estimates of the 'pledged' contributions would place the increase between 3 and 3.5 ° C before 2100. We are quite far from 2 ° C."

Raise ambition

To counter global warming and generate a sign of hope, on December 12, 2015, the 195 countries of the UNFCCC adopted the "Paris Agreement." Through the document - which was achieved at COP21 - the countries pledged to follow the recommendations of the International Panel of Experts on Climate Change (IPCC) and keep the increase in global temperature “well below 2 ° C ”, a figure considered as the maximum limit by science if catastrophic effects on ecosystems and societies are to be avoided.

In addition, they agreed to "continue with the efforts" to limit this increase to 1.5 ° C, in order to preserve the most vulnerable countries, such as islands, which already present serious climatic risks and in some cases could even disappear. For this reason, during the COP21 negotiations, the Alliance of Small Island States (AOSIS) and the Climate Vulnerability Forum, which includes countries such as the Philippines and Bangladesh, demanded more ambitious objectives from the rest of the countries. Saleemul Huq, spokesperson for the group, said: "We are the countries that will suffer the most impacts, against the large negotiating groups such as the United States, the European Union or the G77."

Faced with this reality, the fact that 1.5 ° C has been placed in the Paris Agreement is considered a milestone, as well as evidence of the countries' commitment to the new climate scenarios.

The fight not to exceed 2 ° C

To prevent the planet's temperature from exceeding 2 ° C, the Paris Agreement proposes that global emissions must reach their maximum point as soon as possible - without specifying the year - and from that moment on "reduce rapidly". Additionally, it proposes to achieve a balance between the gases emitted and those that can be absorbed, in other words that the planet is carbon neutral, in the second half of the century.

To achieve the reductions, all countries must communicate their national contributions every 5 years, and each new commitment must be more ambitious than the previous one.

Science provides more concrete data on the steps to follow. A study by the United Nations Environment Program (UNEP) shows that in order to limit the temperature by 2ºC, it is necessary to achieve zero net CO2 emissions - which is equivalent to being carbon neutral - between 2060 and 2075. But If you want to limit it to 1.5ºC, net CO2 emissions must be zero a couple of decades before, between 2045 and 2050.

Mario Caffera recalls that the increase in temperature is bringing disease-transmitting vectors to regions where they could not establish before. "Added to that is a greater circulation of goods and people, that is why we have new epidemics such as Chicungunya, Zika, and dengue in regions where these outbreaks were unlikely," he explains.

For his part, Jorge Carrasco, a Chilean meteorologist, who participated in the elaboration of the Fifth IPCC Report, maintains that if 2 ° C is exceeded, there will be increased rainfall in Chile, a generalized retreat of glaciers and ice fields will be generated along the along the Andes Mountains, with impacts on water availability.

“The impacts of climate change are on ecosystems and these ultimately affect people. The new agreement, rather than avoiding world disasters, will make them less impactful. For example, the scarcity of water, although it may vary from region to region, does not stop being a factor that can generate migrations of populations, which under this agreement would not occur or if they do occur will be of lesser magnitude. Food can be affected by shortages and / or changes in quality, seasonally high prices, but agreements can cushion these impacts. Finally, the Paris Agreement can accelerate the development of a low-carbon economy at a global level more quickly, which at the same time accelerates the mitigation of GHG and generates clean and sustainable energy, ”concludes Carrasco.

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