2ºC degrees is too much. Limiting global warming to that temperature means accepting too many irreversible effects on health, safety and the ecosystems on which life depends. Containing that warming at 1.5 ºC has gone from being something desirable, as it appeared in the 2015 Paris Agreement, to becoming a necessity, according to the conclusion of the International Panel of Experts IPCC in its last report approved on Sunday in Korea. South. Scientists alert governments: CO emissions2 from fossil fuels should be cut to half that they were in 2010 in just over ten years.
The report, in which 91 authors from 40 countries participated, accounts for a wide range of serious effects attributable to climate change that would entail leaving global warming at 2ºC: in the oceans, fields, safety and health of people and different habitats. "We are already seeing the consequences of the 1ºC warming in the form of extreme weather events or sea level rise," said one of the coordinators of the report, Panmao Zhai. The document is a battery of messages especially addressed to governments and policy makers .
"This report marks the end of the era of fossil fuels" has been analyzed by the NGO Friends of the Earth, which focuses the IPCC calculations on greenhouse gases. The report is clear in establishing that a "deep reduction in CO2 emissions is required in all sectors". By 2030, at least 45% compared to what was issued in 2010 (which were more than 33, gigatons according to the World Bank). The industrial sector should cut to 90% in 2050. By the middle of the century between 70 and 85% of electricity should come from renewable sources.
The path marked by the IPCC requires "quick and deep changes". But they are imposed, say the scientists because of the significant and verified differences that half a degree more or less in the global temperature has in terms of the increase in the average temperature of the land surface and the sea, extreme heat peaks, torrential rainfall and the drought. "It is the moment of truth, there is no time to lose since today's decisions will define the kind of world we will leave behind," Greenpeace executive director Jennifer Morgan has urged.
At stake health, water and food
The IPCC is clear in this regard: cutting the warming would reduce the "populations" susceptible to the risks of climate change and poverty to "several hundred million people". "Any increase in global warming affects the health of human beings."
At the top of these risks is the mortality related to heat and ozone (as the emissions of the gases necessary for the formation of this gas remain high). "Normally, heat islands in cities amplify the effects of waves in urban environments," the report specifies. Likewise, they warn of the multiplication of vector-borne diseases such as mosquitoes and even "a change in their geographical distribution", if the threshold limits for global temperature are exceeded.
In the same way, depending on some variables, getting to lower the warming that half a degree could cut by 50% the population exposed to water scarcity. It would also contain the loss of productivity of crops that provide food (corn, wheat or rice) that will cause climate change: poorer crops, that is, less food. The Mediterranean area is specifically mentioned in this section.
Mitigate the loss of biodiversity on the planet
That half-degree makes a big difference. Would, that the extension of land at risk of transforming from one type of ecosystem to another was reduced by half. It would also divide by two the number of species of animals and plants whose habitat would be drastically reduced because it is not "climatically" adequate.
Other major risks against biodiversity, such as forest fires and the expansion of invasive species are lower if the warming is 1.5ºC. This multiplies the possibility that these ecosystems "retain more the services they provide to human beings".
Marine ecosystems are especially threatened by climate change. The acidification of water by CO emissions2 they damage the banks of species sought by the fishermen: already with this more ambitious goal of containment of warming a loss of 1.5 million tons of catches is projected. It is half of what was projected for 2ºC. Many other species are forced to move to other latitudes.
A very palpable example of how to get to limit the temperature will have very specific consequences is the Arctic Ocean. The probability that this sea is completely thawed during the summer is one every ten years with the warming to 2ºC. The threshold of 1.5 transforms that probability into once every century. The half degree is the difference between the total extinction (99%) of the coral reefs and giving them some opportunity (decrease between 70-90%).
Opportunity for survival
Climate change has two iconic images: the Arctic thaw and the rise in sea level that threatens the survival of island states, but it is also a true and analyzed risk for a state like Spain. Sea level will continue to rise well into the twenty-second century, but the pace and magnitude depends on the level of greenhouse gas emissions, predicts the IPCC report: the 1.5ºC warming would reduce that rise by 0.1m . It seems like little thing. However, the scientists stress: "It would give many more opportunities and time to adapt to the island states, the coastal zones and the deltas."