A rise in temperatures of 2ºC will have important consequences
Main climatic anomalies registered in 2017
Although the world manages to limit the rise in global temperatures to 2 ° C, the goal that was set in the Paris climate agreements, the consequences will be significant: rise in sea levels, loss of biodiversity, etc., according to studies published this Monday.
“We detected important changes in climate impacts for a world with an increase of 2ºC, so we must take measures to avoid it,” Dann Mitchell, professor at the University of Bristol and lead author of the text that opens a special issue of the British magazine “Philosophical Transactions of the Royal Society A”.
More than two years after the signing of the Paris agreement, which sought to maintain the rise in temperatures below 2ºC, or even 1.5ºC, compared to the pre-industrial era, the twenty published studies compare the consequences of both scenarios .
“One of the challenges has to do with the speed at which we will reach + 2ºC,” adds Mitchell. Or in other words, the time we will have to adapt to the multiple consequences of global warming.
The group of experts of the climate of the UN (IPCC, by its acronyms in English) must publish in October a report on a world with an increase of the temperatures of 1,5ºC. The draft text, however, considered in January that, given the current commitments of States and trends in CO2 emissions, it was “extremely unlikely” to achieve that goal.
– Ascent of the level of the seas –
Estimated number of climate migrants by 2050 in the three most vulnerable regions
Although the increase in temperatures stabilizes at + 1.5ºC or + 2ºC, sea level will continue to rise “for at least three centuries”, between 90 and 120 cm between now and the year 2300, causing flooding, erosion and salinization of the groundwater layers.
If the most optimistic forecasts are fulfilled, the Pacific islands, the Ganges delta and the coastal cities will have time to build dykes or displace their populations.
In case of doing nothing to limit CO2 emissions, the average rise in sea level, caused by the melting of glaciers and the expansion of water, will reach 72 centimeters between now and the year 2100.
But that perspective would be delayed 65 years if temperatures rise 2ºC, and 130 years if they increase by 1.5ºC.
“The impacts for the 21st century can be postponed rather than avoided,” the researchers point out. So “adaptation is paramount,” insists Robert Nicholls of the University of Southampton.
– Access to food –
A rise in temperatures will cause more food insecurity worldwide, due to floods and more serious droughts, warns one of the studies.
With a 2ºC warming, Oman, Bangladesh, Mauritania, Yemen and Niger would be the most vulnerable countries in the face of food shortages.
On the contrary, Mali, Burkina Faso and Sudan would experience an improvement in their situation as they would suffer less harsh droughts. But those countries are an “exception,” says Professor Richard Betts, who leads the study.
If there were an increase of 1.5ºC, “76% of the countries studied would have a weaker increase in their vulnerability to food insecurity.”
– Growth of inequalities –
Although an increase of 1.5ºC should not affect the global economic growth, “a warming of 2ºC allows for much lower growth rates in many countries, especially around the equator,” indicates to AFP Felix Pretis, economist at the Oxford University.
The difference is even clearer with GDP per capita. By the end of the century, it would be 5% lower if the warming reaches 2ºC instead of 1,5ºC, according to that study.
In addition, “countries that are already poor should be even poorer with climate change, and even more so in the case of an increase of 2ºC (…), while rich countries will probably be less affected,” says Pretis.
– Biodiversity –
Although a rise in temperatures will alter some of the fauna and flora, “containing the heating at 1.5ºC instead of 2ºC (…) would allow to increase between 5.5% and 14% the zones of the world that could serve as a climatic shelter for plants and animals, “according to another study. Its surface would be equivalent to that of “the current network of protected areas”.
Limiting climate change could also reduce the number of species that risk losing half of their natural habitat by up to 50%.