As we all know, the consumption of fossil fuels by human beings is causing the increase in temperatures on our planet due to greenhouse gas emissions, with the consequent climate change.
The rate of warming is such that forests do not have time to migrate and many species of animals cannot evolve fast enough to adapt to such rapid change.
Some species can migrate to the polar regions or up in the mountains to escape the rise in temperature, but other species cannot because they already live at those latitudes or heights. The mountains simply cannot be higher or the Arctic colder.
In addition, the emigration of certain species is blocked by barriers such as mountain ranges, deforestation or urban development.
A new study led by Mark Urban (University of Connecticut) argues that global warming will extinguish at least 1 in every 13 species on the planet, but these extinctions will have an uneven geographic distribution. Thus, for example, in North America "only" 1 in 20 species will become extinct, a percentage similar to that in Europe.
However, in South America the impact will be greater than average with 23% of the species extinct, the worst percentage of all.
This study is based on a meta-analysis of 131 articles published in peer-reviewed scientific journals using computational models. All the studies in this regard agree that with greater global warming, more species are lost.
It was found that, on average, the global extinction rate will be at least 7.9%.
This rate is based on various assumptions, including the trend in greenhouse gas emissions.
Urban's results probably underestimate the real extent that climate change will have on species extinctions.
This is because it only takes into account the temperature and not the interaction with other species, pollution, the destruction of habitats or the effect of acidification of the oceans.
Ecosystems can suffer a domino effect or a chain reaction, in such a way that the extinction of one species triggers the extinction of others that depend totally or partially on the first.
Sometimes the metaphor of an airplane in flight is used to exemplify how ecosystems work.
You can remove one rivet or screw after another and the plane keeps flying for a while. But, after a certain point, the structure of the plane falls apart and the plane crashes.
The authors of this study say that the extinction due to climate change is dwarf compared to that produced by the loss of habitats, something of which humans are also to blame. They calculate that for every species that disappears due to natural causes, 1000 do so because of the human being.
Urban's prediction depends on the rate of our carbon dioxide emissions. Currently the extinction rate is 2.8%, but these emissions are increasing steadily. If the temperature rise can be stabilized at 2 degrees Celsius above the pre-industrial temperature (we are now at 0.8 degrees), 5.2% of the species will become extinct.
If carbon dioxide emissions are not controlled so well then an extinction rate of 7.8% is predicted. If the temperature reaches 4.3 degrees above pre-industrial levels then one in six species (16%) will go extinct.
The most pessimistic predictions of other authors predict an extinction of 54% of species due to global warming.
"I don't know at what point we can call it a mass extinction event, but we are certainly heading down that road unless we change direction," Urban says.
A different study published in the same journal has analyzed marine fossils from the past 23 million years to determine which marine animals are most at risk of extinction and where. It appears that mammals such as cetaceans and seals and the like are most at risk.
The Gulf of Mexico, the Caribbean, the western Indian Ocean and the Pacific between Australia and Japan would be the places where there would be more extinctions.