To save species, limit global warming
The Red List of threatened species is getting longer every year.
Currently, the International Union for Conservation of Nature lists 5,583 species as critically endangered, including subspecies of animals and plants.
Another 20,000 species are classified as endangered or vulnerable.
Hunting and poaching are among the top reasons for species endangerment.
Take the pangolin: their meat and scales are sought-after as food and for traditional medicine, respectively.
Some pangolin species are already critically endangered, and their population is still declining.
In 2016, the CITES committee put all eight pangolin species on Appendix I, giving them full protection against international trade.
That hasn't stopped the illegal animal trade: Pangolins are the most trafficked animals in the world.
But illegal animal trade and trafficking are among several major factors pushing so many species to the brink.
Read more: Five of the world's biggest environmental problems
For many other species, the biggest challenge is habitat loss.
All three species of orangutans are threatened with extinction because the trees they live in are being cut down, for example to make room for palm oil plantations.
Grasslands are converted into housing estates, and country ponds are drained to set up a barbecue grill instead — in our modern industrialized world, many animals and plants have no more room to thrive anymore.
And climate change will make matters worse.
Species that are adapted to living on savannah simply cannot survive when their savannah turns to desert.
"Every species has a preferred climate. Just as you and I don't like it too hot or too cold, too wet or too dry," Rachel Warren of the University of East Anglia in Norwich, United Kingdom, tells DW.
Warren and her colleagues in East Anglia and at the James Cook University in Australia studied some 115,000 species around the globe, examining their habitats and how their geographic range would develop in a warming world.
The warmer the climate gets, the more plant and animal species will be at risk of extinction due to habitat loss, they found.
Even a 0.5 degree Celsius difference can be a matter of existance or extinction for many species, they reported Thursday in Science.
The Paris Agreement aims to limit global warming to maximum 2 degrees Celsius above preindustrial levels, while aiming "to pursue efforts" to limit it to 1.5 degrees.
"We found that achieving the ultimate goal of the Paris Agreement, to limit warming to 1.5 degree above pre-industrial levels, would reap enormous benefits for biodiversity," Warren said.
What a difference in half a degree
They investigated three different scenarios: warming of 1.5, 2 and 3.2 degrees Celsius. The latter is the current global warming trajectory if countries meet national pledges to reduce CO2 emissions.
The researchers found that with current pledges, about 49 percent of all insects, 44 percent of all plants and 26 percent of all vertebrates would lose half their habitat by 2100.
By limiting global warming to 2.0 degrees, this numbers would decrease tremendously, to 18 percent, 16 percent and 8 percent.
At 1.5 degrees, those numbers would be more than halved, to 6 percent for insects, 8 percent for plants and 4 percent for vertebrates. Taking the lower limit for global warming would save the majority of global species from climate change.
Christian Hof, a researcher at the Senckenberg Center for Biodiversity and Climate in Frankfurt, called the study "the largest of its kind." Hof, who did not participate in the study, called the methodology "solid" and added that the large difference in the 2 and 3.2 degree results were surprising.
Kirsten Thonicke, a researcher at the Potsdam Institut for Climate Research in Potsdam (PIK), pointed out that the study builds off of a WWF study and others before it. She called new the consideration of insects, also the "astounding" number of 115,000 species analyzed. She was also not involved in the study.
The big winners
Species across the globe would benefit from a 1.5 degree warming limit, but particularly those in Southern Africa, the Amazon, Europe and Australia, the researchers write.
Among the big winners would be species which are also hit hardest by poaching, such as the critically endangered black rhinoceros, they found.
Warren adds that among the species particularly vulnerable to global warming are insects.
"It probably is because they are cold-blooded animals and don't have much control over their body temperature," she says, adding that many insect species don't have much ability to move to other areas when the climate gets unsuitable for them, such as beetles that live in the soil.
How we depend on insects
Saving insect species from extinction is particularly important, the researchers write: They are at the bottom of the food chain and are a main food source for many birds, reptiles and mammals.
When insects die, a lot of other species will die with them.
In addition, insects offer services we humans cannot do without, such as pollinating crops and flowers.
The economic value of insect pollination was estimated in a 2005 study at 153 billion euros ($181 billion), accounting for 9.5 percent of global agricultural food production.
"We found that particularly those groups of insects important for pollination are one of the more sensitive ones to global warming."
Read more: Supply chains at risk as pollinators die out
Even without climate change, insects are already in bad shape: intensive farming with monocultural fields full of pesticides makes life particularly hard for them.
Insects have declined by 76 percent over 27 years in 63 nature protection areas in Germany, one survey found.
On Monday, researchers in the Netherlands reported a similar trend in their country: in two Dutch nature reserves, the number of insects has dropped in the same period by about two-thirds.
Worthy of protection
Protecting species can pay off in many ways: Rich biodiversity guarantees fertile soil, and clean water and air, researchers point out.
It might even allow for finding a cure for cancer, for example in a type of coral that conservationists have been struggling for years to protect.
While limiting global warming to 1.5 degrees could save the majority of species from climate change, the report's authors acknowledge that this might be a difficult goal to achieve.
That's why it is important to "allow ecosystems to adapt naturally to climate change," they write, suggesting that enlarging protected area networks could be one way to do so.
This would species give the opportunity to move into new suitable habitat.
Just a bigger nature reserve won't save the pangolins, though.
Experts fear that those shy, secretive mammals might go extinct within the next 10 years, long before scientists have even a chance to study their behavior and learn more about them.
Yet, Warren points out that it is important to think about climate change now even if other problems seem more urgent.
"If we don't do something about the future, there is a problem waiting around the corner."
Looks like the IUCN Red List is set to get even longer in the future.