About 21 percent of reptiles are threatened with extinction, according to a first-ever class-wide study published last week in Nature.
An international team of researchers has compiled data on population sizes, distribution areas and physiology of over ten thousand reptile species and classified them into endangerment categories according to the guidelines of the International Union for Conservation of Nature (IUCN).
Crocodiles (58 percent of the species) and turtles (50 percent) are said to be particularly threatened.
"This is worrying news," says Alex Slavenko, a zoologist at Tel Aviv University.
"Both are absolutely key species in the corresponding ecosystems."
Reptiles are much less studied than other vertebrate classes.
According to Slavenko, most of the species live secluded in areas that are difficult to access, which has always made it difficult to observe populations over many years.
Co-author Bruce Young calls the work done by his team a tremendous effort: "The data is really poor." Threat assessments, while they have been made for decades, are typically limited to individual species and specific regions.
The global investigation now makes it possible to incorporate knowledge about the condition of reptile populations into the planning of appropriate protective measures.
What role does climate change play?
Surprisingly, the study found that the most important causes of endangerment hardly differ from those of other vertebrates.
Agricultural land use, deforestation, invasive species and urbanization are mentioned as central.
Since all processes would have a particularly strong impact on forests, species living there are particularly threatened.
According to the study, reptiles are most endangered in Southeast Asia, West Africa, the Caribbean, the northern Andes and Madagascar.
The role played by climate change has so far been difficult to quantify.
The study suspects that higher temperatures and changes in precipitation are responsible for around ten percent of the endangered reptiles.
"However, there is a lack of knowledge
the extent to which reptiles can respond to climate change through migration or physiological adaptations,” says Young.
The estimates are expressly provisional.
With the rise in sea level and the increased risk of forest fires, some side effects of warming have not even been investigated.
Young sees it positively that the causes of endangerment between the vertebrate classes are so similar.
“We know how to address these issues.
Now it takes the political will to act accordingly.” The study even found that reptiles and other vertebrates tend to be particularly endangered in the same places.
Alex Slavenko emphasizes that there are exceptions: "Reptiles are very susceptible on small islands where other vertebrates do not necessarily have to live.
A large part of the last recorded extinction events took place here.”
In general, more and more data gaps are being closed with a view to the endangerment status of a wide variety of living beings.
A study was published in "Nature Plants" in mid-April that found a negative influence of global warming on the distribution area of 60 to 90 percent of all cactus species.
Another study published in "Science" warns of a mass extinction in the ocean: If the average temperature on the earth's surface rises by more than four degrees by the year 2100, an event in no way inferior to the five major mass extinctions of the past is the logical consequence.