A recent study has found that climate change could cause a large-scale migration of venomous snake populations across many countries in Africa and Asia.
The findings, published in the Lancet Planetary Health journal, predicted that low-income countries in south and south-east Asia, as well as many regions in Africa, would suffer an increase in snake bites by 2070.
Venomous Species
The World Health Organization (WHO) classifies venomous snake species into two types: type I (high risk and likely to cause disability or death) and type II (low risk).
The study focused on 209 species, 43 of which were from the African continent. One of the study authors, Macroecology professor Pablo Ariel Martinez, told the Conversation that 30 of the African snakes included in the study were type I and 13 were type II. Among type I snakes that will experience a change in distribution patterns are the carpet viper, black mamba, spitting cobra, and Gaboon viper.
Ecosystem Disturbance
The study modelled the geographical distribution of 209 venomous snake species with high risk to public health to project the potential distribution of species in different climatic scenarios in 2070.
The results showed that while most snake species will decrease in number due to unfavorable climate, some venomous species could find favorable areas of habitation in countries such as Niger, Namibia, China, Nepal, and Myanmar.
Researchers pointed out that the loss of venomous snake biodiversity in low-income countries will impact ecosystems, causing the loss of valuable genetic resources and creating new challenges to public health.
According to the study, habitats for some species, such as the west African Gaboon viper, will increase by up to 250%, whereas the ranges of European asp and the horned viper are projected to more than double by 2070. Other species, such as the variable bush viper widespread in Africa and the hognosed pit viper endemic to the Americas are expected to lose over 70% of their range.
Changing Habitats
Study authors, Martinez at the Federal University of Sergipe in Brazil and Talita F Amado at the German Centre for Integrative Biodiversity Research in Leipzig, Germany, said that the natural habitats of snakes are destroyed as more land is converted for agriculture and livestock rearing, reported the Guardian.
However, some snake species, especially those of medical concern, “can adapt to agricultural landscapes and even thrive in certain crop fields or livestock areas that provide food sources like rodents,” they added.
They noted that their study showed that “when venomous snakes start showing up in new places, it’s a wake-up call for us to start thinking about how we can keep ourselves and our environment safe.”
High Risk
According to the estimates of the World Health Organization (WHO), 1.8 to 2.7 million people are bitten by venomous snakes each year, causing around 138,000 deaths and at least 400,000 amputations and permanent disabilities. Envenomation by snakebites was categorized by WHO as a neglected tropical disease of the highest priority in 2017.
Anna Pintor, a research scientist with the WHO’s neglected tropical diseases group, said: “We are now finally getting a better handle on how snakes will change their distributions with climate change but there is also a major concern that they will bite more people if warm temperatures, severe wet weather events, and flooding that displaces snakes and people get more frequent.”
“We urgently need to understand better how exactly this will affect where people get bitten, and how many people get bitten, so that we can prepare,” she told the Guardian.
Martinez, one of the study authors, noted that the only cure for a snakebite is specific antivenom to that species. And as a result of climate change, some species may cross borders and cause snakebite incidents in countries that do not have specific antivenom, leading to public health problems.
Other Consequences
According to Martinez, climate change is having an impact on all species distribution across the globe. Some species face extinction, while others expand their distribution to new areas.
Martinez said that the loss of snakes in one country may have negative consequences for people. This is due to the critical role played by snakes in controlling other organisms, such as rodents, that can transfer various diseases. If the number of snakes declined, rodents will spread, causing disease outbreaks.
Another potential loss would be snake venom, which is of a high economic value. Martinez explained that snake venom is used in the manufacturing of several medications for cancer, neurological diseases, high blood pressure, and heart diseases. Therefore, the reduction of snake populations would mean the loss of highly valuable pharmacological products.
