April 24, 2024

Venomous snakes could start migrating in large numbers if we reach 5ºC warming

A global group of scientists has predicted that climate change could cause dramatic shifts in venomous snake populations in many African countries. Scientists took into account climate change predictions about changes in the current habitats of 209 venomous snakes and mapped where these environments were found elsewhere. Based on this, they predict that snakes will likely migrate to African countries whose environments remain suitable for snakes after 2070. This could change snakebite dynamics across Africa.

Macroecology professor Pablo Ariel Martinez, one of the study’s authors, says the international community must take measures now to prevent this from happening.

What snakes did you study?

Of the 209 venomous snakes we mapped, 43 species were from the African continent. The World Health Organization classifies venomous snake species as type I (high risk and likely to cause disability or death) and type II (low risk) according to their risk to public health.

In our study, 30 of the African snakes were type I – extremely venomous – and 13 were type II.

Some of the type I snakes whose distribution patterns we predict will change include the carpet viper, the black mamba, the spitting cobra, and the Gabon pit viper (one of the largest viper species in the world, known for emitting a lethal dose of venom when biting).

How did you conduct your research?

This was an interdisciplinary study involving public health researchers and ecologists from Brazil, Costa Rica, Spain and Germany. A large part of the team was made up of a group of young researchers who are currently studying a master’s degree in the Postgraduate Program in Ecology and Conservation at the Federal University of Sergipe, in Brazil.

We use mathematical models (predictive modeling) to predict where there may be ideal climate conditions for different species of snakes to live by 2070.

A long black snake crawls across the sand
A venomous black mamba on the move in Botswana.
JMx Images/Shutterstock

By knowing the locations where snakes could potentially live in the future, we were able to calculate which snakes would begin to spread over an area larger than their current habitat. This allowed us to assess which species would have the opportunity to cross geographic borders and inhabit countries where they previously did not exist.

Most snake species – especially those associated with rainforests – will decline in numbers as the climate becomes unfavorable for them. Some species, however, will expand the area in which they live because a favorable climate will exist elsewhere, and they will find it.

Why is it a problem if snakes cross borders?

Climate change is affecting the distribution of all species on the planet. Some are declining to the point of extinction, while others may change or even expand their distribution areas. The loss of snakes in a country has negative consequences for people. For example, snakes play a crucial role in controlling other organisms, such as rodents, which can cause various diseases. If snakes die or their population declines, there could be disease outbreaks.

Snake venom is also economically valuable. Snake venom is used in the manufacture of many medicines for cancer, neurological diseases, treatment of hypertension and heart problems. Therefore, the loss of snakes would mean the loss of products of high pharmacological value for the countries.

However, the expansion of the distribution areas of some venomous snake species can lead to public health problems. Often, the only cure for a snake bite is species-specific antivenin. As a consequence of climate change, some species may cross political barriers, leading to snakebite incidents in countries where they did not previously inhabit and where specific antivenom is not readily available.

What have you discovered will happen after 2070?

It is estimated that between 81,000 and 138,000 people die annually and around 400,000 are permanently disabled as a result of snake bites. This occurs mainly in East Asia, Sub-Saharan Africa and the Neotropical region.

If greenhouse gas emissions continue to increase over time, the global average temperature is expected to increase by an average of 5ºC, leading to changes in the distribution of some species. Countries such as Uganda, Cameroon, Guinea, Sierra Leone, Nigeria and Somalia are predicted to have extensive rural areas dedicated to agriculture and livestock farming by 2070. This is based on information about the future of large rural areas or agricultural data from a global land use database. These same countries will have the right climatic conditions to support a large number of snake species in the future.

Read more: Snake bites: We thought we had created a winning new antivenom, but it failed. Why this turned out to be a good thing

This situation is worrying because snake bites predominantly affect farmers and young rural workers in low-income countries. Venomous snake bites also kill a significant number of animals belonging to small farmers. Snake bites therefore have economic consequences and can worsen food crises for families and communities in the poorest rural areas.

We also identified some African countries, such as Niger and Namibia, that are likely to receive four to five new snake species from neighboring countries due to anticipated migration. Their public health systems will have to deal with new types of snakebite poisoning cases.

What can we do to avoid this scenario?

Climate change is mainly driven by human activities. Pollution caused by high-income countries in the Northern Hemisphere has been the main contributor to climate change. But its impacts are felt worldwide, especially in regions of high biodiversity such as Africa.

Many high-income countries also benefit from Africa’s vast biodiversity, using its natural resources for medicine, food, scientific research and tourism. Therefore, global measures are needed to strengthen science, research and conservation policies.

Investing in infrastructure in Africa is necessary to promote scientific research and effectively address the challenges of climate change.

The research team was formed by Irene Barbosa da Fonseca Teixeira, Tuany Siqueira-Silva, Franciely Fernanda Barbosa da Silva, Luiz Antônio Gonzaga Lima, Jonatas Chaves-Silveira, Miguel Ángel Olalla-Tárraga, José MarÍa Gutiérrez and Talita Ferreira Amado.

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