Climate change will drive venomous snakes away from arid interiors and towards densely populated coastlines, increasing the risk of deadly encounters for millions of people, a new global study says.
It notes that snake populations will broadly move towards higher latitudes and more heavily populated areas as rising temperatures make their current habitats less suitable.
In Australia, the shift is expected to be especially pronounced along the east coast where snakes will move from the arid centre into more heavily populated southern areas.
The research published in the journal PLOS Neglected Tropical Diseases models the habitats of all 508 medically important venomous snake species and projects how their ranges will shift by 2050 and 2090.
"Before this study surprisingly little was known about the exact distribution of many medically important snakes, even some widespread ones that cause many bites," the study notes.
"A big reason snakebite is considered a 'neglected' tropical disease is that we know so little about exactly how many people get bitten and where, despite the enormous burden these bites cause in many countries."
Globally, the highest overlaps between snake and human populations exist in Sub-Saharan Africa, South Asia and Southeast Asia, regions that already bear the greatest burden from snakebite. The overlaps are projected to increase significantly across the Indian subcontinent as well as eastern North America and parts of China as the world warms.
The four snake species with the highest predicted increases in exposure to humans by 2090 are the black-necked spitting cobra, the many-banded krait, the cottonmouth, and the copperhead.
The study is the first to model all medically important venomous snakes, including species for which data is sparse, at a resolution of around one kilometre.
It draws on public and private databases, citizen science platforms, museum records, scientific literature and expert observations, with all data vetted by an international panel of around 30 specialists.
Snakebites kill about 138,000 people and cause 400,000 disabilities each year, mainly in poor rural communities in poor and middle-income countries. The WHO aims to reduce that burden by 50 per cent by 2030.
Human behaviour adds further complexity to the risk picture. Farm workers without protective equipment are far more exposed to snakes than those using machinery. Floods driven by extreme weather events are known to increase snakebite incidence by displacing both humans and snakes.
The study says its predictions can help guide where antivenoms are stockpiled, how health facilities are resourced and where conservation efforts should focus.
“The first step in helping victims of snakebite is to know where people and snakes interact the most so we can get support to the right places and the right people, often in remote rural communities," it says.
Not all snake species will expand their ranges. Many species in the Congo and Amazon basins and Southeast Asia, particularly those with already small ranges, are predicted to see net decreases in range size, raising conservation concerns. The wide-ranging puff adder, which currently causes a substantial number of bites across Africa, is also predicted to lose much of its current range.
"Our predictions can be used to decide where to stockpile which antivenom, how to ensure adequate capacity of individual health facilities, how to improve health care accessibility of remote at-risk communities, and where to focus conservation efforts for threatened snake species," the researchers say.
The findings come as the UN warns that the global climate system is in a state of emergency. The World Meteorological Organization’s State of the Global Climate 2025 report found that the 11 years from 2015 to 2025 were the hottest on record, with 2025 about 1.43C above pre-industrial levels.
UN secretary general António Guterres said every key climate indicator was "flashing red", adding that the planet's addiction to fossil fuels was "destabilising both the climate and global security”.
The rate of ocean warming between 2005 and 2025 more than doubled compared with the period from 1960 to 2005. WMO secretary general Celeste Saulo said human activities were "increasingly disrupting the natural equilibrium" in ways that would be felt "for hundreds and thousands of years”.
The snake study uses a worst-case emissions scenario for its projections, reasoning that planning for the most severe outcome offers the best basis for public health preparation.
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