Climate change is one of the greatest threats to global health, experts warn

Anne Gulland
Honduras has declared a state of emergency because of a severe drought affecting the country's biggest cities - AFP

Climate change poses a huge threat to global health and is likely to trigger mass migration, food and water shortages and the spread of infectious diseases, experts have warned.

Tropical medicine specialists from around the world were asked to rank the greatest threats to the world’s health and they listed climate change, antimicrobial resistance and emerging infectious diseases as the biggest dangers.

Climate change poses a range of health threats, the 619 experts polled by the Royal Society of Tropical Medicine warned.

Half of those polled said that mass migration, emerging infectious diseases such as dengue and a shortage of food would be the biggest health-related implications of climate change.

The World Health Organization estimates that between 2030 and 2050 climate change will lead to approximately 250,000 additional deaths per year from malnutrition, malaria, diarrhoea and heat stress.

Experts believe that soaring temperatures, failing harvests and water scarcity will drive a wave of migration, putting pressure on existing services, fuelling the spread of infectious diseases and leading to unrest. 

Drought and flood-resistant crops are already being developed - and climate-mitigation strategies are thought to have reduced the worst effects of a recent drought in Ethiopia. 

But Dr Adrian Hopkins, a spokesman for the society, said that people in poorer countries would be hardest hit by climate change and less able to mitigate it.

“There’s also a question of food storage - a lot of these people [in low income countries] are subsistence farmers and they live pretty much hand to mouth. They don’t have the resources to grow massive yields and store them. Climate change is going to impact the poorer populations and that’s what’s going to lead to mass migration and more instability,” said Dr Hopkins. 

Another climate-change related concern is the spread of  infectious diseases - both completely new infections and the emergence of diseases in new regions, a trend identified by Public Health England last week when it revealed that 12 “novel” infections, including Ebola, Rift Valley Fever and Zika, had been identified in the UK since 2009.

Dr Hopkins said that vector-borne diseases could spread to new parts of the world.

“It’s perfectly possible that malaria could return to England - we have had it before,” he said. 

Experts believe that climate change is to blame for the huge rise in the number of outbreaks of dengue fever around the world this year as higher temperatures provide a perfect breeding ground for the mosquitoes that spread the disease. 

Rising sea temperatures could also lead to a higher incidence of water-borne infections and toxin-related illnesses, such as cholera and shellfish poisoning, said Professor Peter Piot, director of the London School of Hygiene and Tropical Medicine.

“Microbes need a certain temperature to multiply and when the temperature of the water increases there will be more bacteria and viruses, which could infect shellfish such as mussels and oysters,” he said.

Cholera bacteria also multiply faster in warmer water, leading to a rise in the number of cases, said Prof Piot. 

Earlier this year the UK Department of Health announced a £56million research fund to investigate the health implications of climate change. However, the survey respondents - 40 per cent of whom are based in Africa - overwhelmingly thought that governments and health bodies were not doing enough in preparation.

Prof Piot said that countries needed to firstly honour the agreements made under the Paris Climate Treaty to limit carbon emissions. But he also called for better cooperation between health and climate change experts.

“You have people working on climate change and people working on health and only in very few instances do they come together,” he said. 

Protect yourself and your family by learning more about Global Health Security