The debate around the effects of the climate crisis often centres around the extreme weather conditions, destruction of habitats and economic costs of damage. But the consequences of climate change are also becoming an increasingly dangerous threat to global health. With a growing risk of infectious disease spread and a sharp rise in heat-related mortalities and malnutrition within the last two decades, it’s clear that the World Health Organisation were right to declare climate change one of the major health challenges of the 21st century. What remains to be seen is how we can combat the interacting crises and protect vulnerable populations from the jeopardy of a rapidly changing world.

One of the most concerning repercussions of the climate crisis is the increasing risk of infectious diseases. A warming climate means that longer periods of the year are suitable for transmission of vector-borne diseases such as malaria, Dengue fever, and Lyme disease, and rapid urbanisation in rural areas like the Amazon rainforest allows mosquitoes and the viruses that they carry to move into urban centres and neighbouring rural spaces. 

Before 1970, only nine countries had experienced serious outbreaks of Dengue, a seasonal mosquito-borne disease usually found in the tropics. 50 years later, it is endemic to over 100 countries. Scientists say that hotter, warmer weather produces ideal conditions for mosquitoes and their associated disease transmission, and the rising global temperatures mean that they can survive better at higher altitudes and latitudes. International travel and global trade have further contributed to the spread of the disease, with insects hitchhiking on used tires and in shipping containers. It’s impossible to attribute an exact number of infections and deaths to the change in climate, but evidently movements to combat the climate crisis would help, not hinder, global health.

On the topic of infectious diseases, one outbreak has affected more of us worldwide than any other in recent memory: Covid-19. Scientists have speculated on the relationship between the climate and the pandemic, and it has been suggested that among other dynamics, the socio-economic changes caused by the climate crisis have pushed humans closer in proximity to livestock, pathogens and vectors. Factors such as the increase in international travel and global trade have contributed to both crises. 

But perhaps the most important element of the relationship between climate change and the pandemic to consider is the impact of our response to Covid-19 on the climate. Economic recovery packages will need to prioritise forms of energy and transport which are beneficial to global health. This will require investment into renewable energy and active travel policies, instead of focusing on fossil fuel intensive investments. The 7% decrease in carbon dioxide emissions in 2020 due to a frozen economy and limited travel will translate into a reduction of only 0.01°C by 2050. A potentially harmful rebound in economic activity, similar to the boom in gas emissions after the 2008 financial crisis, could have disastrous effects. In combatting the pandemic by protecting vulnerable populations, developing preparedness measures and focusing on our healthcare systems, we can take similar steps to those needed to tackle the extreme effects of climate change.


Climate change also threatens global health in ways other than infectious diseases. Decreases in crop yields and the resulting raised prices lead to malnutrition, disproportionately affecting children in areas that rely on agriculture. Rising global temperatures are causing significantly more heat-related deaths; the heatwave of 2003 is estimated to have killed more than 70,000 people in Europe. Those temperatures are projected to occur every other year by the 2030s. More extreme weather like flooding can create ideal conditions for the outbreak of waterborne diseases, and the deadly effects of air pollution, caused by industrial gas emissions, are heightened in warmer weather. 

The combination of effects the climate has on our health is most drastically felt by those in areas prone to climatic weather like floods, living conditions with improper infrastructure, areas affected by rapid urbanisation, air pollution, and other interacting circumstances. Undoubtedly, these threats to global health have a disproportionate impact on developing countries and more vulnerable populations. 

So, in implementing preventative measures, we need to account for these unequal effects. Increasing risk reduction education in hazard-prone regions, working to eradicate malaria and other diseases, and investing in sustainable urban expansion will all benefit those who are most at risk of health threats. But we can best tackle the effects of climate change on global health by combatting the climate crisis. If the pandemic has taught us anything, it’s that we can uproot and restructure our health services and daily lives almost overnight. If we use the same framework of social and infrastructural changes to confront climate change, we may beat both crises altogether. 

Image credit: Photo by Paddy O Sullivan on Unsplash