Climate change is harming health: The need for urgent action

While often framed as ‘just’ an environmental issue, climate change also has a profound impact on human health and wellbeing. Although this has been recognised for decades, it is often overlooked or downplayed. The health consequences of climate change were clearly outlined in a 2017 report from the Royal Society of New Zealand,¹ and since then, both the evidence and the urgency to act have only grown stronger.²

The most obvious impacts of climate change on human health are the ones we hear about on the news: injuries and deaths associated with extreme climate events. Increasing trends in the frequency and severity of extreme temperature and precipitation are partly attributable to climate change, and these are what impact people directly. In recent decades, about 37% of the ‘excess mortality’ associated with heat waves globally has been attributed to climate change.³

Droughts and heatwaves can lead to devastating fires, as observed in many parts of the world, resulting in loss of infrastructure and livelihoods, and 1.5 million deaths from air pollution globally.⁴ Floods in this country and elsewhere regularly result in loss of livelihoods, injuries and deaths, all of which are devastating for families and communities.⁵ Increasingly violent storms are wreaking more havoc and causing injuries and deaths beyond the direct effects of flooding. Recent evidence suggests that adverse health impacts of tropical cyclones can persist for months or years after the event.^{5 6}

Indirect effects of climate change can be as significant as those discussed above, including exposure to microbial contamination and carriers of new diseases.⁷ When and where it isn’t raining, droughts are becoming more of a problem as the climate warms, damaging food production and limiting water availability, leading to malnutrition, increased disease susceptibility, and deaths.^{8 9} Moreover, as the climate warms, vector-borne diseases (such as dengue fever) have spread in latitude and altitude, affecting populations previously unexposed to those diseases.^{10 11}

Sea level rise (a result of the warming of ocean water and the melting of land ice) is relentlessly eating away at coastal land and leading to displacement of populations, as is already happening in Pacific Island nations. As the number of displaced people rises and the need for them to find a new home intensifies, this stresses the displaced populations and the infrastructure and politics of countries receiving such climate migrants.¹² Health services and other aspects of the operation of society can be disrupted, weakening the integrity of communities and countries.¹³

The health impacts of climate change are unevenly spread, as are most of the impacts of climate change. High-vulnerability regions are often some of the least well-resourced regions, deepening international inequalities. 

All these negative impacts on communities, on livelihoods, and on the ability of societies to operate take a toll on our mental health. The stresses associated with seeing climate change impacts, alongside knowledge of our collective responsibility for making it happen, can be hard to cope with. ‘Eco-anxiety’ can be caused by observing the impacts of climate change, and knowing that worse is to come in future, unless we take action to cut emissions of greenhouse gases.^{14 15} Knowing that the world’s political leaders are well informed about the hazards of climate change and at the same time seeing them taking no action results in a kind of cognitive dissonance, a doublethink that’s required to accommodate the science and the lack of an effective policy response.

Should the global community fail to address climate change by reducing emissions of greenhouse gases, especially carbon dioxide, the impacts of climate change will only worsen. Currently, most of those impacts can be coped with, most of the time, at least in Aotearoa New Zealand. But there will come a point when adaptation is not possible, when the heat makes parts of the globe uninhabitable, or climate change takes away land from under our feet, displacing large populations. 

On the other hand, transformative action to avoid the worst consequences of climate change would also have substantial health co-benefits, for example, by reducing urban air pollution. 

In a unanimous decision issued on 23 July 2025, the International Court of Justice concluded that the production and consumption of fossil fuels “may constitute an internationally wrongful act…”. Unfortunately, Aotearoa New Zealand's current Government is paying lip-service to climate change commitments, while rolling back mitigation policies and promoting the interests of polluting industries.¹⁶

Meanwhile, present adaptation policies pay insufficient attention to broader determinants of health and are likely to worsen health inequities. We agree with the Public Health Advisory Committee, who stated that: “Solutions for existential challenges like the climate crisis sit outside the health system, but can be ‘win-win’, with benefits for health equity, and for other positive social, economic, and environmental outcomes.”¹⁷ 

Author details

Prof James Renwick, School of Geography, Environment and Earth Sciences, Te Herenga Waka | Victoria University of Wellington 

Prof Simon Hales, Co-Director, Public Health Communication Centre, Department of Public Health, Tākou Whakaihu Waka, Pōneke | University of Otago, Wellington

Prof Rebecca Priestley, School of Science in Society, Te Herenga Waka | Victoria University of Wellington 

Prof Alistair Woodward, School of Population Health, Faculty of Medical and Health Sciences, Waipapa Taumata Rau | University of Auckland