The greatest threat to global public health is the continued failure of world leaders to keep the global temperature rise below 1.5° C and to restore nature.
There’s no doubt that for most people 2021 is the second year of the great pandemic, and for many it has been much, much worse than 2020. It’s the year of Delta and Delta-plus, and possibly soon the new variant Mu. So it might be hard to imagine why the climate crisis could be more important in 2021 than the COVID-19 pandemic. Yet 228 international medical journals will simultaneously publish an editorial this week saying exactly that.
The unprecedented editorial in these medical journals is aimed at the UN General Assembly which opens on 14 September 2021 that will discuss the need for collective action on climate change. This will be followed by the UN Biodiversity Conference [COP15] on October 11-15, 2021 and the UN Climate Change Conference [COP26] on 1-12 November 2021.
The sense of urgency is heightened by the report to the Intergovernmental Panel on Climate Change [IPPC] released in early August. The report, Climate Change 2021: The Physical Science Basis runs to over 3,900 pages. There are summaries, and summaries of summaries, for policy-makers. And there are Tweet-length explanations for them too. What it all says is clear enough.
Human activities have contributed to global climate change, including extreme weather, rising sea levels and rising surface temperatures. Hot extremes, including heatwaves, have become more frequent and more intense. Human-induced climate change has contributed to increases in agricultural and ecological droughts.
The evidence of this is visible. There were devastating heat waves, wildfires and droughts in several countries this year and it’s far from over.
What is also clear from the IPCC report is that we’re at a critical juncture. We’re about to exceed the internationally agreed 1.5 ºC limit on rising global temperatures. The report determined that we could pass this 1.5°C limit between 2030 and 2035.
What this means for human health is made clear in the editorial of the medical journals:
The risks to health of increases above 1.5° C are now well established. Indeed, no temperature rise is “safe.” In the past 20 years, heat-related mortality among people over 65 years of age has increased by more than 50%. Higher temperatures have brought increased dehydration and renal function loss, dermatological malignancies, tropical infections, adverse mental health outcomes, pregnancy complications, allergies, and cardiovascular and pulmonary morbidity and mortality. Harms disproportionately affect the most vulnerable, including children, older populations, ethnic minorities, poorer communities, and those with underlying health problems.
Global heating is also contributing to the decline in global yield potential for major crops, which has fallen by 1.8 to 5.6% since 1981; this decline, together with the effects of extreme weather and soil depletion, is hampering efforts to reduce undernutrition. Thriving ecosystems are essential to human health, and the widespread destruction of nature, including habitats and species, is eroding water and food security and increasing the chance of pandemics.
Even in the best possible scenario explored in the IPCC report we’ll still pass this 1.5°C limit. So no more talking, no more voluntary carbon emissions levels, no more ‘let’s wait and see’. We’ll see nothing through the fires, haze, heat exhaustion, and hunger. It’s time for action.
Urgent, society-wide changes must be made and will lead to a fairer and healthier world. We, as editors of health journals, call for governments and other leaders to act, marking 2021 as the year that the world finally changes course.
So 2021 will be remembered as the year that the world changed course and averted a global ecological and health catastrophe. Or didn’t. It can’t get much clearer than that.
Hidayat Greenfield, Regional Secretary
 Call for Emergency Action to Limit Global Temperature Increases, Restore Biodiversity, and Protect Health, a joint editorial of 228 international medical journals. This is published online here in The New England Journal of Medicine.
 In 2009 more than a hundred Small Island Developing States, Least Developed Countries called to limit global temperature rise to 1.5°C above pre-industrial levels to prevent the worst of climate change impacts. This 1.5°C temperature limit was included in the 2015 Paris Agreement. In 2018, the IPCC published a report called Global Warming of 1.5 ºC which explained the climate impacts at 1.5°C of warming and why it is a critical limit we should not pass. A global increase in the earth’s surface temperature of more than 1.5°C compared to pre-industrial levels will have devastating and irreversible effects on the environment, food supply and human health.