By Caleb Dresser

The human impact of COVID-19 has been horrific, and the health impacts of climate change continue to mount. Rather than focus on comparing the scale of these catastrophes, we should heed the lessons of our experience with COVID-19 as we face a changing climate and future pandemics.

In the spring of 2021, Mark Carney, the United Nations envoy for climate action and finance, remarked that “from a human mortality perspective, [climate change] will be the equivalent of a coronavirus crisis every year from the middle of this century” (1). While the middle of a global pandemic may be a difficult time to bring attention to other issues such as climate change, this assertion bears examination.

From a numerical standpoint, Dr. Carney is probably correct about the relative scale of these problems. As of this writing, approximately 3.5 million people are known to have died of COVID-19 (2), although the true toll is likely much higher because of inadequate testing and interruptions to routine healthcare. In addition, the pandemic will continue to affect many people for months or years to come.

While the annual mortality attributable to climate change impacts is currently an order of magnitude smaller, it is expected to accelerate rapidly in coming decades. The World Health Organization anticipates around 250,000 excess deaths attributable to climate change every year in the 2030s (3), but by 2100, one study suggests these could climb to 5.8 million per year, assuming a population of 8 billion, substantial adaptation efforts, and a higher-emissions trajectory (4). This number changes dramatically under different population, adaptation, and emissions scenarios, but it seems likely that the long-term, cumulative death toll from climate change will greatly exceed the number of lives lost to COVID-19, and may well exceed it annually within the lifetime of younger readers of this piece. In addition, any discussion of mortality related to climate change must also consider deaths attributable to air pollution from the ongoing use of fossil fuels, which already contribute to as many as a fifth of all premature deaths globally (5). Climate change will also affect future infectious disease risk in ways that are difficult to quantify, through poleward displacement of biomes, changes in the habitat of disease vectors such as mosquitos, increased animal-human contact, and changing patterns of antibiotic resistance.

Simply comparing numbers does not present a path forward. While comparisons of the human impacts of climate change with those of COVID-19 may be an effective way to push for macroeconomic policy, such comparisons quickly move into territory that is detached from any normal human scale. The order of magnitude of population-level mortality may mean little to a husband mourning the death of his wife in a lonely ICU or to a family searching for a lost child in the aftermath of a flood.  As we face these threats, it is important that a question of “which is worse” does not direct resources away from much-needed action on either; assertions about the scale of one problem should not discount the anguish and suffering caused by the other. The worst disaster is the one that affects you and those you love.

We should instead seek to learn from our experience over the past year. There are important lessons in the tragedies of the COVID-19 pandemic that we must internalise as we face a rapidly changing climate and the spectre of future pandemics. Decisions at every level of society, from individuals to policy makers, will have a dramatic impact on whether we face these challenges collectively and effectively, or in an uncoordinated manner that leads to unnecessary suffering.

First, we must improve our societal ability to understand complex, nonlinear, politically polarising health threats. Both COVID-19 and climate change are difficult to visualise; the movement of invisible virus particles in the air or the gradual warming of a region may be imperceptible to the casual observer. Their most severe effects are nonlinear; a virus surge that overwhelms local health resources or a major hurricane that overwhelms a city can occur with little warning. While this can make them challenging to understand, there has been great success with communicating these issues in accessible ways in settings ranging from journalism (6) to governments advisories (7) to primary school education (8). Such communication can help provide a shared sense of purpose – an important antidote to the political polarisation that may develop as complex threats uncover societal faults and challenge preexisting social and economic narratives.

Second, we would do well to consider transformative solutions that will address the structural causes of unequal health outcomes. The COVID-19 pandemic brought into focus the degree to which social determinants of health in historically and structurally marginalised communities can contribute to disproportionate health impacts during a crisis, at scales ranging from neighbourhoods to nations. Looking to the future, many of these communities also face disproportionate threats from air pollution, sea level rise, urban heat, and other effects related to climate change. Increasing local control over adaptation decisions and allowing for community-led development can help improve resilience to both climate change and future pandemics (9).

Third, we have seen how important coordinated international action on shared threats is during a globalised health crisis – a lesson that leaders considering climate mitigation and adaptation policy would do well to take to heart. There is no vaccine for climate change impacts, no heralded “herd immunity” or “reopening” to look forward to. However, there are many highly effective ways to “stop the spread” of the climate crisis, ranging from investments in renewable energy systems to a rethinking of transportation systems and building design. Some of these climate solutions, such as halting deforestation, can even reduce our risk of future pandemics (10). It is essential that we undertake aggressive, coordinated action on climate change before the worst effects occur.

Finally, and most importantly, the COVID-19 pandemic has shown us that our actions matter. We have seen how communities can save thousands of lives through individual decisions to wear a mask or get vaccinated; we have also seen how disagreement over COVID-19 precautions and disregard for others can contribute to virus surges, hospitalisations, and deaths. We have watched failures of governance sow discord and allow the virus to run rampant, but we have also witnessed effective government policies that provided life-saving vaccines and protected our most vulnerable from the socioeconomic side effects of the pandemic.

These experiences carry profound lessons for the climate crisis. If we made personal changes in our red meat consumption, air travel, and other aspects of our carbon footprints on the same scale that many of us have learned to wear masks, we would collectively have a tremendous impact on carbon emissions. The US government could cover the expense of rapidly decarbonising the US energy grid ($4.5 trillion) if it invested on the same scale that it provided emergency relief funds ($5.3 trillion) during the pandemic (11,12). Our actions, individually and as a society, will continue to have a tremendous impact on the trajectory of our society.

Both COVID-19 and climate change are monumental challenges shared by the whole of humanity. They are also a test of our ability to care for one another. Solutions to both issues exist, but in the absence of committed, coordinated international action and widespread societal investment, outcomes will be dire. As we try to establish a “new normal” for society in a world fundamentally altered by COVID-19, it is important that our investments focus on long term solutions. We have already seen how badly things can go when we fail to take effective action and make necessary investments in the context of a global pandemic. We must choose a better path as we face the challenges of climate change.


  1. Sharanjit Leyl. Mark Carney: Climate crisis deaths ‘will be worse than Covid’. BBC News. February 5, 2021.
  2. COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University. Accessed June 2, 2021.
  3. World Health Organization. Climate Change and Health. February 1, 2018.
  4. Carleton, Tamma and Jina, Amir and Delgado, Michael and Greenstone, Michael and Houser, Trevor and Hsiang, Solomon and Hultgren, Andrew and Kopp, Robert E. and McCusker, Kelly and Nath, Ishan and Rising, James and Rode, Ashwin and Seo, Hee Kwon and Viaene, Arvid and Yuan, Jiacan and Zhang, Alice Tianbo. Valuing the Global Mortality Consequences of Climate Change Accounting for Adaptation Costs and Benefits (Aug. 3, 2020). National Bureau of Economics Working Paper No. 27599, Available at NBER:
  5. Karn Vohra, Alina Vodonos, Joel Schwartz, Eloise A. Marais, Melissa P. Sulprizio, Loretta J. Mickley, Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem, Environmental Research, Volume 195, 2021, 110754, ISSN 0013-9351,
  6. Damian Carrington. Why the Guardian is changing the language is uses about the environment. The Guardian. 17 May 2019.
  7. Tran, Thi Phuong Thao et al. “Rapid response to the COVID-19 pandemic: Vietnam government’s experience and preliminary success.” Journal of global health vol. 10,2 (2020): 020502. doi:10.7189/jogh.10.020502
  8. UNESCO. Not just hot air: putting climate change education into practice. ISBN:978-92-3-100101-7. Collation:89 p. Language: English Year of publication: 2015
  9. Rosa Gonzalez et al. Community Driven Climate Resilience Planning: A Framework: Version 2.0. National Association of Climate Resilience Planners. May 2017.
  10. Dobson A, Pimm S, et al. Ecology and economics for pandemic prevention. Science. 24 July 2020. 379-381.
  11. John Parnell. Cost Of Decarbonizing U.S. Power Grid Put At $4.5 Trillion. Forbes Magazine. June 27, 2019.
  12. Here’s everything Congress has done to respond to the coronavirus so far. PGPF. March 15, 2021.

Caleb Dresser is an Emergency Medicine physician at Beth Israel Deaconess Medical Center in Boston, Massachusetts and a Fellow at the Center for Climate, Health, and the Global Environment at the Harvard T.H. Chan School of Public Health. 

Disclaimer: The ideas expressed in this article reflect the author’s views and not necessarily the views of The Big Q.

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