By Steve Holt

When it comes to fighting climate change, global nations have fallen off track to meet the Paris Agreement target to keep the global temperature from exceeding 1.5 degrees Celsius above pre-industrial levels. This means that without swift and sweeping action curbing carbon emissions, the worst consequences of climate change will almost certainly come to pass. Climate change is catastrophic for all the world’s ecosystems, including humans. The World Health Organization estimates that between 2030 and 2050, climate change will cause approximately 250,000 additional deaths per year, from malnutrition, malaria, diarrhea, and heat stress.

To help us understand the potential human toll from climate change, arts&sciences asked three faculty members: What is the greatest threat to human health from climate change—and what can we do to mitigate it?

Lucy R. Hutyra, a professor of earth & environment, researches carbon dioxide in urban contexts. Her recent work has focused on improving ecosystem models for carbon exchange within cities, emissions inventories, and the development of urban carbon monitoring systems. Hutyra is the associate director for the National Science Foundation Research Traineeship PhD training program on biogeosciences and environmental health at BU. 

Benjamin Siegel, an associate professor of history, studies modern economic life and politics, agriculture, and the environment. He teaches courses on the global history of food, agriculture, and medicine.

Richard Primack, a professor of biology, is a plant ecologist who works on the effects of climate change on the flowering times and abundance of trees and wildflowers. He also writes textbooks in the field of conservation biology and was the editor-in-chief of the journal Biological Conservation.

 Lucy R. Hutyra, professor of earth & environment 

As a consequence of a warming planet, we are seeing increased fires, food security challenges, and unrelenting heat. Heat is the top cause of weather-related death in the US. Most Americans live in urban areas that experience the urban heat island, wherein cities are hotter, on average, due to reduced vegetation cover, nonreflective building materials, and waste heat released into the city from vehicles and air conditioning units. The urban heat island is compounded by climate change-induced increases in temperatures and heat waves, as well as poor urban air quality. I see urban heat as the greatest threat climate change poses to human health. 

To alleviate the suffering caused by extreme urban heat, we must address the climate crisis, which is exacerbating the heat in the first place. To do this, we will have to focus on big solutions, like the passage of significant climate legislation, like the Inflation Reduction Act, which Congress passed in August. This legislation—the largest monetary investment in the climate crisis in US history at an estimated $369 billion—is a step in the right direction, but certainly, much more is required on the legislative front.  

In the short term, local solutions hold the most promise to help city-dwellers suffering from extreme urban heat. Most of the world’s population lives in cities, and extreme urban heat is affecting people across the globe—including here in Boston. Now is the time to implement heat mitigation solutions that focus on immediate relief, such as subsidizing air conditioning for vulnerable populations and changing the heat absorption profile of our cities by painting roofs white and shifting to materials that keep our built environments cooler. In the longer term, expanding the urban tree cover is also critical, but tree planting needs to be undertaken thoughtfully, with consideration of species, invasive pests, growth constraints, and the availability of water. A popular Chinese proverb says, “The best time to plant a tree was 20 years ago. The second-best is now.” Trees take time to grow, and their benefits for human health and the community increase with time. Just planting trees in our cities is not enough of a solution; we need to strategically prioritize where and what we plant to have the greatest impacts, engage communities in the process, and include a focus on keeping them alive and healthy. Small and big actions are needed to tackle and live with climate change, and individuals and communities are where we see the biggest impacts—and the most innovative solutions. 

Benjamin Siegel, associate professor of history

Every aspect of human life on earth will be radically reshaped by anthropogenic climate change, from where we live and how we make our livelihoods, to how freely we move and how long and healthy our lives will be. For many of us in the global North, what we’ll notice quickly after turbulent and unpredictable weather will be drastic changes to our diets. We can expect a future in which global tomato production is decimated, chickpea prices make hummus a special occasion purchase, or—as Sriracha fans found out this year—drought decimates the global supply of chili peppers.

The threats to crops like mustard, apples, chocolate, and coffee will make our diets duller. But more vital will be the fundamental threat to the world’s grain supply. The United Nations’ Intergovernmental Panel on Climate Change has shown how rising temperatures have lowered yields of corn, wheat, and rice by 5.3 percent since 1961 and with every degree Celsius that global temperatures rise, crop yields will fall by another 10 to 25 percent. By the end of this century, nearly 30 percent of the world’s agricultural land will be unsuitable for food cultivation. If one of the great triumphs of the 20th century was defeating Thomas Robert Malthus’ dire, late-eighteenth century prediction that the world’s food supply would not keep up with infinite population growth, the 21st century will see a diminishing global food supply stoking hunger, inequality, and even armed conflict.

For now, the best methods we have at our disposal are democratic ones; the power of the vote remains important even in deeply threatened democracies. Changes in our personal habits aren’t everything, but if you’re not eating less meat and dairy, traveling more by public transportation, bicycle, or foot, and reducing your air mileage, you’re not doing much to help, either. It’s also increasingly likely that we’ll have to take more drastic measures. Last year, the Swedish human ecologist Andreas Malm courted controversy with an important book arguing that resisting climate change will require sabotage of the fossil fuel industry. If a time bomb had been set off in your home, he argued, you’d be entitled to dismantle it. 

Historians have reminded us of the uncomfortable truth that the greatest political struggles of the modern world—like the civil rights movement and efforts to dismantle colonialism—were successful because more direct and powerful resistance worked to make legislative strategies more palatable. Democratic and nonviolent struggle won the day—but sometimes because they were better than the prospect of sabotage, or worse. I’d like to think that the immense urgency of climate change will stoke us to legislative and technical solutions before then. But given how slow and unpromising our fight against climate change has been so far, it’s hard to imagine that this struggle for the human future will chart a different course.

Richard Primack, professor of biology 

The single greatest threat to human health from climate change will likely be the danger it poses to plants and our food security. Throughout the world, stable crops such as wheat, corn, and rice will be harmed by the combination of heat waves and drought associated with climate change. In many tropical areas with dense, rural populations, crop yields are predicted to decline by 20 to 50 percent in coming decades. This decline and loss of harvests will lead to sharply rising food prices or no food, hunger, starvation, and emigration. In countries already experiencing hunger and food shortages, the situation will become much worse as the effects of climate change become more apparent.

The solutions to these problems are obviously to transition to an economy in which fossil fuels are greatly reduced and alternative energy sources—such as wind, solar, hydroelectric, geothermal, and perhaps nuclear power—are greatly expanded. The need for this transition is well understood, and this need has been made more apparent in the US and Europe with the unprecedented heat waves and floods of the 2022 summer.

However, the main barrier to implementing these various solutions is political; that is, getting the US government to recognize that climate change is a grave threat to the country and pass the legislation and allocate the funding needed to deal with the problem. Just as important, the US government needs to be motivated to work closely with the government of China and international organizations to implement strong policies to deal with climate change at an international level. 

For individual people, reducing one’s carbon footprint is an important personal responsibility. However, even more important is for each of us to be socially engaged with others in taking action. And equally important, we need to be involved in political parties, whether the Democratic or Republican Party, and to urge our leaders to take stands, to pass legislation, and to form alliances locally, nationally, and internationally to address climate change.

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