The choices humanity makes in the next 75 years could determine the fate of billions of lives — and whether our species makes it past the 21st century.

In an extraordinary report from dozens of scientists, researchers compiled 17 of the most urgent health threats humanity will face before 2100.

They estimated amenable disability-adjusted life years, or DALYs — in short, how many healthy years would be lost from a given health threat. They found that these 17 catastrophic threats could account for tens of billions of years of lost health if trends continue. Of these threats, two have the potential to wipe out humanity entirely.

But all hope isn’t lost — the threats outlined by researchers can be averted if we take action now. Here’s what to know.

Catastrophic threats Researchers found that 15 threats were each associated with at least 1 billion DALYs, about the equivalent of two COVID-19 pandemics, researchers said.

These were:

Antimicrobial resistance: Bacteria, fungi and parasites that harm humans evolve so that drugs designed to kill them no longer work Childhood malnutrition: Children whose growth is stunted, are underweight or dangerously thin (wasting) Climate change: This includes heat-related death, increased natural disasters and disease related to increasing temperatures, such as malaria and dengue Collapse of development assistance for health, or DAH: Cuts to global health funding — researchers point out this was most notable in the US, which fell 21% in 2025 Conventional conflict: War and other violent conflicts between people Income inequality: Inequality and poverty are associated with poorer health Low educational attainment: People with less education have a higher risk of mortality Unhealthy aging: People are living longer, but with increasing chronic illness and disability Naturally occurring pandemics: Diseases that emerge without human engineering Of these, the threat associated with the biggest loss of healthy years by far was obesity, at 23.1 billion.

Researchers said obesity is rising in every country in the world, with food being higher in calories and exercise decreasing.

Authors also highlight income inequality, which they estimate will have an avoidable health burden equivalent to 25 COVID-19 pandemics by 2100 (13.8 billion DALYs), and climate change, which they say could cost us at least 1.89 billion years of healthy life — though the burden is “likely even greater.”

For all these threats, “humanity still has the agency to act,” said author Christopher J.L. Murray.

“The decisions made by leaders today will shape the health and well-being of the next generation. But delaying action will only serve to shift and increase the costs into the future,” he said.

Extinction-level threats Of the 17 threats, two were deemed to have the potential to lead to human extinction: nuclear conflict and famine, and malicious use of AI.

While the likelihood of both “remain low,” researchers said they present “consequential threats.”

To put things in perspective, researchers didn’t include threats such as asteroid strikes or supervolcano eruptions because the probability of those occurring were too low.

First, AI. “Although AI’s potential to advance health and well-being is enormous … the risk of catastrophic harm is equally profound,” the authors wrote.

They believe AI could cause catastrophic harm by 1) designing and making new biological weapons that could be used by bad actors, 2) causing societal infrastructure to fail because it relies too heavily on AI that could be hijacked or simply malfunction and 3) breaking free from human control and it independently seeks to harm us.

They say reducing the risk of malicious AI could avert an estimated 10.4 billion DALYs.

Nuclear war and a resulting famine is probably nothing new, as it’s something society has been worrying about for over 80 years, but that doesn’t mean the threat is gone.

Researchers found that avoiding nuclear conflict would save 133 million lives and 9.35 billion DALYs by 2100.

“The future is not inevitable,” said author Dr. Natalia Kanem. “Governments and communities must act decisively starting today, to protect health and build a fairer, more peaceful and more secure future for the coming generations.”