Humans could become extinct by the year 2100 due to malicious use of AI or nuclear conflict, according to a new global risk assessment.

They top a list of 17 major threats to human health over the next 75 years, which also includes cuts to aid spending by wealthy countries, the climate crisis and childhood malnutrition.

The experts behind The Lancet Commission on 21st Century Global Threats to Health said all the threats interact, meaning they must be addressed together – but stressed that there was “a realistic route to act” on each.

“Decisions made by leaders today will shape the health and wellbeing of the next generation,” said Prof Christopher Murray, commission co-chair and the director of the Institute for Health Metrics and Evaluation, University of Washington.

To create its list, the commission modelled how many years in good health might be lost due to sickness, disability or early deaths due to each threat, based on current trajectories – a measure known as disability-adjusted life years (Dalys).

“Malicious use of AI, including bioweapons, and nuclear conflict with nuclear famine carry risks of extinction in the next 75 years,” the report said, adding that while their likelihood remained low, they had the potential to end humanity in the case of nuclear conflict by injecting enough particles into the upper atmosphere to block sunlight and cause famine, or via AI-created biological weapons. An accompanying Lancet editorial, published alongside the report, warned: “The scale of harm, should they be realised, would inflict an apocalypse on humanity.”

Other risks that could cause more than 1bn cumulative Dalys, and therefore deemed “major catastrophic threats”, included air pollution, antimicrobial resistance, childhood malnutrition and climate breakdown, as well as conventional conflict, declining overseas aid, high alcohol use, high blood pressure, income inequality, low educational attainment, naturally occurring pandemics, obesity, poor mental health, smoking and unhealthy ageing.

To be included on the list, threats not only had to potentially cause a high number of lost healthy years, but also to have potential solutions.

Ibrahim Abubakar, commission member and professor of infectious disease epidemiology at UCL, said: “We are not starting from a point of view of ‘oh look, we want to scare you – we’ve got X many threats facing humanity’. We’re starting from the premise that if you are a policymaker today, whether at the global multilateral level or at the national level, these are the potential threats that you could face, and this is the magnitude by which, if you act, you can actually make a difference.”

Action to limit global heating to about 1.8C (3.2F) rather than letting it reach 4.4C could prevent 1.89bn years of healthy life being lost, according to the report, which modelled best and worst case scenarios for each threat.

In higher income regions, non-communicable diseases such as obesity and poor mental health were the dominant threats, while in lower income regions health loss was driven by issues such as low educational attainment.

Many major donor nations, including the US and UK, have announced large cuts to aid spending over the past year. The potential collapse of, or steep reduction in, international health aid could cause up to 1.5bn Dalys before 2100, the commission found, nearly 70% of which would be in sub-Saharan Africa. The region also bears the brunt of child malnutrition.

The commission was made up of 35 experts, and its findings will be shared on Sunday at the World Health Summit in Berlin, Germany. Their assessment will be updated annually to re-evaluate the 17 threats identified, incorporating new data and any emerging hazards.

The authors urged leaders to address the risks before they escalated into crises, including via investment in technological innovations and by strengthening health systems.

“We started this process three years ago, thinking that there were three big threats: conflict, climate, and pandemics,” said Murray. “There’s a much larger number of threats that we need to worry about, and governments really need to dedicate some money and staff to the task of anticipation, prevention and preparation for this more diverse set of threats.”