In 2024, humanity edged ever closer to catastrophe. Trends that have deeply concerned the Science and Security Board continued, and despite unmistakable signs of danger, national leaders and their societies have failed to do what is needed to change course. Consequently, we now move the Doomsday Clock from 90 seconds to 89 seconds to midnight—the closest it has ever been to catastrophe. Our fervent hope is that leaders will recognize the world’s existential predicament and take bold action to reduce the threats posed by nuclear weapons, climate change, and the potential misuse of biological science and a variety of emerging technologies.

In setting the Clock one second closer to midnight, we send a stark signal: Because the world is already perilously close to the precipice, a move of even a single second should be taken as an indication of extreme danger and an unmistakable warning that every second of delay in reversing course increases the probability of global disaster.

In regard to nuclear risk, the war in Ukraine, now in its third year, looms over the world; the conflict could become nuclear at any moment because of a rash decision or through accident or miscalculation. Conflict in the Middle East threatens to spiral out of control into a wider war without warning. The countries that possess nuclear weapons are increasing the size and role of their arsenals, investing hundreds of billions of dollars in weapons that can destroy civilization. The nuclear arms control process is collapsing, and high-level contacts among nuclear powers are totally inadequate given the danger at hand. Alarmingly, it is no longer unusual for countries without nuclear weapons to consider developing arsenals of their own—actions that would undermine longstanding nonproliferation efforts and increase the ways in which nuclear war could start.

The impacts of climate change increased in the last year as myriad indicators, including sea-level rise and global surface temperature, surpassed previous records. The global greenhouse gas emissions that drive climate change continued to rise. Extreme weather and other climate change-influenced events—floods, tropical cyclones, heat waves, drought, and wildfires—affected every continent. The long-term prognosis for the world’s attempts to deal with climate change remains poor, as most governments fail to enact the financing and policy initiatives necessary to halt global warming. Growth in solar and wind energy has been impressive but remains insufficient to stabilize the climate. Judging from recent electoral campaigns, climate change is viewed as a low priority in the United States and many other countries.