APOCALYPSIS

GUIDE · APO-01B

Doomsday Clock — history and method

Created in 1947 by the Bulletin of the Atomic Scientists, the Doomsday Clock is the most widely recognized symbolic instrument for measuring existential risk. This guide lists every movement since its founding, explains the calibration criteria of the Science and Security Board, and shows how the dial moved from minutes to seconds.

What the clock measures

It is not a forecast. It is the Bulletin's annual judgment of humanity's proximity to a self-inflicted global catastrophe — nuclear, climate, biological, and, since 2007, disruptive technologies. The Science and Security Board (SASB), advised by the Board of Sponsors (which includes multiple Nobel laureates), reviews the trends of the past twelve months and decides whether the hand advances, retreats, or stays.

Calibration criteria (SASB)

  • Nuclear risk — arsenals, doctrines, active or collapsed treaties, use rhetoric, modernization, and alert posture.
  • Climate change — emissions trajectory, effective policy, physical signals (temperature, ice, oceans), and governance failure.
  • Biological threats — pandemics, laboratory biosafety, and hostile use of biotechnology.
  • Disruptive technologies — AI, cyber, mass disinformation, and autonomous weapons.
  • Institutions and information — democracies' capacity to respond to collective risk; quality of the information ecosystem.

Timeline — every movement since 1947

  • 1947 — 7 minutes. Clock founded by artist Martyl Langsdorf on the Bulletin's cover.
  • 1949 — 3 minutes. USSR detonates its first atomic bomb (RDS-1). End of the US nuclear monopoly.
  • 1953 — 2 minutes. US and USSR test thermonuclear bombs (Ivy Mike, 1952; Joe 4, 1953). The closest reading up to that point.
  • 1960 — 7 minutes. Growing scientific cooperation and first mutual public acknowledgment of nuclear risk.
  • 1963 — 12 minutes. Limited Test Ban Treaty.
  • 1968 — 7 minutes. Vietnam War, Arab–Israeli wars, Chinese and French tests.
  • 1969 — 10 minutes. Signing of the NPT (Non-Proliferation Treaty).
  • 1972 — 12 minutes. SALT I and the ABM Treaty between the US and USSR.
  • 1974 — 9 minutes. India conducts the "Smiling Buddha" test; SALT stalls.
  • 1980 — 7 minutes. Arms race intensifies; Afghanistan.
  • 1981 — 4 minutes. Reagan escalation; end of détente.
  • 1984 — 3 minutes. US–USSR dialogue frozen; Star Wars.
  • 1988 — 6 minutes. INF Treaty eliminates intermediate-range missiles.
  • 1990 — 10 minutes. Fall of the Berlin Wall; end of the Cold War in sight.
  • 1991 — 17 minutes. START I signed; dissolution of the USSR. Farthest reading in the clock's history.
  • 1995 — 14 minutes. Disarmament stagnation; risk of loose fissile material.
  • 1998 — 9 minutes. India and Pakistan conduct nuclear tests.
  • 2002 — 7 minutes. US withdraws from the ABM Treaty; post-9/11 terrorism.
  • 2007 — 5 minutes. First formal SASB judgment naming climate change as an existential threat.
  • 2010 — 6 minutes. New START; Copenhagen Accord.
  • 2012 — 5 minutes. Copenhagen failure; nuclear modernization.
  • 2015 — 3 minutes. Climate acceleration; arsenal modernization.
  • 2017 — 2.5 minutes. Trump's nuclear rhetoric; climate rollback.
  • 2018 — 2 minutes. North Korea, INF at risk, climate denial.
  • 2020 — 100 seconds. First reading in seconds. Collapse of arms control and climate inaction.
  • 2023 — 90 seconds. Russian invasion of Ukraine and nuclear threats; hottest year on record.
  • 2025 — 89 seconds. War in Ukraine, the Middle East, weaponized AI, New START collapse looming. Closest reading to midnight in history.

Why the switch from minutes to seconds

In January 2020, with the INF collapse, climate paralysis, and broad erosion of global governance, the SASB concluded that a "minutes" granularity no longer captured the acceleration of risk. The reading became timed in seconds — not as rhetoric, but as recognition that the interval between political decision and systemic consequence had shrunk. Since then, the clock has moved only toward midnight.

How the SASB decides

  • The Board meets twice a year; one meeting produces the January public statement.
  • Each domain (nuclear, climate, bio, disruptive tech) is reviewed by dedicated specialists.
  • The decision is collegial; the SASB consults the Board of Sponsors but retains editorial responsibility.
  • The rationale is published as an open document with citations to primary sources (IPCC, SIPRI, IAEA, WHO).
  • There is no mathematical formula — it is a qualitative judgment calibrated by historical comparison.

Critiques and limits of the instrument

The clock is often criticized for compressing multiple risk categories into a single hand and for being more symbolic than probabilistic. The Bulletin itself acknowledges these limits: the instrument serves as a political-cultural signal, not a quantitative extinction estimate. Models such as the Global Catastrophic Risk Index (GCRI) and the work of the Future of Humanity Institute offer complementary quantifications.

Primary sources

  • Bulletin of the Atomic Scientists — annual Doomsday Clock statements (1947–2025).
  • SASB — January press releases and press briefings.
  • IPCC — Sixth Assessment Report, AR6 WGI/II/III cycles.
  • SIPRI Yearbook — Nuclear Forces.
  • IAEA — Board of Governors reports.
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