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    Climate tipping points: coral reefs, AMOC, ice sheets and the Amazon

    A tipping point is a threshold beyond which part of the Earth system shifts abruptly and often irreversibly; the IPCC says such changes cannot be ruled out.[1] The Global Tipping Points Report 2025 concluded that warm-water coral reefs are already passing theirs, and put the Atlantic overturning circulation and the Amazon at risk below 2 °C of warming.[2][3][4]

    Editor reviewedUpdated Climate science and carbon removalEnergy and climateScience

    What a tipping point is

    Most climate change is gradual: a bit more warming brings a bit more impact. A tipping point is different. It is a threshold where a system, such as an ice sheet or a forest, starts changing on its own and may not come back even if temperatures later fall. The IPCC says abrupt changes like this, including much faster Antarctic ice melt and forest dieback, cannot be ruled out.[1]

    Tipping elements are subsystems with strong internal feedbacks, so that past a critical forcing level the change becomes self-sustaining. In AR6 the IPCC treated them as low-likelihood, high-impact outcomes, stating with high confidence that abrupt responses and tipping points, such as strongly increased Antarctic ice-sheet melt and forest dieback, cannot be ruled out.[1] The Global Tipping Points Report, a non-IPCC synthesis led by the University of Exeter with about 160 authors from 87 institutions, assesses thresholds for individual elements.[5]

    Coral reefs: the first threshold passed

    The 2025 Global Tipping Points Report concluded that warm-water coral reefs are passing their thermal tipping point, with a central threshold estimate of 1.2 °C and a range of 1–1.5 °C.[2] Current warming is above that central estimate: human-induced warming reached 1.37 °C in 2025.[6] WMO separately reported that ocean heat content reached a record in 2025.[7]

    The Atlantic overturning circulation (AMOC)

    The AMOC carries warm water north in the Atlantic. The IPCC assessed that it is very likely to weaken over the 21st century in all emissions scenarios.[8] The 2025 tipping points report went further, judging it at risk of collapse below 2 °C of warming.[3] The two judgements come from different processes four years apart: a government-approved IPCC assessment in 2021 and an independent scientific synthesis in 2025.[8][5]

    Ice sheets and the Amazon

    The report warned that parts of the polar ice sheets may already have crossed tipping points that would eventually commit the world to several metres of sea-level rise, and that the Amazon rainforest is at risk below 2 °C from climate change combined with deforestation.[4] The IPCC flagged ice-sheet processes as a deep uncertainty that cannot be ruled out.[1]

    Positive tipping points

    The same report argued that “positive” tipping points, where clean technologies become self-reinforcing, have been crossed for solar PV and wind power globally.[9]

    Why it matters for carbon removal

    If warming overshoots a threshold, bringing temperatures back down requires net removal of CO2. All scenarios that reach net zero and halt warming already rely on carbon dioxide removal at gigatonne scale.[10] Whether removal can reverse tipping-point damage is an open question; see direct-air-capture and the carbon removal debate.

    Questions readers ask

    Has any climate tipping point been crossed?

    The Global Tipping Points Report 2025 concluded that warm-water coral reefs are passing their thermal tipping point, with a central threshold estimate of 1.2 °C.[2]

    Will the Gulf Stream system collapse?

    The IPCC found the Atlantic Meridional Overturning Circulation is very likely to weaken this century, and the 2025 tipping points report put it at risk of collapse below 2 °C. Timing and likelihood remain uncertain.[8][3]

    Does the IPCC agree that tipping points are a risk?

    Yes. The IPCC states with high confidence that abrupt responses and tipping points, such as strongly increased Antarctic ice-sheet melt and forest dieback, cannot be ruled out.[1]

    Are there positive tipping points?

    The 2025 report argued that positive tipping points have already been crossed in solar PV and wind power globally.[9]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      The IPCC states with high confidence that abrupt responses and tipping points, such as strongly increased Antarctic ice-sheet melt and forest dieback, cannot be ruled out. confirmedas of 2021-08-09

    2. [2]

      The Global Tipping Points Report 2025 concluded that warm-water coral reefs are passing their thermal tipping point, with a central threshold estimate of 1.2 °C (range 1–1.5 °C), making it the first Earth system tipping point reached. reportedas of 2025-10-10· interpretation

    3. [3]

      The Global Tipping Points Report 2025 assessed the Atlantic Meridional Overturning Circulation as at risk of collapse below 2 °C of warming. reportedas of 2025-10-10· interpretation

    4. [4]

      The report warned that parts of the polar ice sheets may already have crossed tipping points that would commit the world to several metres of sea-level rise, and that the Amazon rainforest is at risk below 2 °C from climate change and deforestation combined. reportedas of 2025-10-10· interpretation

    5. [5]

      The Global Tipping Points Report 2025, led by the University of Exeter's Global Systems Institute, involved about 160 authors from 87 institutions in 23 countries. confirmedas of 2025-10-10

    6. [6]

      The Indicators of Global Climate Change 2025 study estimated human-induced warming at 1.37 °C above 1850–1900 in 2025, rising at about 0.27 °C per decade over 2016–2025. confirmedas of 2026-06-11

    7. [7]

      Ocean heat content in the upper 2,000 metres reached its highest level since records began in 1960, according to WMO. confirmedas of 2026-03-23

    8. [8]

      The IPCC assessed that the Atlantic Meridional Overturning Circulation is very likely to weaken over the 21st century in all emissions scenarios. confirmedas of 2021-08-09

    9. [9]

      The report also identified "positive tipping points" already crossed in solar PV and wind power globally. reportedas of 2025-10-10· interpretation

    10. [10]

      All scenarios that reach net zero and halt warming deploy CDR at gigatonne scale, while in cost-effective Paris-compatible scenarios emissions cuts provide at least 80% of the effort to reach net zero CO2. confirmedas of 2026-06-01

    Revision history (1)
    1. Page created.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Climate tipping points: coral reefs, AMOC, ice sheets and the Amazon." ContentLora, updated Oct 10, 2026. https://contentlora.com/explain/climate-tipping-points

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