Climatologists dislike round numbers. They know that the planet doesn't cross a fine line at +1.5°C like passing a toll booth: the global average is a statistical measure, smoothed over long periods, and annual variations can depend as much on transient climate phenomena (El Niño, La Niña) as on the underlying trend. Yet, the figure published in May 2026 by the European Copernicus observatory made headlines worldwide: for the second consecutive year, the global average temperature remained above +1.55°C compared to the pre-industrial period of 1850-1900.

What Science Says, What Remains to Be Confirmed

The 2015 Paris Agreement set the goal of 'keeping the temperature rise well below 2°C, and pursuing efforts to limit it to 1.5°C'. The 1.5°C threshold was never an annual one, but a long-term one—typically a twenty-year rolling average. That's why the scientific community, led by the IPCC, remains cautious before declaring the threshold crossed in the sense of the Agreement.

But the mechanism is now difficult to reverse. The IPCC's interim synthesis report, published in May 2026, considers that it is now probable (>66%) that the 2020-2040 rolling average will reach 1.5°C in the early 2030s, unless there is a drastic and synchronized reduction in emissions—a scenario that current commitments (NDCs revised at COP29 in Belém) do not allow.

Key Climate Figures for 2026

  • +1.55°C: Global average temperature anomaly 2025-2026 (Copernicus).
  • 425 ppm: Average CO₂ concentration in the atmosphere, continuously rising.
  • −12%: Annual average Arctic sea ice extent compared to 1981-2010.
  • 15%: Estimated slowdown of the AMOC (Atlantic Meridional Overturning Circulation) over 70 years.
  • 63 million hectares burned in 2025 in boreal and tropical forests, a historic record.
  • 2.3 million: Number of people displaced by climate disasters in 2025 (UNHCR).
  • $1,850 billion: Global investments in the energy transition in 2025 (BloombergNEF).

The Indicators That Truly Worry Climatologists

Behind the global average, three indicators are drawing particular attention. First indicator: Arctic summer sea ice. The 2025 minimum was the second lowest ever recorded, and revised projections suggest a potentially ice-free Arctic in summer as early as the 2030s, compared to 2050 in previous estimates.

Second indicator: the Atlantic Meridional Overturning Circulation (AMOC). Several studies published in 2024-2025—notably in Nature and Science Advances—converge on a significantly sharper slowdown than expected, with potentially major consequences for the European climate, rainfall patterns in West Africa, and sea-level rise on the US East Coast.

Third indicator: mega-fires. The 2025 season broke the all-time record, with a total of 63 million hectares burned—Siberia, Canada, the Amazon, Indonesia. Fires are no longer just a consequence of warming: they are becoming an accelerator, through the massive CO₂ emissions they release.

Adaptation Finally Takes Its Proper Place

What's new in 2026 is that adaptation is ceasing to be the neglected aspect of climate policy. COP30 in Belém, in November 2025, saw the doubling of the Adaptation Fund for Southern countries, and several major capitals—Singapore, Rotterdam, Barcelona, Bangkok—published quantified ten-year plans to cope with rising sea levels, heatwaves, and water shortages. In France, the National Climate Change Adaptation Plan (PNACC) version 2025-2030 adopts a reference trajectory of +4°C for long-life infrastructure. A paradigm shift: France is no longer planning solely to limit warming, it is also planning to survive it.

"We have stopped debating the reality of warming. We are now debating its speed, its plateaus, and how quickly we will adapt. That's a different conversation." — Valérie Masson-Delmotte, climatologist, at COP30 in Belém, November 2025.

Key Takeaways

  • +1.55°C: 2025-2026 average, the second consecutive year above 1.5°C.
  • The Paris threshold remains defined as a long-term average, but its sustained crossing is now probable in the 2030s.
  • Three critical indicators: Arctic sea ice, AMOC, mega-fires.
  • COP30 in Belém: Doubling of the Adaptation Fund.
  • The French PNACC version 2025-2030 plans for a +4°C trajectory for infrastructure.
  • Adaptation is no longer a complement to mitigation: it is becoming its mandatory counterpart.