Earth on the Edge: 1.5°C Global Warming Threshold Could Be Breached by 2029

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Redacción HC
08/09/2024

The planet is approaching a critical tipping point. According to the latest multi-agency climate forecast led by the UK Met Office and coordinated by the World Meteorological Organization (WMO), there is now an 86% chance that the Earth will temporarily exceed 1.5°C above pre-industrial levels between 2025 and 2029. This threshold, long viewed as a guardrail to avoid the most dangerous impacts of climate change, may soon be crossed—not permanently, but often enough to signal profound systemic risk.

The findings, published in WMO’s Global Annual to Decadal Climate Update (2025), are based on cutting-edge simulations from ten climate prediction centers worldwide. While the Paris Agreement’s 1.5°C limit refers to a 20–30-year average, a single year breaching this level is no longer hypothetical—it is imminent.

Why 1.5°C Matters: From Scientific Threshold to Global Alarm

The 1.5°C benchmark is more than a number. It’s the threshold at which climate impacts accelerate dramatically:

More frequent and severe heatwaves
Unprecedented droughts and floods
Faster sea-level rise due to Arctic ice melt
Irreversible damage to ecosystems and coral reefs

While these events are already occurring, crossing 1.5°C, even temporarily, is a flashing red light for governments and societies worldwide.

The new report seeks to quantify just how likely these events are in the near term—and the outlook is sobering.

Behind the Forecast: How the Predictions Were Made

To produce the five-year climate outlook, scientists used more than 200 simulations from advanced climate models, a method known as ensemble forecasting. These models were run by institutions from Europe, North America, and Asia.

Key elements included:

Baseline reference: Pre-industrial temperatures (1850–1900)
Recent observations: 2023 reached 1.45°C above baseline; 2024 is expected to reach ~1.54°C
Probabilistic projections: Factoring in both greenhouse gas trends and natural variability, such as El Niño events

While the models are robust, the authors caution that natural climate variability can cause short-term deviations, and a single year above 1.5°C does not mean the Paris Agreement is void—that would require a sustained breach over decades.

Key Findings: A Climate Warning Signal

1. Near-Certain Temporary Breach of 1.5°C

There is an 80% chance that at least one year between 2024 and 2028 will exceed the 1.5°C threshold.
For the window between 2025 and 2029, that probability rises to 86%, according to the WMO’s ensemble projections.

2. Five-Year Average Could Cross 1.5°C

The probability of a five-year average exceeding 1.5°C is:
- 47% for 2024–2028
- 70% for 2025–2029

This is significant because sustained averages, not single-year spikes, are what the Paris Agreement aims to avoid.

3. New Global Temperature Record on the Horizon

The likelihood that a new hottest year on record will occur in the next five years is 86%. If 2024 sets a new benchmark, 2025 or 2026 could easily surpass it.

4. A Distant Yet Troubling Possibility: 2°C in One Year

Though unlikely, there is a 1% chance that a single year before 2030 could temporarily reach 2°C above pre-industrial levels—a scenario once thought nearly impossible.

5. Escalating Extreme Events

As global temperatures rise, so does the frequency and intensity of extreme weather, including:

Record-breaking heatwaves
Megadroughts and crop failures
Flash floods and supercharged hurricanes
Arctic warming at 3.5x the global average, contributing to sea level rise

These impacts will not be distributed evenly. Vulnerable regions like South America, South Asia, and Sub-Saharan Africa are expected to bear the brunt.

Urgency in Practice: What Governments Must Do Now

Strengthening Climate Policy and Commitments

The findings reaffirm that climate action cannot wait for 2030. Governments must:

Accelerate emission reduction targets
Phase out fossil fuels and expand renewable energy
Enhance carbon sinks through reforestation and conservation

This year’s data will likely shape negotiations at COP30 and national climate adaptation strategies.

Preparing for Extreme Heat

With killer heatwaves becoming more frequent, nations need:

Resilient urban planning (cooler buildings, shaded spaces)
Expanded public health systems to prevent heatstroke deaths
Water infrastructure upgrades to manage droughts and floods

Protecting Biodiversity and Food Security

Climate stress on ecosystems is intensifying:

Coral bleaching in marine ecosystems
Wildfires threatening tropical forests
Declining agricultural yields in heat-prone zones

Proactive investment in adaptive agriculture, indigenous land management, and climate-resilient biodiversity corridors will be key.

Can the 1.5°C Target Still Be Saved?

The UN Secretary-General and WMO leadership insist that breaching 1.5°C in a single year does not mean failure—but it does mean that the window for meaningful action is closing fast.