1.5°C Warming Overshoot- UNEP’s Warning and the Future of Climate Action

The United Nations Environment Programme (UNEP) released its report “Limiting overshoot” on 2nd September 2026. It warns that the world is likely to cross the 1.5 degree Celsius global warming limit within the next few years.

Why in the News?

• UNEP’s “Limiting Overshoot” report says temporarily crossing the 1.5°C warming threshold is now unavoidable.
• Even if current climate plans and net-zero pledges are fully implemented, warming could peak at around 1.8°C.

What is 1.5°C Overshoot?

• Overshoot means global warming temporarily rises above 1.5°C above pre-industrial levels and is later brought down.
• Crossing 1.5°C for a few months or years does not automatically breach the Paris Agreement, which refers to long-term warming over decades.
• UNEP says the strategy should now be to approach 1.5°C “from above rather than below”:
  • Keep the peak as low as possible.
  • Keep the overshoot as short as possible.
  • Bring temperatures back down.

Why is 1.5°C Important?

• Under the Paris Agreement (2015), countries agreed to:
  • Keep warming well below 2°C.
  • Pursue efforts to limit it to 1.5°C.
• Every additional fraction of warming increases risks from:
  • Extreme heat and drought
  • Water stress
  • Glacier and ice-sheet loss
  • Wildfires
  • Ecosystem degradation

Key Findings of UNEP

UNEP’s Global Environment Outlook, Emissions Gap Report, and Limiting Overshoot assessments indicate that the world is likely to exceed the 1.5°C warming threshold. This underscores the need for an “overshoot, peak, and decline” pathway, combining rapid emission reductions with long-term carbon removal to eventually restore temperatures below 1.5°C. Let's look at the Key Findings of UNEP:-

1. Some Damage May Be Irreversible

Overshoot increases risks of:

• Greenland and West Antarctic ice-sheet loss
• Amazon rainforest dieback
• Permafrost thaw
• Coral reef destruction
• Changes in Atlantic Meridional Overturning Circulation (AMOC)
• Long-term sea-level rise and biodiversity loss

Even if temperatures later fall, some impacts may continue.

2. Extent of Overshoot Matters

• Smaller + shorter overshoot = lower climate damage.
• Rapid cuts in methane and other short-lived climate pollutants can slow near-term warming.

3. Carbon Removal Will Be Needed

• Returning to 1.5°C would require Carbon Dioxide Removal (CDR).
• But CDR has limits and cannot substitute for immediate emission cuts.
• UNEP estimates that afforestation and forest management alone could take over 100 years to reduce warming by just 0.1°C, under the stated assumptions.

Three-Step Response

Net-negative emissions = removing more CO₂ from the atmosphere than is emitted.

Unequal Burden

• Developing countries that contributed relatively little to historical emissions are often more vulnerable to climate impacts.
• UNEP estimates their adaptation needs could exceed $310 billion annually by 2035, around 12 times current international public finance flows.
• This strengthens the case for greater adaptation finance and climate justice.

Way Forward

• Accelerate GHG emission reductions.
• Prioritise methane reduction for faster near-term benefits.
• Scale up adaptation and resilience.
• Increase climate finance for developing countries.
• Develop responsible carbon-removal capacity.
• Protect vulnerable ecosystems and communities.

Summary

The UNEP warning on 1.5°C warming overshoot shows that the world is entering a difficult phase of climate action. UNEP says that crossing 1.5°C is now likely in the next few years. Even in the most optimistic scenario, global warming could peak at around 1.8°C, while other pathways could lead to warming above 2°C. However, crossing 1.5°C does not mean that climate action has failed. The focus should now be on keeping the overshoot as small and short as possible. Every extra fraction of a degree can increase heatwaves, floods, droughts, sea-level rise and damage to ecosystems. Longer periods of high warming can also increase the risk of serious and possibly irreversible changes in the climate system. UNEP suggests an “overshoot, peak and decline” approach. This means limiting the temperature rise, reaching the lowest possible peak, and then bringing global temperatures down towards 1.5°C and below. This will require faster cuts in greenhouse gas emissions, a shift to clean energy, better climate adaptation, and responsible use of carbon removal. The message is simple: 1.5°C should not be treated as a lost goal. Instead, it should become a goal that the world works towards from above. Stronger climate action today can reduce the level and duration of warming and protect vulnerable countries and communities. The future of climate action will depend on how seriously they work together on Mitigation, adaptation, climate finance, and technology.