Limiting Overshoot Report

Why in News?

Recently, a UN report says global warming will exceed 1.5°C, demanding urgent corrective action.

• Released by – UN Environment Programme (UNEP)
• Key highlight – It identifies “Overshoot → Peak → Decline” as the most viable remaining strategy to limit climate damage and ultimately reduce global temperatures below 1.5°C.
• 1.5°C Target – Under the 2015 Paris Agreement, countries aim to keep the increase in global average temperature well below 2°C above pre-industrial levels and pursue efforts to limit it to 1.5°C.

• Current Situation – According to UNEP, global warming is likely to exceed 1.5°C within the next few years.
• If countries fully implement their current climate plans and net-zero targets:
• Peak warming is projected to reach approximately 1.8°C.
• Under current policies:
  • Warming is expected to reach around 2.6°C by 2100.
  • The possible range is 1.9°C to 3.6°C.

At COP30 (2025, Belém), the “Global Mutirão” decision became the first COP text to explicitly acknowledge the likelihood of a temporary 1.5°C overshoot.

It also committed to limiting the extent and duration of the overshoot and to closing adaptation gaps.

• Climate overshoot – It occurs when temperatures temporarily exceed the 1.5°C threshold before being reduced.
• “Overshoot, Peak and Decline” Pathway
  • Overshoot – Temperatures are projected to exceed 1.5°C, which is now considered unavoidable.
  • Peak – Global warming reaches its highest point, ideally remaining as low as possible, with the best-case scenario around 1.8°C.
  • Decline – With net-negative emissions, temperatures are reduced below 1.5°C by 2100.

• Compound Risks – Additional warming will
  • Accelerate sea-level rise,
  • Increase the risk of coral collapse,
  • Cause a 25% loss of glaciers by 2100,
  • Reduce food production by 14% by 2050, and
  • Raise the likelihood of tipping points in Antarctica, Greenland, the Atlantic Meridional Overturning Circulation (AMOC), and the Amazon.
• Hard Physics – Every five years of high emissions increases global temperatures by approximately 0.1°C.
  • Reversing this trend requires the removal of about 220 gigatonnes of CO₂.
  • One tree absorbs roughly one tonne of CO₂ over 30 years.
• CDR (Carbon Dioxide Removal) Limit – A credible return to 1.5°C is only possible if peak warming remains below 2°C.
• The UN report’s policy toolkit stresses deep emission cuts, rapid methane reduction, supplementary carbon dioxide removal, and transformational adaptation as the combined pathway to limit overshoot and return towards 1.5°C.

Reference

The Hindu | Global Warming Limit Breach