UN charts course to manage global warming-limit breach
Prelims:
Environment
& Ecology
Mains:
GS Paper II –
International Environmental Cooperation, GS Paper III – Environment
Current relevance:
The
United Nations Environment Programme (UNEP), in its report Limiting
Overshoot, has for the first time outlined a detailed “overshoot, peak
and decline” pathway, warning that crossing the 1.5°C global warming
threshold is now unavoidable.
Highlights:
1.
‘Overshoot, Peak and
Decline’ Pathway:
i.
Overshoot: Global average temperature temporarily
rises above the 1.5°C limit.
ii.
Peak:
Warming is contained at
the lowest possible level after the overshoot.
iii.
Decline: Global temperatures are subsequently
brought back below 1.5°C by 2100.
iv.
UNEP
projects that global warming will cross 1.5°C within the next few years
and describes the pathway as the “best remaining option”, rather than an
acceptable or preferred pathway.
v.
Since
a temporary breach of 1.5°C is considered unavoidable, the pathway
focuses on keeping the magnitude and duration of the overshoot as small and
short as possible.
2.
Global Warming
Trajectories:
i.
Even
if every country fulfils its national climate plan and net-zero target, peak
warming is projected to reach around 1.8°C.
ii.
Under
current policies, global warming could reach approximately 2.6°C by 2100,
with a projected range of 1.9°C–3.6°C.
iii.
Every
five years of continued high emissions could add roughly 0.1°C to
peak warming.
iv.
Reversing
the same 0.1°C of warming would subsequently require removing about 220
billion tonnes of CO₂ from the atmosphere, over and above continuing
emissions.
v.
Thus,
delayed emission reductions increase both the peak level of warming and
the scale of future carbon removal required.
3.
Risks of Prolonged
Overshoot:
i.
Remaining
above the 1.5°C threshold for longer periods could accelerate sea-level rise
and contribute to coral reef collapse.
ii.
Glacier
loss could exceed one-quarter of global mass by 2100.
iii.
Without
effective adaptation, global food production could decline by up to 14%
by 2050.
iv.
Overshoot
could also increase the risk of irreversible tipping points involving the West
Antarctic and Greenland ice sheets, Atlantic Meridional Overturning Circulation
(AMOC), and the Amazon.
v.
Therefore,
the longer the world remains above 1.5°C, the greater the risk of compounding
and irreversible ecological and socio-economic losses.
4.
Carbon Removal and
Methane Reduction:
i.
As emission reductions alone will no longer be
sufficient, the pathway requires a steep expansion of nature-based carbon
removals, including large-scale reforestation.
ii.
Climate
action therefore needs to combine deep emission reductions with enhanced
carbon removal to eventually bring temperatures below the 1.5°C threshold.
iii.
Methane
contributes about 0.5°C of warming, the report identifies reducing methane emissions as the most
effective measure to slow warming in the near term.
5.
Paris Agreement and
COP30 :
i.
The
2015 Paris Agreement has the central goal of limiting the rise in
average global temperatures to 1.5°C above pre-industrial levels.
ii.
At COP30
in Belém, Brazil, in 2025, the consensus “Global Mutirão” (collective
effort) decision became the first COP text to acknowledge that a temporary
overshoot of the 1.5°C threshold was likely.
iii.
This
acknowledgement reflected concerns over the rapid consumption of the remaining carbon
budget.
iv.
UNEP’s
pathway therefore represents a shift towards limiting the scale and duration
of an expected overshoot and subsequently bringing temperatures back below
1.5°C.
Source: THE
HINDU - https://www.thehindu.com/sci-tech/energy-and-environment/global-warming-will-exceed-limit-un-says-in-a-report-that-maps-path-to-get-back-below-danger-zone/article71418475.ece