UNEP says 1.5°C will be crossed and maps an 'overshoot, peak and decline' path
If 1.5°C can no longer be held, can the world go above it and still come back down?
Published 3 September 2026. Written by Pratidin from the reports linked at the end; every fact checked by a separate review before publishing. How we work
On 2 September 2026, the United Nations Environment Programme (UNEP) released a report titled Limiting Overshoot: Navigating exceedance of 1.5°C and pathways towards return. It says that exceeding 1.5°C of warming above pre-industrial levels, the lower goal of the Paris Agreement, "is now widely assessed as unavoidable", and that the crossing is likely within the next few years. In UNEP's best case, warming peaks at about 1.8°C; in most scenarios the peak is higher, above 2°C. Reacting to the report, climate scientist Andy Reisinger of the Australian National University called it the first report by a UN agency that says unambiguously that the world will cross 1.5°C.
UNEP's answer is an "overshoot, peak and decline" pathway: keep the rise above 1.5°C as small and as short as possible, then bring temperatures back down. This needs deep and immediate cuts in carbon dioxide, methane and other greenhouse gases, net-zero emissions to stop warming, and then sustained net-negative emissions, supported by carbon dioxide removal (CDR), to reverse it. The report stresses that both the height of the peak and the time spent above 1.5°C matter, because each raises the chance of crossing irreversible thresholds, such as ice-sheet collapse or permafrost thaw, and of hitting the limits of adaptation. It says mitigation and adaptation must advance together.
UN Secretary-General António Guterres said: "We must make the overshoot above 1.5 degrees as small and short as possible." UNEP Executive Director Inger Andersen said 1.5°C "remains the goal" but must now be approached "from above", and that countries with greater historical responsibility for climate change should do the most work. The report itself calls this "by no means an acceptable or preferred pathway" but "simply the best remaining option". Scientists reacting to it warned that CDR should not be seen as an easy option in place of cutting emissions; UNEP notes that novel removal methods such as direct air capture can cost up to $600 a tonne.
Prelims facts
- UNEP's report Limiting Overshoot (2 September 2026) says exceeding 1.5°C is now widely assessed as unavoidable, likely within the next few years.
- In UNEP's best case, warming peaks at about 1.8°C; most scenarios peak above 2°C.
- UNEP proposes an 'overshoot, peak and decline' pathway: a small, short overshoot followed by a return below 1.5°C.
- Returning below 1.5°C needs sustained net-negative CO2 emissions and carbon dioxide removal, which cannot replace rapid emission cuts.
- Article 2 of the Paris Agreement aims to hold warming well below 2°C and pursue efforts to limit it to 1.5°C.
Quick recall
- Which UN body released the report 'Limiting Overshoot' on 2 September 2026?
- The United Nations Environment Programme (UNEP).
- What pathway does the Limiting Overshoot report propose?
- An 'overshoot, peak and decline' pathway: keep the overshoot above 1.5°C small and short, then bring warming back down.
- What is UNEP's best-case peak warming in the report?
- About 1.8°C above pre-industrial levels; most scenarios peak above 2°C.
- Which article of the Paris Agreement sets the temperature goal?
- Article 2: well below 2°C, pursuing efforts to limit warming to 1.5°C.
- Which was the first calendar year with global warming above 1.5°C?
- 2024.
- What is the difference between net zero and net-negative emissions?
- Net zero balances emissions and removals; net negative removes more than is emitted, which is needed to reverse warming.
- Give one example each of conventional and novel carbon dioxide removal.
- Conventional: afforestation or soil management. Novel: direct air capture.
- Who heads UNEP?
- Executive Director Inger Andersen.
Prelims practice question
With reference to the report 'Limiting Overshoot' released in September 2026, consider the following statements:
1. It was released by the United Nations Environment Programme.
2. It proposes an 'overshoot, peak and decline' pathway.
3. It projects that warming will peak below 1.5°C if all current commitments are delivered.
Which of the statements given above is/are correct?
- 1 only
- 1 and 2 only
- 2 and 3 only
- 1, 2 and 3
Show answer
Answer: (b) 1 and 2 only. UNEP released the report and proposes the 'overshoot, peak and decline' pathway. Statement 3 is wrong: even the best case peaks at about 1.8°C.
Use this in UPSC Mains: previous-year questions
Recurring theme: Climate change: temperature goals, carbon removal and global climate governance
- How to use this
Use the UNEP report to support India's stand in climate fora that historically responsible countries must do the most, while India pursues its own net-zero path.
- UNEP Executive Director Inger Andersen said countries with greater historical responsibility for climate change should do the most work, reinforcing common but differentiated responsibilities.
- UNEP's Limiting Overshoot report (2 September 2026) says exceeding 1.5°C is now widely assessed as unavoidable, with a best-case peak near 1.8°C.
- India's 2070 net-zero path needs finance and technology; scientists warn carbon dioxide removal, with novel methods costing up to $600 a tonne, cannot replace early cuts by high emitters.
- How to use this
Open with UNEP's warning that crossing 1.5°C is now unavoidable, to frame why impacts on India will intensify.
- UNEP's Limiting Overshoot report (2 September 2026) says exceeding 1.5°C is likely within the next few years; most scenarios peak above 2°C.
- The report warns that a higher, longer overshoot raises the chance of irreversible thresholds such as ice-sheet collapse and permafrost thaw, and of hitting the limits of adaptation.
The overshoot pathway depends on carbon capture and removal; the report's split between conventional and novel removal helps you judge which listed activities count.
Mains practice question
What is meant by climate 'overshoot'? Discuss the 'overshoot, peak and decline' pathway proposed by UNEP and its implications for developing countries such as India. (150 words)
Model answer
Overshoot means global warming temporarily exceeding 1.5°C before being brought back down. UNEP's Limiting Overshoot report (September 2026) says crossing 1.5°C is now widely assessed as unavoidable.
The pathway
- Overshoot: limit how high and how long warming exceeds 1.5°C; the best case peaks near 1.8°C.
- Peak: deep, immediate cuts in CO2 and methane.
- Decline: net-negative emissions using carbon dioxide removal.
Implications for India and developing countries
- Adaptation must be scaled up now, since impacts grow with every tenth of a degree.
- Removal cannot substitute for early cuts by high emitters.
- UNEP says countries with greater historical responsibility should do the most, reinforcing common but differentiated responsibilities.
- India's 2070 net-zero path needs finance and technology.
Concerns
- Reliance on future removal may delay cuts today.
- Novel removal can cost up to $600 a tonne.
1.5°C remains the goal, but it must now be approached from above.
The basics
Why this matters
For a decade, 1.5°C has been the number at the centre of climate diplomacy. A UN agency now says plainly that the world will pass it. That changes the question from "how do we stay below 1.5°C?" to "how high do we go, for how long, and how do we come back?" Expect this idea in Prelims (terms such as overshoot and carbon dioxide removal) and in Mains (climate justice and India's position).
What "1.5°C" measures
The figure is the rise in global average surface temperature compared with the pre-industrial period, usually taken as 1850 to 1900. The Paris Agreement temperature goal refers to long-term warming averaged over decades, not a single hot year. That is why 2024, the first calendar year above 1.5°C, did not by itself mean the goal was breached.
Overshoot is a pathway, not a moment
UNEP describes overshoot as a multi-decade path with distinct stages. Two things decide how much damage it does: how high the peak is, and how long temperatures stay above 1.5°C. Both raise the odds of crossing Climate tipping points.
- 1ExceedanceWarming rises above 1.5°C
- 2PeakWarming reaches its highest level, which deep cuts in emissions keep as low as possible
- 3DeclineNet-negative emissions bring temperatures down
- 4StabilisationThe climate settles at a new, lower level
How temperatures could come down
Reaching Net zero and net-negative emissions is the hinge. Net zero halts further warming from carbon dioxide; only net-negative emissions, where more CO2 is removed than emitted, can reverse it. That is the job of Carbon dioxide removal.
- Afforestation and better soil management
- Most feasible today
- Needs large areas of land
- Storage is not guaranteed to be permanent
- Technology-based, such as direct air capture
- Can cost up to $600 per tonne removed
- Still needs to scale up sharply
The honest caveat
UNEP itself calls the pathway "by no means an acceptable or preferred pathway" and "simply the best remaining option". Removal adds only fractions of a degree of cooling in the models, so it cannot replace rapid emission cuts. Even if temperatures fall again, some damage, such as species loss, will not reverse.
The takeaway
1.5°C stays the goal, but it is now a target to return to, not a line to stay behind. Every tenth of a degree and every year above it matters.
Go deeper
In one line: UNEP's Limiting Overshoot report (2 September 2026) says exceeding 1.5°C is now widely assessed as unavoidable and asks the world to keep the overshoot small and short, then bring warming back down.
Why it matters for UPSC
The report reframes the central number of climate diplomacy. It links Prelims terms (overshoot, net zero, carbon dioxide removal, tipping points) with Mains themes (climate justice, India's development space, adaptation).
The core idea
The Paris Agreement temperature goal asks countries to hold warming well below 2°C and pursue efforts to limit it to 1.5°C. UNEP now says the 1.5°C line will be crossed within the next few years, with a best-case peak of about 1.8°C. Its answer is an "overshoot, peak and decline" pathway: deep cuts now, Net zero and net-negative emissions later, and Carbon dioxide removal to pull temperatures back. The height and length of the overshoot matter because they raise the risk of crossing Climate tipping points.
Numbers and dates to remember
- 2015: Paris Agreement adopted (Article 2 sets the temperature goal).
- 2024: first calendar year above 1.5°C.
- 2 September 2026: UNEP releases Limiting Overshoot.
- About 1.8°C: UNEP's best-case peak; most scenarios exceed 2°C.
- Up to $600 per tonne: cost of novel removal such as direct air capture.
Where to go next
- Paris Agreement temperature goal: what 1.5°C and 2°C actually commit countries to.
- Carbon dioxide removal: the tools meant to bring temperatures back down.
- Climate tipping points: why the length and height of the overshoot matter.
- Net zero and net-negative emissions: the hinge between stopping and reversing warming.
Go deeper: is 'overshoot, peak and decline' realism or retreat?
The case that it is realism. Andy Reisinger of the Australian National University called it the first report by a UN agency that says unambiguously that the world will cross 1.5°C. Admitting this lets governments plan for adaptation at higher warming instead of pretending the line will hold. UNEP Executive Director Inger Andersen framed it as a change of direction, not of goal: 1.5°C "remains the goal", now to be approached "from above".
The case that it risks retreat. An overshoot pathway leans on future removal. Scientists warned that Carbon dioxide removal should not be treated as an easy substitute for cutting emissions today. If countries bank on later removal, the peak could be higher and last longer, raising the risk of Climate tipping points.
The equity question. Andersen said countries with greater historical responsibility should do the most work, and that those who contributed least should not bear the greatest burdens. This echoes the principle of common but differentiated responsibilities and respective capabilities in the climate regime. For India, which has set a net-zero target of 2070, the question is how fast developed countries reach Net zero and net-negative emissions and fund removal and adaptation.
The legal frame. Nothing in the report changes the Paris Agreement temperature goal. What changes is the path: from avoiding exceedance to limiting its size and length, then returning.
Paris Agreement temperature goal
What 1.5°C and 2°C actually commit countries to.
In one line: Article 2 of the Paris Agreement (2015) aims to hold warming well below 2°C above pre-industrial levels and to pursue efforts to limit it to 1.5°C.
What the goal means
The baseline is the pre-industrial period, usually 1850 to 1900. The goal refers to long-term global warming, averaged over decades, not to the temperature of one year. So 2024, the first calendar year above 1.5°C, was a warning rather than a formal breach.
How countries act on it
Each country submits a nationally determined contribution (NDC), its own plan to cut emissions. The goal is collective; there is no binding national temperature quota.
Why it is in the news
UNEP's Limiting Overshoot report says exceeding 1.5°C is now widely assessed as unavoidable, but Inger Andersen stressed that 1.5°C remains the goal.
Where to go next
Carbon dioxide removal
The tools meant to bring temperatures back down.
In one line: Carbon dioxide removal (CDR) means taking CO2 out of the atmosphere and storing it on land, in the ocean, in rocks or in products.
Two families
- Conventional CDR: ecological practices such as afforestation and soil management. It is the most feasible today but needs a lot of land, and storage is not guaranteed to be permanent.
- Novel CDR: technology-based methods such as direct air capture, which can cost up to $600 per tonne of CO2.
CDR is not the same as capture at source
Capturing CO2 at a chimney only stops new emissions from reaching the air. Removal takes out CO2 already in the air, which is what an overshoot pathway needs to reduce temperatures.
Why it is in the news
UNEP says returning below 1.5°C needs sustained net-negative emissions supported by CDR, but models show removal delivers only fractions of a degree of cooling. It is "not a substitute for rapid emission reduction".
Where to go next
Climate tipping points
Why the length and height of the overshoot matter.
In one line: A tipping point is a threshold beyond which a part of the Earth system shifts to a new state that may not reverse even if temperatures later fall.
Examples UNEP highlights
- Dieback of the Amazon rainforest.
- Thawing of permafrost, which can release more greenhouse gases.
- Collapse of ice sheets, which raises sea levels for centuries.
Why overshoot raises the risk
The chance of crossing such thresholds rises with both the magnitude of warming and the time spent at high temperatures. A short, low overshoot is less risky than a long, high one. That is the logic of keeping the overshoot "as small and short as possible", in the words of UN Secretary-General António Guterres.
Why it is in the news
The Limiting Overshoot report warns that some damage will persist even after temperatures decline.
Where to go next
Net zero and net-negative emissions
The hinge between stopping and reversing warming.
In one line: Net zero means greenhouse gases emitted are balanced by those removed; net negative means more is removed than emitted.
Why the difference matters
Warming from CO2 depends on the total amount accumulated in the air. Reaching net-zero CO2 stops that total from rising, so warming from CO2 largely stops. To bring temperatures down after an overshoot, the total must fall, which only net-negative emissions can achieve.
Three phases in UNEP's pathway
- Immediate cuts in CO2, methane and other gases to limit the peak.
- Deep decarbonisation to reach net zero, alongside adaptation.
- Sustained net-negative emissions to bring warming back towards 1.5°C.
India's position
India has announced a target of net-zero emissions by 2070, set out at COP26 in Glasgow in 2021.
Where to go next
Take the 3 September 2026 quiz: 18 Prelims-style questions with answers