UNEP's 1.5°C warning: The world may cool down again. What happens when the heat retreats but the damage stays?

We have been witnessing the change in seasons for the past few years. They are shifting, and most of the time it is warmer than usual. You are using air conditioning in the months when a fan used to bring you the chill. Earth is becoming a bit warmer every few years, and it raises a question for everyone who is trying to make it cooler: If the world eventually brings temperatures down, will life return to what it was before?

Now, a United Nations Environment Programme report has warned that long-term global warming is expected to cross 1.5°C above pre-industrial levels within the next few years. Bringing temperatures back below that threshold is possible, but some damage could be permanent. UNEP’s warning about exceeding 1.5°C raises a difficult economic question: how can countries protect people whose losses cannot be reversed by a future fall in temperatures?

A fall in global temperatures would be welcome news for everyone, but there are strings attached to it. For example, if a family was forced to abandon its coastal home, it would offer no guarantee of getting that home back.


UNEP has taken note of these kinds of losses and prepared a report on Climate “Overshoot”. It refers to the period when global temperature exceeds a limit before eventually returning below it.

The United Nations Environment Programme published the report in September 2026, titled Limiting Overshoot: Navigating exceedance of 1.5°C and pathways towards return.

The report analysed how the world can work towards reducing the temperature below the threshold mentioned in the Paris Agreement. However, the UNEP warning report also addressed the question of where it would leave societies facing huge irreversible consequences even if we are able to bring the heat down, as for some people their lives have completely changed.

What can the government do to contribute in making the world cooler?

The first step which any government can take is to cut emissions. They need to put a limit on the future temperature rise before focusing on how to tune it down. The second step involves caring about people who are most impacted because of this climate change. They need to build plans to protect the homes and incomes of those who have already incurred damages or are going through that.

What does a temporary breach in the Paris Agreement actually mean?

The temperature has crossed the threshold mentioned in the Paris agreement but we need to understand the intensity of the situation. There is a difference between an unusual hot year and temperatures rising every year contributing to global warming.

The World Meteorological Organization estimated that 2024 was approximately 1.55°C warmer than the 1850–1900 average. A single year above the threshold, does not establish that the Paris Agreement’s long-term temperature limit has been crossed. That assessment concerns warming measured over decades.

Overshoot means a sustained increase in temperature after which a decline happens. According to the UNEP report, it is important to note the temperature peak but one more factor needs to be considered before confirming the problem. Climate researchers need to consider the time spent above the 1.5°C temperature threshold. The longer the duration of rising temperatures the more damage it does to our planet and the changes may be irreversible.

A lower temperature will not turn back every clock

The rising sea level does not make the problem easier to handle but it surely makes it clear. The Intergovernmental Panel on Climate Change has mentioned that sea levels will continue to rise for centuries to millennia because of deep-ocean warming and ice-sheet melt. Elevated seas can persist long after the emissions that helped cause them.

For coastal economies, bringing the temperatures down is not going to solve all their problems. They would still need resources for protection during floods. They would need planning for relocation.

Investment for the public is required to resolve these issues. A port, a housing development or a water network may operate for decades. Decisions about where to build, and what to protect, cannot depend solely on an expectation that temperatures will eventually decline.

The economic consequences are also devastating. UNEP’s report described how climate vulnerability can increase sovereign borrowing costs even before a disaster strikes. Rising debt and declining insurability can then constrain investment in more resilient infrastructure.

Countries may consequently face higher costs of protection precisely when their ability to finance it is weakening.

The adaptation bill is already underfunded

An earlier UNEP assessment reveal the financing challenge. Its Adaptation Gap Report 2025 estimated developing countries’ annual adaptation needs in 2035 at $310 billion using modelled costs. An alternative estimate, based on needs expressed in national plans, put the figure at $365 billion. Both are expressed in 2023 prices.

International public adaptation finance flowing to developing countries was $26 billion in 2023, down from $28 billion in 2022. These are different measures and time periods, but together they show how far available international support falls short of projected needs.

For policymakers, adaptation spending raises difficult distributional choices. Which settlements receive protection first? How much support reaches people who must move? Who can afford the remaining risk?

Assessing success requires looking beyond money committed to whether people can use the protection it finances.

What can climate action still achieve?

UNEP’s overshoot report calls for immediate emissions reductions alongside stronger adaptation. It also identifies carbon dioxide removal as part of a possible return to lower temperatures. This should be accompanied by cutting down emissions.

That future possibility cannot settle today’s investment decisions. Governments still need to decide how much risk their infrastructure can withstand and how communities will participate in choices about their future.

UNEP highlights measures that can help with both emissions and resilience, including nature-based cooling. It also argues that countries with greater responsibility for climate change should act faster and with greater ambition.

The central economic question is how to finance protection while preventing further damage. Delaying either task makes the other harder.

Reducing the temperature below the threshold would be a huge achievement for the world. It would mean less people would lose their homes and incomes and people could continue a normal journey.