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UNEP CONFIRMS: SURPASSING 1.5ºC OF GLOBAL HEATING IS NOW UNAVOIDABLE
But why is it so important to us? Here's what crossing 1.5°C means for our health, food, water, and the natural systems our lives depend on
By Sigrid Vestergaard Frandsen, Director of Environmental Health
09/14/2026
We've heard it numerous times before: the UN, climate scientists, and nature conservation organisations have all warned us about the average global temperature rising more than 1.5ºC above pre-industrial levels, and urged decision-makers and world leaders to take action and the necessary steps to stop the burning of fossil fuels to prevent it from happening.
The Paris Agreement of 2015 legally binds the 195 parties who adopted the agreement to substantially reduce global greenhouse gas emissions to hold global temperature increase to well below 2°C above pre-industrial levels and pursue efforts to limit it to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change.
On September 2nd 2026, the UNEP released a new report saying a global temperature increase of 1.5ºC above pre-industrial levels is now unavoidable. The necessary steps have not been taken, and the goals have not been met.
But what damage can a mere 1.5ºC do? It sounds like very little, right? It matters because that number is a global average, and averages hide the extremes that do the damage. In fact, many cities around the world already live in a 2ºC or even a 5ºC world. A small rise shifts the whole range of weather, so a heatwave that was once rare becomes common.
Here is a list of things that happen when the average global temperature rises above pre-industrial levels by 1.5ºC:
Our health
The deadliest weather on Earth isn't a storm — it's heat.
489,000 people die from extreme heat every year. That is more than hurricanes, floods, and tornadoes combined. In fact, the 2026 heat death toll in Europe alone surpassed 25,000 people before the summer was even over. Heat can overwhelm the body's cooling system, causing organ failure and blood flow to stop. With a 1.5ºC rise in the average global temperature, heatwaves and extreme heat events will be our new normal, with the most vulnerable people in most danger.
Heat creates the perfect habitats for bacteria, mosquitoes, ticks, and snails to reproduce and spread diseases such as Yellow Fever, Zika, Dengue, and Chikungunya. These are diseases we normally associate with the tropics, but are quickly moving into the U.S., too.
The air we breathe
A 1.5ºC rise in the average global temperature means more wildfires and more air conditioning.
Excessive air conditioning puts a massive toll on our power plants, and contributes to health issues, such as heart attacks, respiratory conditions, asthma attacks, and premature death, because power plants and air conditioners release particulate matter, nitrogen oxide, sulfur dioxide, and carbon emissions into the air.
Wildfires create smoke that is too toxic to inhale and can reach more than 100 million people and kill more than 10,000 people. Smoke does not care about country or state borders and will impact human health from afar.
The water we drink
Warmer bodies of water are likewise excellent habitats for bacteria, copepods and larvaes to reproduce and spread diseases once ingested by humans or animals.
In the U.S., such diseases include Cholera, Norovirus, Giardia, Cryptosporidiosis. But in the tropics the list is much longer. Eating fish from certain infected water sources can even spread diseases, too.
In order to prevent contracting waterborne diseases, treating the water is crucial. But certain water treatments don't come without its issues, such as chemical side effects, high energy use, micro and nano plastics, and water waste.
The food we eat
Climate change is a threat multiplier, with farming and fishing taking a big toll. The UNEP projects that global food production could fall by up to 14% by 2050 without serious adaptation. Due to the June heatwave in Europe, the total crop yield for 2026 is forecasted to have lost 23.4 million tonnes of grain compared to last year's harvest. A loss like that will have serious consequences for years to come.
A damaged food supply pushes Europe towards dependence on imports from some of the major grain producers in the world (Ukraine, Brazil, the U.S.), and food insecurity is therefore intensified further by ongoing heatwaves in the U.S. and the war in Ukraine. Food prices rise 15-25%, and inflation rises by one full percentage point.
Our ecosystems
A 1.5ºC rise means our ecosystems may collapse.
Warmer bodies of water hold less oxygen, and fish are losing habitat: about 4% of underwater species lose over half their range at 1.5°C, and 9% at 2°C. Coral reefs start to die near 1.2°C, and more than 80% of tropical reefs were bleached between 2023 and 2025, with the half degree to 2°C deciding how much reef and Arctic ice survive.
Warming that stays above 1.5°C also risks tipping points for Amazon rainforests and polar ice sheets, meaning bees struggle to stay alive and polar bears lose their hunting grounds. All changes that would not be reversible.
When ecosystems collapse, human survival, health, and stability break down because we depend entirely on nature for our basic needs.
Environmental injustice
A 1.5ºC global average temperature rise is a death sentence for many people around the planet. The people who are hit hardest did the least to cause the problem, have the fewest resources to adapt, and lack the voices to speak up.
Global warming is an uneven distribution of who gets to adapt and who doesn't. A study estimates that 99% of the disease burden from climate change falls on developing countries, most if it on children under five.
Small island states are now faced with losing not just land but their standing as nations — an entire nation's history, culture, and sovereignty threatened by a crisis it did not create. Meanwhile, the countries responsible for the largest share of historical emissions are, according to the UNEP, best positioned to lead a fast response and have the least excuse not to.
And the list goes on.
This is why what we do next really matters that much. The 1.5ºC threshold and how far past it we go, and for how long, remains ours to decide. Every fraction of a degree avoided, and every year the overshoot is shortened, means fewer deaths and fewer irreversible losses. Not just for humans but for animals and ecosystems, too. None of this means the fight is over. But the work now isn't to prevent something that's already arriving. It's to make sure it doesn't stay longer, or go further, than it already has.