Global warming must peak below 2°C then return under 1.5°C to limit risk of dangerous “tipping points”, experts say

However, the share of the UK public who say the country needs to reduce carbon emissions to net zero sooner than 2050 has nearly halved since 2021, according to a new study

Global warming must peak below 2°C then return under 1.5°C as quickly as possible to limit the risk of dangerous “tipping points”, experts say.  

A new paper by an international team of researchers, reviews the latest evidence and says global temperatures must cool to around 1°C above pre-industrial levels in the long term.  

The paper, The implications of overshooting 1.5°C on Earth system tipping elements – a review, has been published in a special issue of the journal Environmental Research Letters. 

The global transport sector is a major driver of climate change, accounting for approximately 16% to nearly 27% of global greenhouse gas emissions. Road transport is the largest contributor, responsible for over 70% of these emissions, driven by a 95% reliance on fossil fuels. Total transportation emissions have nearly doubled since 1990, according to 2024 figures from the International Energy Agency. 

Under current trends, transportation emissions are expected to continue to rise, threatening Paris Agreement targets, although some projections suggest road emissions in Europe may peak around 2025.

The UK has committed to net-zero carbon emissions by 2050, with transport responsible for 29% of total UK greenhouse gas emissions in 2023, making it the largest emitting sector of the UK economy. More than half (54%) of the UK’s transport emissions come from cars and taxis, state figures from the Transport Select Committee in 2025.

UK support for net zero declining

However, the share of the UK public who say the country needs to reduce carbon emissions to net zero sooner than 2050 has nearly halved since 2021, according to a major new study.

The findings come in a new study carried out by the Policy Institute at King’s College London, Ipsos and the Centre for Climate Change and Social Transformations which updates several long-term trends in public opinion, as issues related to climate change have increasingly being drawn into “culture war” debates in the UK.

According to Ipsos: "Between 2024 and 2025, support for low-traffic neighbourhoods, taxes on those who fly more, subsidies for electric vehicle purchases, and a tax on environmentally damaging foods all declined, with opposition to some of these measures now greater than support for them – a stark reversal of attitudes from just a few years earlier. 

Support tends to have fallen more amongst older people than younger people."

They add that 29% of the public now say the UK should achieve net zero before the government's 2050 target – down from 54% in 2021, when this question was last asked.

The proportion who feel the UK either doesn't need to reach net zero by 2050 or shouldn't have a net zero target at all has risen from 9% to 26% over the same period.

But despite this declining sense of urgency, a significant majority (64%) still believe the government's target for net zero should be at least 2050, if not earlier.

Tipping points

A tipping point defines when a small change in environmental conditions can spark a transformation that can be rapid and is often irreversible.   

Earth systems at risk of tipping include the dieback of tropical coral reefs and the Amazon rainforest, and the melting of permafrost and major ice sheets on Greenland and Antarctica.  

Such tipping events could have devastating consequences for people and nature and could rapidly accelerate climate change – leading to further tipping events.    

The new review – which builds on a chapter of the 2025 Global Tipping Points Report – warns that up to eight tipping points could be reached below 2°C warming. 

The research was led by the University of Exeter, the Potsdam Institute for Climate Impact Research (PIK) and the Centre for International Climate Research (CICERO).  

“It is increasingly likely that global warming will exceed 1.5 °C in the late 2020s or 2030s,” said lead author Dr Paul Ritche, from Exeter’s Global Systems Institute.    

“The tipping point for several Earth systems could therefore be crossed – at least temporarily.   

“However, tipping does not occur immediately upon crossing a tipping point.   

“If we limit the maximum level of warming, and keep the duration of the overshoot short, tipping could still be avoided for many tipping elements of the Earth system.”    

Dr Ritchie explained that some systems – such as tropical coral reefs – respond very quickly to higher temperatures and are therefore especially vulnerable to “overshoots”, even when they are short.  

With current global warming at about 1.4°C, warm-water reefs are passing their thermal tipping point (central estimate 1.2°C, range 1-1.5°C). This means coral reefs on any meaningful scale will be lost unless the global temperature returns towards 1°C warming or below very quickly.  

In contrast, potential tipping points with slower response times – such as polar ice sheets – may be less sensitive to temporary overshoot.   

“Therefore, we need to develop a proper risk assessment for tipping elements,” said study co-lead author Nico Wunderling from PIK and Goethe University Frankfurt.  

“This paper begins that work, but more is urgently needed.  

“It’s concerning that, even with a small and relatively brief overshoot of the 1.5°C target, up to five Earth system tipping points could be triggered.  

“Like an individual assessing the risk of a house fire or a plane crashing, we can’t simply plan based on a ‘best guess’ – we need to anticipate the dangerous outcomes and take action to prevent them.”  

Additional human pressures

The researchers say that “additional human pressures” – such as deforestation in the Amazon or pollution and overfishing of coral reefs – can lower their temperature tipping points.  

Norman Steinert, co-lead author from CICERO, concluded: “Minimising the peak of an overshoot is crucial, but arguably minimising the duration is even more important.   

“However, it’s important to note that these things are related: the higher the peak temperature, the more difficult it is to reverse temperature below critical levels and the longer it’s likely that we’ll remain in ‘overshoot’.”