Expert reaction: 2024 hottest year on record

Climate scientists and policy experts from the University of Reading offer expert comment after global average temperatures went beyond 1.5°C above pre-industrial levels for an entire year for the first time.  

Professor Hannah Cloke, Professor of Hydrology at the University of Reading, said: "The natural world is a beautiful and powerful vessel that carries us all. The delicate balance of nature that sustains human life, providing everything we need from our food and water to our homes and jobs, is moving further and further away from what human society is capable of withstanding.

"Reaching this point, with 1.5 degrees of extra heat across the globe in the atmosphere for a full year, is a troubling milestone in a journey that is taking us away from the safe home in which we can live and thrive. For the sake of my children and their futures, I hope it also marks the point where everyone, every world leader, every government, every business, wakes up to the danger and quickly turns around what they are doing. If we do not, this will not be a milestone but a stepping stone towards our survival."

Professor Chris Merchant, Professor in Ocean and Earth Observation at the University of Reading, said: “The main factors behind the record-breaking global temperatures are global warming combining with the El Nino event that picked up in early 2023 and continued in 2024. These years where characterised by unprecedented wildfires and by a long list of devastating flooding events all around the world – each one a human and economic tragedy. These events are getting worse because of global warming, driven by burning fossil fuels. The fossil fuel industry makes exaggerated profits because it isn’t paying for the climate-related disasters that greenhouse gases cause. Yet we continue to allow them to invest in expanding fossil fuel resources. This needs to change. We need to accelerate the switch away from fossil fuels.” 

Professor Chris Hilson, Director of the Centre for Climate and Justice at the University of Reading, said: “We cannot yet definitively say we have surpassed 1.5C for the purposes of the Paris Agreement that sets this as a key temperature goal we should remain within. That would require more than a decade of average global temperatures above this level, and not just a year or two. 

“But we don’t have time to wait for that long-term confirmation. We are already seeing the havoc that 1.5c of warming is wreaking globally with extreme weather events like storms and flooding. Unless governments globally act with real purpose, we are on course for warming of more like 3-4 degrees, which will have catastrophic outcomes. 

“Many governments are running scared of the costs of addressing climate change in a cost-of-living crisis. Populists have begun to attack the ‘net zero’ policies needed to remain within 1.5C, on cost grounds. This is a myth that must be tackled head-on. Most of the net zero policy mix will lead to cheaper bills for people. Where there are extra up-front costs, governments need to ensure that ‘just transition’ plans are in place to help the less well-off.

“More than anything, we can’t afford not to aim for 1.5C and net zero. The insurance costs of extreme weather events exacerbated by climate change are already in the hundreds of billions. And the less well-off in exposed areas typically don’t have or can’t get insurance. Populists tend to play down this side of the ledger, but that aspect of climate costs – i.e. the costs of not meeting net zero and 1.5c – are ignored at our peril.

“There is an abstractness to temperature figures like ‘1.5C’ (of warming above pre-industrial levels) and targets like ‘net zero’. Lawmakers need to find ways to make these meaningful to people. Without that, populists can easily make them sound like words from the technocracy that only they can protect people against. What people really need protecting from though are false promises and climate mis- and dis-information. Climate temperature data matters, but so does data on the costs of not taking action in time.”

Dr Patrick McGuire, Land Surface Processes Computational Scientist and co-author on the Global Carbon Budget since 2019, said: “Hitting 1.5°C is like watching the first domino fall in a devastating chain reaction. While we may dip below this threshold temporarily as El Niño subsides, we're playing with fire. Every fraction of a degree unleashes more intense storms, longer droughts, and deadlier heatwaves. If we continue this trajectory toward 3-4°C, we're not just crossing a line - we're jumping off a cliff into a climate future our societies aren't built to survive." 

Dr Akshay Deoras, National Centre for Atmospheric Science Research Scientist at the University of Reading, said: “Surpassing the 1.5°C mark over a shorter time scale of a month has become the new normal. The limit has been surpassed over several consecutive months since summer 2023, showing how serious the problem of global warming is.  

“We are treating our planet like a credit card with no limit by continuing to dump greenhouse gases and supercharging extreme weather events. The annual global temperature breaking the 1.5°C mark for the first time in 2024 shows the bill is coming. This means a more frequent and more intense extreme weather events. 

“We're already seeing homes become uninsurable and disasters costing billions. This isn't about future generations anymore—it's about us, today. We are on track to see new warming records getting broken, unless we immediately cut down the emission of greenhouse gases.” 

Professor Richard Allan, Professor in Climate Science, said: “Earth’s climate is racing into territory uncharted by human societies and the ecosystems upon which we depend.

"Record global warmth in 2023 and 2024 was dominated by the continued increases in heat-trapping greenhouse gases and further amplified by a tendency toward cleaner, less polluted skies allowing more sunlight to reach Earth’s surface. Global temperatures were given an extra natural boost as warm El Niño conditions returned heat temporarily buried below the ocean surface during cooler La Niña conditions persisting before 2023.

"The alarm bells are sounding as global surface temperatures in 2024 hit 1.5 degrees Celsius above pre-industrial levels. The Paris climate agreement determined that to avoid dangerous climate change, the planet should not substantially exceed the 1.5 degree threshold over many decades. Although a temporary breach of the 1.5 degree threshold, as the warming influence of El Niño wanes, it is a clear harbinger of progressively more dangerous climate impacts close on the horizon.

"The only way to halt further global warming beyond the 1.5 degree threshold and limit the worsening extremes of rainfall, heat and drought is to rapidly and massively cut greenhouse gas emissions across all sectors of society.”