The world is currently not on track to limit global warming to 1.5°C.
In the last five years, the warmest global temperature on record has been documented twice - in 2016 and 2020. The Earth’s mean surface temperature in 2020 was 1.25°C above the global average between 1850 and 1900, before industrialisation and before anthropogenic activity began pumping out huge amounts of the greenhouse gas, carbon dioxide.
But that’s just 0.25°C below the 1.5°C figure set by the Paris Agreement in 2015, to limit global temperature rise to prevent, or at least avoid, some of the most harmful impacts of climate change.
However, the world is currently not on track to limit global warming to 1.5°C, according to COP26. The targets announced in Paris would result in warming well above 3°C by 2100 compared to pre-industrial levels. If we continue as we are, temperatures will continue to rise, bringing even more catastrophic flooding, wildfires, extreme weather and destruction of species.
Warming different for everyone
Regardless of how much the world warms, it will not be the same for everyone. Previous research using climate models suggests that the Arctic, central Brazil, the Mediterranean basin and mainland US will warm much more than the global average. But what does that mean?
Climate projections at the postcode level suggest that 4°C of warming could bring temperatures of 43°C to Cambridge.
“Statistics for ‘global mean temperatures’ and ‘regional hotspots’ are abstract concepts – helpful for policymakers, but not something anyone can actually feel,” explains Professor Robert Wilby, an expert in hydroclimate modelling at the University of Loughborough.
“What’s more, temperature projections from global climate models are typically for wild or agricultural landscapes, averaged over tens to hundreds of square kilometres. These projections are far removed from the conditions that will be encountered on city streets, inside workplaces, public spaces, and our homes. But these are the places where health, comfort and productivity will be decided during the more intense heatwaves that climate change will bring.”
Wilby says UK Met Office analyses suggest global temperatures that are 4°C above pre-industrial levels may be reached as soon as the 2060s. “Climate projections at the postcode level suggest that 4°C of global warming could bring temperatures of 43°C to Cambridge,” he says. But this projection for the hottest summer day for Cambridge in the 2060s involved tuning climate models with temperatures averaged from weather stations.
43°C temperatures in Cambridge would be a reality under 4°C of global warming.
“These tend to be located away from artificial heat sources and often in areas with grass and vegetation,” Wilby adds. “Asphalt surfaces and high-density city centres are typically several degrees warmer and behave very differently to rural weather stations.”
So, what feels like 4°C in one area, may feel warmer somewhere else. Climate models tend to simulate temperatures for urban areas, smoothing out the peaks and troughs of individual days. They also ignore measures taken by cities to adapt to rising temperatures, such as increased green spaces or reflective roofs. Complex variations in temperature between streets remain unresolved, meaning even state-of-the-art models likely underestimate the true severity of future warming in urban areas.