By Sophie Turner
So far, 2019 has seen the hottest winter day on record with temperatures reaching 21.2°C in London back in February, the hottest July day on record, and the hottest August bank holiday Monday with temperatures of 33.2°C, ‘smashing’ the previous record of 28.2°C set two years ago. And that is just in the UK. In June, France recorded a new national temperature of 46°C in the southern village of Vérargues, Germany broke a record that had lasted over 70 years and new national records were set in Belgium, Luxembourg and the Netherlands.
Research published earlier this year in the journal Nature Climate Change suggests that more than half of the world could see new temperature records set in every single year by the end of the century if global gas emissions are not reduced.
The study looked at the rate at which existing high temperature records have been broken, and the rate at which historical records are projected to be broken over the coming century. The authors used 22 climate models to explore two possible future scenarios: one with very high greenhouse gas emissions (RCP8.5) and one where global warming is limited to below 2°C (RCP2.6).
The research found that in both scenarios, the frequency of record-breaking heat is higher than it would be in a world with no human-induced warming. But the risk is substantially higher in in the scenario where no deliberate action is taken to mitigate climate change.
“We found that you’re going to smash and set records far more frequently if global greenhouse gas emissions continue to rise the way they have been,” said Dr Scott Power, a Bureau of Meteorology scientist from Melbourne, Australia who led the research.
The results show that under a high emissions scenario, new temperature records will be set in at least one month every year for 58% of the world, by 2100. The situation is worse for developing countries and small island developing states which will see 67% and 68% of records being set every year.
The likelihood of setting at least one monthly record that ‘smashes’ the previous record by more than 1.0°C is also eight times more likely if global greenhouse gas emissions are not markedly reduced, and over twenty times more likely than would be the case if human-induced greenhouse gas emissions had not occurred at all.
These findings reinforce the need to reduce greenhouse gas emissions to avoid new temperature records being set every year until 2100. It also highlights the importance of adapting to and preparing for unprecedented temperatures over the coming decades.
However, the study also found that even if emissions are reduced, extreme monthly temperatures are projected to occur over the coming decades. This is because the carbon dioxide already in the atmosphere means we are now committed to some level of climate change. People who work in sectors and manage systems that are affected by extreme temperatures will therefore need to start considering and managing the risks associated with these extreme temperatures now.
For many city leaders, the increasing vulnerability of their residents to extreme heat is something they are already acutely aware of, particularly with the risks of the urban heat island effect (UHI), a phenomenon where cities are warmer than surrounding rural areas. In Berlin, for example, heat-related mortality rates are particularly high in the city’s most densely built-up districts. In response, the city aims to become a ‘sponge city’ by replacing hard surfaces with green space and water-permeable surfaces to combat the UHI effect and adapt to more frequent days of ‘record-setting heat’.