Even cool periods in the UK are now warmer than they used to be, meteorologists have warned, as an assessment of last year’s weather showed average temperatures higher across the country, in sync with rising heat across the globe. Britain’s record-breaking heatwave last week, when the mercury topped 40C for the first time on record, has subsided into scattered showers and cooler temperatures across much of the country, but forecasters have warned that smaller heatwaves could return in the next month. Heatwaves around the world this year are showing clear evidence of the climate crisis, experts have said. There were unprecedented heatwaves at both of the earth’s poles at once in March, followed by heatwaves in South Asia, China, Europe and north America. Wildfires are also raging in many regions, including north America and parts of Europe. Drought is also a formidable challenge for the UK, with water levels in many rivers and catchment areas at dangerous lows in recent days. This poses a serious threat to wildlife, particularly as many UK river systems are already badly afflicted by pollution, much of it from intensive farming. Government officials held a drought summit on Tuesday to prepare, as forecasters warned of the driest conditions seen since 1976, when a long hot dry spell led to drastic measures to conserve water. Though no drastic measures were agreed at the meeting, hosepipe bans are under consideration. Farmers may have to restrict irrigation in some areas and water companies are bracing for high demand and low rainfall. Wouter Buytaert, professor of hydrology and water resources at Imperial College London, said: “We experience drought in the UK when the water stored in our rivers, reservoirs, and groundwater runs exceptionally low. The south-east of the UK is particularly vulnerable, not only because it receives the least rainfall, but it also has the highest demand.” He said people could make a big difference to the availability of water by reducing their use, but in the longer term the government must act. “We should focus on the reduction of leakage, better use of rainwater in buildings, and water reuse in industrial processes.” This year’s extremes follow a relatively moderate year in 2021, when winter and spring were “near-normal” in temperature compared with the long-term average, but summer and autumn showed a clear global heating trend, warmer by 1.5C and 1.8C respectively than the benchmark average of 1961-1990. The maximum temperature recorded in the UK in 2021 was 32.2C, well below last week’s peaks but still markedly above the 31.4C average hottest day per year in the benchmark 1961-1990 period. Advertisement Overall, last year was the 18th warmest year on record, based on the UK’s comprehensive temperature series dating back to 1884. But 2021 also saw significant storms and weather damage, including the destructive Storm Arwen that hit last November – which would have been far more damaging had it not occurred at neap tide, when waters are low – as well as Storm Darcy in February, and heavy rain last October. Mike Kendon, of the Met Office National Climate Information Centre, said last year’s weather had been highly variable, as laid out in the State of the UK Climate report published on Thursday. “It is telling that whereas we consider 2021 as near-average for temperature in the context of the current climate, had this occurred just over three decades ago it would have been one of the UK’s warmest years on record,” he said. Unusually, last April was colder than March, which has only happened 15 times in the central England temperature record, which goes back 363 years. This led to a “split spring”, when a warm March helped to bring earlier trees into leaf sooner, but those that would be expected to leaf in April were delayed by the cold. Experts said this probably had an impact on other species, as insects would have been less available for birds in the crucial spring nesting season. The rate of sea level rise around the UK has also accelerated, from about 1.5mm a year over a century ago to about 3mm to 5.2mm a year at present, varying by location around the UK. This makes a cumulative rise of about 16.5cm in over a century, measured since the early 1900s, and is contributing to the faster erosion of coastal areas. The State of the UK Climate report is published annually, and has been subject to peer review.