On 15 July 2022, a Level 4 alert, colour-coded red, was issued by the Met Office’s National Severe Weather Warning Service (NSWWS) for the first time ever, declaring a major incident for parts of central, northern, eastern, and south-east England on 18 and 19 July. On the same day, the UK Health Security Agency’s (UKHSA) Heat-Health Alert service announced the first national Level 4 Heat-Health emergency. It was predicted that parts of the UK could see temperatures rise to 400 C and above for the first time in history, with ‘tropical nights’ and night-time temperatures of 200 C and over a distinct possibility. These announcements were followed by a second emergency meeting of COBRA (Cabinet Office Briefing Rooms) civil contingencies committee on 16 July, to help coordinate the UK government’s response to the impending emergency.
According to the Met Office, “a heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity”. A heatwave is formally declared when daily maximum temperatures meet or exceed a pre-designated heatwave temperature threshold, which varies by UK county, on at least three consecutive days. The immediate causes of the heatwave in the British Isles are the northward movement of a hot airmass from Northwest Africa and the Sahara, and of the ‘Azores High’ subtropical high-pressure system. This is at a time when the jet stream, a long, narrow, high-speed, easterly moving, high-altitude air current, is at its strongest over the UK, creating warm and dry weather. The same phenomena have contributed to the crippling heatwaves and devastating wildfires in France and the Iberian Peninsula that have preceded the British heatwave.
Around the world, heatwaves are becoming more frequent, more intense, and often last longer. The consensus is that this is a manifestation of global warming, although not all are convinced. Sir John Hayes, MP for South Holland and The Deepings and Chair of the Common Sense Group of Conservative MPs, even criticised those responding to the latest extreme heat warnings as “cowards” and “snowflakes”. The highest temperature in the UK hitherto, at 38.70 C, was reported from the Cambridge University Botanic Garden as recently on 25 July 2019. During the heatwave of 23 June-2 July 1976, which is frequently remembered with nostalgia as a joyous occasion, despite the inconveniences of water rationing, hosepipe bans, and communal standpipes, the peak temperature was only 35.90 C, at Cheltenham on 3 July. The ten hottest years in British history have all been after 2002. During 4 to 13 August 2003, over 2,000 excess death were reported in England, compared to the same period over the previous five years, while 15,000 excess deaths were reported from northern France over a three-week period in the same month.
The human body is very susceptible to excessive environmental temperatures. Those at highest risk are older people (75 years and above), the very young (below 5 years), and people with pre-existing medical conditions, including diseases of the heart, lungs, kidneys, liver, thyroid, and blood vessels, diabetes, Parkinson’s disease, and some mental health conditions. The risk is even greater for socially isolated people, who live alone or are homeless, with no one to check on their health, and the victims of alcohol or substance abuse. Good Samaritans, good neighbours, family, and friends all have a part to play in this national emergency.
Heat stress can progress from heat exhaustion to life-threatening heat stroke, over minutes to hours. Heat exhaustion, which may be accompanied by profuse sweating, a cold and clammy skin, dizziness, faintness, tiredness, headache, nausea, muscle cramps, intense thirst, and dark-coloured urine, is not serious if recognised and dealt with in a timely manner. Heat stroke, on the other hand, is a medical emergency, characterised by a core body temperature of 40.50 C or above, a hot and dry skin from inability to sweat, rapid breathing, a fast pulse, and the features of of brain involvement, such as confusion, disorientation, fits, and loss of consciousness. At this stage, the body is no longer able to cool itself by its usual physiological corrective mechanisms. Whenever heat-related illness is recognised, the priority is to rapidly cool down the victim, using cold water, ice slush, cold packs, circulating fans, cooling blankets, or other available means, and to simultaneously call 999 when heatstroke is considered likely.
The Heatwave Plan for England: Protecting health and reducing harm from hot weather, first published on 13 May 2014, and updated on 15 July 2022, provides guidance for public agencies, professionals working with people at risk, and individuals, local communities, and voluntary groups. The NHS response to the national emergency has included increasing the numbers of call handlers for the 111 helpline, providing extra ambulances, and freeing up capacity in hospitals in anticipation of increased attendances and admissions by restricting elective activity. Hospital appointments have been cancelled, while the public have been advised to call 999 only for genuine emergencies.
The UK’s infrastructure has demonstrated weaknesses in the face of previous extreme weather events, in response to both excessively hot as well as freezing cold temperatures. Hot weather can affect critical infrastructure, depleting water supplies, and buckling rail tracks, as well as affecting overhead power cables and railway signalling equipment. Temporary speed restrictions may be required for the safe operation of any trains that continue to operate. Foreseeing problems with public transport, working from home has been encouraged and schools have closed, while sports days and other outdoor events have been cancelled to protect attendees and participants from the smouldering heat.
For self-protection, it is important to keep hydrated by drinking plenty of cold water and other drinks, while avoiding beverages containing alcohol and caffeine, and eating cold foods, especially salads and fruit with high water content. To prevent overheating, one should stay out of the sun whenever possible, especially between 11 AM and 3 PM (when UV rays are strongest), ideally keeping indoors unless it is absolutely necessary to go out. A wide-brimmed hat (rarely seen in the UK), sunglasses, and light-coloured, loose-fitting clothing in breathable fabrics are recommended for personal protection for those venturing outdoors, who should preferably seek out the shade wherever possible. Sunburn can be prevented by the use of a broad-spectrum sunscreen with a high SPF and UVA rating.
Heatwaves require a coordinated public and governmental response and can be considered a wake-up call for action on climate change. It is, however, left to politicians to decide on the best course of action, as they juggle short-term economic priorities, such the cost-of-living crisis, with the implementation of longer-term, and sometimes costly, zero-carbon policies. Meanwhile, given recent trends, we can expect yet more heatwaves to come and have to build on our resilience to deal with such extreme weather events over the coming years.
Ashis Banerjee
PS: A temperature of 430 C was recorded at RAF Coningsby in Lincolnshire during the afternoon of 19 July 2022. On the same day, at least 22 major wildfires were reported from across England and Wales, and major incidents were declared by fire brigades in Greater London, Leicestershire, and South Yorkshire.