By Bill McGuire (ex-IPCC scientist writing exclusively for XR Blog)
Here in the UK, with snow drifting down and the papers full of warnings of the imminent arrival of ‘the beast from the east’ – the bitterly cold weather pattern that brings the worst of winter weather – it is hard to imagine that elsewhere on the planet temperatures are soaring to dangerous levels. A world away from the frost and icy wind, Australia is in the grip of an unprecedented heatwave. Last week, temperatures across much of the country topped 40°C and, in many places breached 45°C. A few days ago, at Port Augusta in South Australia, the temperature peaked at a record-shattering 48.9°C. Probably most astonishing is the record overnight temperature, which – at Noona in New South Wales – fell to just 35.9°C; an all-time record for the country. I have always thought of Australia as essentially a desert with a few green bits around the outside. The prospects for the country on Hothouse Earth are bleak, so it is particularly ironic that successive governments have proved to be some of the least climate-friendly on the planet.
The scorching temperatures down under are likely to be just the advance guard of what may well be Planet Earth’s hottest year ever. With a new El Niño looking to build across the Pacific – a phenomenon that acts to boost global temperatures as well as supercharge extreme weather – 2019 is widely predicted to be hotter than each of the last three years which, themselves, make up the three hottest on record. As a consequence, heatwaves are likely to be widespread – as they were in 2018. Last year saw unprecedented heat across four continents, especially in July, when more than 3,000 daily high temperature records and 55 all-time highs were shattered.
It hardly takes an Einstein to appreciate that heatwaves will become one of the most damaging, disruptive and lethal hazards as the world continues to heat up. According to the University of Hawaii’s Camilo Mora, one of the authors of a study published last year in Nature Climate Change, when it comes to future heatwaves ‘our options are now between bad and terrible.’ What this means is that, even if we slash greenhouse gas emissions dramatically, by the end of the century nearly half the world will experience deadly heatwaves. If we take no effective action, then three-quarters of our planet’s population will be under threat.
Furthermore, the nature of the worst future heatwaves will be very different from those currently baking Australia and that scorched much of the world in 2018, and their impact potentially catastrophic. As global temperatures continue to ramp up, a deadly conspiracy of heat and humidity, measured by the so-called ‘wet-bulb’ temperature, will bring about murderous heatwaves from which there can be no relief and no escape. When the wet-bulb temperature reaches 35°C, the combination of heat and humidity is such that losing heat through sweating is impossible for the human body. In such circumstances anyone without access to air conditioning – however young or fit – has only six or so hours to live, whether sheltering in the shade or not. Research (1,2) reveals that as the century progresses – and under a business as usual scenario – more and more of the planet will come under severe threat from such devastating heat, in particular the Middle East, South and South East Asia and China. Ground zero looks like being China’s northern plain where – today – four hundred million people toil in the country’s agricultural heartland. By the second half of the century, fatal humid heatwaves are forecast to strike the region repeatedly, effectively making China’s breadbasket uninhabitable.
No human has yet had to experience such heat-death conditions, but it can only be a matter of time. In Bandar Mahshahr (Iran) temperatures of 46°C combined with 50 percent humidity, brought conditions, in July 2015, to the very limit of survivability. Perhaps 2019 will be the year the threshold is breached, bringing a first taste of what it will be like when parts of the world that brought forth and moulded our species finally become off limits to us.
Bill McGuire is Professor Emeritus of Geophysical & Climate Hazards at UCL and author of Waking the Giant: How a Changing Climate Triggers Earthquakes, Tsunamis and Volcanic Eruptions. He was a contributor to the IPCC 2012 report on Climate Change & Extreme Events and Disasters.