In a morass of bad climate news, from collapsing ice shelves to the potential resurgence of coal in Europe, there is a sliver of good news. There could be fewer heatwaves declared in England this summer. However, this won’t be due to a reversal of global heating, or a summer cool snap across Britain. Instead, the Met Office is changing the definition of a heatwave in eight counties by raising the required temperature threshold. Rather than marking some new scientific standard for heatwaves, this new definition is simply a normalisation of higher temperatures in the UK. It will probably lead to fewer news reports and official statistics about heatwaves, without representing any actual respite from the record high temperatures of the past decade. It seems it’s easier to change the optics of climate breakdown than it is to address runaway warming. The shift varies from county to county. In six southern counties, the boundary has nudged up from 27C to 28C, and jumps from 26C to 27C in Lincolnshire and from 25C to 26C in the East Riding of Yorkshire. Heatwave limits were originally calculated based on the climate between 1981 and 2010, while the new thresholds will use a 1990-2020 average. The bad news is the UK was heating up significantly in the 1990-2020 period due to climate breakdown; an “undeniable warming trend” is behind the moving of the goalposts, according to the Met Office. Thresholds themselves seem relatively arbitrary, but given the Met Office explains that the purpose of a heatwave definition is to “provide the media and public with consistent and reliable messaging”, this shift will probably mask the escalation of climate impacts in the UK. Heatwaves kill in England and will continue to do so even below the new threshold. There’s a term for this in the environment world: shifting baseline syndrome. It refers to the gradual change in accepted norms for the condition of the natural environment. As we lose knowledge and experience of the environment of the past, the direction of travel is a steady lowering of standards, normalising deterioration, destruction and species decline. The term was first used in 1995 by marine biologist Daniel Pauly, regarding fish. He noted that marine scientists often assumed the “normal” baseline for fish numbers was the “unaffected” quantity at the beginning of their careers. Rather than restore stocks to the abundance of three centuries ago, conservation was confined to a window of a couple of decades, ignoring the drastic lowering of the baseline before their careers. This was leading to an unconscious acceptance of species decline. Shifting baseline syndrome permeates all elements of our natural world, as familiarity of wilder habitats and cooler climes recedes. Our baseline standards of heat are no different. This is the danger in redefining heatwaves: these definitions are pegs on which to hang our experiences, and indeed our expectations. If the barometer changes through time too, what is left to measure extreme heat events against? Take as one example the literal shifting of baseline years used to calculate emissions reductions. Some nations compare their net zero targets against emissions in 1990, others in 2005 (the latter a higher emissions year). Calculating from a higher point makes subsequent annual cuts appear deeper and more impressive in percentage points, even though there is no material difference in carbon reduction. Similarly, the lifting of the heatwave bar could play into the hands of climate deniers by implying there are fewer extreme heat events in England. England is famous for its drizzle and inhospitable greyness, but this is changing rapidly as climate impacts increase. Prof Nigel Arnell of the University of Reading said that the temperature threshold change likely won’t be the last – we will have to keep redefining heatwaves “otherwise we’ll have a heatwave every summer”. Unfortunately, a new name won’t stop soaring temperatures shocking our health, infrastructure and working conditions. Definitions matter profoundly and the instability of our climate deserves stable classifications against which to measure it. Without them, we risk losing our grip on the natural environment before the shocks of fossil capitalism. Like frogs in a slowly boiling pot, we may even begin to tolerate extreme heat on this formerly inclement island. Eleanor Salter writes about climate, culture and politics