Received this from a friend? Sign up here

What has been especially cataclysmic is the smoke. Dozens of places in the eastern US broke their records for harmful particulate matter, including major cities like Chicago, Milwaukee and Detroit, and for a day Toronto surpassed New Delhi to become the most polluted city on Earth. Particulate matter has also exceeded safe levels across swathes of Spain, France and Italy. Wildfire smoke raises the risk of heart attacks, strokes and respiratory illness over the short term and of pregnancy complications and developmental conditions over the long term.

Donald Trump threatened to raise tariffs on Canada over the smoke, accusing it of “refusing to engage in basic forest management and debris removal”, and law-makers proposed sanctions. That reveals a misunderstanding of the problem. Only one-fifth of Canada’s total burned area has historically been in managed forests. The vast majority is in the boreal forest, which, for the most part, doesn’t have roads or logging operations. There’s no build-up of fuel to be removed, since fires there are typically allowed to burn.

Global warming, not poor management, is driving these wildfires. Canada is heating up at twice the worldwide average rate, and warmer air sucks more moisture out of vegetation, turning it to tinder. It also tends to generate more convective storms and lightning, the main ignition source, and the fire season is getting longer as snow melts sooner and returns later.

Trump has exacerbated the root cause of the fires by paying energy companies billions of taxpayer dollars to cancel offshore wind projects, while extending the life of coal power plants. Michael Mann at the University of Pennsylvania has compared his tariff threat to recklessly crashing into the car in front of you and then charging its driver for the damages.

The wildfire problem is only going to get worse. Heatwaves are getting more severe, and the heat domes that have amplified the fire weather in Canada and Europe may also become more frequent. Wildfires in Canada are releasing carbon that is up to 5000 years old, warming the world even further. And Trump can’t close the borders to smoke.

Marie Roman, Roslyn Budd, AIMS, Carly Randall

Earth contains more than enough heat to power humanity many times over, but so far only a few lucky places have been able to exploit it. Now we may have a way to tap this vast clean energy source almost anywhere. Read more.

The super El Niño now developing in the tropical Pacific has a 90 per cent chance of becoming the strongest in 150 years, breaking global temperature records and unleashing extreme weather. Read more.

It will be some months before the true toll of Europe's worst-ever heatwave is confirmed, but researchers can estimate a death count based on how many people died in Europe during previous hot periods. Read more.

I went into a heat chamber at the University of Brighton to see how I’d withstand temperatures and humidity at the levels of the record-breaking June heatwave. Like many people, it turns out I’m poorly adapted to extreme heat, but employing smart cooling techniques and exposing yourself to heat in small doses can build tolerance. Read more.

The fate of the Atlantic Ocean current that keeps Europe’s climate warm depends on our carbon emissions and the rate of ice melt from Greenland, but there is a chance that a shutdown is already inevitable. Read more.

Today, most rechargeable batteries are made from lithium ions, but sodium-ion alternatives could make battery tech much cheaper and offer other advantages. Read more.

Climate change is already having a big impact on crop yields, and the subsequent financial losses will continue to rise as the world keeps warming. Read more.

A modelling study suggests marine cloud brightening could shade the eastern Pacific and reduce a global temperature spike from El Niño, but there could be unexpected consequences. Read more.

To understand where climate change is heading, we have to look at the planet’s distant past and appreciate the disturbing uniqueness of our situation, says Bill McGuire. Read more.

As Chris Packham gears up for his new TV show, Evolution, he tells Penny Sarchet why understanding the latest evolutionary science is so important if we are to truly appreciate the natural world – and how he would happily die at the hands of a Tyrannosaurus rex. Read more.

James Yungel

Living within Earth's planetary limits while ensuring everyone's essential needs are met might seem like an impossible challenge. But in the medieval city of Guimarães, Portugal – the European Green Capital for 2026 – sustainability scientists are drawing up a blueprint for how residents can flourish while reining in their use of resources. Still, in the face of growing inequality, can well-meaning efforts like these be put in place quickly enough to avoid the destruction of ecosystems on which we all depend – and who ultimately gets to decide how much is enough to live well? Read more.