The world likely just had its hottest month on record. What a time to be a climate science denier

<span>Photograph: AFP/Getty Images</span>
Photograph: AFP/Getty Images

With the planet seeing record-breaking temperatures, and after more than 100 million people in the US were placed under heat warnings, now seems the perfect time for climate change contrarians to tell their readers that it’s all overblown hype.

Heatwaves? Not as bad as they used to be. Wildfires? They’re on the decline.

The Australian newspaper’s Washington correspondent, Adam Creighton, wrote this week that most Americans were getting on with life during the heatwaves and had simply taken refuge “in the plentiful supply of air-conditioning” while the intense summer heat blew over.

Yet despite all that air-conditioning, more people die from heat in the US than any other weather-related event.

Related: Heavy on the rhetoric, light on facts: campaign against net zero fields familiar tropes | Temperature Check

One study has linked between 5,000 and 7,000 cardiovascular deaths from 2008 to 2017 to extreme heat.

Dr Sameed Khatana, a cardiovascular physician at the University of Pennsylvania who has researched the effect of extreme heat on death rates, said an estimated 1,300 to 2,000 people die from extreme heat every year in the US.

“Given our, and many other researchers’ work, it would not be surprising if similar, if not even higher numbers of deaths occur this summer due to the ongoing extreme heat events around the country,” he told Temperature Check.

Waves of heat

Creighton points to a “heatwave index” on the website of the US government’s Environment Protection Agency that suggests heatwaves were more common in the country before the 1960s than now, particularly in the 1930s.

The index is the work of Prof Kenneth Kunkell, a climate scientist at the North Carolina Institute for Climate Studies who has helped coordinate several national assessments of climate change in the US.

Kunkell said the extreme dust-bowl heat of 1930, 1931, 1934 and 1936 was driven by “extreme drought and poor land management” in central US.

“It is true the above mentioned four years in the 1930s represent the benchmark for extreme heat. But outside of those four years, the frequency and extent of intense heatwaves over the last 20 years is higher than any other similar length period going back to 1895,” he told Temperature Check.

“In the south-west US the index is already the second-highest on record, the record being set only two years ago in 2021.”

Dr Sarah Perkins-Kirkpatrick, an extreme heat expert at University of New South Wales Canberra, says the dust-bowl conditions in the 1930s are well known. The global picture is very clear.

“Not only are heatwave days increasing almost everywhere, heatwave trends are accelerating. And that includes the United States,” she said.

Hottest July ever?

The World Meteorological Organization said this week that July will very likely turn out to be the hottest month on at least one record that dates back to 1940. The previous month, according to the US National Atmospheric and Oceanic Administration, was the hottest June on its 174-year record.

This week, some media outlets suggested the first three weeks of July could have been the hottest period the planet has seen for 120,000 years.

Creighton was not impressed, saying any average taken over three weeks is “meaningless” and that in any case “reliable measures go back a little over a century”.

But while it’s true that observations of temperature only started in the middle of the 19th century, those observations tell a very clear story. It’s getting hotter.

Knowing for certain that there has been no period like it in 120,000 years is tough without observations. But that doesn’t mean there’s nothing we can say about temperatures in the past.

According to the UN’s most recent climate assessment, temperatures today are on average higher than at any time in at least the last 100,000 years.

Given the burning of fossil fuels and clearing of land over the course of a century or so has pushed the climate beyond anything known by human civilisation, that is a long way from being meaningless.

Nobody denies

“No one denies that the climate changes. It always has, for reasons obviously unrelated to human activity,” Creighton wrote, saying the issue was “how much of the change is our fault”.

So how much is “our fault”? Creighton doesn’t try to find an answer. But there are answers out there.

Related: The lesson from the Greece wildfires? The climate crisis is coming for us all | Nesrine Malik

The UN’s latest assessment of climate change science says about 1.07C of global heating measured since the preindustrial era was caused by humans.

Natural swings caused by volcanoes and changes in the energy from the sun changed the global surface temperature by plus or minus 0.1C and internal variability (think climate patterns such as El Niño) also changed the temperature by plus or minus 0.2C.

In fact, the warming caused by burning fossil fuels that loads the atmosphere with CO2 is offset by the cooling effect of particulates that are also emitted from burning fossil fuels and from wildfires. That effect is likely larger than the effect of natural swings.

So the short answer to Creighton’s unanswered question of how much warming “is our fault” is … all of it.

Burning facts

Hundreds of fires have been burning across North America and Mediterranean countries in recent weeks, but fear not. The Danish political scientist Bjørn Lomborg is here to tell you things are just not as bad as they seem.

“Climate alarmists scare us of ever more fire. But satellites show the world is burning ever less,” he wrote on the social media site formerly known as Twitter.

So what’s going on?

Lomborg pointed to a study explaining how the data is put together. The lead author of that study, Prof Louis Giglio, told Temperature Check: “The global burned area time series shown in isolation is misleading because it is dominated by Africa, where most of the burned area worldwide is located and where regular burning has been a normal part of the environment for millennia.

“The contribution from smaller fire-prone and heavily populated regions like California and parts of Australia, where fire intensity and burned area are increasing, is dwarfed.”

Giglio and his colleague Dr Mike Humber, both at the University of Maryland, said Africa accounted for about 67% of the burned area globally, and the reduction in burn area in the last 15 years was due mostly to natural variability in the weather that had seen more rain, as well as the expansion of croplands.

Dr Grant Williamson, a bushfire expert at the University of Tasmania, said: “Dr Lomborg’s claim that global burnt area is declining is misleading if not understood in the true context of global fire activity.

“Taken as a whole, fire activity has declined globally, but that change is primarily occurring in tropical savanna systems, which are the most fire-prone on Earth and have an outsized influence on the global total. Decline in those systems is driven by human land-use change, such as the increase in agricultural activity and the shift in population to cities.

“It is clear that within temperate and boreal forest, including Europe, Australia and North America, burnt area is increasing, fires are becoming more frequent and intense, and extreme fire weather is becoming more common.”