There was a time not long ago when one of the visual metaphors of choice for our planet's sombre future was a sad looking polar bear standing on a fast-diminishing ice floe. As carbon emissions belched into the atmosphere, rising temperatures were devouring the bears' icy habitat and threatening their starvation.
In his 2006 climate-change documentary, An Inconvenient Truth, Al Gore raised just such a spectre. And two years later, following a fierce campaign by environmentalists, the US government declared the polar bear "threatened".
Yet there was something wrong with this picture. There was no real evidence that polar bear numbers were collapsing. According to estimates compiled by the Polar Bear Specialist Group, part of the International Union for the Conservation of Nature, bear numbers have actually been going up — from roughly 15,000 in 1970 to about 26,500 today.
It's a fallacy explored by Bjorn Lomborg in his book, False Alarm. The main threat to polar bears was not changing climate, he claims, but (now curbed) wild hunting. "If we want to protect [polar bears], rather than dramatically reducing carbon dioxide emissions to try to tweak temperatures over many decades with a clearly uncertain impact . . . our first step should be to stop shooting them," he writes.
Lomborg's is one of two books that set out to challenge what one might call "climate miserabilism". The other is Apocalypse Never by Michael Shellenberger, an American environmentalist turned pro-nuclear campaigner. They explore the way in which climate policy is increasingly shaped by emotive, alarmist and sometimes misleading messages.
Such messages are not just depressing the public and prompting neuroses in the young, the authors argue. They are radicalising political opinion and leading developed nations to make duff choices about remedial action. This, both authors argue, makes our predicament not better but worse.
As well as polar bear populations, Lomborg challenges other frequent claims such as the one that wildfires are massively increasing, pointing to satellite data showing that the amount of land burnt has fallen by a quarter in the past two decades. As for extreme weather and the rising cost of flood damage he notes that as a percentage of gross domestic product, US flood losses today are a tenth of what they were in 1903 — at just 0.05 per cent.
Some may see such puncturings as an attempt to play down the reality of climate change. A controversial figure in the eyes of many environmentalists, Lomborg has been accused of "lukewarmism". But it's precisely because the problem is so serious that he argues it is necessary to approach it cool-headedly. The alternative? In Lomborg's view it is letting ourselves be panicked into the most expensive course — trying to fix the climate quickly without having the necessary technology to hand.
Lomborg argues powerfully that this is a fool's errand. Take New Zealand's 2007 promise to go carbon-free by 2020. Not only was the goal missed; the country's emissions actually went up. Nor are its latest set of promises certain to fare much better. Lomborg estimates that it will cost New Zealand between 16 and 32 per cent of GDP annually to hit its declared net-zero target in 2050 — or $12,800 for each citizen. And all that to deliver a reduction of 0.004 degrees Fahrenheit in global temperatures in 2100, according to the standard estimate by the UN climate panel. "Sooner or later," he writes, "a politician is successfully going to argue to dump the net-zero promise that will deliver zilch in a century, and instead double spending on things like health, education and environment, and get some tax reductions."
His main argument is that we should place greater emphasis on adaptation, while focusing on research to find zero-carbon energy sources that work at acceptable cost. Many of his points hit home. Renewable energy isn't likely to be the world's saviour. It has actually been falling as a share of global energy — from 25 per cent in 1900 to just 11 per cent today. And most of that isn't fashionable "new" renewables such as wind and solar, but traditional fuels such as wood and dung fires. Pushing poor countries into adopting wind and solar isn't just counter productive; it's immoral, preventing them from achieving higher levels of development through the only means we know how — the burning of fossil fuels.
Some of his suggestions will raise hackles. Take his ideas about adaptation. Rich countries might have the wherewithal to build sea defences to keep out rising sea levels. But poorer ones? Especially those that are already in a chronically vulnerable position?
Much in the end hangs on whether you share his faith in how much headroom the world has available. Citing research from the Nobel Prize winning economist William Nordhaus, Lomborg suggests that a temperature rise of 4C is possible — more than twice the 1.5C targeted in the 2015 UN Paris climate arrangement — while shedding only 2.9 per cent of global GDP relative to where it otherwise would have been.
If he is right, then the world can endure quite a lot of adaptation. But what if rising CO2 levels lead to tipping points, with galloping rises in temperature? Lomborg isn't sure, which is why he holds out the possibility of geo-engineering as a form of emergency brake. Some will take this as an admission that the underlying thesis may be reckless.
Shellenberger takes fewer risks with global temperatures. He is more concerned with the puritanical and anti-development streak among environmentalists, provocatively making the case for such green bugbears as fast fashion and industrial farming.
His big point is that the world does have one technology that can replace fossil fuels and generate reliable power: nuclear. Yet as a share of energy output this is rapidly and perversely declining.
Shellenberger explores the way civil nuclear has been cast as unsafe, when it is in fact among the safest of energy sources. He roots this in the concerns of wealthy environmentalists who sought to oppose America's nuclear expansion in the 1950s on the basis that it could be so cheap and ubiquitous that it would lead to excessive and unsightly development.
The author sees this brand of thought as a modern offshoot of the (groundless) fears expressed by the 18th-century scientist Thomas Malthus about excessive population growth depleting the world's resources. He also cites the Club of Rome, an influential think-tank which predicted (wrongly) that many of the world's vital raw materials would be exhausted by 2004.
Surveying these bad calls, it is easy to sympathise with Lomborg when he warns about our fixation on scary stories leading to poor decisions. Individuals end up feeling "compelled to transform [their] lives in ways both minor (not eating meat) and major (forgoing parenthood)," he writes. Meanwhile as societies we espouse policies "that promise to squander hundreds of trillions of dollars on incredibly inefficient carbon cutting policies".
Many will take issue with some of the detailed arguments. Is the Paris agreement really as expensive as Lomborg says? Are extreme weather events really the phantoms that both authors claim?
But these books provide a corrective to many of the green assumptions that dominate the media. And if they make the world a little more questioning of the next polar bear story, that is no bad thing.