Over the next 10 days, 140 world leaders – including Barack Obama, Vladimir Putin, Xi Jinping and David Cameron – will descend on Paris to join 40,000 delegates at the UN’s COP21 climate conference.

Here is why they might just as well not have bothered.

1. There has been no ‘global warming’ since 1997

So, of all the children round the world currently being taught in schools about the perils of man-made global warming, not a single one has lived through a period in which the planet was actually warming.

2. The polar bears are doing just great.

As they have been for the last five decades, during which time their population has increased roughly five-fold. So why does the IUCN still classify them as “vulnerable”? Because the environmentalists needed a cute, fluffy white poster-child for their “the animals are dying and it’s all our fault” campaign, and the snail darter and the California delta smelt just didn’t cut it. So various tame conservation biologists came up with all sorts of nonsense about how polar bear populations were dwindling and how the melting of the ice floes would jeopardize their ability to feed themselves etc. How can you tell a conservation biologist is lying? When his lips move.

3. Antarctica is growing.

According to the greenies, this just wasn’t meant to happen. But it is. Even NASA admits this.

4. The Maldives aren’t sinking

Or, if they are, their government is responding in a very odd way. Just a few years back, they were staging photos of their Cabinet meeting underwater to symbolize how threatened they were by “climate change” – a problem that could only be cured, apparently, with the donation of large sums of guilt money from rich Western industrialized nations. But a few months ago they completed work on their 11th international airport. So that all the climate refugees caused by global warming can escape quickly, presumably.

5. Ocean acidification is a myth

If I were an eco-Nazi I would seriously think about killing myself at this point. Ocean acidification was supposed to be their Siegfried Line – the final line of defense if, as has grown increasingly obvious over the last few years, “anthropogenic global warming” theory proved to be a busted flush. But it turns out that ocean acidification is as big a myth as man-made climate change. a) it’s based on dubious, possibly even fraudulent, research and b) if anyone’s acidifying the ocean it’s those wretched bloody coral reefs…

6. The alarmist climate scientists are talentless low-lives who cannot be trusted

Possibly there are exceptions to this rule, somewhere. But just look at NASA GISS, NOAA and the Climatic Research Unit at the University of East Anglia/Hadley Centre at the Met Office – three of the main organizations responsible for maintaining the world’s temperature data sets.

NASA has been caught red handed turning cooling trends into warming trends. NOAA is currently under Congressional investigation for its mendacious, politicised attempts to pretend that the “Pause” in global warming doesn’t exist. The CRU was ground zero of the Climategate scandal. The Met Office is a joke. Yet these shysters have the gall to demand that the world’s leaders take urgent action on the basis of their dodgy data.

7. Winter Is Coming

Sunspot activity is diminishing in a manner worryingly similar to that experienced during the Maunder Minimum (1645 to 1715) when ice fairs were staged on the River Thames and the Dalton Minimum (1790 to 1830) which gave us Napoleon’s retreat from Moscow and the Year Without A Summer. Some scientists are predicting the imminent return of a Little Ice Age.

8. CO2 is greening the planet

The Sahel region in Africa is getting greener and more fertile. This is something we should be celebrating, not trying clumsily and expensively to prevent.

9. There has been no increase in “extreme weather events”.

Who says so? The IPCC in its most recent Assessment Report. Droughts, heatwaves, heavy rain events, cyclones, storms: they just haven’t increased in the alarmists assured us they would.

10. People are losing interest in global warming.

A) they don’t believe it’s a real threat, b) they keep being reminded of things that ARE real threats

11. $1.5 trillion is a lot of money to pay every year for a problem that doesn’t exist

This, according to Climate Change Business Journal, is how much it costs every year to “combat climate change.” $1,500,000,000,000 may not sound like a lot of money when the world’s polar bears, not to mention “the children of the future” are at stake. But you’d be surprised: spend $1,500,000,000,000 here and $1,500,000,000,000 there and pretty soon you’re talking serious money.

12. It will make (almost) no difference

If all the world’s leading nations stick to the carbon-reduction commitments they will make in Paris this week, then they will stave off “global warming” by the end of this century by 0.170 degrees C.

Oh – and that’s the optimistic scenario, calculated by Bjorn Lomborg, assuming that countries like, say, China don’t lie or cheat about how much CO2 they’re burning secretly.

His more pessimistic – ie more realistic – scenario is that the best we can hope for is a reduction in global warming by the end of the century of 0.048 degrees C.

This temperature reduction – five hundredths of one degree – is so small as to be almost immeasurable. But if you want to know what it feels like, Willis Eschenbach has done the calculations. It’s the equivalent of walking five metres higher up a mountain. Or, if you prefer, climbing two flights of stairs.

And there you have it: the lunacy of the Paris climate conference in one sentence: $1.5 trillion every year till the end of the century to effect the equivalent of walking to your bedroom.