Danish boffins have uncovered an unforeseen, extra downside of the melting of the Arctic ice cap, according to reports. Not only will there be sea level rises and massive flooding*; there will also be a plague of enormous, invulnerable, heavily armoured meat-eating cannibal spiders.

The worrying yet exciting news comes courtesy of National Geographic, which has been speaking to top arachno-boffin Toke Høye of Aarhus University. Høye has spent ten years studying the flesh-eating "wolf" spider Pardosa glacialis which lives in Greenland, north of the Arctic circle.

Disturbingly, the Scandinavian spider specialist reports that over that period the polar arachnids have increased significantly in size - and correspondingly increased the thickness of their exoskeletal armour plates. In just one warm year, it seems, you can see a 10 per cent increase: and over the decade that Høye has been visiting the Greenland spider colonies there has been a 2 per cent upward trend, which he puts down to global warming.

On its own this is quite bad enough. We here on the Reg big-game and military tech desk calculate that if the spider-wolves of the Arctic grow by 10 per cent annually**, in just fifty years they will be the size of Humvees. But it gets worse: oh yes.

We aren't just looking at a swarming, ravenous horde of hairy meat-eating arachnids the size of offroad vehicles. That would be easy to deal with, as a well-placed slug from a big-bore rifle would put such a creature down. Big-game hunters worldwide would rush to Greenland to join in the sport; every sportsman's entrance hall would be adorned with enormous spider-head trophies; wealthy socialite ladies would wear fur coats made of Arctic wolfspider-hair.

By the year 2070 or so, mournful Eskimo trackers would point dolefully across the empty prairies of Greenland, where once the mighty herds of flesh-eating buffalo-sized spiders had roamed - after the glaciers left, but before the hunters came.

So, basically no problem. But in fact, these spiders aren't going to be nearly as easy to kill as a buffalo or a charging elephant. A measly .50-calibre express bullet isn't going to knock one of these puppies down, no sir.

Why? Because spiders, as everyone knows, can actually extrude bulletproof-vest material out of their arses: True fact. And all their hard body structure is worn on the outside, as an exoskeleton, thus forming a natural coat of armour plate.

Thus when the mighty hordes of four-metre-long spiders appear in 2060 or so, they will - by our calculations - be plated with 26cm arachnocomposite protection, in the same league as or better than modern ceramic body armour but immensely thicker.

They'll be as hard to take out as a tank. This won't be a jolly day's sport blasting away with a heavy rifle: nothing short of a hypervelocity depleted-uranium penetrator, a volley of antitank missiles or a huge roadside bomb is going to stop one of these. Dealing with a spider infestation is going to be like stopping a Nazi panzer blitzkrieg.

It's always possible that humanity will be saved by radical big-game hunters mounted in battle tanks or attack helicopters - or possibly ones gutsier still, who insist on taking their arachnid trophies on foot using man-portable antitank weapons for ultimate kudos. But it sounds like an expensive and dangerous hobby.

As the National Geographic points out, we might do better to hope that the spiders' natural cannibalistic propensities come into play. Pardosa glacialis are apparently well known for snacking on their young, and (among the females) on insufficiently alert sexual partners. Enormous and correspondingly peckish lady spiders might control most of the rest of their species for us, leaving only relatively small numbers to be occasionally culled by game wardens armed with cruise missiles. ®

*Before you all start going on about floating ice, do please remember that much of the arctic ice cap sits on Greenland.

**Naturally we haven't chosen to use the more realistic 2 per cent per decade figure, as it is boring.