If global warming is real then why is it cold, part 379

As you may have heard, there’s currently a climate conference taking place in Cancún, Mexico. As you may also have heard, it’s snowing.

Uh-oh!

If, last week, frozen behind a snowdrift, you heard a faint hysterical squeaking, it might well have been the sound of those 20,000 delegates holed up behind a wall of armed security guards in the sun-drenched Mexican holiday resort of Cancun, telling each other that the world is more threatened by runaway global warming than ever.

Yes, it’s the classic “If global warming is real why is it cold?” argument from Christopher Booker, blithely ignoring the fact that 2010 is set to be one of the hottest years on record (and 2000-2009 was the hottest decade on record) regardless of what the weather is like for one week on a small northerly island. To be fair, this isn’t his only argument (even if he does return to the subject three more times in the space of the column). After all, he also has “If the oceans are getting more acidic, why are they still alkaline?”

Far from the oceans acidifying, their pH currently ranges between 7.9 and 8.3, putting them very firmly on the alkaline side of the threshold, at 7.0.

Of course, the fact that the seas are alkaline doesn’t mean they can’t be less alkaline than they were years ago. And sure enough, according to the Australian Antarctic Division:

CO₂ from human activities has caused the pH of ocean surface waters to drop by 0.11 pH units. This might not sound like much, but it is equivalent to a 30% increase in acidity.*

Ocean acidification is never going to turn the oceans completely acidic – that would require a 1580% rise in ocean acidity, which is a bit unlikely. What acidification will do – and what it has already done, in fact – is bring acidity up just enough to interfere with creatures like coral, which rely on the precise chemistry of the ocean to produce their skeletons.

His other argument?

It is only those same old computer models that predict that Tuvalu and the Maldives are about to drown, when real measurements show the sea around them not to be rising at all.

It’s true that one dataset from Tuvalu did appear to show no sea level rise. Unfortunately (for both Booker and the Tuvaluans) that data was taken from a single station over a relatively short period and presented without uncertainties, making it effectively meaningless. Analysis of more data from Tuvalu (PDF, p.11) finds a sea level rise of 1.2 ± 0.8 mm/year. The uncertainty in the data is still quite large (not least because the island of Tuvalu itself is moving by a small but unknown amount), but there certainly appears to be a sea level rise. At any rate, regardless of whether or not the sea level is rising at Tuvalu right now, it’s certainly rising worldwide at a rate which threatens people living in low-lying land.

The global warming scare may have been fun for the children while it lasted. But the time has come for the joke to be declared well and truly over.

Some joke.

Incidentally, Booker finishes off his column with a link to some people singing Handel’s Hallelujah in a food court which, he claims, is “the very opposite of all that is stood for by global warming, social workers, the European Union, the Coalition Government and the rest of this column’s usual fare“. Because if there’s one thing environmentalists really hate, it’s people singing.

* pH is a logarithmic measure of acidity, which means that numbers appear to work slightly oddly. A drop of about 0.3 on the pH scale corresponds roughly to a doubling of the activity of H⁺ ions (the ions that cause acidity), and a drop of 1 (from 8 to 7, for instance) represents a tenfold increase in H⁺ activity.