In some ways, the recent letter by 16 scientists to the WSJ, claiming that there is 'no need to panic about global warming', is indeed reassuring. The very fact that this slice of global warming skepticism has attracted such a feeble number of scientists - of whom only 2 have published in the climate science field recently - shows how global warming denialism has failed to gain any traction in the scientific community.

But the global warming debate matters most, not in the rarefied sphere of climate science, but in the hurly-burly world of opinions formers and political spinmeisters. And there, for the last few years, the climate skeptics have had a much better run at things. Charges have been flung, mud has stuck, and doubt been cast. For many, across the political spectrum, climate change is now a dirty word. And far less of the public is concerned about the threat from global warming than was the case 3 years ago.

Much of this softening of opinion comes from a confusion about whether global warming is real - or whether it really heralds such a looming calamity. So in that sense, worthy-seeming letters, signed by scientists who question the need for action on climate change, really do matter. They keep open the illusion that the science on global warming is still 'unsettled'. That's why its worth digging deeper into the claims made in the WSJ piece, to help separate reasonable doubt from unjustified claim. Sadly, though, there appears to be very little of the former in this skeptics' letter.

There are just two solid claims made in this article. The rest is a reworking of accusations of scientific witch-hunts and collusion between money-grabbing climate scientists, and big bad government. However, given how conspiracy theories have a life of their own, which readily defy any attempts rational argument, let's pass those by - and focus instead on the more concrete claims.

The first is that global warming is much less of a scary monster than the 'alarmists' have painted - and may even have shrunk to a poodle over the last decade. 'Perhaps the most inconvenient fact is the lack of global warming for well over 10 years now,' say the 16, repeating a common skeptic mantra. One, however, that shows a woeful misunderstanding of what 'global warming' means. While it is true that 1998, 14 years ago, was one of the warmest years on record - and that many years since have been a little cooler - drawing lines between cherry-picked point on the graph does not define global warming or cooling.

The global thermometer runs up and down, year-on-year, for any number of natural reasons - the cooling from volcanic eruptions, changes in the radiation coming in from the sun, or yearly flips between warmer El Nino and cooler La Nina years. To get a proper feel for the longer-term energy being trapped by greenhouse gases, you need to smooth out those cycles. One approach is to average out global temperature points over longer time-frames - 17 years is an accepted convention. Another is to subtract the known effect of those natural changes from the global temperature graph.

That's what was done in a recent paper by Grant Foster and Stefan Rahmstorf, in the journal Environmental Research Letters. They took 4 of the most widely used measures of global temperature, and then carefully removed the cooling kicks and warming nudges, from the things like last year's strong La Nina - or the dust thrown up by the dramatic Mount Pinatubo eruption. The resulting temperature graph is one of a relentless rise - and shows little sign of any let-up in global warming over the last decade:

Credit: Environmental Research Letters - Paper includes average of all five data sets (GISS, NCDC, HadCRU, UAH, and RSS) with the effects of ENSO, solar irradiance, and volcanic emissions removed (Foster and Rahmstorf 2011)

The other claim - following on from this less-than-convincing rubbishing of global warming's onward march - is that even if global warming is happening, the 'modest' temperature rises seen require no action. That's based on research by William Nordhaus, an economist who looked at the costs-and-benefits of tackling global warming, compared to just letting economic growth continue unfettered. It 'showed that nearly the highest benefit-to-cost ratio is achieved for a policy that allows 50 more years of economic growth unimpeded by greenhouse gas controls,' they say.

But for this claim to have any validity, the assumptions underlying Nordhaus' economic models would need to hold over the next five decades. And you would have to believe that the well-being of the planet, and of humanity, can be reduced to the slide-rule accountancy of the economics. Both of those points seem contentious.

Economic models have been shown to melt like snow in the sun - just look at how the captains of the global economy were short-footed by the credit collapse of 2008-9. In fact, economic models can make climate models seem like cast-iron certainties, in comparison. And can economic growth really can carry 'unimpeded'? That seems unlikely, when the last few years have shown how depleting resources can smother smug notions of endless economic growth.

Far more problematic, for the 'cost-benefit' analysis of Nordhaus and his ilk, is the essentially unpredictable nature of the climate change experiment we are undertaking. Of course it's possible that the consequences of global warming will be easier to deal with than many suspect. It is also possible that the consequences could be far worse. We are tampering with a system that the WSJ sixteen admit is poorly understood - a system on which all our futures depend. When there are routes to a greener, safer, cleaner future, which can readily reduce those risks, surely it would be madness to forge on regardless our current reckless path?