Simple messages, which make headlines and create doubt amongst the laity, are an easy sell in the pseudo-sceptical world of climate science contrarianism. Many sound (kind of) plausible, and so gain an undue amount of traction among the general public and non-science decision-makers. Ian Plimer’s recent book capitalises on these themes to full advantage, and, as Tim Lambert has patiently detailed over the past year or so, some media outlets such as The Australian also give such unscientific messages an extended and unbalanced run.
One that never seems to go away is that ‘1998 was the hottest year and every year since has been cooler‘ meme, or similar such variants. This little gem preys upon most people’s lack of appreciation of statistical inference, just like the ‘climate models didn’t predict recent variability‘ exploit a lack of understanding of the difference between a mean model output and any single realisation of a stochastic model run. Another one that’s come up quite a bit recently — including a number of editorials and reports in The Oz (I’m quoted in one of them) — is the claim that Antarctica (and worldwide) ice extent is growing. It’s a great one for climate contrarianism, because it immediately raises people’s suspicion levels — ‘How can the Earth be warming if the ice is growing?‘. You get the picture. Doubt is their product.
Now it would be nice to give people a simple explanation to these — ideally, some analogy that is easily visualised in the mind. Alas, the scientific explanations for these will always be, by necessity, somewhat technical and therefore easily glazed over by 95% of readers. Recently, the Australian Science Media Centre asked some scientists for an explanation, in simple terms, as to why ice in Antarctica might be growing. You can find their answers here. Ian Allison gave the most technically comprehensive and scientifically satisfactory reply, but I don’t imagine it meant much to most folks. I had a stab at a simpler explanation, which I reproduce below, but I also struggled, I think, to really make it clear.
Question: With confusion in the media this week over whether ice is decreasing or increasing in the Antarctic, here experts clarify the apparent anomaly.
Answer: This is a common source of confusion among climate change sceptics. As the world warms, the atmosphere’s ability to hold water vapour increases. Think of how humid it is in the tropics, and how dry the Arctic air is. The largest desert on Earth is the continent of Antarctica — it receives very little annual precipitation. In a warming world, more water vapour allows for more snowfall in Antarctica, which accumulates particularly in East Antarctica where the temperature never rises above freezing point. So, ice accumulates on that side of the continent. In the Antarctic Peninsula and West Antarctica, this extra accumulation of snow is more than offset by summer surface melt.