The Guardian has a great article on one of the usual recurrences of climate skepticism that accompany any annual arctic sea ice shrinkage not being as large as a preceding year - Arctic sea ice delusions strike the Mail on Sunday and Telegraph.
The reason so many climate scientists predicted more ice this year than last is quite simple. There's a principle in statistics known as "regression toward the mean," which is the phenomenon that if an extreme value of a variable is observed, the next measurement will generally be less extreme. In other words, we should not often expect to observe records in consecutive years. 2012 shattered the previous record low sea ice extent; hence 'regression towards the mean' told us that 2013 would likely have a higher minimum extent.
The amount of Arctic sea ice left at the end of the annual melt season is mainly determined by two factors – natural variability (weather patterns and ocean cycles), and human-caused global warming. The Arctic has lost 75 percent of its summer sea ice volume over the past three decades primarily due to human-caused global warming, but in any given year the weather can act to either preserve more or melt more sea ice. Last year the weather helped melt more ice, while this year the weather helped preserve more ice.
Last year I created an animated graphic called the 'Arctic Escalator' that predicted the behavior we're now seeing from the Mail on Sunday and Telegraph. Every year when the weather acts to preserve more ice than the previous year, we can rely on climate contrarians to claim that Arctic sea ice is "rebounding" or "recovering" and there's nothing to worry about. Given the likelihood that 2013 would not break the 2012 record, I anticipated that climate contrarians would claim this year as yet another "recovery" year, exactly as the Mail on Sunday and Telegraph have done.
In short, this year's higher sea ice extent is merely due to the fact that last year's minimum extent was record-shattering, and the weather was not as optimal for sea ice loss this summer. However, the long-term trend is one of rapid Arctic sea ice decline, and research has shown this is mostly due to human-caused global warming.
The Guardian also has an article on the bout of unseasonally hot weather in eastern Australia - Bushfires in September: voting while the planet burns.
We still get more or less the same rainfall but it now seems to come down in huge torrents, rather than weeks of slow drizzle, so we get more raging floods and then it stops completely, like it has now. It hasn't rained a drop up here for almost three months and the place is dry – very dry. It's also getting much hotter much earlier. My husband used to complain bitterly that we didn't see even a hint of spring until October at the earliest.
In the last few years, however, the daffodils are finished already and the wisteria is in full bloom – and it's only just September. And as we drove along the narrow dirt road towards our place yesterday, my daughter and I observed something much more sinister. The valley was in flames. Now don't get me wrong, spring is the traditional time when farmers up here burn to keep down weeds and ticks, so the grass fires we passed didn't worry us unduly at first. Though, as we commented, at 30 degrees (in September!) and with everything so tinder dry, it seemed high risk to do even a controlled burn. Then we got to our own property, and it was on fire too. Which couldn't be a controlled burn because we had not been there to either light it or control it. And, as well as breeding cattle, we grow trees as a commercial plantation – so when we burn, we watch it very carefully.
As a neighbour explained, the fires had been burning for three solid weeks, slowly eating their way up the valley. They hadn't done any real damage, sticking to the undergrowth and not getting into the canopy at all. To be honest, they've probably done us a favour by getting rid of the built up fuel that might be a real danger once summer hits, particularly if it stays this dry. Nevertheless, it spooked us a bit. In 40 years of visiting this valley, we had never seen or heard of such a slow fire, especially in August and September. Nor can anyone remember spring coming quite so early or being quite so hot. In fact, the world has just experienced its 342nd consecutive month of hotter-than-average temperatures.
In the evening as we watched Australia elect a government sworn to repeal the carbon tax, we couldn't help remarking on the irony, particularly as we watched the results come in while listening to the fire in the paddock across the river crackle and burn. As darkness fell, we could see little red pockets of fire scattered amongst the thick woodlands to our north and hear the crash of the occasional burnt out tree as it fell – in early September, on the edge of a temperate rainforest. We may have got a little drunker than we'd intended listening to the fire while watching Australians decide that what we could see, smell and hear either didn't matter or, if it did, wasn't important enough to truly do anything about it.
According to leaked details from the most recent report from the Intergovernmental Panel on Climate Change in the Sydney Morning Herald yesterday, the world's ice sheets are melting rapidly as the planet warms. Greenland's ice added six times more to sea levels in the decade up to 2011 than in the previous 10 years and the Antarctic melt produced a five-fold increase.