The big heat of 2016 is taking its toll on sea ice at both poles
For the past couple of months, global sea ice extent (Arctic plus Antarctic) has been at record low levels. The way the northern and southern seasonal cycles add up, the maximum in global sea ice extent occurs on average in early November, at around 27 million km2. This year, the global extent curve has been relatively flat since June. In past years, climate change “deniers” have pointed to the global extent curve as a way of claiming that climate change is not a problem, as the relatively high Antarctic extent was partly offsetting the Arctic loss, making it look as though nothing much was changing. Strangely enough, we’ve heard nothing from the usual “deniers” this year! Through most of November, there has been around 4 million km2 less sea ice than normal globally (peaking at 4.5 million on 20 November), an area roughly the size of Greenland missing near each pole. What’s going on? Continue reading “Global sea ice in uncharted territory”
I sat down to write a piece looking at recent depressing climate news, and the diminished prospects of significant US climate action now that Trump is on his way to the White House. I may still: but then I heard the news that Leonard Cohen had died and the will to wax analytical left me. This has been a pig of a year in so many ways — from Bowie, Prince and Cohen, to Brexit and Trump. In memory of one of the greatest songwriters of the last 100 years, here’s one of my favourite Laughing Len tunes, in a 2014 live performance. He was 80 at the time. I hope I have half his vitality if I get that far…
Geoff Simmons of the Morgan Foundation tells a good story about dodgy uncle Trev, fake bank notes and real moro bars while he fact-checks Paula Bennett on the integrity of the surplus emission units. It’s a real triple-dip!
It seems that Richard Treadgold, he of the “climate conversation” that isn’t, wants me to engage in an exchange of views. Following a brief flurry of comments at the Coal Action Network blog, Treadgold writes:
Here’s my challenge: let us, you and me, persevere with this most crucial of national debates.
The piece is riddled with errors and misrepresentations. Here’s a selection:
The “recent” paper on sea level rise de Lange and Leyland (dLL) reference in their first paragraph is from 2010! The latest Royal Society of NZ climate info was published last month, and is presumably what dLL meant to refer to.
The rise in sea level around NZ over the last 100 years is 17cm, not 14cm, according to the RSNZ (page 28 here).
dLL state that the current rate of sea level rise measured by satellite is 3.2 mm per year, with “indications of recent decline in the rate”. In fact it is 3.4mm per year, and shows no signs of any recent slowdown. If anything, there are hints of an acceleration in the underlying rate.
dLL claim that satellite measures are “about twice the tide gauge rate”. They’re not. They’re in good agreement. From Trends and acceleration in global and regional sea levels since 1807, Jevrejeva et al, Global and Planetary Change, 2013 (pdf)
There is an excellent agreement between the linear trends from GSL12 [latest tide gauge data] and satellite altimetry sea level since 1993, with rates of 3.1 ± 0.6 mm/yr and of 3.2 ± 0.4 mm/yr respectively.
The latest RSNZ projections are not “much more than anybody else” – they’re based on the IPCC’s AR5 and draw on the current literature. Larger projected future rises are widely used in planning overseas.
dLL state: “All the observational evidence indicates that the sea level is likely to rise 0.1 to 0.2 m by 2100.”This appears to be nothing more than wishful thinking. The current SLR rate gives 30cm plus by end of the century as a minimum.
There’s strong evidence of increased and increasing ice sheet mass loss in Greenland and Antarctica, which will add significantly to the amount of sea level rise by the end of the century. If we’re lucky, that might only be a metre. If we’re unlucky, it might be a great deal more.
If this were de Lange and Leyland’s only contribution to the debate on how communities should cope with sea level rise, it might be possible to shrug it off as a slapdash attempt at propaganda from a couple of people with a long history of climate denial. But de Lange is getting involved with the Christchurch community’s efforts to deal with this most challenging of issues.
Do Christchurch ratepayers really want to pay for advice from an “expert” who can’t get his facts right, and who is apparently happy to put his name to rubbish? The council should immediately ask for his withdrawal from the panel.
Future sea level rise is a certainty. Dealing with it is going to be challenging for any coastal community. We need a national framework that covers realistic assessments of local risk, and provides a process that allows communities to adapt as equitably as possible as their coastline changes. Trying to ignore or downplay the problem is only going to increase the costs faced by ratepayers and taxpayers in future years. If we allow the process to be contaminated by the input of propagandists we simply set ourselves up for greater losses.