The fat lady’s not yet in the building, but her limo’s outside the theatre. There’s another five or six weeks of melting to go, but there’s more than just sea ice melting in the Arctic, and more than my few meagre wagers riding on how summer turns out ‘oop North. Here’s a compendium of interesting recent stuff…
Category: Climate science
Ballad of broken seas
The Ministry for the Environment released an updated Coastal Hazards and Climate Change manual for local government last week, based on work done by NIWA. It incorporates the latest NZ thinking on where sea-levels are heading. If you’re planning to build something that has to last until the end of the century (and that covers a lot of coastal infrastructure), you should allow for half a metre of sea-level rise, and consider the consequences of an increase of up to 80cm. The report says:
For planning and decision timeframes out to the 2090s (2090–2099):
a. a base value sea-level rise of 0.5 m relative to the 1980–1999 average should be used, along with
b. an assessment of the potential consequences from a range of possible higher sea-level rises (particularly where impacts are likely to have high consequence or where additional future adaptation options are limited). At the very least, all assessments should consider the consequences of a mean sea-level rise of at least 0.8 m relative to the 1980–1999 average.
For planning and decision timeframes beyond 2100 where, as a result of the particular decision, future adaptation options will be limited, an allowance for sea-level rise of 10 mm per year beyond 2100 is recommended (in addition to the above recommendation).
Local authorities have a duty to understand this stuff (under the RMA and other legislation), so the report is highly detailed. If you’ve ever hankered after an in-depth understanding the processes that underlie storm surges, beach (and bach) erosion, tidal ranges and tsunamis, there’s no better place to start. If you want to see what impact that sort of rise might have on your area, try Global Warming Art’s excellent Google Maps mashup Sea Level Rise Explorer, or check NASA JPL’s new climate change site for the global sea level picture [Flash required].
Also released last week: the edited highlights (with pretty pictures) version of the Preparing For Climate Change guidance manual published last May which incorporates NIWA’s latest climate projections for NZ. Essential. And free.
Melt your heart
Typical winter weather down here – we’ve gone from snow last weekend to sunny days and sharp frosts, and now howling Norwester and unseasonal, but not atypical warmth (having said that, the radio reports that Kaikoura recorded 21ºC at 1am last night, which is both). Further south, however, strange things are afoot at the Wilkins Ice Shelf. It began a spectacular break up earlier this year, and this is continuing in the middle of the Antarctic winter according to imagery from the European Space Agency’s Envisat. The ESA press release includes a fantastic animation showing how the ice has fractured over the last couple of months. Ted Scambos from the National Snow and Ice Data Center in the US explains how this might be caused:
“The persistently low sea ice cover in the area and data from some interesting sources, electronic seal hats [caps worn by seals that provide temperature, depth and position data] seems to suggest that warm water beneath the halocline may be reaching the underside of the Wilkins Ice Shelf and thinning it rapidly – and perhaps reaching the surface, or at least mixing with surface waters.”
I’d love to see a picture of those seal hats! And a scientist fitting one… I’ve heard some references to anomalous warm water around the Antarctic as a mechanism for ice sheet melting – here it seems to be in action.
Up North, the summer melt continues, and the odds on my bet with William “Stoat” Connolley seem to be tilting in favour of my vicious, sharp-toothed friend. Both the Cryosphere Today and NSIDC measures are showing area/extent tracking above the same time last year, and this week a team at the Alfred Wegener Institute provided a new form guide.
The ice cover in the Arctic Ocean at the end of summer 2008 will lie, with almost 100 per cent probability, below that of the year 2005 — the year with the second lowest sea ice extent ever measured. Chances of an equally low value as in the extreme conditions of the year 2007 lie around eight per cent.
They derive this by taking ice conditions at the end of June, feeding them into their sea ice model, and then forcing the model with the weather experienced over previous melt seasons. Looks pretty convincing, but any forecast is limited by the accuracy of the initial conditions data fed into the model. Still plenty of melt season left. It ain’t over ’til Dame Nellie finishes her peach Melba.
[Update: Wayne Davidson, in a comment at RealClimate, clearly thinks I’ve still got a chance.. 😉 ]
Finally, this will be an interesting blog to follow over the next few weeks. A team of US and Russian scientists are rafting down a Siberian river, gathering data on forests and tundra. Some people have all the fun…
[Update 2: It looks like the increased popularity of the AMSR-E sea ice images from Bremen has prompted Cryosphere Today to update their graphics for the Arctic. Positively groovey, perhaps even psychedelic, man. Way to go, Bill! Much easier to see what’s going on.]
[Update 3: The BBC reports on a Russian scientific team having to be rescued from their drifting research station because it’s melting fast.]
Stuck in the (balanced) middle with you
Hot news from the Royal Society of NZ: they’ve released a new statement on climate change to address what they describe as the “controversy over climate change and its causes, and possible confusion among the public“. The RS’s expert panel includes many of NZ’s top climate scientists. Here’s a handy summary of the statement:
The globe is warming because of increasing greenhouse gas emissions. Measurements show that greenhouse gas concentrations in the atmosphere are well above levels seen for many thousands of years. Further global climate changes are predicted, with impacts expected to become more costly as time progresses. Reducing future impacts of climate change will require substantial reductions of greenhouse gas emissions.
The full statement goes into a lot more detail. Well worth reading. The Royal Society is New Zealand’s top scientific body “charged by its Act with informing the public about science, and fostering evidence-based scientific debate.” Sadly, I don’t think those who argue against action on climate change are much concerned with the evidence, but it will be interesting to see the mighty popguns of the NZ C”S”C turned on the Royal Society. It’s a “go ahead, make my day” moment…
All together now
It’s getting hectic down here in the Waipara bunker: articles to write, truffles to harvest – stuff is piling up, not least in a multitude of tabs in my web browser, items set aside as possible subjects for posts here. So here’s one of my infrequent omnibus posts to give me some room to move around the web…