It is quite easy to reproduce this death spiral diagram using Excel, using the radar chart and the data from
http://psc.apl.uw.edu/research/projects ... e-anomaly/ This data is kept up to date, now showing July 2020 ice volume of 9305 cubic kilometres.
Wadhams explains in this chapter how the advance of satellite monitoring has enabled more exact measurement. The data involves some assumptions, but these do not affect the inexorable downward trend, which has seen average yearly ice volume fall by nearly half since 1979.
The melodramatic title ‘the Arctic Death Spiral’, reflects the observation that once the summer ice is gone in the next few years it will be very difficult to get it back.
A study published this week in Nature Climate Change estimates the likely end date of 2035, based on study of the geological data from the last interglacial.
Wadhams suggests it could be much faster, but as I mentioned this may be based on using shorter trend periods that don’t recognise all the wiggles in the annual data. It is highly possible that the 2035 calculation is conservative.
All this brings up the widely used concept of a tipping point, a threshold which once crossed serves as a point of no return, marking a phase shift into a new hotter climate. Wadhams gives the example of the elastic limit of a metal spring – once it is stretched beyond this limit the spring will never return to its previous coiled up state because the crystalline structure of the metal has changed. He argues that Arctic sea ice has already reached a tipping point because the situation now is that all first year ice is melting, and the remaining multi year ice is reducing steadily.
As field data has become more alarming, Wadhams observes that governments are relying on models that justify a more complacent view. The data in 2015 showed a possible range of dates for the end of summer ice between 2020 and 2040. But Wadhams regularly encountered modellers who argued their theories (ignoring the facts) showed the ice might still be there in the summers to nearly 2100.
Such impossible advice enables governments to ignore the problem. Even the IPCC accepted this complacent model in its 2013 Fifth Assessment Report, using the strategy that Wadhams describes as “consciously ignoring the observational data in favour of accepting models that have already shown themselves to be false.”
For example, the IPCC ignored historical data after 2005 in favour of previously modelled gentler falls in ice volume, and suggested the ice extent would take until 2030 to reach the level that was actually seen in 2012. This “brilliant exercise in legerdemain” produced the perfectly reasonable response from media that we don’t have to do anything about climate change, which Wadhams surmises was its intended purpose, meaning there will be a terrible price to pay.
The IPCC is controlled by governments, many of whom quite like the idea of an ice free Arctic to enable shipping and oil and gas mining, as
Mike Pompeo told the Arctic Council last year.
Russia is also keen to open more northern trade routes for shipping.
The history of the navigation of the North West Passage from Baffin Bay to Bering Strait tells a tale of intrepid adventure, with Swedish explorer Raoul Amundsen succeeding in 1906 by using a small engine powered herring trawler, always sticking close to shore while the main channels were full of ice. Canadians next traversed the passage in 1942, followed by big icebreakers in the 1950s such as the John Macdonald. Failures led to the expensive decision to build the Trans Alaska Pipeline, since shipping oil was just too hard.