Measuring Ice

While preparing another episode in the Agnostic’s Guide to Global Warming I came across a post in Anthony Watts’s WUWT (‘Watts Up With That?’ — the most-visited sceptical blog about global warming) about what is happening in the Arctic Ocean. It is such a good example of the intrinsic problems in making sense of almost any aspect of climate that it is the subject of today’s post.

First, you need to know that it is argued that whatever warming is occurring through the human addition to greenhouse gases should be most apparent in the polar regions, and the North Pole, which is situated, so to speak, in the middle of the ocean, therefore attracts a lot of attention. Each year there is intense inspection of the summer warming of the Arctic Ocean. How much of the ocean is ice-free? In 2007 a new record was set for the largest ice-free area, and in 2012 there is some anticipation of that 2007 record’s being broken — indeed, that the Arctic Ocean might be ice-free by September 22^nd.

For initiates in this arcane stuff, some of the ice melts in summer and then re-freezes from about September. A clear sea at the North Pole can occur, and there is a photo of a US submarine at the surface there in 1958. It is said that the ‘old’ ice, which has been laid down for centuries, is gone, and that all we have is new ice. Oh, and since most people live in the Northern Hemisphere, and the Arctic is close to them, and the Arctic is a sea, and the satellites photograph it all the time — most attention focusses on the Arctic. You need to know that there is no significant loss of sea ice around the Antarctic, and that the land-mass of the Antarctic seems to be getting colder, not warmer, as the predictive models say should be the case.

OK, back to our action-packed saga.  The National Snow and Ice Data Center (NSIDC) in Boulder, Colorado recently released a news story suggesting that the melting had set a new record, of 4.1 million square kilometres compared to the winter high of around 14 million square kilometres. ‘This is it! This is it!’ came the chorus of those who are arguing that AGW is real, and the humans are causing it.

Since I know that there is evidence to suggest that there is nothing unusual in this event — like the sub photo and fact of an ice-free Northwest Passage in the same decade, as well as in the 1920s and 1930s — I was tempted just to shrug and to move on. But Anthony Watts was intrigued by what is a classic measurement problem. Because there are other measurements.

One is by MASIE (the Multisensor Analyzed Sea Extent), which is also produced by NSIDC. It suggests that the ice extent is 4.7 million square kilometres, which is no sort of record. Yet another measurement is that of the National Oceanic and Atmospheric Administration (NOAA), whose National Ice Center Interactive Multisensor Snow and Ice Mapping System (IMS), puts it at 5.1 million square kilometres.

There’s yet another one, too, and it (NATICE) says 6.2 square kilometres. NATICE means the National Ice Center, and it is a section of NOAA. (How are you going with these acronyms?)

So there are four separate and different measurements, and they all come from satellites, and they all have some kind of official imprimatur. Which should we take most seriously? Any of them? I don’t know. Watts says that measuring sea ice by satellite comes with its own problems, one of them the sensor technology itself. Another is the fact that the sea-ice is a mixture of floating ice islands of varying sizes and water, and is much affected by storms (there has been a recent powerful storm in the Arctic Sea, and it may have contributed to the apparent reduction in size of the ice).

He also points out that although the NOAA (a US Government agency) has a connection with all four measurements, only one message came out, and that was about the lowest, the scariest — if you’re in the mood to be scared. Why weren’t the others mentioned at all? Because, I guess, the scary message helps to attract attention, and then, at least in prospect, more funding.

I have come to the view that one should suspect the bona fides of all statements about global warming that are released at the time of an international or national meeting on the environment. That applies in particular to statements from the executives of learned academies, which have become akin to government agencies — quangos, perhaps.

In the same fashion, bodies like the Red Cross, the Salvation Army and Vinnies, which do exemplary work in the community, have become agencies of the Commonwealth Government through applying government funding (as transfers) to the needy. Yes, they are closest to the needs that are being addressed, and yes, it is cheaper to do it this way. But they are no longer independent.

The same is true of learned bodies that receive government funding to carry out tasks that the government wants done. Yes, they become wealthier and more important. But they lose their independence.

And when what is at stake is the meaning and accuracy of scientific measurements, we are all the poorer.