Sunday, July 20, 2008

Bias at NSIDC and BBC? You decide

This link is to a report from the (US) National Snow and Ice Data Center entitled "A different pattern of ice retreat" which states:
Arctic sea ice extent on July 16 fell roughly between the extent for the same day in 2007 and the long-term average. The spatial pattern of summer ice loss has evolved differently from last year; this reflects the prevailing pattern of atmospheric circulation. Areas of low-concentration ice are also developing at unusually high latitudes.
The casual reader would grasp from the headline that ice had retreated, and would read the words "Arctic sea ice extent fell" and is below average, and might even grasp that concentrations of ice are lower at high latitudes. The reader would put these thoughts together and worry that the Arctic really was melting. The message is reinforced when the next paragraph includes "extent was below the 1979 to 2000 average of 9.91 million square kilometers (3.83 million square miles)". My goodness, things really ARE getting dangerously warmer up there.

Imagine, then, my puzzlement when the last sentence quoted above goes on to say , "[however] it was 1.05 million square kilometers (0.41 million square miles) above the value for July 16, 2007.

This IS a different kind of ice retreat, a retreat that GROWS ice coverage by 10%.

The BBC was on the story back in June when 2008 and 2007 areal extents were comparable, and their environment correspondent Richard Black posted this story: Arctic Sea Ice Melt 'Even Faster'. It has not been updated or corrected with the graph that appears at the top of today's blog entry, which shows that the sea ice melt has slowed and in the space of a month has fallen two weeks behind last year's pace.

I may just be imagining bias where in fact there are honest and busy people just trying to do their jobs. But why choose wording like "fell" and "retreat" when in fact coverage rose and increased? And BBC, why not give your worried viewers and readers some reassurance that things aren't as bad as you thought?

Update: BBC admits its own bias.


PKD said...

Hello Half,
Perhaps you'd like to update your graph with the new one from Aug 26th?

Ice coverage is now 2nd lowest on record and now only marginally behind last years record low.

Bottom line, climatic is for the ice cap to be retreating not extending as you so over optimistically concluded in this post of yours...

Oh and BTW, this time it was the Australian that was reporting this story that drew my attention to it, not the BBC. Are they biased too?


PKD said...

Climatic trend that is...sorry for the missing word!

Halfwise said...

Sorry PKD I am en route to Aus as we speak and have not had much time to keep up. I see that this year's ice coverage is approaching last year's levels which have been widely touted as the lowest on record. Sadly the record is simply the satellite record so we are talking of 30 years of history. 30 years basically coincides with the warming period that we have all enjoyed lately.

Meanwhile Antarctic ice extent is higher than before. For some reason the NSIDC does not cover the southern hemisphere in the same detail as the northern hemisphere.

Before we lose our breath entirely let us look at temperature records back to the PREVIOUS warming cycle of the 1930s. Check my May 11 2007 posting

I don't see the cause for panic, PKD.

PKD said...

And was the North-West passage likewise clearing for shipping traffic in the 1930's? Doubt it some how.

Given climate is measured over 21 years by NSIDC then they have enough data to start commenting on climatic trend for the last 8 years.

Amusing how you'll claim we don't have enough accurate data on the Arctic as satellites have only been measuring there since 1979, but you'll happily quote some supposed warm period in the 30's. Who were operating the satellities back then Half, and were they biased??? ;)

And if I was to take a punt I reckon your data on Antartic ice extent is no more histroically complete than the NSIDC's is on the Arctic - yet you'll grab onto one while discrediting the other...happy to be proven wrong of course!


Halfwise said...

How very poorly informed you seem to be.

Roald Amundsen first navigated the Northwest Passage over three difficult summers beginning in 1904. The Canadian icebreaker St Roch navigated it BOTH WAYS in one summer in the 1940s. (It was warm then, which is my very point.) If you come to Vancouver you can tour this little vessel for yourself. The largest ship to pass through was the US supertanker Manhattan which traversed in 1969.

You are welcome to your biases; I will cling to mine. I do not claim a monopoly on insight -- anyone nicknaming himself Halfwise has to be aware of his limits. What I do object to is the illusion of AGW certainty and a sense that today's circumstances are unprecedented.

Please, next time, bring facts.

PKD said...

Oh dear.

Amundsen took 3 years to travel the route as he spent the first couple of years stuck in ice. All the other examples you cite were only done using ice breaker ships, including your supertanker example.

Ice breakers getting through IS NOT the same as a commercially navigable route, for which it needs to be ice FREE in order to allow normall merchant shipping through on a regular basis.

So no, it was not possible in the 30's for commercial shipping as the ice was indeed severe enough to mandate ice-breakers. So yes, in terms of accessability to shipping last years (and possibly this years too) ice levels ARE uprecedented, given the propect / spectre that is being raised about the NW passage being commerically naviagable.

Please, next time, don't bring misleading facts.

Halfwise said...

I see. So if I find a ship traversing the NW passage that is not an icebreaker that clinches the argument? How about a ship that finds very little ice and sails right through? If that ship is an icebreaker but has no ice to break, then what? I think you are being remarkably selective. Taking a ship to the Arctic that is not prepared to break ice is irresponsible, methinks.

I mentioned Amundsen's difficult summers; nothing misleading there.

St Roch was a strong wooden boat. Hardly a supertanker.

Temperatures were warm. I am not debating that they are warm today, I am challenging your contention that today's temperatures are somehow unprecedented. As that chart from my May 11 2007 posting showed, the facts show otherwise. If you can present temperature records for the Arctic from 70 years ago, please do so.

And surface records seem to be good enough for today's alarmists, so old surface records will be good enough for me. They are probably biased to the up side because met officers did not always enjoy the long walk to the Stevenson Screen in the worst weather. But they are mercifully free of UHI effect.

PKD said...

I think you are being remarkably selective.

And I think you are being remarkably myopic. Yes the point is you can navigate it now without an ice-breaker as the passage is ice free.

Interesting article - or perhaps their biased too? The Beaufort Sea area is particularly being noted of its unprecedented ice-loss in the article.

Anyway the fact the passage is ice-free without needing a non-commerically funded expedition to spend 3 years hacking your way through it means your comparing of the current ice-loss with the 30's is indeed a tad misleading.

I am challenging your contention that today's temperatures are somehow unprecedented

I'm actually being saying the current ice-loss is unprecedented, not temperatures, but nice try and mis-stating my position!

Keep up comparing your 30's moggy with today's tiger and one can only wonder if you're a denialist too...

Halfwise said...

PKD: care to provide your explanation of what caused last year's and this year's Arctic ice extent?