Arctic Ice And Another Little Ice Age

  • Date: 24/03/16
  • Dr David Whitehouse

Journalism, especially science journalism, can be either descriptive or analytical. Recently those articles covering climate change have been concentrating on the former to the detriment of understanding the story.

Take for example the story about the Arctic sea ice extent reaching record low for this time of year. See here and here.

Sounds ominous, especially when coupled with the news that February was the warmest month on record by a long way. But look a little deeper into the data. The extent seen in February 2016 was 14.22 million sq km. This is definitely below the 1981- 2010 average by 1.16 million sq km, but only 200,000 sq km below the previous low for that month which was set in 2005. (Click on image to enlarge).

Arctic Ice 1

Looking at the graph shows that 2015 was really no different from 2011, 2007 and 2005. This means another headline for the same story could have been that this February’s ice extent is essentially the same as it was a decade ago!

Another example of where more analysis could have been done concerns the recent story based on a paper in Nature Geoscience that suggests that mankind is putting more carbon dioxide into the atmosphere since the dinosaurs lived some 56 million years ago.

Dinosaur 1

A team of researchers have studied temperature-sensitive isotopes in sediments laid down during the so-called Palaeocene-Eocene Thermal Maximum – a period of exceptionally warm temperature for something like 200,000 years. It seems that during that period ocean temperatures rose rapidly and reached 5 deg C warmer than today and carbon dioxide in the atmosphere reached 1000 ppm (it’s 400 ppm today).

They concluded that some 4 billion tonnes of carbon dioxide was deposited in the atmosphere which is only about a tenth of today’s rate. Reports suggested that the PETM event provides a comparison with today’s events and could be useful in working out what might happen in the future and models and projections have their problems and wide errors. The problem is, of course, that the Earth was a very different place 56 million years ago. There was no ice, sea-levels were higher, the distribution of continents different which affected ocean circulation. Also there is good evidence that back then temperature rise preceded the release of carbon dioxide by about 3,000 years. Few reporters mentioned these facts.

Another Little Ice Age

Another interesting piece of research was published in Nature Geoscience. By looking at tree rings in Central Siberia over the past 2,000 years scientists found evidence for a cold period between 536 AD and 660 AD which they call the Late Antique Little Ice Age. They say it occurred partly as a response to major volcanic eruptions in 536, 540 and 547 that released aerosols that cooled the Earth. It could be the coolest period in the past 2,500 years.

LALIA 1

It was rarely mentioned in reports of this research that the LALIA highlights the importance of natural climatic variability and provides another example of the highs and lows in temperature that nature has produced in the past 2,500 years into which out modern warm period must be put into context.

Finally I come to the global temperature of that remarkable month February 2016. Two things strike me about its coverage, in addition to this GWPF video.

Firstly, I hope none of those who say that global warming has taken off, or that it’s astronomical etc will ever criticise anyone for cherry-picking data ever again. Secondly, some analysts say the contribution to February’s temperature from the El Nino was minor and that underlying global warming contributed more. Perhaps they might reflect that background global warming has put on a spurt in the very same month that we have one of the strongest El Ninos on record. What a coincidence!

Feedback: david.whitehouse@thegwpf.com



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