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The Daily Mail's different views of sea level rise

  • 05 May 2011, 13:00
  • Christian

The Daily Mail has produced an article covering this week's Arctic Monitoring and Assessment Project report on Arctic melt and sea level rise. While it gives a clear picture of the report, it raises some questions about their coverage of the same issue just a few months ago.

Here's the start of the piece:

Sea-level-1

The AMAS report presents itself as 'the most comprehensive synthesis of knowledge about the Arctic that has been presented in the last six years,' and draws on the work of over 200 scientists who contributed to it.

It concludes that taking into account Arctic ice melt, sea levels could rise 0.9-1.6m by 2100 (1.6m is around 5.2 feet). The Mail article takes the top end of that range as 'the latest doomsday prediction'.

Because the science of how ice sheets melt is not settled, it has been difficult to provide definite estimates of how much sea level will rise as the planet warms.

The Mail article notes this:

The most recent report from the United Nations' Intergovernmental Panel on Climate Change (IPCC) in 2007 said the sea was likely to rise between 18 and 59cm by 2100.

However, those numbers did not include a possible speeding up of the Arctic thaw.

Alongside their 2007 assessment of potential sea level rise, which gave estimates of possible sea level rise under different emissions scenarios, the IPCC said this:

[Computer] Models used to date [to estimate sea level rise] do not include uncertainties in climate-carbon cycle feedback nor do they include the full effects of changes in ice sheet flow, because a basis in published literature is lacking. … Larger values cannot be excluded, but understanding of these effects is too limited to assess their likelihood or provide a best estimate or an upper bound for sea level rise.

In other words, in 2007 the science was not sufficiently advanced to put a firm upper limit on sea level rise. Realclimate helpfully provided more context on this at the time here.

What do the sceptics have to say about this? The Daily Mail article includes a contribution from a climate sceptic commentator:

Dr Benny Peiser, of the sceptical Global Warming Policy Foundation, said:

"These figures seem a bit alarmist to me given that even the IPCC has come to a different , more moderate conclusion. If you look at what has actually been happening over last 50 years there's no evidence of any acceleration in sea level rises. The rise has been quite steady. Unless we see a clear signal that something dramatic is happening to sea levels, I would be cautious."

Two points about this comment are questionable. First, there is evidence that sea level rise is accelerating. A major gathering of climate scientists in early 2009, for example, concluded that

The rate of sea-level rise has increased in the period from 1993 to the present…largely
due to the growing contribution of ice loss from Greenland and Antarctica.

Secondly, it is strange to characterise the AMAS report - new scientific research - as 'alarmist' compared to a more 'moderate' IPCC of four years ago, given that the IPCC  noted their figures could well be underestimates, and that it was the limited state of the science on the issue which was preventing a clearer picture.

Indeed, the AMAS press release notes the report will apparently serve as the basis for the IPCC's consideration of the issue in their next assessment report.

This piece does raise a question about how the Mail is representing the IPCC's work. Compare and contrast with an article from three months ago:

sea-level-2

The two articles don't flat-out contradict one another, but it seems odd that this week's article describes a rise of 5 feet as 'twice as high' as the IPCC's estimate for sea level rise, while in January, the Mail described the IPCC's 'worst case' forecast for the same date as 6ft of sea level rise.

Is this confusion a hazard of using punchy language to cover a complicated subject? Perhaps. Using terms like 'alarmist' and 'doomsday' doesn't help to capture the fact that this is an area of science where understanding is advancing, but not yet fixed.

However, I have been unable to find any claim by the IPCC that 6ft (or around 2m) of sea level rise by 2100 was the 'worst case'. Rather, their message seemed to be that they couldn't put a value on the 'worst case' because of limited scientific research in the area - although I may have missed it.

(More recent research suggests that, based on an assessment of glacier flow, it is highly unlikely sea level rise would be greater than 2m by 2100.)

If you can find an IPCC source for this, please leave it in the comments and I'll update this.

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