Surprised by accusation – I used to be a lecturer

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I was surprised to be accused by one of your letter writers of ‘displaying total ignorance of the scientific method’ in my assertion that climate change is a danger to the planet that we should take seriously and seek to ameliorate.

Surprised, because I used to give lectures on scientific method to postgraduate students in Nottingham.

I wouldn’t pretend to know everything about scientific method, but to be described as totally (not slightly or somewhat) ignorant about a subject I taught at university is just a tiny bit rich.

This is, I fear, a rather typical example of the unjustified conclusions reached by people who deny that climate change matters, on the basis of little or dubious evidence.

The classic work on this subject is Karl Popper’s The Logic of Scientific Discovery, published in 1934.

He proposed that scientific theories can never be finally proven, because science progresses and what is accepted today might be disproven tomorrow, or at least replaced by a better theory.

So we can only say that theories that seem to withstand current tests have been temporarily ‘corroborated’.

So Ian’s demand that scientists must ‘predict the future until they get it right and can prove to us that they have’ is logically impossible.

Not only that, but, in grappling with the enormous complexity of the Earth’s natural systems, science is limited to predicting probable outcomes, not absolute certainties.

Ian states that climate change theories are bad because their predictions have proven false.

He cites hypotheses that the Arctic ice cap should have melted by now, that Venice should have flooded and that the Antarctic ice cap should have started to shrink.

Unfortunately, he doesn’t cite any sources for these predictions. But, nonetheless, let’s look for evidence to either disprove or corroborate them.

Chapter four of the Fifth Assessment Report of the IPCC (Intergovernmental Panel on Climate Change – draft available at www.ipcc.ch) reproduces data from a large number of scientific research studies that show: The annual Arctic sea ice extent decreased over the period 1979-2012, by between 3.5 and 4.1 per cent per decade; the average winter sea ice thickness within the Arctic Basin decreased between 1980 and 2008; the Greenland ice sheet has lost ice during the last two decades and this has accelerated since 1992.

From the evidence available, the authors are able to make these statements with either ‘high’ or ‘very high’ confidence.

Maps in The Atlas of Climate Change by Dow and Downing, 2011, based on satellite photographs, show a marked decline in the extent of summer sea ice in the Arctic, potentially opening up new shipping routes and threatening the survival of polar bears.

At the South Pole, two major ice shelves, Larsen A and B, collapsed in recent years. Larsen B comprised more than 3,000 square kilometres of ice, more than 200 metres thick.

It completely broke up between January and March 2002. Over the last century, more than 7,700 square miles of ice shelf has been lost in this region.

The IPCC report also states: The Antarctic Ice Sheet (a mass of glacier ice that covers the land) has been losing ice during the last two decades.

And, more generally: Glaciers worldwide show a general trend of retreat, and some have completely disappeared in Arctic Canada, the Rocky Mountains, Patagonia and the European Alps.

But, whereas Arctic sea ice has declined much more rapidly than predicted, ice in East Antarctica has increased over the last decade.

Scientists are well aware of the need for greater understanding of this situation, but still regard their conclusions about climate change as very robust.

As to Venice, it floods fairly regularly (the Aqua Alta – high water) and this isn’t new, but the increasing frequency of floods is. The authorities are keenly aware of the greater flood danger and have initiated an ambitious engineering project that aims to prevent sea water penetration along all the waterways.

Finally, there are many indicators of climate change other than melting ice and rising seas, such as rising average temperatures on land and sea, increased ocean acidity, heat waves, forest fires, droughts, devastating storms, changes in the ranges of animal and plants species.

But don’t despair – this is the ultimate challenge worth fighting for – to help save our wonderful planet.

Regardless of which national newspaper you read, don’t let the doubters persuade you otherwise.

Ian demands an explanation for periods of global warming, followed by periods of cooling.

Ice core samples drilled in Antarctica do indeed show periodic warm periods followed by ice ages, with cycles of relative warmth and cold within the longer term cycles, so it is complicated.

Several factors seem to play a part in creating these cycles, including the position of the Earth in its orbit round the sun; the inclination of the planet’s axis; variations in atmospheric gases such as carbon dioxide and methane; and movement of the continents affecting ocean currents.

It seems unlikely that even the most sophisticated research would be capable of confidently stating which of these factors had precisely what effects on surface temperature.

So all we can rely on are the best, informed estimates that scientists can provide:

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2013/dec/10/global-warming-un paused-fast-forward

http://www.theguardian.com/en vironment/climate-change-scepticism

http://www.skepticalsci ence.com

http://www.telegraph.co.uk/earth/environment/climatechange/10338569/IPCC-report-Sceptics-guide-to-climate-change.html

http://science.howstuffworks.com/environmental/green-science/climate-skeptic.htm

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