How do you know?

Recently a very good friend of mine claimed that the recent volcano in South America put out more carbon dioxide that humans did in a year. I tried to explain to him that this claim was not true and that my source was the United States Geological Union who were experts on geological issues. Here is a link to the source that I quoted. (Note that the web page gives a link to a recent article on this issue).

This conversation highlighted to me the issue of sources of information. There is an enormous amount of misinformation currently in circulation. How does the sort of misinformation claimed by my friend get so widely disseminated? I think the reason is that when people hear ideas that they agree with they don't bother to check out the validity of the idea of the reliability of the source.

The video below by Peter Harfield, who produces the potholer54 channel of on YouTube discusses the importance of checking sources of claims that are made in the media.



I first became aware of this issue of sources when reading an online article by Andrew Bolt in 2006. the article was on Al Gore's film An Inconvenient Truth. The article can be found here.

The article was online so I started researching using Google. I fairly quickly started to have doubts about Bolt's claims.

Bolt's first objection was this one:

1: Gore claims that a survey of 928 scientific articles on global warming showed not one disputed that man's gasses were mostly to blame for rising global temperatures. Only dumb journalists and bad scientists in the pay of Big Oil pretended there was any genuine debate.

In fact, as Dr Benny Peiser, from Liverpool John Moores University has demonstrated, Gore relies on a bungled survey reported in Science.

The first article that I found was here.

It appeared that Peiser was finding difficulty maintaining the claims that Bolt relied on.

I then came across this email communication. In it Peiser seems to retract his major claim and at the finish notes:

I do not think anyone is questioning that we are in a period of global warming. Neither do I doubt that the overwhelming majority of climatologists is agreed that the current warming period is mostly due to human impact.

That, of cause is not the sort of message that Andrew Bolt tries to give on his site.

I then checked out Bolt's third criticism:

3: Gore says ice cores from Antarctica, that go back 650,000 years, show the world got warmer each time there was more carbon dioxide in the air.

In fact, as the University of California's Professor Jeff Severinghaus and others note, at least three studies of ice cores show the earth first warmed and only then came more carbon dioxide, many hundreds of years later. So does extra carbon dioxide cause a warming world, or vice versa?

I Googled Severinghaus and first I found articles about rapid warming in Greenland. I eventually found articles that discussed the last deglaciation, including this one. In these articles and in an email reply to me Seveinghaus emphasised that carbon dioxide was very important in the last deglaciation, providing between 35% and 50% of the warming. I later found this article where Severinghaus cries foul on Bolt's reporting.

When I returned to Bolt's article and re-read his point 3 I realised that Bolt had not directly stated that Severinghaus agreed with Bolt's interpretation, so technically Bolt had not mislead his readers. But most people who read the article would expect that the expert that he referenced would agree with Bolt's argument - and the expert clearly does not agree with Bolt's argument.

After that experience, I realised that it was very important to check the sources of claims that are made in the media, which is the point that Peter Harfield is making in his video.