Inconvenient Truths

Former US Vice-President, Al Gore, and his new movie "An Inconvenient Truth" have triggered a remarkable amount of public interest and discussion on the subject of global warming.

But it's not really a documentary.  Gore presents some interesting information, but he also leaves a lot out.  Indeed he omits a lot of inconvenient truths.

In the movie Gore suggests that carbon dioxide from the burning of fossil fuels is the sole cause of global warming.

This carbon dioxide is shown as responsible for the melting of the world's glaciers, bleaching coral reefs and hurricane Katrina.

But hang-on.  There was coral bleaching, category five hurricanes and glacial melt before motorcars and oil refineries.

In failing to distinguish between possible human-caused warming and natural variability Gore does his cause and science a terrible disservice.

Students of geology known that over the last 2.5 million years there have been 50 ice ages initially of 40,000 years but more recently of about 100,000 years.  Between these ice ages have been warm periods of about 10,000 years.

The last interglacial warm period was 120,000 years ago.  Back then carbon dioxide levels were almost as high as they are now, but sea levels were about 6 metres higher and the earth was about two degrees warmer than it is now.

Like Al Gore, I'm concerned about the current high levels of atmospheric carbon dioxide, but unlike Gore I haven't observed any global climate crisis.

It's been dry in western NSW, but it has been dry in the past -- remember the early 1980s, and the Murray River ran dry in 1914.

Ice sheets melt during interglacial warm periods, but it is wrong to suggest, as Gore does in the movie, that polar bears are in trouble -- drowning on mass.  Numbers of polar bears have actually increased over the last 40 years from about 5,000 polar bears when there were no controls on hunting, to about 25,000 polar bears now existing as 19 discrete populations.

It is interesting that in "An Inconvenient Truth" Gore only shows the hurricane record since 1970.  There are good records back to 1851 for the US, and this data shows the 1940s were particularly bad years.

Further, global warming won't destroy coral reefs.  They occur in tropical waters because they like it warm.  As sea temperatures warm, southern hemisphere reefs may extend their range a little further south.

It will be the next ice age and falling sea levels that leave the Great Barrier Reef high and dry.

Then again, as Gore explains in the movie, for him global warming is a moral issue rather than a scientific issue and "An Inconvenient Truth" is part of his campaign of public persuasion.

So let's stop calling it a documentary.  It is full of misinformation including the assertion that there is currently a global climate crisis.

When I study the climate record all I can find are a lot of inconvenient truths for this politician come-environmental crusader.

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