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The Earth Bites Back – Professor Bill McGuire’s Lunch Hour Lecture

By Carly Schnabl, on 11 March 2011

Can climate transitions trigger potentially hazardous geological responses such as tsunamis, landslides, earthquakes and volcanic activity? It would appear so.

UCL alumna Mel Green reports from Professor Bill McGuire’s Lunch Hour Lecture, 3 March, on the hard facts of climate change and the possible link to catastrophic geological events.

Infrequent but destructive geological events have continually occurred during Earth’s long history.

But now, with the global population predicted to reach at least nine billion by 2050, the effects of such geological events have the potential, more than ever before, to cause devastating loss of life – and lasting damage to our environments and the global economy.

By the end of this century annual economic losses due to climate change are predicted to be a third of the current global economy, with half the world becoming uninhabitable by end of century!

Now, don’t get me started on the issues on unsustainable population growth – but do check out this website:
Population matters

Also this upcoming UCL conference 25th-26th May 2011:
Population footprints

The recent earthquake in Japan has illustrated the visibly destructive powers of such massive geological events and – probably unbeknown to most – their power to affect things such as the Earth’s rotation – shortening our day by 1.8 microseconds. This will mark a change in the passing of the seasons – although it will only be observable using precise satellite navigation systems.

“Only 1.8 microseconds” I hear you say – yes, but add that to the 1.26 microseconds from the Chilean earthquake last year etc., etc. and one can begin to see the implications.

But anyway – back to the question in hand: Can recent ‘anthropogenic’ climate change (human induced that is) trigger potentially hazardous geological events?

“The past provides a key to the future” – as good a place to start as anywhere…….

In simple terms – climate change redistributes the world’s water mass. During the last ice age, much of the Earth’s water was locked up in northern hemisphere ice sheets, 1-3 km thick. Ice sheets depress the crust, affect changes in its stress and strain and can suppress the activity of active faults beneath.

As the ice melts during a climate transition, the crust begins its slow ‘post-glacial rebound’ – the bounce back if you like – and can begin to release some of it’s accumulated strain, albeit thousands of years later.

The trigger for a number of past geological events has been attributed to post-glacial rebound and the water mass transfer back into the ocean basins:

• increased volcanic eruption rates – (Iceland – since 20,000 years ago)
• high magnitude intra-plate earthquakes – (1356 Basel, Switzerland)
• submarine landslides – (Storegga slide 8,200 years ago) – causing a tsunami in Shetland and Eastern Scotland.

Talking of tsunamis – climate change can destabilise the flanks of coastline volcanoes: check out Ward and Day (2001) on the mega tsunami that would follow the collapse of the Cumbre Vieja volcano on La Palma, Canary Isles.

Click to read report

It is clear that we are enhancing the greenhouse effect at an unprecedented rate:

• Atmospheric carbon dioxide (CO2) is up almost 40 % since pre-industrial times (mid 1700s).
• Average global temperature is likely to increase by six degrees centigrade by the end of this century. Northern polar region temperatures could increase by 14-16 degrees centigrade (goodbye Greenland ice sheet).
• Sea level rise is predicted to be between one and two metres by 2100 and beyond (half of humanity lives within the coastal zones).

The geological effects of anthropogenic climate change are already being seen in terms of ice loss, avalanches and landslides.

It is clear what else is in store for our beautiful blue planet, meaning that unmitigated emissions in the next 10 years are not an option.

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