Volcanologist Professor Bill McGuire delivers Roscoe Lecture
27 April 2012
Professor Bill McGuire, expert in natural hazards and climate change, delivered one of Liverpool John Moores University's popular Roscoe lectures entitled 'Waking the giant: how a changing climate triggers earthquakes, tsunamis and volcanoes.'
Bill divided the lecture into three parts, discussing the past, present and future. He commented that some people believe there is no correlation between rapid climate change and geological hazards but said this can be proven from what we know about what happened after the last ice age, what is currently happening in places such as Alaska, and the research being done which predicts that as the climate warms, so too will the solid earth between our feet which will cause the planet's crust to respond.
Bill explained that 20,000 years ago much of the Northern Hemisphere was covered in ice sheets which then melted and caused a dramatic rise in sea levels. So impactful was this, he said, that the change in mass from the rising sea levels actually lengthened the Earth's day by four seconds. The weight of the ice sheets had also been pushing the Earth's crust down and the ice effectively locked any faults - these were unable to move with the ice present but when the ice melted and disappeared they were freed, generating large earthquakes such as those which happened in Scandinavian countries at the end of the last ice age. He also explained that the ice sheets surpressed volcanic activity and so, at the end of the ice age, volcanic activity also peaked.
To discuss the present situation, Bill used Alaska as an example. It is the place, he said, where we can see signs of how the climate and the solid earth interact. He added that we haven't yet seen what is happening in Alaska on other parts of the planet but we may do so in the future. This is due to the fact, he added, that it is one of the fastest warming areas on Earth and, as such, it is also one of the most tectonically active areas, with many earthquakes and volcanic eruptions. Bill then went on to outline the link between heatwaves and landslides, giving recent examples from across the globe including those in Italy and Russia and he explained that tiny changes in pressure can cause geologocal hazards; giving examples such as typhoons and heavy rainfall triggering earthquakes and volcanic eruptions.
Focussing on the future, Bill used Greenland as an example, explaining that if the ice sheet on the country melts, any surpressed faults underneath it will be freed which could trigger earthquakes and, he said, there is also the possibility that if there is loose sediment around the edges of the country these could be shaken off, triggering tsunamis around the Atlantic.
Bill summarised the lecture by saying that climate change is undoubtedly set to be severe and effectively we are doing nothing at all to reduce greenhouse gases, which are the cuase of global warming. He added that there is no question that when the global economy bounces back there will be a huge rise in CO2 emissions. He also explained that at the Durban Climate Conference it was decided to effectively take no action until 2020 when at the same time we have a situation where we have just ten to 20 years to save the Greenland ice sheet. If in that time we have done nothing, the ice sheet won't have disappeared, he said, but after that time any action we do take would have no impact.
To listen to the full lecture, go to: http://ljmu.ac.uk/roscoe/97603.htm