"The volcano eruption in Iceland has forced millions of people to think the unthinkable: a world without air travel.  Its impact across Europe is nothing compared to the possible impact of global warming by 2050. 

“Volcanic eruptions remind us of the vast energy beneath our feet, which could power our future.  There is 250,000 times more geothermal energy available than is currently used – enough to power the lives of 7 billion people many times over, so long as it can be distributed from the most suitable sites to where it is needed.

“Unlike wind or solar, geothermal energy is always available, and will last for hundreds of millions of years. We can expect huge growth in geothermal power production, especially in America, thanks to Federal grants and subsidies.  The largest geothermal plant in the world is Larderello in Italy, which supplies 10% of all global geothermal output.

“Investment in geothermal is just part of the £25 billion green tech boom that we will see over the next 30 years as our world adjusts to a low-carbon, sustainable future."

* Dr Patrick Dixon is co-author with Johan Gorecki of the book Sustainagility, published by Kogan Page.