TIM Glanvill (HAS, Oct 27) is correct that shifting tectonic plates cause earthquakes and volcanoes. However, if internal changes within the core of the planet leading to a change in the planet’s magnetic poles are occurring, then such changes would logically have an affect on the iron found within magma flowing under the planet’s crust, which is expelled as volcanic lava or which forms new oceanic crust.

Any such affect would be small, but could have an accumulative effect on the natural processes which ultimately lead to earthquakes and volcanic eruptions.

Equally, it should be remembered that the damage to the climate and environment caused by a single volcanic eruption can equal that of decades and even centuries of human industrial activity.

Also, undersea earthquakes regularly occur in parts of the world, in some cases causing the release of methane hydrates.

These rise through water and into the atmosphere as methane which is believed to be a contributory factor in global warming.

While human activity contributes to climate change, it seems people are forgetting the natural processes of the planet.

CT Riley, Spennymoor, Co Durham.

THE Copenhagen Climate Summit in December is a great occasion to start discussing how a low-carbon economy would look in the North-East.

On November 13, anybody interested in tackling climate change at a local level is invited to take part in a lunchtime debate organised by Climate Durham to come up with a positive vision of a low-carbon future.

The resulting vision statement will be presented by Durham’s secondary school pupils to a panel of politicians and climate experts in Copenhagen in December. The event on November 13 will take place from 12.30pm to 2pm in Durham Town Hall. Please email Janie@climatedurham.org if you would like to come.

Angelika Schneider, Durham.