ONCE again Susan Thomas tries to play down the effects of burning fossil fuels (February 4). At present the earth’s orbit is almost circular and has little effect on climate but, if there is a change, it should be for the earth to become cooler, whereas it is becoming warmer.

The amount of CO2 in the atmosphere may be low but that small amount is significant since it has increased dramatically since the start of the industrial revolution. This increase is also apparent in methane, another greenhouse gas, created largely by industry.

I have yet to read a report by any reputable scientist who isn’t convinced that the world’s extreme climatic changes are not due to man’s activities.

As the earth becomes warmer, more water evaporates from the surface, thus giving more rain. Warm air rises and circulates in an anticlockwise direction in the northern hemisphere and clockwise in the southern – a bit like water going down a plug hole.

With greater amount of warm air circulating and moving up through the atmosphere, more hurricanes, tornadoes and high winds are created. At present, the jet stream is passing across or close to these islands. One has to hope that in future years it will take its more northerly track.

DERRICK HOLT Fortnam Close Headington Oxford