Prof. McNulty left gaps in her argument about climate (Letters, May 3).

She sounded learned when she wrote “The weather is not a ‘closed system’ because you cannot know the initial conditions”.

But her argument would be more convincing if she acknowledged some basic truths.

The science is simple and has been around since Victorian times. It’s sunlight in and infrared out. Carbon dioxide reacts less with the former and more with the latter.

It’s like a greenhouse. Sunlight comes in through the glass. Some of the sunlight is reflected off the glass. Most of the sunlight comes in.

The sunlight hits things inside the greenhouse and warms them up. Some of that goes into the air in the form of heat. Some heat is reflected by the glass back into the greenhouse.

The difference makes the greenhouse warmer on the inside. That’s why it’s called the greenhouse effect. It helps to make life on Earth possible.

McNulty seems to be confused about the difference between weather and climate. Weather is rain and shine from day to day. Climate is the pattern over years that gives you the sorts of plants and animals you get.

Yes, the climate has changed in the past. Sea levels have gone up and down. So have CO2 levels in the atmosphere. Scientists can measure rocks. Ice samples from Antarctica go back 800,000 years, according to the British Antarctic Survey.

But there has never been a sudden step. Not in all of geological history. Yes, there is a natural cycle, but we are tweaking the tail of the tiger called the climate and no-one knows what the effect could be.

Phil Jones

Geralds Road, High Wycombe