Re ‘Jury out on climate change (The Weekend Sun, July 20).

Climate change has been called the greatest scientific scam in history. Simply put, a trace gas like CO2 cannot and does not control our climate, the sun does.

Here's some real science: our atmosphere is made up of nitrogen 78 per cent, oxygen 21 per cent, argon 0.97 per cent and carbon 0.03 per cent.

We live in a cyclical solar system – 24 hours, 365 days, nine-year lunar cycle – and the sun also has a cycle where every 206 years it goes into a solar hibernation called a ‘grand solar minimum' where the sun has less output and the Earth cools dramatically.

The last two were the Maunder Minimum of 1615-1725 and the Dalton Minimum of 1790-1820.

In 1610 the telescope was invented and observations of the sun started. The amount of sunspots on the sun seemed to control Earth's climate. During the Maunder Minimum there were no sunspots on the sun, the same as today. We have just gone for 120 days with no sunspots as we descend into the Eddy Minimum 2018-2048.

Solar hibernations cause more intense winters in the northern hemisphere and ice remains after the spring melt, crops are adversely affected, and it is always a societal game changer.

R Colmore, Oropi.