History reveals several global warming periods

IN RESPONSE to the letter from Ragnor Debrun (TB 4/2/20). Like you and M. Warren I am not a global warming expert. I am, however, a student of history. I notice in all your facts you do not mention the Roman warm period 250BC to AD400. Literary fragments from the time (4th and 5th century BC) suggests that the climate in Greece at the time was basically the same as it was in 2000AD.

Dendrochronological (tree ring dating) evidence from wood found in the Parthenon shows variability of climate in the 5th century BC which represents the modern pattern of variation. Hannibals’ famous crossing of the Alps with elephants in 218BC probably indicates the mild (warm) conditions at that time.

Your history lesson on climate change also conveniently skips the Medieval Warm Period 950AD1100AD. This was probably the reason the Vikings may have made it to the Americas.

Then we have the little ice age from 1500BC to 1700BC. This was the coldest Earth climate phase since the prehistory ice ages. The Earth started warming again from about 1750 to the present day.

The above facts are also attributed to scientists and are not from some blog on social media. It may be prudent for us to keep an open mind. There may be forces other than CO2 in play contributing to climate change.

We should be encouraging our best and brightest young minds to find ways to survive climate change. Writing letters in

Australia is not going to stop

China producing in 18 days the same amount of CO2 that Australia produces in one year. MERVYN JOHNSTON,

Kirwan.