Hot under collar on causes of CO2

Sir, – May I respond to a contribution on the global warming discussion and its root causal factors (Letters, May 16).

Sean Galbally states that global warming stopped in 2000 and CO2 is still increasing, therefore CO2 is not the cause.

Let’s examine the first part of this statement – global warming stopped in 2000. This is patently not true, as the Nasa-NOAA satellite measurement systems provide the following assessment that global temperature is rising between 0.8C and 1.4C depending on where you live.

Agreed in 2020-21, it fell back, that is directly attributed to reduced human activity caused by Covid-19. The total increase since 1950 is currently 1.2C, the upper target limit agreed at COP26 was 1.5C and reports this week indicate that it is likely to overshoot 1.5C.

Mr Galbally’s statement or proposition is therefore incorrect as the temperature is still rising and, by his own admission, CO2 is still increasing and therefore a root cause of global warming.

In a previous letter to this paper I have explained the link between water vapour and CO2, where CO2 is the amplifier and small increases result in larger temperature rises. As the temperature increases more water vapour can be supported, also adding to the temperature increase – not the reverse as is being proposed.

CO2 stays in the atmosphere for many years and water vapour eventually precipitates out as rain or snow in nine days on average.

Mr Galbally cited the Ordovician Period of Earth history and where CO2 was in the region of 4,000ppm (parts per million), so why are we bothered about 400ppm?

I checked another source and it appears it was as high as 5,600ppm whereas it is currently 417ppm. That seems quite a lot more than now.

How did we survive? We didn’t exist at that time, the Earth was a water world, with most life water-based. This CO2 ppm information was obtained using ice core samples. However, these cores were sectioned down to samples each 10 million years apart.

The explanation I read advised that at the end of the Ordovician Period the second largest mass extinction of life on Earth took place. At that time the tectonic plates were moving from the southern to northern hemisphere and an ice age resulted of about 500,000 years in length. Hence, the mass extinctions.

The ice core samples were taken at 10 million year intervals. It is highly likely the CO2 level during this ice age could have been missed. The point is that the high levels of CO2 in the ice cores is irrelevant to land animals as we know them as they did not exist. This is borne out by the fossil record.

Therefore Mr Galbally’s contention that higher levels of CO2 have existed in the historical record and as such we should not worry our pretty little heads, is a fallacy.

Nuclear fusion is a future technology, which may well allow humans to keep fossil fuels for the key areas where they are indispensable, as opposed to allowing them to simply go up in smoke. If nuclear fission is anything to go by – we were promised free lecky – I suspect fusion will be reserved for Musk’s Mars missions.

The cause of global warming is being hotly debated.