On GLOBAL warming and climate change, the Royal Society is crystal clear: “Much of the warming [of this planet] has occurred in the last four decades. Since the very warm year 1998… the increase in average surface temperature has slowed relative to the previous decade of rapid temperature increases. Despite the slower rate of warming, the 2000s were warmer than the 1990s.”
Global warming is increasing, with each of the last four decades being warmer than the one before. There is no pause, as GM Lindsay (Letters, 5 August) claims, just a slight slowing down.
Professor Trewavas (Letters, same edition) looks back to a time before mammals existed and indeed to times when, because of the environmental conditions which existed on Earth, they could not have existed. We are not in the then but the now. A now where one species is having such an adverse effect on the environment that we, the human race, could, without urgent action, be well on the way to destroying much, if not all, of life as we know it.
The Royal Society states that “atmospheric carbon dioxide increased by about 40 per cent from 1800-2012”, with most of this increase having taken place since 1970. This increase, according to the Royal Society, is due to human activities. This raising of carbon dioxide in the atmosphere is due to the rapid increase in the burning of fossil fuels.
If we are going to hand on this planet in a decent state to our children, grandchildren and their descendants, we must take urgent action to curb our excessive use of fossil fuels, plan for and develop an increase in renewable energy sources and seek to do this on a global basis.
Friends of the Earth Stirling
Carolyn Taylor (Letters, 6 August) wishes to associate the known Triassic Jurassic extinction with very high levels of atmospheric carbon dioxide. This extinction is predicted to have lasted 10,000 years and occurred 50 million years after carbon dioxide had already reached these high levels, if proxy data is to be believed. Some other (unknown) event was clearly responsible, since this extinction is not marked in the carbon isotope record.
I know of no evidence that massive amounts of methane were released from the oceans at this specific extinction period as Ms Taylor suggests. Indeed this period is marked by the rise of giant fern forests responsible, it is thought, for removing the high carbon dioxide down to current levels.
Ms Taylor also omitted the period much earlier when carbon dioxide in the atmosphere was 25-fold higher. Applying current climate models with positive feedback from humidity increases to 500 million years ago would have seen the planet boiled.
Identifying only atmospheric carbon dioxide as the sole driver of climate change is misleading, and the complexity of climate change needs to be constantly emphasised.
(PROF) TONY TREWAVAS FRS FRSE
Scientific Alliance Scotland
North St David Street