NATURE has a will of its own especially when it comes to climate change. Geological aspects on global warming need to be considered according to Grant Cawthorn, professor of igneous petrology at Wits.
Cawthorn takes an alternative perspective on climate change, focusing on its geological causes. He gave a public lecture at the Origins Centre last Tuesday night hosted by the Wits Geological Society.
His presentation focused on research from 6000 years ago to the present as he maintained that looking at climate variability from past centuries can give us a good estimate of recent climate change.
Some highlights of his talk included investigating past core temperatures of the polar ice caps, specifically addressing the rising and cooling of these by 10 degrees Celsius and the effects they caused for hundreds of years. Cawthorn said: “We do not know why [this happened]”. He then pointed out that the Earth was warmer then which led ice caps to melt and sea levels to rise. Sea levels have since dropped which shows that the Earth is now cooler.
Cawthorn made his stand on global warming clear from the beginning of the lecture: “I am not a climate change denialist,” he said. He believes climate change is occurring but pointed out that it is not due to CO2 emissions only but rather to unpredictable geological causes.
Greenpeace Africa climate campaigner Melita Steele said however that there was a high level of agreement among scientists that carbon dioxide emissions are caused by humans. She said the earth does have natural warming cycles but humans have speeded up the process.
Cawthorn also made it clear that CO2 is a useful gas, saying that without any of it in the atmosphere the Earth’s average temperature would be about -18 degrees Celsius. He clarified CO2 as not being a runaway gas as it becomes less effective when more of it is released into the atmosphere.
Cawthorn concluded by saying that while this greenhouse gas (CO2) does contribute to climate change it certainly does not have as big an impact as unpredictable geological variability. To prepare for and discover future temperatures scientists need to investigate previous warming temperatures of the Earth such as about 1400 years ago.