Peter Allen - Climate Change
Thu 27th July 2017 at 19.15 - 21.15
What's the difference between global warming and climate change?
27 July 2017Climate Change – Dr. Peter Allen
Peter was formerly a Director at the British Geological Survey at Keyworth, so spoke on his subject with great authority, knowledge and experience. He explained that there was much misunderstanding about the terms: Climate change and Global Warming, then proceeded to clarify the details for us.
He started way back, 430 000 years ago when Nottinghamshire was under about 500m of ice, then 23 000 years ago it was an arctic desert. Cycles of extreme cold, then extreme warm/dry were identified. The term ‘ice age’ was thus proposed by Louis Agassiz in 1840. A Serbian mathematician called Milutin Milankovitch (1879 to 1958) demonstrated in the 1920s that there were cycles relating to the Earth and its relationship with the Sun: 21 000 years – wobble on the axis; 41 000 years tilt on the Earth’s axis; 100 000 years – eccentricity of the Earth’s orbit (which he identified as the cycle for the ‘ice age’.) Then in 1967 Nick Shackleton used ocean sediment cores to prove Milankovitch Cycles on the ice age. In the 1990s ice core from boreholes in the Greenland and Antarctic icecaps were analysed for the greenhouse gasses. He described the ‘Greenhouse gasses’ of Carbon Dioxide, Methane, Nitrous Oxide and their impact on the environment and showed the results from the Vostok ice core analysis
He then showed graphs of how these cycles were changed, 8000 years ago when humans started farming, clearing trees which absorb CO2. Similarly the Methane graph changed 5000 years ago when Asians started making Rice Paddies. In the current Milankovitch cycle the Earth should be cooling, but human interference with the atmosphere is causing warming, which has been most intense in the last 200 years.
The impacts of the consequential environmental changes are: Change in the boundaries of the climatic zones; increase in the number of severe weather events; sea level rise; disruption of rain and weather patterns; possible runaway global warming.
The conclusions are somewhat alarming. The disruption of rain and weather patterns is already having a profound impact by forcing migrations out of dryland areas and threatening agricultural yields. Other changes are unlikely to impact in our or our grandchildren’s lives. Runaway warming, caused by the release of methane from permafrost, could be averted by taking action on carbon dioxide emissions now in order to avoid reaching the trigger point.
Questions were raised about Carbon capture and storage (Sequestration) which is currently uneconomic and the politics involved in solutions to Climate change, so the future is not ‘rosy’! BN/AR