You are here: UNA Twickenham & Richmond: Climate change, the scientific basis


On 28th June 2019 Dr. Arnaud Czaja of the Department of Physics & Grantham Institute, Imperial College, London, addressed an audience of 10, Members of the United Nations Association, Twickenham and Richmond and their guests, on the subject of “Climate Change Fundamentals”.

The Grantham Institute makes up a hub uniting all those working on Climate and at the Imperial College, London, a group of a dozen Physics Department academics are working on Climate.

The world is 1% above pre-industrial 1850 Global Average Temperature.

Dr. Arnaud Czaja put forward four points:-

  • A historical perspective on climate research – is there anything new since Swedish scientist Arrhonius (1896) worked on climate science.
  • The relationship between global surface temperature change and carbon emissions.
  • The global water cycle – floods and droughts.
  • A few quotes and reflections.

In 1827 Joseph Fourier discovered the “greenhouse effect”.   Energy is transmitted by the sun.   Infrared radiation is lost but re-transmitted to earth twice as much as the sun’s energy due to the influence of the atmosphere absorbing some of earth’s energy.   In 1859 John Tyndall discovered carbon dioxide and water vapour have an impact on earth’s surface temperature.   In 1896 Arrhonius estimated a surface temperature increase in response to doubling of atmospheric carbon concentrations due to use of coal, oil and gas.

The World War 2 interest in weather triggered studies in climate from 1960 into the 70s.   In 1990 came the first assessment of how human activity is affecting climate change.   The sixth assessment has been able to produce more details.   Every climate scientist contributes but the United Nations is in the forefront of the studies – a huge endeavour.

Ric Williams assesses that 2,000 units of carbon emissions can result in up to 6 degrees of surface warming no matter what country’s model you use.   The Japanese is the most extreme, the USA model the least.   We need to stop increased carbon emissions by 2050.   This refers to industrial emissions but there are also emissions from living beings.   To limit a temperature increase to 2 degrees, carbon emissions need to be less than 500 units.   The ratio being 1 degree to 500 units of carbon, to avoid warming beyond 1.5 degrees, carbon emissions need to stop at 250 units.

Between 1870 and 2014 we have increased carbon by 400 units by use of fossil fuels and 145 units by changing land use from forests to agricultural uses.   To counter-balance the increases, the ocean reduced carbon by 155 units compared to 160 units reduced by forests.

A rise of 2 degrees in temperature will see the end of coral and sea level rise will be 5 metres.   By the 21st century the present Thames Barrier will be over-whelmed.   Jim Hansen, formerly with NASA, said present greenhouse gases will commit to an ice-free planet by 2100 and a sea-level rise of 75 metres (almost 250 feet).

Following the talk and questions from the audience, a tasty buffet was served by the obliging staff of The Adelaide Pub, Teddington, where the event took place.

Olivia Richardson, Committee, Twickenham and Richmond UNA