At SW23 he provided a powerful and thought-provoking talk on how simulation can help predict the effects of pandemics and climate change via MultiWave skew-logistic processes. The parameters he input for his Covid simulation included the number of active cases at any given time, rate of increase of infection, rate of decrease of infection and location of infection.
He spoke of the use of a SEPIR model which focused on Susceptibles, Exposed, Pre-symptomatic, Infected (symptomatic) and Removed; the importance of fitting the model to the data; calculation for any given value and; the use of stepwise integration and measurement of likelihoods and trajectories in the simulation process.
Moving on to the climate change simulation, he presented several slides along with commentary, which illustrated how carbon dioxide (CO2) in parts per million (ppm) could be plotted against planetary temperature rise.
One slide was a chart of CO2 against temperature starting with values from the year 1800 when the level was 280 ppm. This clearly shows exponential growth. In the first 100 years, the increase was around 15 ppm, (to 295 ppm) from 1900 to 2000 the increase was an additional 75 (to 370 ppm) and from 2000 to today, it has gone up another 45 ppm (to 415ppm) and is showing no signs of slowing down. At the predicted rate of increase, CO2 levels could reach 700 ppm by 2100 corresponding to a life-threatening 7-degree Celsius rise in planetary temperature over that of 1800.
There are currently almost 3,300 gigatonnes of CO2 in the atmosphere. To return to pre-1800 levels requires the removal of 1,300 GT plus any additional CO2 that is released while this is being extracted. Net zero is not enough!
Russell’s PowerPoint presentation is available at: https://bit.ly/445IQX9