I have now completed 50% of the Climate Change MOOC. Just like a good holiday, time is going too quickly. It's really enjoyable. This week we learnt about two topics that are of particular interest to me - climate modelling and geoengineering. I think it's important to understand some of the science behind predicting climate change including how the models are constructed and verified. Likewise, whereas the obvious solution to the planet's problems would appear to be a drastic reduction in CO2 emissions, another option, which is somewhat controversial, is geoengineering.
The Met Office in the UK has very advanced computer models that are used for weather prediction and many of the processes that are employed to forecast the weather over a five-day period are similar to those required to predict the climate over 250 years. The computational demands are huge and even with the Met Office's latest super-computer, a typical climate simulation can take three months of elapsed time. But a model is a model and despite all the fancy charts and spreadsheets, in order to have credibility any model should be validated. The easiest way to do this is to run the model with past data and see if the computed result matches what actually happened. The results with data collected over the past 150 years, since reliable records were kept, are interesting. We know the globe has warmed by about 0.8 degrees C in that timeframe. When only the natural factors were input to the model, which include variations in the sun's output and volcanic activity, the climate simulation followed recorded data up to about 1970. After that date the simulation showed the global temperatures cooling, whereas in reality there was significant warming. However, when human factors were added to the inputs to the model, particularly the increase in carbon dioxide due to the burning of fossil fuels and deforestation, the simulation followed the observed climate very closely. So it would appear we have a good model. This should give confidence in predicting climate over, say, the next 250 years BUT only if we can predict human behaviour, and that's a big BUT. The way the scientists cope with the vagueries of the human race is by assessing a number of different scenarios. These scenarios include variables such as population growth and the ability of mankind to take the appropriate actions to reduce carbon dioxide emissions.
What about geoengineering? Well, I have stated previously that I have tried to be open-minded on this course in order to assess objectively the expert opinions. I have to admit that it didn't take long for me to have grave concerns about geoengineering, which is the use of technology to control the climate. There are two branches of geoengineering, carbon dioxide removal mechanisms and solar radiation management. The latter, which includes spraying aerosol particles into the upper atmosphere, really scares me. Apart from the obvious unknowns and therefore high probability of unintended consequences, I have a real concern that if these techniques were pursued with vigour, the world's politicians would see it as a good reason to avoid any short-term painful decisions associated with meeting tough carbon dioxide emission targets, and would continue with business-as-usual government policies. What a disaster!
It's been another thought-provoking and interesting week. I am getting more concerned about the future and particularly the demands that are being placed upon the planet's resources by a rapidly increasing human population. Maybe extreme climatic conditions will lead to self regulation of the population - is there a model for that?! Whatever, the course is billed to cover challenges and solutions. I think the challenges are already very clear, but whilst the low risk technical solutions are common sense, as is often the case, common sense is not very common! I look forward to week 5.
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