Prof Brian Cox had a TV discussion with Australian Senator Malcolm Roberts, who is a member of the One Nation Party (think UKIP). Roberts asked for empirical evidence that climate change is caused by humans. This is a fair question.
Empirical evidence is evidence that is based on observation and experience, as opposed to reasoning from a strongly held belief.
There is a very interesting opposition between empiricism and reasoning that flows from strong belief.
For instance, if I believed very strongly in a free market, as an ideal, then the continued profitability of a number of big corporations becomes the most important principle in the modern world, I might argue that anything that threatened that profitability was absolutely and completely wrong.
Now, what is the empirical evidence that drives scientists to the conclusion that man made greenhouse gases are causing our planet to become dangerously warm?
The science gets to its conclusion in 4 steps:
- The Greenhouse Effect is real. Physical laws, arrived at by observation and experimentation, show us that without the greenhouse effect our planet would have an average surface temperature of -15*C, instead of the present +15*C.
- Carbon Dioxide is a greenhouse gas. This was established by physicists using simple but elegant experiments at the end of the 19th century.
- Carbon dioxide levels in the atmosphere are observed to be increasing. The kind of carbon that we are finding points to an origin in the fossil fuels we have been burning. The levels of CO2 that we are producing are higher than natural variations going back tens of thousands of years.
- Earth surface temperatures have been observed to be increasing, and natural cycles that affect temperatures are inadequate to explain the increase. The only explanation that fits the observation is the enhanced greenhouse effect that we have produced.
- We have raised temperatures by about 1*C, and already we are seeing extreme heat, and extreme precipitation events. If we do not change our habits, these extremes will get worse.
So there is the summary of the empirical evidence - based on an enormous amount of observations and experimentation. Malcolm Roberts's question has been answered - but he will continue to argue, to deploy the 100-odd talking points that those in denial use. This is because his belief is that the profitability of the fossil fuel companies is the overriding priority in our world. He demands empiricism, but he personally is in fact a free market idealist. He reasons from the ideal - Free Market - and arrives at the conclusion that climate science is a massive conspiracy on the part of scientists to overthrow the Free Market. Malcolm Roberts is not the first politician to believe in impossibilities. Many in our present UK Government are in the same category, unfortunately.
These politicians would be harmless oddities, were it not for the fact that a substantial minority of voters share their beliefs. Why? Because the Times, Telegraph, Mail, Sun and Express give voice to these beliefs. How can we stop them? By persuading corporations who claim to be environmentally and socially responsible to stop taking our advertisements in those papers.