The Earth is very slowly slipping back into a proper ice age
Well, this is just nonsense. It is quite probable that the Earth will – at some stage in the future – enter another ice age. It’s also true that if we were following the same pattern as we’ve followed for the last 800000 years, we might expect this reasonably soon, but we’re not, and we don’t. The reason is very simply that anthropogenic influences are now swamping the natural forcings that act to trigger the glacial cycles, and the current trajectory is very clearly not towards another proper ice age.
moderate anthropogenic cumulative CO2 emissions of 1,000 to 1,500 gigatonnes of carbon will postpone the next glacial inception by at least 100,000 years
The basic idea being that whether or not we move into another glacial period depends on the solar insolation at high northern latitudes and the amount of CO2 in the atmosphere. Our emission of CO2 has essentially guaranteed that atmospheric CO2 will remain enhanced for more than 100000 years, and – consequently – has delayed the next glacial cycle by at least the same timescale.
Matt Ridley’s overall argument, however, is that we don’t really need to be concerned about the next ice age, because it is still quite a long time away, by which time – as long as we keep using cheap, plentiful energy – we’ll have the technology to deal with it, and we can still thrive. The problem, though, is that if we simplistically follow Matt’s advice, we could pump enough CO2 into the atmosphere to produce a change comparable to that between a glacial and an inter-glacial, but in the other direction, and at least 10 times faster.
It’s also not only that could we produce rapid changes to our climate, we could also produce changes in some regions that lead to temperature and humidity levels that would be difficult to endure. We may also pass tipping points; sudden climatic shifts that are essentially irreversible.
So, for some reason Matt Ridley thought it worth talking about something that is unlikely to happen for another 100000 years. Even though Matt suggests we shouldn’t be concerned about this, he does suggest that we should prepare for this eventuality by using cheap plentiful energy. If, however, this cheap, plentiful energy is associated with the emission of CO2 into the atmosphere, we could produce changes on human timescales that may make it difficult for us to continue to thrive. I guess it’s just another example of people being willing to consider anything other than the possibility that we should think of ways in which we can reduce the emission of CO2 into the atmosphere.