As someone who believes greenhouse gas emissions do cause warming and sea level rise, I find such scenarios actually counter-productive and are what lead to more and more people just thinking it is all scare-mongering (it isn’t, but stuff like this is exaggerated).
The scenarios shown are 1000 cm, 2500 cm and 8000 cm rise in sea levels. Mr Musther states ” the 10 metre rise could happen within the 21st century” and “a 25 metre sea-level rise could occur within the 21st century”.
I believe in looking at the science. First what has been the actual increases. It has been 1.7 mm a year from 1950 to 2009 and 3.3 mm a year from 1993 to 2009. The consensus scientific projection in the latest IPCC report is an increase this century of 26 to 82 cms.
So these scenarios are based on increases 1200% to 10000% greater than the IPCC projects. Not 20% greater or 50% greater but magnitudes greater.
Again this does not mean that we will not face some challenges from global warming, and that there are not long-term risks with greenhouse gas emissions. It would be an incredibly bad thing if the West Antarctic Ice Sheet melts. However the notion of sea level increases this century in the range of 1000 to 8000 cms is just junk science.
Over many centuries or millenia, you could get increases of that magnitude, and again this is an undesirable thing. But trying to make decisions today on the basis of what the world will be like in say 2250 is deeply challenging – and highly likely to be wrong. Could you imagine sitting in England in 1750 trying to work out the impact of things done in 1750 on the world in 2000? We rarely get it right 10 years out, let alone 250.
Again this is not to say we should not be lowering our level of greenhouse gases. But to try and scare people into thinking we could have sea level rises of this magnitude within the next 100 years is actually counter-productive. It just pisses people off, and makes more people sceptical. The extremists make it harder for the moderates.