If the 'green brigade' was responsible, why on earth do we still have so many coal-fuelled power stations? As Julian has said far more down-to-earth political issues set the path for the UK coal industry long before the debate of global warming versus global freeze was settled.
http://www.gov.uk/government/uploads/system/uploads/attachment_data/file/548008/Coal_since_1853.xls
Just to spoil a good argument with facts, here's a graph I made from this data:

I am somewhat surprised by this graph First, how it shows the decline in employment in coal slightly SLOWED after the big coal strike in the 80s. the industry had been nosediving for decades.
Secondly, the 'environmental awareness' of the last twenty or thirty years seems to have had no real effect on a consistent decline in UK coal production (the sudden drop in the early 90-s is the completion of the deep mine closures planned in the early 80s, not the impact of a new bit of environmental legislation).
Even so, perhaps those bemoaning the decline in coal use should remember the effects of smog, acid rain and other pollution. I grew up in South Wales and did not imagine some of the sterile landscapes and poisoned places that ere the direct results of coal extraction and its use (does anyone else remember they stink or Port Talbot or the hillsides above Llanwern with only dead trees?)
Coal has two disadvantages over other fossil fuels: it is relatively filthy in terms of other contaminants (sulphur especially) and has minimal hydrocarbon content, so it produces almost all CO2 when burned and very little H2O compared to say oils (just over two H20 for every CO2) and natural gas (four H20 for every CO2). So in simple terms you get roughly five times as much CO2 for a given amount of energy from coal compared to natural gas. The technology to handle, burn and extract energy from gas is also simpler (just throw it straight into a gas turbine).
There is slow progress being made with the scrubbers to remove CO2 (the other contaminants are better dealt with these days, at least in power stations) but there's a long way to go.
There's no global shortage of coal, and the UK still produces both deep mined and opencast coal, but demand is now so low that the deep mines are barely economically viable.
The problem is that the type of coal that suits locomotive firing has pitiful demand and is expensive to extract.
Neil