Climate science isn’t clouded, it’s clear fossil fuels are responsible for global warming - Yorkshire Post Letters

After a brief interlude to focus on the shenanigans in Westminster, the conversation about global warming has returned to the letters page (29 October), as Paul Morley pleads for 'an unbiased, truthful account of it all'.

On the same page, Liz Whitehouse answers Rosemary O'Dea and reminds us that geological evidence shows the current warming rate is some ten times that which typically followed the major prehistoric ice ages.

Also, in just the past century or so the concentration of CO2 in the atmosphere has increased by 25 per cent from its maximum level over many preceding millennia, evidenced geologically and from ice-cores.

However, Charles Wardrop contends that water vapour ‘overwhelms CO2 as a greenhouse gas’, so no wonder Mr Morley is a bit confused. What can unbiased and truthful science tell us?

There is a clear and widely agreed scientific consensus that global warming is real, significant, and exacerbated by human activity. Those who contend otherwise are a vocal but tiny minority of commentators.

We can all agree that our planet's surface gets its warmth overwhelmingly from the sun.

Over the millennia, variations in the earth's rotation and orbit, and in the sun's output, cause patterns of change in global mean temperature which are clearly evidenced also in the geological record.

Different molecules have various resonances to incident energy, and it is molecules with more than two atoms which are particularly sensitive to infra-red radiation. This is why the majority nitrogen and oxygen components of the atmosphere do not play a part in global warming, and CO2 as the next highest-concentration gas is the major player.

Without the historical baseline level of CO2, the Earth would be too cold for life, but the increase of atmospheric CO2 from 300ppm to 400ppm in the last century or so coincides very closely with directly recorded current trends in global average temperatures which do not fit the established long-term patterns.

There was once a debate about cause and effect, which is now resolved. The excess CO2 released from fossil fuels globally since the industrial revolution is a cause, not a consequence of additional global warming.

Methane (CH4) with several intra-molecular bond angles is considerably more potent than CO2, but (for now) much less prevalent in the atmosphere. However, rising temperatures do threaten a positive feedback in which melting sub-arctic permafrost releases copious amounts of methane, which may cause a significant further rise in global mean temperatures.

Finally, then, what about water vapour? Clearly, Mr Wardrop has never felt the shadow of a cloud on a sunny day. While water vapour (as a gas) is thermally active like CO2 and methane, the natural working of the atmosphere at current temperatures means that most water molecules in the air are in liquid form as clouds. A blanket of cloud results in reflection of solar radiation back into space, and this action (along with the albedo effect of sadly diminishing polar ice-caps) is essential to the natural regulation of global temperature which has always been in place

It is the unprecedented rapid change in CO2 concentration which is the un-natural 'smoking gun' in the scientifically agreed evidence of current global warming.