THE simple answers to Dr Charles Wardrop’s questions (Letters, February 6) are that we can be sure that man-made climate emissions dominate natural cycles because the scientific consensus tells us so, indeed both the IPCC 5th report and the US 4th National climate assessment found that the earth would actually have cooled slightly since 1951 without human-caused warming. Svante Arrhenius had a decent estimate of the effect of CO2 on temperature in 1896, and even Exxon managed to predict fairly accurately the current level of global warming from CO2 in 1979.

The huge costs of decarbonisation are not that huge, many estimates are around two per cent of GDP. For comparison, this is roughly the difference between the UK defence budget during the Cold War, and after it. Or within the middle of the range of estimates of softer or harder Brexits. Cost didn’t stop us from preparing to fight a war against the Soviet Union, or from abandoning Brexit.

And we should lead because we are a rich country with above-average emissions. We should do the morally right thing because we can, just as the Royal Navy set out to end the slave trade despite the financial losses it caused for British merchants. (If nothing else, Sir Humphrey would argue we should do it to demonstrate our superiority over the French, who are both richer and have lower emissions.)

Dr Wardrop argues that we cannot afford to bell the cat, but that fable ends with all the mice eaten. But imposing a carbon equivalent tariff on imports would reward countries that join us in lowering emissions. Big emitters such as China and India will happily join a carbon tax agreement, because they recognise that their domestic carbon consumption per capita is lower than ours, just as we will gain from strengthening the EU Emissions Trading Scheme because our emissions are lower than the EU average. Even Donald Trump recognises the power of tariffs to change policy in other countries.

So yes, we should avoid “green tokenism”, of pledges to ban fossil fuel car sales and meet reduction targets in the distant future. It was once a key principle of the UK constitution that no Parliament could bind its successors. So enough talk of zero emissions targets in 2050, we need to ensure that we stay on a path of at least a three per cent reduction this year, preferably five per cent, and at least 15 per cent and ideally over 25 per cent by the next General Election, or future cuts will be even steeper. The only questions should be where we trust the free market approach of taxing carbon or take the authoritarian approach of banning things; and where do we invest to kick start the technologies and industries that we need.

Alan Ritchie, Glasgow G41.

DOUG Maughan (Letters, February 7) makes many important points about aviation and carbon emissions therefrom. However the oft-repeated aviation mantra that the industry produces only two per cent of global carbon emissions, and therefore should not be curbed, fails to acknowledge that at flying altitude the effect of those emissions is more than doubled by radiative forcing.

Additionally, the industry proudly boasts of the mass tourism that has developed from cheap flights. There must be substantial carbon emissions from this aspect of modern life but these are apparently not quantified. A study is long overdue.

The evidence is that we are in a climate emergency. Perhaps governments everywhere should adopt the Second World War slogan “is your journey really necessary?”

John Edwards, Linlithgow.

ANDREW McKie's column ("We can't reach our destination with today's green cars", The Herald, February 5) was shocking in its ignorance. He writes off electric cars as ineffective replacements for the familiar carbon-emitting vehicles of today, making statements that are just wrong. For example: "it takes most electric vehicles eight hours fully to recharge". Well, it takes my four-year-old Nissan Leaf about 45 minutes to fully recharge, using a rapid charger such as the ones well placed along all trunk roads. Just time for a comfort break and coffee.

Mr McKie's worry about how rural areas like the West Highlands could cope with the necessary infrastructure suggests he doesn't get out much. There are plenty of rapid chargers between, say Glasgow and Skye. His comment, too, about how unlikely it is that car manufacturers can make the necessary switch to non-carbon-emitting products, again indicates that he hasn't done his research. Did he pick up the phone to ask any of the manufacturers what they are doing, and where the bulk of their R&D is focused, or whether they see a future for themselves in the climate crisis? I think not.

Of course there is a need for further infrastructure as electric vehicles become more numerous, but as their range and charging speed are steadily improving, that shouldn't be an impossible task..

Mr McKie's estimable colleague Iain Macwhirter wrote some time ago about the experience of driving an electric car, which as I recall favourably impressed him. Perhaps it's time for Mr McKie to do a test drive himself.

Ken Wardrop, Glasgow G14.