Published in 1989, the first report of the UN’s Intergovernmental Panel on Climate Change and the expanding flow of follow-up documents has narrowed to virtual disappearance the scope for scepticism about the reality of global warming.

Denial that the scientific data is conclusive and that carbon emissions need to be contained, or ‘mitigated’ in the jargon, has become the political home of cranks and conspiracy theorists.

But scientific controversy continues about the likely future pace of climate deterioration and the economic and social consequences of failing to do enough, in good time, to control emissions.

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The optimists argue that there is plenty of time and celebrate whatever progress has been made, while doomsters fear it may already be too late and that catastrophic outcomes are becoming inevitable. In that case, adaptation and countermeasures, such as flood prevention, may make more sense than a futile attempt to prevent a climate catastrophe already in train.

John Gibbons in his recent book belongs to the group fearing catastrophe, and the international scientific community is increasingly in agreement. His prescription is a more vigorous mitigation effort in Ireland where he sees the agricultural sector as a large part of the emissions problem.

If you believe that the climate scientists are right to be alarmed and the evidence is ever harder to ignore, then we must ask whether mitigation in pursuit of national emissions reduction targets a sensible response?

Gibbons, himself from a farming background, repeats the familiar statistic that the agricultural sector is responsible for 38% of total emissions in Ireland and for widespread environmental degradation, including pollution of waterways and biodiversity loss.

Measurement

The measurement of each nation’s carbon emissions is problematic – if based on the location of production, Saudi Arabia is to auto fuels what Ireland is to dairy output.

However, EU countries almost all impose substantial indirect taxes on auto fuel, permitting free trade to dictate the production of crude oil in the countries with the lowest production costs.

Since estimates of the export percentage of Irish dairy output range up to 90% depending on the product category, whose problem is the high apparent 38% share?

If you believe that the climate scientists are right to be alarmed and the evidence is ever harder to ignore, then we must ask whether mitigation in pursuit of national emissions reduction targets a sensible response

Is it just a mistaken method of measurement, which should focus on consumption rather than production by country, and policy likewise?

The EU is currently embarked on a process called CBAM, which stands for Carbon Border Adjustment Mechanism. The idea is to penalise, with differential tariffs, countries which are deemed to have lax carbon reduction policies, giving them an unfair advantage over European competitors.

The result will be higher indirect taxes (tariffs) on imports into Europe, and an incentive for trading partners to join in the mitigation effort.

In Saudi Arabia’s case, it can hardly be blamed for having an efficient fossil fuel extraction industry, but petrol is subsidised in the domestic market and sells for around €0.52/litre, about one-third the typical price in Europe.

As a result of of low sales taxes, the retail price in Donald Trump’s USA is around €0.80 per litre, half the figure in the EU. If only Europe is making a serious effort at mitigation, the climate pessimists will be proved right.

Global warming is a planetary emergency, every tonne emitted to meet high demand internationally does similar damage and Europe is not a planet. Nor is Ireland – no conceivable extra effort in any EU country will make a serious difference if the USA, China, India and others do too little.

John Gibbons is more persuasive when it comes to farming practices which diminish biodiversity and damage watercourses according to the Environmental Protection Agency.

The survival of sheep grazing on low-quality uplands is known to be unproductive in income terms but also worsens flood risk downstream, and Gibbons is scathing of government subsidies.

The economist Nicholas Stern reported on climate policy to the British government in 2006, drawing attention, as economists had long been doing, to the case for imposing on consumers the externality costs of their choices.

These include congestion, carbon emissions and damage to air quality in built-up areas. Governments have instead focused predominantly on engineering solutions and on regulatory interventions.

A current example in Dublin is the political support for an underground rail project, MetroLink, for which no definitive cost estimate is available.

If a demand-side solution was to be preferred, the Exchequer would be spared the unknown costs, possibly €15bn or €16bn, and road users on busy routes at peak times would face the full externality costs of their modal choices.

The revenue would become available for alternative priorities, including extra reserved lanes for the bus operators in the city, helping to reduce emissions at low cost. The imperative should always be the search for the most cost-effective solutions, and the avoidance of risk to State finances.