John FitzGerald: Forestry and timber houses are the way forward

State needs to look to trees and their rich capacity to offset fossil fuel emissions

On some of the specimen trees in Fernhill Park, Dún Laoghaire Rathdown Council has labelled the amount of carbon they store. A very fine Giant Redwood there has sequestered 7.5 tonnes of carbon dioxide, equivalent to over half the average annual emissions per person of greenhouse gases in Ireland. It has, however, taken over 100 years for this tree to reach maturity.

This example of what a single tree can absorb, albeit a particularly large one, illustrates the potential that afforestation offers to tackle climate change. The agreement at Cop26 to tackle deforestation, however loose it may be, reflects the important capacity of trees to offset fossil fuel emissions.

When forest cover is reduced, as is happening in the Amazon, greenhouse gases are emitted as trees are cut down and burned. To make a net difference to climate change, we need not only to replace this lost resource, but also to expand the overall extent of forest coverage.

Because much of Europe already has quite extensive forestry, there is limited capacity to expand such cover. However, here in Ireland, we still have plenty of potential to build back the forestry we lost to shipbuilding and barrel staves in the 17th century.


The Climate Change Advisory Council’s research suggests we could remove 100 million tonnes of carbon dioxide from the atmosphere by 2050 through expanding forestry, combined with measures such as rewetting bogs. To achieve this, we would need to expand the planting programme well beyond what is currently taking place.

Mature harvest

Such new forestry would still only constitute a small share of agricultural land. This work should start immediately, as it takes time before young trees begin to suck up carbon.

Carbon dioxide in 2050 is priced at €256 a tonne in the Public Expenditure Guidelines, reflecting the vital importance of ending greenhouse gas emissions. That price would value new afforestation up to 2050, sequestering 100 million tonnes of carbon, at over €25 billion.

When trees are harvested at maturity, the effect on atmospheric greenhouse gases depends on what happens to the timber. If it is burned, the carbon sequestered over the life of the trees is released into the atmosphere. But if replanting replaces what has been cut down, then the carbon released is offset over the lifetime of the new trees.

However, if the cut timber is used to build homes, then the carbon remains fixed for a further 50 to 100 years, adding to the value of our forests.

Most Irish homes are built from cement blocks. About 6 per cent of Irish greenhouse gas emissions come from cement, and these emissions are technically difficult to abate. Ramping up our housebuilding programme is likely to increase those emissions, unless we change how we build.

In the US and most of Europe, houses, and even some apartments, are largely built with timber. Traditionally, that was favoured as a cheaper and faster way to build, not for environmental reasons.

Cheap and fast housing

If we were to adopt these tried-and-tested timber-based construction methods, we would reduce emissions from cement, and sequester carbon for longer in our forest products. In the long run, it could make for cheaper and faster housing. A win-win.

For these benefits to be realised, there would have to be a commitment to timber-based technology. Our builders and their teams would need training in alternative building methods, based on assembly of prefabricated panels. We would need to build new factories to create the required precision timber-based panels.

Housing for All was silent on timber-framed housing, but the Department of Housing needs to take a leadership role on this. The Land Development Agency could help drive such a change in technology via its role in the social housing building programme.

The policy obstacles to reaping the major environmental benefits from forestry need to be tackled.

Coillte should have an expanded mandate to drive afforestation at scale. This was inhibited by a court case in the 1990s on state aids. Europe might be encouraged to revisit this restriction in the light of the climate crisis.

The Government needs to replace the current licensing regime, which is preventing forest development, with a regulatory regime run by the Environmental Protection Agency. That regime should set appropriate standards, leaving farmers and foresters free to get on with planting trees, and harvesting them when mature.

If we want farmers to plant more trees, they need to know they will be able to harvest and replant in due course, so they will have the incentive to do so today.