The Incredible Carbon Storage of Giants Grove

Written by Sean

January 25, 2023

The joint Crann – Trees for Ireland and Birr Castle Giants Grove Project at Birr, Co. Offaly is the largest Redwood Forest outside of the USA. Already in its fifth year, one thousand redwoods have been established amongst native broadleaves on previously bare ground. The project has a wide range of environmental benefits from protecting the sequoia species from the effects of climate change, to providing new diverse habitats for protected and endangered flora and fauna. However, the Grove’s greatest benefit may be in its phenomenal ability to capture and store carbon – carbon sequestration.

What is Carbon Sequestration?

The world’s climate is changing, this last decade has been the hottest on record and the next will be even hotter as we continue to produce and burn fossil fuels on a massive scale. Carbon sequestration is one pillar of decarbonisation we can use to limit global warming in the long term. Trees absorb carbon from the atmosphere during photosynthesis as CO2 and it is then stored as wood in their stem, roots, and branches. Carbon generally makes up about 50% of the dry mass of wood, and as long as the tree is alive that carbon is trapped and cannot return to the atmosphere.

Redwood Carbon Storage

Giants Grove is home to both Giant Redwoods (Sequoiadendron giganteum) and Coastal Redwoods (Sequoia sempervirens), the largest and tallest tree species on Earth that take 1,200 years to reach maturity and can live up to 2,500 years. Different tree species store carbon at different rates, on different sites, but an average tree will typically sequester 1 ton of carbon in its lifetime. However, coastal redwoods can sequester up to 250 tonnes of carbon, and giant redwoods can sequester even more – the carbon stored in the famous General Sherman giant redwood has been calculated at 392 metric tonnes!

Giants Grove Impact

Even using the UK Forestry Commissions conservative figures, the 1,000 redwoods in Giants Grove will store more carbon in their lifetimes than 250,000 average trees, and the main reason for this is their longevity. That is a truly amazing statistic and doesn’t even account for the native Irish broadleaves growing among them.

In just 100 years the Redwoods at Giants Grove will store over 2,600 metric tonnes of carbon per hectare, and the 8 hectares at Birr Castle will sequester a whopping grand total of just under 21,000 metric tonnes of carbon from our atmosphere in that time. And remember, these giants take 1,200 years to reach maturity, and the total carbon sequestered during the grove’s lifetime could be as high as 250,000 tonnes. That is an enormous amount of carbon to be absorbed from the atmosphere and safely stored away at Birr, Co. Offaly, Ireland.

Carbon sequestration is a hot topic these days, and rightly so, we all must do whatever we can to reduce our emissions and offset our carbon footprints. Forestry and afforestation is not the quick solution to climate change, but it can be a major part of the long-term solution. And if it’s done right, afforestation will not only store carbon, but will provide food, shelter, and habitat, for countless species, and provide a much-needed sanctuary from our hectic, stressful, lives. Giants Grove takes so much carbon from our skies, and it gives so much more in return.

To learn more about Giants Grove or to sponsor a Redwood, visit

The Giants Grove Project is an Partnership between Birr Castle Estate and Crann – Trees for Ireland, it is managed by Ecoplan Forestry.

Sean McGinnis Ecoplan Forestry

Tags: carbon sequestration, carbon storage, giant redwood, Giants Grove, sequoia

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