Can trees save the world?

WTPL/Dick Todd

Photograph: WTPL/Dick Todd

Aren’t trees amazing? From the tiniest seed they can grow into the largest of living things, bestowing a wealth of benefits upon the wildlife that clambers, crawls, flits and buzzes among their branches. Trees provide food and shelter, regulate and cleanse water supplies. They offer protection against soil erosion and the worst impacts of wind and tides. They even create wonderlands for us to visit.

All this they do using the barest minimum of raw materials. Sunlight drives photosynthesis, the process by which the sugars that fuel growth are created. And as a tree grows it locks up tonnes of carbon – the stuff we have been blasting into the atmosphere in increasing quantities ever since we first discovered how to dig coal and suck oil out of the ground.

The world’s ecosystem depends on trees. Yet on a global scale, deforestation accounts for almost one fifth of all greenhouse gas emissions. That’s more than the entire transport sector – every ‘plane, train, automobile, ocean liner, ferry, cargo ship and oil tanker. Deforestation is a double whammy too: when the forests go, so does their ability to draw, or sequester, carbon dioxide out of the atmosphere. Losing trees means both emitting carbon and losing the ability to remove it.

We must all reduce our greenhouse gas emissions, but also accept that some are inevitable. These “residual” emissions – those that are currently impossible or simply too expensive to avoid – can be “offset” by reducing emissions elsewhere. Carbon offsetting schemes cover a range of activities, including methane (a far more potent greenhouse gas than carbon dioxide) capture at landfill sites, providing more efficient wood-fuelled cooking stoves to people in developing countries, and investing in renewable energy projects. Most offset schemes concentrate on avoiding emissions: planting trees is unique in that atmospheric carbon is actually sequestered.

Carbon offset schemes have attracted criticism. Some say they do nothing to address the important issue of emissions reduction; others point to the many projects that have failed to deliver their objectives. However, properly regulated and monitored projects can play a role in helping to reduce global emissions of greenhouse gases, and the fact that some past schemes have failed does not necessarily doom future schemes to the same fate.

The Woodland Trust is developing a range of carbon offset products that allow companies and individuals to offset their unavoidable emissions by helping us to plant native trees in the United Kingdom. According to our conservative estimates, planting five trees removes at least one tonne of carbon dioxide from the atmosphere by the time the trees have reached maturity. A hectare of woodland – an area roughly the size of one and a half football pitches – can absorb and store more than 100 tonnes of carbon, equivalent to the average annual emissions of more than thirty cars, or ten people in the UK.

Once planted, the trees need time to grow. We aim to look after our woodlands in perpetuity. Trees planted as part of a carbon offset scheme are therefore assured of permanence. We can’t do much to prevent occasional losses, whether through fire, wind, drought, flood or disease, but we plant additional trees as an insurance policy, should the worst happen.

Without funding from the sale of carbon offsets, those trees cannot be planted. Although the money doesn’t pay for the full cost of acquiring, preparing and planting the land, then maintaining the trees and managing their early survival, it nevertheless pays for a vital chunk of it. That ensures that the trees are additional – they would not have been planted without that funding. The remaining cost is sought through our many fundraising activities, which include grants from the government and other bodies such as the Heritage Lottery Fund.

Carbon sequestration is not the only benefit that planting trees can bring in the fight against global warming. Because our focus is on planting close to existing ancient woodland, we can provide wildlife with additional habitat into which it can expand as climatic conditions change. The very act of tree planting is symbolic of a human reconnection with the natural world: by engaging people to think about their dependence on trees, so much more can be changed than simply drawing a few tonnes of carbon dioxide out of the sky.

Offsetting our emissions is by definition not the solution to the climate challenges we face, but it can play an important role as the final step in a process of emissions reduction. It should not be seen as a licence to continue with “business as usual”, but as a way to focus attention on the ecological and humanitarian crisis that – after decades of unheeded warning – is now unfolding.

The UK’s native woodland is our equivalent of the rainforest. Helping to increase the UK’s woodland cover not only provides direct benefits to both ourselves and our wildlife, it also sends a powerful message that we are doing everything we can to restore our damaged ecosystem.

Planting trees gives us a small, hopeful way to put right the wrong. But that hope, just like a planted seed, can in time grow into something of inspirational stature. If there is one thing we can do for the environment right now it is this: plant more trees.

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What are the best ways of controlling and reducing greenhouse gas levels?

The Trust ranks these in increasing order of importance

1. Planting new woodland to allow carbon dioxide to be taken up from the atmosphere.
2. Protecting the carbon stored in existing woodland (and other stores such as peat soils).
3. Changing products and materials that use high amounts of energy (eg concrete and aluminium) to those that use less energy.
4. Using renewable energy which achieves genuine reduction in carbon dioxide emissions.
5. Reducing energy use and increasing energy efficiency.

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