Speaking for the trees

We have an ally in the effort to combat climate change, writes Colin Campbell-Hunt.

Colin Campbell-Hunt.
Colin Campbell-Hunt.

We humans have become very good at pumping carbon into the atmosphere, and thence the oceans. To avoid disrupting a balance that has persisted for at least the last 600,000 years, it would help if something — or some creature — would absorb at least some of this carbon.

That creature is of course a tree. It was only late in life that I learned that trees are made of carbon, sucked out of the very air and converted into those marvellous huge beings. We have few friends in the battle to limit climate change, but trees must be our best living ally. You may have missed it, but March 21 was the International Day of Forests.

We have been  slow to realise how important trees are to our future wellbeing. Instead of expanding the world’s forests, we have been cutting them down faster than we have been planting them,  reducing the amount of carbon they absorb. And less carbon absorbed has the same effect on the amount of carbon in the atmosphere as more carbon emitted.

Over the decade 2000-2009, the Intergovernmental Panel on Climate Change (IPCC) estimates that forest destruction and other changes to land use outweighed the positive contributions of new forest plantings, with a net effect responsible for 12%  of all human-induced additions to atmospheric carbon. Instead of soaking carbon up, we have been cutting down the trees that should be our best ally, primarily to expand agricultural land.

The good news is that the rate at which forests are being destroyed is slowing. Starting in the 1990s, the rate of net deforestation has been falling in all parts of the world except the Mid-East and Africa. Since 2005, an international collaboration known as REDD+ (Reducing Emissions from Deforestation and Forest Degradation) has been working to reduce the incentives on landowners in developing countries to destroy their forests. Brazil, for example, has reduced deforestation by 80%  over the  past decade.

But for the world as a whole, we are still cutting forests down faster than we are planting them. At the rate we are going it will be decades before the world’s forests start to absorb more carbon than they lose. To meet the Paris target of no more than 1.5degC warming, Climate Action Tracker suggests that we should cease net deforestation by 2020. The rewards of making the switch are huge. The World Wide Fund for Nature (WWF) estimates that returning the land that has been cleared back to forests would offset more than 30%  of our current carbon emissions.

You would think that commitments to expand forests would form a key strategy in countries’ efforts to reduce CO2 emissions. But only a few of the countries signing up to the Paris Agreement in 2015 include forest management in their Indicative Nationally Determined Contributions, New Zealand being one of them. The problem is not just that some countries have limited potential to grow trees. More important is a lack of confidence (and trust) in countries’ estimates of the carbon absorbed in their forests. The fear in the international community is that claimed improvements in forest cover would be used to justify limited reductions in CO2 emissions from other sources. Sadly, New Zealand is one country that has contributed to that lack of trust through our history of negotiating emission-reduction targets under the Kyoto Protocol.

We can take more pride in our trees. Forests make up about 30%  of New Zealand’s land area: a substantial store of carbon! The Ministry for the Environment estimates that our extensive indigenous forests store 1.7 billion tonnes of carbon. That amount is growing as areas of indigenous forest regenerate. Unlike many parts of the world, these forests are not being destroyed for agriculture or illegally logged. But these forests grow slowly, and once they are mature their ability to suck more carbon from the atmosphere is reduced. To make a positive contribution to reducing emissions our areas of forest must grow. We need to plant more trees, and we are. The same MfE estimates report that carbon stored in our exotic forests has more than doubled since 1990, totalling 261 million tonnes in 2012.

Relative to the world as a whole, it seems  New Zealand is doing a good job of protecting a substantial proportion of its land area for forestry, and is adding to the carbon stored in our indigenous and exotic forests. The challenge now is to see that growth continue.

Here the story is not quite so promising. Net additions to our forests peaked in 1994 at 90,000ha. Since then, the trend has been downwards and went negative in 2005: we cleared more forests than we planted.  In 2013, removals of forests made up fully one-third of New Zealand’s gross emissions of CO2. To offset this loss of carbon absorption we will have to expand our forests at the same rate as they are being felled, and since 2005 we have failed to do that. It turns out that high levels of planting 20 years or so ago now require harvesting and will continue to do so "well into the future", as we admitted in our contributions to the Paris climate change agreement in 2015.

So the question is, what incentives do New Zealand foresters have to plant?  The Government’s  strategy for promoting carbon reductions and capture is the Emissions Trading Scheme (ETS). Since 2008, foresters have been able to gain New Zealand Carbon Units (NZU) as their trees grow, but  have to return them when the forest is harvested. And NZU are traded: their current value is a little below $20.

So participation in the ETS means that foresters face a financial rollercoaster of asset growth as the trees grow and subsequent liabilities at harvest time. This is thought to be hard for small-scale foresters to manage and a review of the ETS is considering smoothing out these ups and downs. Larger-scale forestry companies can manage by having stands of timber of different ages so that the liabilities at harvest are matched by new-growth forest. 

But the biggest challenge facing New Zealand’s foresters — as in the rest of the world — is that they face a major competitor for land on which to plant trees: agriculture. Putting in place incentives for forestry to plant trees and sequester carbon is only half the job. The same $20 per NZU that foresters have to return when they harvest a forest should also be charged to each tonne of CO2 emitted from agriculture. Until that happens, the incentives will remain to use land for agriculture ahead of forestry.

- Colin Campbell-Hunt is an emeritus professor at the CSAFE Centre for Sustainability, University of Otago. Each week in this column, one of a panel of writers addresses issues of sustainability.


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