Our pressing need to account for terrestrial carbon

We know how much carbon is released by fossil fuel burning, but we are relatively ignorant of what comes out of our farms and forests. The amount of carbon involved is enormous. This is an information battle that we have to resolve. [17 November 2009 | Peter Boyer]

We are in the early stages of knowing the impact of farm and forest activities on the carbon cycle.

We are in the early stages of knowing the impact of farm and forest activities on the carbon cycle.

Humans are land animals. We have ventured into the ocean and learned to exploit its food resources, but all our inherited genetic codes tell us we can’t live without good old terra firma. Our land is our life.

This important fact is starting to make its presence felt in the great climate debate. CSIRO, for instance, has estimated that the Australian landscape is capable of storing an extra billion tonnes of greenhouse gases in soils and vegetation each year for the next 40 to 50 years. Capturing just 15 per cent of this would offset a quarter of Australia’s current emissions.

The Australian Bureau of Agricultural and Resource Economics has said that with forestry offsets included in Australia’s emissions trading scheme, most of the resulting new forests would never be harvested because they would be more valuable as permanent environmental plantings.

Noting the “profound” power of terrestrial carbon to contribute to the climate change solution, Australia’s Wentworth Group of Concerned Scientists reported last month that Australia’s forested and farmed lands held 28 billion tonnes of carbon.

“At a global scale, a 15 per cent increase in the world’s terrestrial carbon stock would remove the equivalent of all the carbon pollution emitted from fossil fuels since the beginning of the industrial revolution,” the report said. With its potential to restore degraded land and biodiversity, this was “an economic opportunity of unparalleled scale”.

But we also need land for food, and the Wentworth report cautioned against over-committing to forest offsets without land and water use controls to prevent carbon forests taking over agricultural land. Nowhere is this problem more apparent than in Tasmania, where thousands of hectares formerly used for food production have been given over to plantation forestry.

So far as food production is concerned, the problem of livestock looms ever larger. This month, a report by Robert Goodland and Jeff Anhang,  two senior environmentalists from the World Bank, offered the startling estimate that over half of all human-induced greenhouse gas emissions comes from livestock, whose numbers are rising strongly in response to a world demand for more meat.

Then there’s the land that’s presently under natural forest, as it has been since time beyond memory. Forest ecosystems are by far the world’s biggest store of terrestrial carbon. We’ve already lost about half of what we once had, through land clearing and forest degradation. We now have to decide how to treat the remaining half.

The burning of fossil fuels has been known for more than half a century to be an important part of our greenhouse emissions, and we can measure it fairly precisely. We know, for instance, the very large energy demands of aluminium smelting makes it a major carbon-intensive industry, and we know the output of coal-fired power generation and oil-powered motor vehicles.

But finding out with reasonable accuracy what our forested and farmed lands store and emit is a much tougher task. Australia set up a CRC for Greenhouse Accounting to research the problem after winning what is turning out to be a pyrrhic victory in 1997 Kyoto Protocol negotiations to include prevention of land clearing in emissions records.

This work is now mainly conducted by CSIRO and Australian National University scientists with Department of Climate Change support. Australia’s National Carbon Accounting System (NCAS) has won accolades for its world-leading work, but all who are involved acknowledge that there remains a mountain of work to be done.

The report on livestock emissions is a wake-up call. We have a long way to go before we can be sure we’re doing things right on farms and in forests to improve our emissions performance.

I’ve had a personal lesson in this. Trying to get a handle on emissions from Tasmanian forestry has been the hardest task I’ve ever attempted. I first wrote in April 2008 of what I saw as a disconnect between some scientific writing about forest carbon storage and Forestry Tasmania’s claims that the industry was carbon-friendly.

In June this year I was sent some information from the Wilderness Society about a “carbon counting” exercise to assess the carbon held in selected Tasmanian forests. The exercise seemed to have been well-planned with a methodology endorsed by forest scientists. It has so far involved 70 people in assessing 12 plots.

I sought Forestry Tasmania’s assessment of this, meeting with General Manager Hans Drielsma and Ken Jeffreys, Corporate Relations Manager. They told me, with some heat, that the Wilderness Society exercise was a waste of effort by a bunch of amateurs without scientific credibility, and that last year’s Green Carbon report by an ANU team was “seriously flawed”.

Dr Drielsma said that assessing a few sample plots here and there could not deliver adequate information. Forestry Tasmania, by contrast, based its assessment on 3000 sites all over the state.

Over the months since then I have sought to find out the basis of Forestry Tasmania’s assertions. I was told I would need special clearance to obtain data from the 3000 sites because it was a major resource commitment. I was referred instead to some of the agency’s publications and reports.

I attempted to marry these with what the outside sources were saying, but it was a comparison of apples and oranges. One side focused on the potential loss of carbon from logging operations in mature forest; the other argued that it was pointless getting data from specific operations because the whole forest estate, with its millions of growing trees, had to be taken into account.

Truth is a casualty of the forest wars, as it is of all wars. While the Tasmanian battles continue, there has been a lot of international discussion about terrestrial carbon. Working out how to manage farms and forests across the world, in developed as well as developing countries, will be a big part of next month’s Copenhagen summit. We may not like what comes out of it.

In our long battle to keep carbon out of the atmosphere, the toughest assignment of all will be to understand how we should manage the life-sustaining resource that is our land.

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