Can we see the woods for the trees?

Carbon moves between forests, atmosphere and oceans in a complex natural rhythm of daily/seasonal/annual and multi-annual cycles. The overall amount in all three carbon stores together rarely increases in nature. This is ‘active’ carbon. Some carbon is locked away and rarely comes into contact with the atmosphere naturally. This ‘fossil carbon’ is stored permanently in coal, oil and gas deposits and therefore is not part of the active carbon pool. When humans mine and extract these reserves this inactive fossil carbon does not go back in the ground, but is added into the active carbon pool,

On the surface this seems like a terrific idea, however, the debate rages that carbon offsets allow for continued extraction of oil, coal and gas, which in turn increases the amount of fossil carbon that is released into the active carbon pool disrupting the cycle. That is why campaigners argue that genuine solutions to climate change require us to keep fossil carbon (oil, coal and gas) in the ground.

They argue that trees only provide temporary carbon storage as part of the normal cycle of carbon exchange between forests and the atmosphere and can easily release carbon into the atmosphere through fire, disease, climatic changes, natural decay and timber harvesting.

The release of fossil carbon in contrast is permanent and, over relevant time scales, will accelerate climate change by increasing the overall amount of carbon in the atmosphere - the very cause of today’s climate change. Fossil fuels such as coal, oil and gas are locked away and their carbon is only released when humans dig up and burn them for energy. Once released, they become a permanent part of the active carbon pool.

Another concern surrounding tree planting is that there are no guarantees that all these trees will survive. An example of this is where 10,000 trees were distributed to small farmers in a largely dry Indian state, and an investigation found that only a few hundred were still alive. The organisation which had purchased the trees, blamed the Indian company they paid to plant them, that company blamed the people who actually planted them and visa versa. There appears to be little accountability, so how can consumers be sure their trees are still alive?

Additionally, many critics see linking forest restoration with carbon credits as a dead-end for forest peoples as well as for the climate, with monoculture tree plantations occupying land needed by local communities.

Finally, it is widely believed that trees and other plants act as a carbon ‘sink’, absorbing carbon from the atmosphere. But a number of exhaustive scientific studies have emerged which cast doubt on this basic assertion.

* Three to four times more carbon is stored in soils than in the vegetation above.
* Scientists concluded that the Kyoto Protocol’s and voluntary offset companies’ promotion of tree-planting projects will enable them to claim carbon credits for the new planting, while in reality many are releasing huge amounts of CO2 into the air, since most tree-planting involves clearing of vegetation such as grasses which absorb carbon, and exposing the soil.
* A six-year study published in Nature assessed the impact of nitrogen depletion in soils. It concluded that rising atmospheric CO2 levels will affect the availability of nitrogen and other nutrients in soils and thus restrict the ability of plant biomass to absorb carbon. One of the scientists in charge of the US research team behind the study concluded we ‘cannot rely on nature to clean up’ industrial carbon dioxide emissions.

At the crux of the argument against tree planting as a way to save the planet, is the notion that carbon stored temporarily in tree plantations, can justify permanent releases of fossil carbon into the atmosphere without any harm to the climate.
The positive arguments put forward by proponents of planting is that trees have further benefits by providing sustainable eco-environments. They provide habitat for wildlife, encourage biodiversity and beautifying landscapes.
Also, let’s not forget that trees produce oxygen and work like giant green air-filters, constantly purifying our atmosphere, taking out particulate matter and other pollutants.
In addition, a proportion of the land that is being re-forested was previously used as pasture for methane generating animals. Methane is more than 20 times more 'warming' than CO2 so when we replace grazing pasture with trees we get the added benefit of a reduction in atmospheric methane concentrations.

To plant or not to plant – an absorbing question? The good news is that most carbon offset schemes reinforce the same message – loud and clear - that this is just one step in what needs to be a multi-pronged attack on greenhouse gases – and on that point we can all agree.

EDITORS NOTE:
Organic farming saves resources and the climate – Promoting organic farming means mitigating climate change!

Organic agriculture achieves high plant yields by making efficient use of organic residues: To fertilize soils, it uses composted harvest residues and animal manure. This saves 50 to 150 kg, depending upon the crop, in synthetic nitrogen fertilizer per hectare which would otherwise need to be produced using non-renewable fuels.

Studies have shown that conventional arable farming operations consume some 17,000 litres of fossil fuels embodied in fertilisers per 100 hectare of land each year. Worldwide, 90 million tonnes of mineral oil or natural gas are processed to nitrogen fertiliser every year. This generates 250 million tonnes of CO2 emissions.

With their low-impact methods, organic farmers boost soil fertility and the humus content of soils. The result is that the greenhouse gas CO2 is returned to the biomass of the soil. Long-term field trials conducted over many years in Switzerland have shown that compared to other methods of farming (conventional, integrated production) organic farming enriches 12 to 15 percent more carbon dioxide in the soil. This means that organic farms return 575 to 700 kg CO2 to the soil per hectare and year more than other farmers. Scientists in Austria and Germany have confirmed this figure. Organic farming thus reduces CO2 emissions by eliminating synthetic fertilizers, and at the same time reduces atmospheric concentrations of this gas by storing it in the soil – a true win-win strategy.