Africa’s tropical forests ‘absorbing more carbon’

Trees across the tropics are getting bigger and offering unexpected help in the fight against climate change, scientists have discovered.

A report in the Guardian newspaper described how a study of the girth of 70,000 trees across Africa has shown that tropical forests are soaking up more carbon dioxide pollution that anybody realised.

Almost one-fifth of our fossil fuel emissions are absorbed by forests across Africa, Amazonia and Asia, the research suggests in the journal Nature.

Simon Lewis, a climate expert at the University of Leeds, who led the study, said: “We are receiving a free subsidy from nature. Tropical forest trees are absorbing about 18% of the carbon dioxide added to the atmosphere each year from burning fossil fuels, substantially buffering the rate of change.”

The study measured trees in 79 areas of intact forest across 10 African countries from Liberia to Tanzania, and compared records going back 40 years. “On average the trees are getting bigger,” Lewis said.

Compared to the 1960s, each hectare of intact African forest has trapped an extra 0.6 tonnes of carbon a year. Over the world’s tropical forests, this extra “carbon sink” effect adds up to 4.8bn tonnes of CO2 removed each year – close to the total carbon dioxide emissions from the US.

Although individual trees are known to soak up carbon as they photosynthesise and grow, large patches of mature forest were once thought to be carbon neutral, with the carbon absorbed by new trees balanced by that released as old trees die.

A similar project in South America challenged that assumption when it recorded surprise levels of tree growth a decade ago, Lewis said.

His study, he added, was to check whether the effect was global.

The discovery suggests that increased CO2 in the atmosphere could fertilise extra growth in the mature forests.

Lewis said: “It’s good news for now but the effect won’t last forever. The trees can’t keep on getting bigger and bigger.”

Helene Muller-Landau of the Smithsonian Tropical Research Institute in Ancon, Panama, used a commentary piece in Nature to suggest that the forests could be growing as they recover from past trauma.

“Tropical forests that we think of as intact [could have] suffered major disturbances in the not-too-distant past and are still in the process of growing back,” she said.

Droughts, fire and past human activity could be to blame, she added: “This recovery process is known as succession and takes hundreds or even thousands of years.”

The research comes as efforts intensify to find a way to include protection for tropical forests in carbon credit schemes, as part of a new global climate deal to replace the Kyoto protocol.

Lee White, Gabon’s chief climate change scientist, who worked on the new study, said: “To get an idea of the value of the sink, the removal of nearly 5bn tonnes of carbon dioxide from the atmosphere by intact tropical forests should be valued at about £13bn per year.”

David Ritter, senior forest campaigner at Greenpeace UK, said: “This research reveals how these rainforests are providing a huge service to mankind by absorbing carbon dioxide from our factories, power stations and cars.

“The case for forest protection has never been stronger, but we must not allow our politicians to use this as an excuse to avoid sweeping emissions cuts here in the UK.”

Source: Guardian newspaper

Date: 18/02/2009

Rich nations ‘must fund global forest preservation effort’

The international community should enable tropical forest nations to halve the rate of deforestation by 2020.

The assertion was among the recommendations made in an independent report commissioned by the UK prime minister.

The Eliasch Review, entitled Climate Change: Financing Global Forests, also said that industrialised nations should look to make the global forest sector “carbon neutral” by 2030.

Its main findings included:

  • Reducing emissions from deforestation should be fully included in any post-2012 global climate deal, which is expected to be struck at the key UN summit in Copenhagen next year.
  • National governments should develop their own strategies to combat deforestation in tropical forest nations.
  • Rich nations should provide financial support to establish the necessary mechanisms to deliver the goals of halving deforestion by 2020 and making the global forest sector carbon neutral by 2030.

The review estimates that the costs to build the necessary mechanisms will be up to $4bn over five years for 40 forest nations.

The review, headed by Swedish businessman Johan Eliasch, was set up by Gordon Brown in order to pull together a comprehensive analysis of the financing and mechanisms needed to support sustainable forest management and reduce emissions resulting from deforestation.

“Saving forests is critical for tackling climate change,” Mr Eliasch said.

“Without action on deforestation, avoiding the worst impacts of climate change will be next to impossible, and could lead to additional climate change damages of one trillion dollars a year by 2100.

He added that deforestation would continue for as long as cutting down and burning trees was more profitable than preserving them.

“Access to finance from carbon markets and other funding initiatives will be essential for supporting forest nations to meet this challenge.”

Mr Eliasch is Mr Brown’s special representative on deforestation and clean energy.

Source: Eliasch Review press release

Date: 14/10/2008

Old forests ‘continue to capture plenty of carbon’

Planting a new tree may be a less effective way to sequester carbon than saving an old tree from the axe, writes’s Emma Marris.

A study in the journal Nature shows that old forests continue to accumulate carbon at a much greater rate than researchers had previously thought, making them more important as carbon sinks that must be factored into global climate models.

Until recently, it was assumed that very old forests no longer absorbed carbon.

The only new growth occurred in the small spaces that opened up when large old trees died and decomposed, releasing their accumulated carbon. The forests at large were therefore considered to be carbon neutral, and accounted as such in climate models.

However, in the past decade or so, murmurs of disagreement with this idea have grown louder, and individual projects have found that even very old forests are capable of storing carbon thanks to tree growth, the addition of new trees and a decreased rate of respiration in old trees.

Since the mid 1990s, more sophisticated data collection projects have measured carbon fluxes in forests around the world. In particular, data has been shared between members of FLUXNET, a global network of observatory towers that measure the exchange of carbon dioxide, water vapour and energy between ecosystems and the atmosphere.

Now Sebastiaan Luyssaert of the University of Antwerp, Belgium, and his colleagues have taken advantage of all this new data to produce a meta-analysis of studies that monitored 519 plots of temperate and boreal forest between 15 and 800 years of age.

Their conclusion, published in Nature this week, is that old-growth forests are, in general, still absorbing carbon1. Primary boreal and temperate forests, which make up 15% of global forests, sequester about 1.3 gigatonnes of carbon a year, give or take half a gigatonne. That amounts to about 10% of the global net ecosystem productivity, which was previously accounted for elsewhere].
Dying dogma

The conclusion makes sense, according to Susan Ustin, a plant ecologist at the University of California, Davis. When determining the age of a tree, one counts its rings. Each of those rings represents the transformation of atmospheric carbon into the living tissue of the tree.

In any one year, the death and decomposition of roots or branches may outweigh the carbon sequestered in the trunk – but over time, any significant growth must involve net carbon uptake. “If they are carbon neutral at 400 years old, how are they going to make it to 1,000?” she asks.

“If it was really carbon neutral, the trees would die.”

Overturning the old idea that mature forests are carbon neutral may be the work of more than one paper, and this certainly isn’t the first to propose that they continue to absorb the greenhouse gas. But Luyssaert hopes this analysis will help tip the scales. “Just challenging the dogma isn’t new, but the data that has been used to challenge it was a lot more limited in the past,” he says.

The implications are many. Scientists who were assuming that old-growth was carbon neutral may have consequently been overestimating sequestration in other ecosystems.

Climate models may have to be re-examined. And policies that give credits to governments or companies for sequestering carbon may want to incorporate the protection of old-growth forests into their menu of options.

Indeed, the heartwarmingly green action of planting a tree may actually be second-best to keeping an old tree from the axe: “probably for a couple hundred years, until the young one got big enough to have the same amount of carbon as one of these old trees,” estimates Ustin.

Tim Griffis, a University of Minnesota researcher who mans one of FLUXNET’s observation towers, adds that the work “shows the power of the FLUXNET network”.

But that network is getting harder to operate, as it segues from being cutting-edge research into part of a longer-term dataset. “Many in the community are already finding it difficult to keep their sites funded,” says Griffis.

“I think there does need to be a serious conversation about how we are going to keep this record going.”


Date: 10/09/2008

Costa Rica tree-planting ‘carbon neutral’ project

Costa Rica has announced plans to embark on a tree-planting project in order to make the biodiversity hotspot nation carbon neutral.

Plane tree leaves and fruit

The goal for 2008 is to plant seven million trees, which officials say will equate to 1.5 trees per person.

The Costa Rica Conservation Trust, which is not directly connected to this proejct, says nearly 26% of the nation’s land is protected in the form of national parks and private preserves, and holds around 6% of the world’s bio-diversity.

But the Trust adds that there are few corridors of protected areas to link together the national parks and reserves and illegal loggers and poachers seek out farmers and landowners boardering national parks by offering them bribes for access through their properties and into the national parks and reserves.

Here is the report from AFP:

SAN JOSE (AFP) — Costa Rica will plant seven million trees in 2008 to soak up as many greenhouse gas emissions as it produces, in a bid to become the world’s first carbon neutral nation, a top official said Monday.

“The stated goal is to be the first neutral country as far as greenhouse gas emissions is concerned,” said Energy and Environment Minister Roberto Dobles.

“To get there, this administration is betting on halting deforestation and on the ‘Plant a Tree’ project,” he added, referring to an ongoing government initiative to plant as many trees as possible in the country.

The project aims to “plant seven million trees this year, meaning that in our country there would be 1.5 trees for each Costa Rican.

He added that in 2007 the country managed to plant five million trees, spurred by the desire to forestall an impending environmental catastrophe.

“Climate change is the main threat facing humanity and, even so, the world still can’t agree to fight this problem,” Dobles said.

Every country can help in the struggle, even a small nation like his own, Dobles said.

“We all know developed countries and big developing nations like China, Brazil and India are chiefly responsible for most of the greenhouse gases that destroy the ozone layer.

“That doesn’t mean a country like Costa Rica should stand by doing nothing. On the contrary, we’re working on a series of initiatives on the national and global levels to lessen the impact” of climate change, the minister said.

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