Planting forests for carbon sequestration

Preserving forests and planting new trees

Undertaking carbon-offset forestry
Reafforesting to reduce atmospheric carbon dioxide
Sequestering carbon in trees

Description

Using forest projects to mitigate global warming by increasing the global uptake of carbon from the atmosphere.

Context

Global CO2 emissions from sources such as car exhausts and industry are predicted to double between now and 2050. More CO2 means that trees will grow faster and lock up more carbon. This led some to hope that plants might mop up all the extra gas.

This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities.

Agenda 21 recommends compiling and analysing research data on species/site interaction of species used in planted forests and assessing the potential impact on forests of climatic change, as well as effects of forests on climate, and initiating in-depth studies on the carbon cycle relating to different forest types to provide scientific advice and technical support.

The 1995 Inter-governmental Panel on Climate Change (IPCC) assessment states that if various measures are implemented in the forestry sector, it is estimated that between 1.1 and 1.8 Gt C per year can be sequestered in 50 years. As such, the possibility of emission reductions in forestry and the potential for increasing carbon sequestration gives the sector an elevated role in measures to mitigate climate change.

The United Nations Framework Convention on Climate Change (UNFCCC) was established in 1992 at the United Nations Conference on Environment and Development (UNCED) held in Rio de Janeiro, Brazil. Its main objective is to stabilize atmospheric greenhouse gases (GHG) concentration at a level that would prevent dangerous anthropogenic interference with the climate system." The Convention is a treaty which provides a framework of principles and processes through which subsequent protocols or specific mechanisms and actions can be developed and agreed. The Kyoto Protocol, which emanated from the Third Conference of the Parties (COP3) to the UNFCCC held in Kyoto, Japan in December 1997, is one such agreement.

Implementation

The Netherlands Face Foundation is using the mechanism of "joint implementation", under the Framework Climate Convention on Climate Change, to increase its global carbon sinks. Face is an acronym for "Forests Absorbing Carbon Dioxide Emissions" and was founded in 1990 by the Dutch Electricity Generating Board with the objective of planting forests in order to compensate for the emissions of carbon dioxide (CO20 in the Netherlands. It plans to finance 150,000 hectares of new forest in the next 25 years which will fix 75 million tonnes of CO2 – as much as a 600 MW coal-fired power station will emit in its lifetime. The first Face projects started in 1992. Apart from four small afforestation projects in the Netherlands, the Foundation has contributed to the maintenance of 16,000 hectares of forest in the Krkonoše National Park in the Czech Republic and the restoration of 25,000 of forest on Sabah, Malaysia. Some 75,000 hectares are being reforested on the slopes of the Ecuadorian Andes and 27,000 hectares of degenerated rain forest are being reforested on Kalimantan, Indonesia.

Claim

While some terrestrial sources are likely to increase CO2 emissions due to warmer climates and expanding agriculture, increased international actions to sequester carbon in forests and soils and continued increase in carbon dioxide fertilization effects could more than offset them. (At least twice as much carbon is locked in soils than above ground in natural vegetation.) Studies suggest that total terrestrial sequestration over the next century may vary from 75 to more than 700 GtC, depending on the emissions and source/sink scenarios used.

Counter-claim

The world cannot rely on trees to solve the problem of CO2 emissions. Forests will be less effective at slowing climate change than expected. A four-year experiment placed trees in a CO2-enriched atmosphere mimicing that predicted for 2050. They converted 27% more carbon dioxide into plant matter than at control sites. However, even if this extra growth occurs in existing temperate forests all over the world in 2050, the trees will only absorb 10 per cent of human-generated CO2.

As CO2 levels rise, the atmosphere will warm, causing more fires in forests and releasing more carbon. The warmer climate could also speed up breakdown of leaf litter by microbes, releasing yet more CO2 into the atmosphere. The breakdown of leaf litter is already releasing large amounts of carbon in the rivers and wetlands of the Amazon rainforest. This means the forest may be releasing as much CO2 as it absorbs, if not more.