Tropical forest sustainability: A climate change boon

Improved management of the world's tropical forests has major implications for humanity's ability to reduce its contribution to climate change, according to a paper published today in the international journal, Science.

The authors – Dr Pep Canadell from CSIRO and the Global Carbon Project, and Dr Michael Raupach from CSIRO – say the billions of tons of carbon dioxide (CO2) absorbed annually by the world's forests represents an 'economic subsidy' for climate change mitigation worth hundreds of billions of dollars.

However, concerns about the permanence of forest carbon stocks, challenges in quantifying changes in the size of those stocks, and concerns about the environmental and socio-economic impacts of reforestation programs, have limited the adoption of policies designed to foster forestry activities.

"With political will and the involvement of tropical regions, forests can contribute to both climate change protection through carbon sequestration and also enhanced economic, environmental and socio-cultural benefits," Dr Canadell says.

"Forestry activities have the economic potential to offset 2-4 per cent of projected CO2 emissions by 2030, with tropical regions accounting for nearly two thirds of the total offset".

"A key opportunity is the reduction of carbon emissions from deforestation and degradation in tropical regions," he says.

An estimated 13 million hectares of the world's forested areas – almost exclusively in the tropical regions – are deforested annually. Dr Raupach says, however, reducing rates of deforestation by 50 per cent by 2050, and stopping further deforestation when countries reach 50 per cent of their current forested area, would avoid emissions equivalent to six years of current fossil fuel emissions by the end of this century.

"This estimate shows that even with significant continuing deforestation, the mitigation potential is large, although major changes in governance and price incentives are required to realize this potential," Dr Raupach says.

They authors also note, however, that efforts to mitigate climate change by increasing both the overall area and volume of biota in those forests, does carry the risk that events such as bushfires and insect outbreaks can release massive amounts of sequestered carbon back into the atmosphere.

"Since 2000, for example, increases in the areas of Canada's forests affected by bush fires and insect outbreaks have transformed them from a 'CO2 sink' to a 'CO2 source' – a situation which is expected to continue for the next 20-30 years," Dr Canadell says.

"Forests also affect biophysical properties of the land surface, such as sunlight reflectivity and evaporation, and that climate models suggest large reforestation programs in the boreal (colder) regions of the word could have limited benefits due to the replacement of large areas of reflective snow with dark forest canopies.

"Conversely, the climate benefits of reforestation in the tropics are enhanced by positive biophysical changes such as cloud formation which further reflect sunlight," he says.

Source: CSIRO Australia

Related stories:

Saving Sumatra: Indonesia reaches historic agreement
The Indonesian government and World Wildlife Fund (WWF) today announced a bold commitment to protect the remaining forests and critical ecosystems of Sumatra, an Indonesian island that holds some of the world's most diverse – and endangered – forests. The historic agreement represents the first-ever island-wide commitment to protect Sumatra's stunning biodiversity.
Climate change: Floods, drought, mosquito disease aim at Europe
Climate change will amplify the risk of flooding in northwestern Europe, water scarcity and forest fires on the northern Mediterranean rim and bring milder winters to Scandinavia, the European Environment Agency (EAA) said on Monday.
'Chemical equator' discovery will aid pollution mapping
Scientists at the University of York have discovered a 'Chemical Equator' that divides the polluted air of the Northern Hemisphere from the largely uncontaminated atmosphere of the Southern Hemisphere.
Climate change, human activity and wildfires
Climate has been implicated by a new study as a major driver of wildfires in the last 2,000 years. But human activities, such as land clearance and fire suppression during the industrial era (since 1750) have created large swings in burning, first increasing fires until the late 1800s, and then dramatically reducing burning in the 20th century.
White roofs, streets could curb global warming
The idea of painting our roofs and roads white to offset global warming is not new, but a recent study has calculated just how significantly white surfaces could impact greenhouse gas emissions. Last week, researchers at Lawrence Berkeley National Laboratory and UC Berkeley presented their study at California's annual Climate Change Research Conference in Sacramento.
Oil palm plantations are no substitute for tropical rainforests
The continued expansion of oil palm plantations will worsen the dual environmental crises of climate change and biodiversity loss, unless rainforests are better protected, warn scientists in the most comprehensive review of the subject to date.
World's water ecosystems under threat
(PhysOrg.com) -- Human activities such as fishing and water use are over-riding the effects of global warming on the ecosystems that support the world’s water and fish supplies, experts have revealed.
Bad sign for global warming: Thawing permafrost holds vast carbon pool
Permafrost blanketing the northern hemisphere contains more than twice the amount of carbon in the atmosphere, making it a potentially mammoth contributor to global climate change depending on how quickly it thaws.

News discussion:

Space & Earth science news