Human interaction with the land biosphere has contributed to climate change. The land biosphere can play an important role in climate mitigation, through measures such as the management of forests and other carbon sinks, management of agricultural practices, and shifts from fossil-fuel energy to renewable forms of bioenergy. The potential for mitigation must be assessed with regard to the multiple demands for land and the services that ecosystems provide to human society.

Introduction: from human perturbation to biosphere management

Living organisms have co-evolved with the atmosphere, oceans and land surface, contributing to the climate that supports life on Earth today. The increasing human appropriation of the biosphere for food, energy and construction materials, which has brought enormous benefits, has also inadvertently contributed to a loss of biodiversity, widespread pollution, environmental degradation, and climate change.

Human activities have altered the balance of terrestrial greenhouse-gas sources and sinks. The replacement of forests and other natural ecosystems with crops, pastures and urban settlements has caused emissions of CO 2 due to losses from the carbon stock in vegetation and soils, and increased emissions of nitrous oxide (N 2 O ) and methane (CH 4 ) due to diverse agricultural practices.