The Millennium Ecosystem Assessment has demonstrated that humans are already undermining or even threatening the capacity of many of the world's terrestrial ecosystems to deliver essential services to humanity. Land use is one major factor that may act as a stressor on ecosystems and has been shown to be able to alter global biogeochemical cycles as well as influence biodiversity on local, regional and even global scales. Climate change will affect land systems both directly, i.e. through impacts of changes in temperature, precipitation or CO2 concentration on terrestrial ecosystems and indirectly, i.e. through climate-response measures (mitigation, adaptation) taken by human societies. The results of this analysis suggest that large-scale schemes to substitute biomass for fossil fuels should be viewed cautiously, as massive additional pressures on ecosystems might result from increased biomass harvest.