ABSTRACT
Humans infl uence climate mainly through fossil-fuel, industrial, agricultural, and other land-use emissions that alter atmospheric composition (Doney et al. 2012). Long-lived, heat-trapping greenhouse gases (CO2, CH4, N2O, tropospheric ozone, and chlorofl uorocarbons) warm the surface of the planet, whereas shorter-lived aerosols can either warm or cool at a lower spatial scale (Doney et al. 2012). CO2 is particularly important for the Earth’s climate system. Its worldwide output is enormous, entailing a ~40% increase of its atmospheric concentration over the past 250 years (Danovaro et al. 2011). According to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the global mean surface air temperature increased by 0.74°C whereas the global mean sea-surface temperature rose by 0.67°C over the last century (Trenberth et al. 2007).
