This chapter reveals the microbial processes which may be responsible for the global increase in greenhouse gases (GHG) concentrations and highlights the soil systems holding environmental conditions conducive to significant net GHG release. Various processes lead to GHG emissions from soil and litter to the atmosphere. Human activities lead not only to an increase in GHG concentrations and air temperature and changes in precipitation regimes, but also to rising atmospheric nitrogen deposition and land use change. Rising temperatures and irregular weather conditions are threatening human health, crop production and natural ecosystems. Climate is influenced by CO2 emissions, not only in the course of fossil fuel combustion for energy and vehicles, but also by land use and management. Changes in climate affect vegetation performance and dynamics, with direct and indirect effects on soil processes. Soil microorganisms are constantly processing organic matter, thereby releasing nutrients essential for plant growth.
