Atmospheric carbon dioxide 4 Atmospheric carbon dioxide-Environmental aspects 2 Carbon cycle (Biogeochemistry) 2 Carbon dioxide 2 Climatic changes 2 Atmospheric carbon dioxide-Climatic factors 1 Carbon dioxide enrichment technologies for plant response 1 Carbon dioxide-Environmental aspects 1 Carbon--Environmental aspects. Energy development--Environmental aspects. Atmospheric carbon dioxide--Environmental aspects. Coal mines and mining--Environmental aspects 1 Climate Change Education and Research 1 Climatic changes-Social aspects 1 Consumers-Environmental aspects 1 Environmental impact 1 Forest ecology 1 Forest plants 1 Forest trees 1 Forestry 1 Forests 1 Forests and Forest Trees (Biology and Ecology) 1 Geological carbon sequestration 1 Global warming 1 Greenhouse effect 1 Greenhouse gases 1 Growth 1 IUFRO 1 Ice cores 1 Land use-Environmental aspects 1 Landscape changes 1 Meteorology and Climate 1 Paleoclimatology 1