• 1700 CO2↑
○ Fossile fuel: greater increase
• [AA]: northern hemisphere= carbon sink
○ Area and density of a forest
§ e.g. since 1920
○ Release or absorbe?
§ Wood: added VS. lost
○ Carbon source → carbon sink
§ source
□ Before 1890
® Bcz: fire and logging
§ Sink
□ After 1920
® Bcz: tree growth↑