In 1997 a second international association was created, the International Association for Environmental Philosophy, with an emphasis on _____________________________. It publishes a journal called Environmental Philosophy.
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A long-term ____________ between these natural sources and sinks leads to the background, or natural, level of CO₂ in the atmosphere.
Human activities increase atmospheric CO₂ levels primarily through the burning of ____________.
The next most significant greenhouse gas is surface, or low-level, _________.
A carbon footprint is composed of two parts, a primary and _____________ footprint.