The earth’s lands and oceans “are becoming steadily less effective at removing excess carbon dioxide from the atmosphere,” making it that much more urgent to get on with deep reductions in greenhouse gas emissions.
“The ocean and the land (including vegetation and soils) are carbon ‘sinks’ that currently absorb more than half of all human-caused carbon dioxide emissions,” ThinkProgress explains. “Scientists have long been concerned that these sinks will become increasingly ineffective at absorbing CO2—because of global warming itself. That would mean a greater and greater fraction of human-caused carbon pollution would stay in the air, which would speed up climate change.”
Study co-author Dr. Josep Canadell, executive director of the Global Carbon Project, noted that “clearly Nature is helping us” by absorbing much more atmospheric carbon than it will in future decades. As that capacity declines, “for every ton of carbon dioxide we emit into the atmosphere, we are leaving more and more in the atmosphere” each year.
Romm lists several other studies that reach similar conclusions. “The bottom line is that our best shot at stopping catastrophic warming is to start cutting carbon pollution immediately,” he writes. “The longer we wait, the less nature’s carbon sinks will be able to help us and the greater the risk that we cross tipping points that cause feedbacks like the permafrost melt to become ‘self-reinforcing.’”