Carbon sinks are nature’s equivalent of a kitchen sink drain, where we’ve been effectively dumping our carbon pollution. Since the dawn of the industrial era, the planet’s rainforests and oceans have been absorbing roughly half the carbon we’ve been putting into the air.
Amazingly, these carbon sinks have been keeping up with the meteoric rise in emissions, which had scientists scratching their heads in disbelief as they cautioned that eventually, this natural resource would be tapped out. New research is showing that time may have finally come.
The Amazon Has Lost its Appetite
A study conducted by the University of Leeds over a period of 30 years focused on the Amazon— a legendary rainforest that’s accounted for 20% to 25% of all carbon sequestered on land. Initially, the report postulates, all the excess emissions may have boosted the growth of plant life, which breathes in carbon dioxide like humans breathe oxygen.
But according to the university’s research, the amount of carbon dioxide absorbed by the Amazon Rainforest climaxed in the 1990s at around 2 billion tons per year, and its capacity has since dropped by half. The exact causes of this falloff are still being researched, but the report suggests that increased carbon emissions may have caused accelerated growth, and faster death, of plant life in the rainforest— locking up more carbon, but then releasing it as plants decay.
Unfortunately, rainforests aren’t the only carbon sinks showing signs of stress. Scientists are predicting that escalating warming and CO2 will lead to oceans stratifying into separate layers, which will greatly hinder their ability to absorb emissions. Other natural carbon sinks, like the tundra and permafrost, will simply release long-stored carbon and methane as they melt, as northern climates shift from perpetually arctic to above freezing in the summer. What’s worse is that the carbon and methane release will only exacerbate the issue, creating a vicious cycle of warming.
What’s clear is that climate change models relying on carbon sinks operating at current levels need to be revised. We can’t take for granted that rainforests, oceans, and other natural carbon sinks will be able to absorb unlimited CO2— a reality that may lead to accelerated global warming if we don’t curb emissions now.
It’s yet another reason why we need to rally behind an international agreement on climate change at the UN Climate Change Conference this December in Paris. Join the movement by adding your name to the Avaaz petition calling for 100% renewable energy by 2050.