The Seafloor Is Dissolving Away – And Humans Are to Blame
Climate change reaches all the way to the bottom of the sea.
The same greenhouse gas emissions that are causing the planet’s climate to change are also causing the seafloor to dissolve. And new research has found the ocean bottom is melting away faster in some places than others.
The ocean is what’s known as a carbon sink: It absorbs carbon from the atmosphere. And that carbon acidifies the water. In the deep ocean, where the pressure is high, this acidified seawater reacts with calcium carbonate that comes from dead shelled creatures. The reaction neutralizes the carbon, creating bicarbonate.
Over the millennia, this reaction has been a handy way to store carbon without throwing the ocean’s chemistry wildly out of whack. But as humans have burned fossil fuels, more and more carbon has ended up in the ocean. In fact, according to NASA, about 48 percent of the excess carbon humans have pumped into the atmosphere has been locked away in the oceans.
The researchers found that most areas of the oceans didn’t yet show a dramatic difference in the rate of calcium carbonate dissolution prior to and after the industrial revolution. However, there are multiple hotspots where human-made carbon emissions are making a big difference.
The biggest hotspot was the western North Atlantic, where anthropogenic carbon is responsible for between 40 and 100 percent of dissolving calcium carbonate. There were other small hotspots, in the Indian Ocean and in the Southern Atlantic, where generous carbon deposits and fast bottom currents speed the rate of dissolution.
The western North Atlantic is where the ocean layer without calcium carbonate has risen 980 feet (300 meters). This depth, called the calcite compensation depth, occurs where the rain of calcium carbonate from dead animals is essentially canceled out by ocean acidity. Below this line, there is no accumulation of calcium carbonate.
Ozone Hole Recovering
The ozone layer that shields life from cancer-causing solar rays is recovering at a rate of one to three percent per decade, reversing years of dangerous depletion caused by the release of harmful chemicals, a UN study said on Monday.
The four-yearly review of the Montreal Protocol, a 1987 ban on man-made gases that damage the fragile high-altitude ozone layer, found long-term decreases in the atmospheric abundance of controlled ozone-depleting substances and the ongoing recovery of stratospheric ozone.
“The Antarctic ozone hole is recovering, while continuing to occur every year. As a result of the Montreal Protocol much more severe ozone depletion in the polar regions has been avoided,” the report said.
The Antarctic ozone hole was expected to gradually close, returning to 1980 levels in the 2060s, the report said.