September ozone hole has shrunk by 4 million square kilometers since 2000.
Scientists at MIT and elsewhere have identified the “first fingerprints of healing” of the Antarctic ozone layer, published today in the journal Science.
The team found that the September ozone hole has shrunk by more than 4 million square kilometers — about half the area of the contiguous United States — since 2000, when ozone depletion was at its peak. The team also showed for the first time that this recovery has slowed somewhat at times, due to the effects of volcanic eruptions from year to year. Overall, however, the ozone hole appears to be on a healing path.
The authors used “fingerprints” of the ozone changes with season and altitude to attribute the ozone’s recovery to the continuing decline of atmospheric chlorine originating from chlorofluorocarbons (CFCs). These chemical compounds were once emitted by dry cleaning processes, old refrigerators, and aerosols such as hairspray. In 1987, virtually every country in the world signed on to the Montreal Protocol in a concerted effort to ban the use of CFCs and repair the ozone hole.
“We can now be confident that the things we’ve done have put the planet on a path to heal,” says lead author Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT. “Which is pretty good for us, isn’t it? Aren’t we amazing humans, that we did something that created a situation that we decided collectively, as a world, ‘Let’s get rid of these molecules’? We got rid of them, and now we’re seeing the planet respond.”
A reduction in the amount of oxygen dissolved in the oceans due to climate change is already discernible in some parts of the world and should be evident across large regions of the oceans between 2030 and 2040, according to a new study led by the National Center for Atmospheric Research (NCAR).
Scientists know that a warming climate can be expected to gradually sap the ocean of oxygen, leaving fish, crabs, squid, sea stars, and other marine life struggling to breathe. But it’s been difficult to determine whether this anticipated oxygen drain is already having a noticeable impact.
“Loss of oxygen in the ocean is one of the serious side effects of a warming atmosphere, and a major threat to marine life,” said NCAR scientist Matthew Long, lead author of the study. “Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it’s been challenging to attribute any deoxygenation to climate change. This new study tells us when we can expect the impact from climate change to overwhelm the natural variability.”
The study is published in the journal Global Biogeochemical Cycles, a publication of the American Geophysical Union. The research was funded by the National Science Foundation, NCAR’s sponsor.
NCAR has multiple facilities, including the I. M. Pei-designed Mesa Laboratory headquarters in Boulder, Colorado. Studies include meteorology, climate science, atmospheric chemistry, solar-terrestrial interactions, environmental and societal impacts.
- Computational & Information Systems Laboratory (CISL)—The CISL was formerly known as the Scientific Computing Division (SCD). CISL manages and operates NCAR’s supercomputers, mass storage system, networking, and other computing and cyberinfrastructure services. The Institute for Mathematics Applied to Geosciences (IMAGe) is a research division within CISL.
- Earth Observing Laboratory (EOL)
- High Altitude Observatory (HAO)
- NCAR Earth System Laboratory (NESL)
- Research Applications Laboratory (RAL)