Carbon dioxide already released into the atmosphere will have influence on temperatures and climate patterns for many years to come, even if emissions are brought down to zero right this moment.
The perfect example for this is the ozone hole over Antarctica. Although the problem that caused it seemed small at first, the consequences are long-lasting and spread a lot further than expected.
In 1985, just two years after the impact of chlorofluorocarbons (CFCs) was established, international action took place to prevent further release of the compound used in refrigerants and aerosols. Unfortunately, the damage was already done and scientists are still discovering the effects even now.
The hole is now beginning to recover, mainly due to limits imposed on CFCs. But two publications in last week’s issue of the journal Science, outline the effect of the depleted ozone layer on wind and rainfall patterns, ocean circulation, and concentration of greenhouse gases in the atmosphere.
In the first one, Sukyoung Lee and Steven Feldstein, professors at Penn State, show that the depleting ozone layer is the main reason for the movement of the southern jet stream toward the pole. The effect that such movement has is clearly visible in the unusual rainfall patterns in the subtropics.
The process of how the ozone layer influences the movement is not entirely clear, however the authors of the paper explain it by the absorption of ultraviolet radiation by the ozone, which warms the atmosphere.
A decline in ozone therefore leads to less absorption and less heating, which cools the polar lower stratosphere, which consequently influence the the winds in the troposphere.
In the second paper by Darryn Waugh, a climate scientist at Johns Hopkins University, and colleagues, the hole in the ozone layer has been shown to affect wind patterns and amplify ocean currents. Moving towards the Equator, water from deep in the ocean is moved up to the surface at the pole.
The scientists measured the concentrations of CFC-12 to determine whether the water has been at the ocean’s surface.
According to Dr. Waugh, the problem here is that deep waters are carbon-rich because of dead organic matter. If this water is brought to the surface, it absorbs less carbon, affecting the carbon cycle.
Nevertheless, it is predicted that the ozone hole might completely disappear by 2060.
