Q: If the ice caps are melting, what is happening to the salt content of the oceans? And might this contribute to weather patterns or cause other environmental problems?
It’s true that the melting of the polar ice caps as a result of global warming is sending large amounts of freshwater into the world’s oceans. Environmentalists and many climate scientists fear that if the climate heats up fast enough and melts off the remaining polar ice rapidly, the influx of freshwater could disturb ocean currents enough to drastically change the weather on the land as well.
The Gulf Stream keeps running because the warmer water travelling north is lighter than cold water, so it floats on top and keeps moving. As the current approaches the northern Atlantic and disgorges its heat, it grows denser and sinks, at which point it flows back to the south, crossing under the northbound Gulf Stream, until it reaches the tropics to start the cycle all over again. This cycle has allowed humans and other life forms to thrive across wide swaths of formerly frozen continents over thousands of years. But if too much dilution occurs, the water will get lighter, idling on top and stalling out the system.
Researchers from Britain's National Oceanography Center have noticed a marked slowing in the Gulf Stream since the late 1950s. They suspect that the increased release of Arctic and Greenland meltwater is to blame for overwhelming the cycle, and fear that more warming could plunge temperatures significantly lower across land masses known as some of the most hospitable places for humans to live.