Understanding the ocean is crucial to understanding how Global Warming is progressing. CO2 has been steadily rising in the atmosphere due to human activity, as concluded by a nearly unanimous agreement among climate scientists (and becoming more so each year) . Increasing CO2 traps increasingly more heat on Earth. This new study indicates a possible mechanism for a cyclic, but still rising, heat curve for the planet that has been a puzzle to scientists for decades. I think its important to understand how science works, and why it works, because there is very little that has ever been so fully understood outside of understanding it through science. And that still leaves us with miles to go. This discovery/theory of a heat sink in the Atlantic, as an explanation for the lower than expected surface temperatures recorded over the past 15 years, does not mean the excess heat due to our CO2 has gone away. Its still here, and very much a danger to everything, especially everything that matters to us, or at least should matter to us. The cyclic warming and cooling of surface temperatures, theorized here to be caused by cyclic variations in major ocean currents--either trapping heat at the ocean surface, or drawing it deep into the ocean depths--is believed to be driven by the cyclic freezing and melting of ocean ice. Melting ice affects ocean water salinity, and therefore its density. Melted ice dilutes surface salinity, making it lighter such that it stays near the ocean surface. In the cool portion of the cycle, when the ice remains intact or increases, surface water is high in salinity, and so denser. The denser water sinks to return to the equator in a corresponding sub-oceanic current. The sinking water carries surface heat as much as a mile below the surface where it hides from our measurements. As ocean ice continues to decline in the future due to the Earths long-term warming, its possible there may come a time when there is no more sea ice to sustain this cycle, though it may get a reprise when the melting of Greenland and Antarctica pick up the slack for a while. When that ice is gone, if it hasnt already, the cycle could stop producing lighter water entirely, causing the denser, sinking currents to more rapidly and continuously inject heat deep into the ocean. This is not good for more reasons than I will say here. Were the temperature of ocean depths to rise high enough, possibly even by only a few degrees, it could thaw and release huge volumes of methane known to lie frozen beneath the ocean floor. Methane is another known greenhouse gas that is quite a bit more potent than CO2. Methane stays in the atmosphere for about 10 years, compared to CO2s 100 years, to do its heat trapping thing; it reacts during that time with oxygen to form more CO2 to then spend 100 more years doing the CO2 heat trapping thing. Im not familiar with what models say about whether a methane release would occur over the course of years or decades, or if, by reaching a certain temperature trigger across broad areas, most of it would thaw rather suddenly. Methane release is also a problem in thawing arctic tundra. The additional risk of releasing continent-sized clouds of sulphur dioxide, theorized as a possible explanation for the Permian extinction of 250 million years ago, is something else we dont want to have to...live through. While we dont know completely which energy transport mechanisms will be affected by an increasingly warmer Earth, and in what ways--or if there are yet mechanisms still unknown to science--it seems clearly evident the heat is not just disappearing and can thus be ignored. Trapping heat is the entire problem. Its not about whether we can live with it, its about taking what we are doing seriously, and doing something about it. Trapping heat in the oceans could be far more consequential than a merely warmer atmosphere. Pretending its all some kind of conspiracy to deprive us of our rights makes no sense at all. Understanding science works with a little effort.
Posted on: Thu, 04 Sep 2014 08:57:16 +0000
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