A London, England newspaper, the Daily Mail, recently ran a headline “ Myth of Arctic meltdown: Stunning satellite images show summer ice cap is thicker…than two years ago” This was rapidly picked up and shot around the blogosphere as a renunciation of the risk of Global Warming.
Really? REALLY? Based on two data points the paper decides that the work of literally thousands of scientists around the world is all wrong. No, no, no. The trend over the last 30 years of sea ice measurement show that the ice is thinning and the area of coverage is shrinking. Even the casual observer will notice that measurement of climatic variables is confounded by the fact of wide variations in both time and space in virtually all the variables – temperature, rainfall, seal level, etc.
We have warm years and cold years, but overall it is getting warmer when all the planet’s surface and air temperatures are averaged. Even though it has been a relatively cool (and wet) summer here in the central Arkansas, the warmest June in the history of recorded measurements happened in 2014. Given this is just one data point, but how about this: 9 of the 10 hottest Junes ever happened in the 21st century.
Another misleading claim is that global warming has stopped or at least slowed over the last few years. It is true that over the last few years it has not been getting hot as fast as previous years. The rate of heating has slowed somewhat, but only when you average surface and air temperatures as mentioned above.
The causative agent for global warming, the amount of heat trapping gasses in the atmosphere, are inexorably increasing, hence the a factor called radiative forcing is increasing. The real question is where is the missing heat. An article published recently in Science, the premier peer reviewed science journal published in the United States, has the answer.
It’s hiding in intermediate depths of the Atlantic and Southern Oceans. New data coupled with reanalysis of previously collected data show that a recurrent anomaly in salinity is the culprit. Changes in the saltiness of water affect its density, which can cause upwelling of the colder deeper water. When the colder water is brought to the surface it warms, absorbing heat.
Major ocean currents such as the Gulf Stream are driven by these kinds of differences in temperature and salinity. The Gulf Stream transports heat from Florida to Europe. Disrupt it and it could get hotter in Florida and colder in Europe.
In a related story, seeps of methane have been detected in the Atlantic ocean. Much methane lies near the continental shelf trapped in ice crystals known as clathrates. Warming of the water in the area of the clathrates could cause thawing which would release the methane.
The story gets even scarier when you consider that methane is a powerful heat trapping gas itself. Global warming is causing the release of methane which causes more global warming which causes more methane release – and around and around we go.