Earth’s average ocean surface temperature in July was the warmest since recordkeeping began in 1880, breaking the previous high mark established in 1998, according to an analysis by NOAA’s National Climatic Data Center. An El Niño natural climate variability pattern is currently superimposed on the human-driven global warming trend. The undersea storage of vast amounts of heat has serious implications for humanity’s future.
Ace Associated Press science writer Seth Borenstein covered this story on August 20 (excerpt):
WASHINGTON – The world’s oceans this summer are the warmest on record. The National Climatic Data Center, the government agency that keeps weather records, says the average global ocean temperature in July was 62.6 degrees. That’s the hottest since record-keeping began in 1880. The previous record was set in 1998.
Meteorologists blame a combination of a natural El Nino weather pattern on top of worsening manmade global warming. The warmer water could add to the melting of sea ice and possibly strengthen some hurricanes….The Gulf of Mexico, where warm water fuels hurricanes, has temperatures dancing around 90….It’s most noticeable near the Arctic, where water temperatures are as much as 10 degrees above average.
Breaking heat records in water is more ominous as a sign of global warming than breaking temperature marks on land. That’s because water takes longer to heat up and doesn’t cool off as easily, said climate scientist Andrew Weaver of the University of Victoria in British Columbia. “This is another yet really important indicator of the change that’s occurring,” Weaver said.
Robert Henson, in his outstanding overview The Rough Guide to Climate Change (2008, second edition), says:
The undersea storage of vast amounts of heat has serious implications for humanity’s future. Although the topmost layer of the ocean stays in balance with the atmosphere over timescales of a month or longer, the much deeper layer below the thermocline is more insulated. This means the heat it slowly absorbs from above will take a long time to work its way out. Even if greenhouse gases magically returned to their pre-industrial levels tomorrow, it would take many decades for the heat tucked away in the deep oceans to work its way out of the climate system. This idea of “climate commitment” is a key theme in research leading up to the 2007 IPCC report. Some of these studies estimate that if global greenhouse gas emissions had levelled off in 2000 (which they didn’t), an additional warming of at least 0.5 degrees C (0.8 F) beyond the year-2000 global average would be guaranteed from twentieth-century emissions alone.
Of course, as climate change unfolds, the oceans will do far more than absorb and release heat. Ocean-driven storms, primarily tropical cyclones, are showing signs of strengthening as their fuel source heats up. Sea levels are rising, too. Much of this is due to the expansion of ocean water as it warms…but over time the rise will be increasingly enhanced by glacial melting. Furthermore, the uneven pattern of ocean warming will influence how, where and when a variety of ocean-atmosphere cycles unfold. This could spell the difference between a life of plenty or a life of poverty for millions of people living close to the land in drought- or flood-prone areas. (pp.106-7)