photo by DAVID L. RYAN/GLOBE STAFF Bicyclists in Falmouth.
Global warming? What global warming? Bostonians who trudged back to work after Labor Day may be wondering where global warming went during what seemed like a particularly cool summer.
In fact, this summer’s temperatures have been pretty much dead-on average in Boston and many cities in the Northeast, according to an analysis by climatecentral.com.
Elsewhere, though, it’s been pretty hot in much of the world during the same time period, according to the National Climatic Data Center of the National Oceanic and Atmospheric Administration. June was the hottest year on record globally for combined land and sea temperatures, according to the data center. This July tied July 2009 for warmest global sea temperatures. The global numbers for August are not in yet, but for the year, 2014 already is the third-warmest on record worldwide, taking into account both land and sea temperatures.
Some areas, of course, felt it acutely. California and much of the rest of North America west of the Rockies had scorching periods, which for many states helped bring home the inevitable arithmetic of using more water than nature replenishes.
Meanwhile, the Northeast avoided the grueling heat served up in the summer of 2013. That’s the difference between weather, which is local and short-lived, and climate, which is marked by long-term averages, usually over a wide area.
Weather can temporarily hide climate change. It does not disprove climate change, and climate change does not always dictate the weather.
In fact, climate change is bringing increased variability in weather to Europe and North America, at least for now, scientists at the universities of East Anglia and Exeter found last year.
But the trend is clear: The US National Climate Assessment released last May predicts an average temperature increase of 4 to 11 degrees by 2100 for this country.
Particularly worrisome — well, it’s all worrisome — is the gradual rise in ocean temperature. While the land heats up and cools off fairly quickly, the oceans were once thought too vast and too deep to be much affected by changes of climate.
Indeed, the seas have buffered the global climate for decades. Now, however, the surface waters this July were more than 1 degree higher than the average of the 20th century, tying July 2009 as the warmest on record, according to NOAA. One degree does not sound like much, but as the oceans warm, they expand. This thermal expansion is thought to be responsible for up to 40 percent of sea level rise and will continue for “many centuries,” according to the Intergovernmental Panel on Climate Change.
And it’s only the start. The intergovernmental panel, which has made consistently too-conservative estimates, predicts ocean waters will warm anywhere from 1 to 7 degrees by 2100. Gone will be the Arctic ice cap, giving shippers open access to the famed Northwest Passage and tempting drillers with prospects of oil and gas under the Arctic seabed.
Gone, too, will be vast chunks of the Antarctic and perhaps Greenland. Because that ice was sitting on land (as opposed to the Arctic), the melting there will raise sea levels. Satellite data over 19 years analyzed in a University of Southampton study released Sunday showed that melting glaciers has reduced salinity in the seas and added 350 gigatons of freshwater to the ocean.
And gone, finally, will be many sea creatures that are sensitive to their habitat. A small rise in ocean temperatures will send them fleeing for cooler waters — if they can. Already, scientists see the migrations: whales, sharks, crabs, sea turtles, and even tropical fish are now probing areas far beyond their usual range. Other organisms, like coral, cannot escape.
The old saw among climatologists is “You pick your vacation spot based on climate, and pack your suitcase based on weather.” But now climate change has the world’s species starting to pack their bags, despite Boston’s cool summer.
Doug Struck has been a journalist for 35 years and reports on environmental matters from Boston. He can be reached at doug@dougstruck.com