Seas will continue to warm for centuries even if manmade greenhouse gas emissions were frozen at today’s levels, say US government scientists
Suzanne Goldenberg The Guardian 16 Jul 15;
The warming of the oceans due to climate change is now unstoppable after record temperatures last year, bringing additional sea-level rise, and raising the risks of severe storms, US government climate scientists said on Thursday.
The annual State of the Climate in 2014 report, based on research from 413 scientists from 58 countries, found record warming on the surface and upper levels of the oceans, especially in the North Pacific, in line with earlier findings of 2014 as the hottest year on record.
Global sea-level also reached a record high, with the expansion of those warming waters, keeping pace with the 3.2 ± 0.4 mm per year trend in sea level growth over the past two decades, the report said.
Scientists said the consequences of those warmer ocean temperatures would be felt for centuries to come – even if there were immediate efforts to cut the carbon emissions fuelling changes in the oceans.
“I think of it more like a fly wheel or a freight train. It takes a big push to get it going but it is moving now and will contiue to move long after we continue to pushing it,” Greg Johnson, an oceanographer at Noaa’s Pacific Marine Environmental Laboratory, told a conference call with reporters.
“Even if we were to freeze greenhouse gases at current levels, the sea would actually continue to warm for centuries and millennia, and as they continue to warm and expand the sea levels will continue to rise,” Johnson said.
On the west coast of the US, freakishly warm temperatures in the Pacific – 4 or 5F above normal – were already producing warmer winters, as well as worsening drought conditions by melting the snowpack, he said.
The extra heat in the oceans was also contributing to more intense storms, Tom Karl, director of Noaa’s National Centers for Environmental Information, said.
The report underlined 2014 as a banner year for the climate, setting record or near record levels for temperature extremes, and loss of glaciers and sea ice, and reinforcing decades-old pattern to changes to the climate system.
Four independent data sets confirmed 2014 as the hottest year on record, with much of that heat driven by the warming of the oceans.
Globally 90% of the excess heat caused by the rise in greenhouse gas emissions is absorbed by the oceans.
More than 20 countries in Europe set new heat records, with Africa, Asia and Australia also experiencing near-record heat. The east coast of North America was the only region to experience cooler than average conditions.
Alaska experienced temperatures 18F warmer than average. Spring break-up came to the Arctic 20-30 days earlier than the 20th century average.
“The prognosis is to expect a continuation of what we have seen,” Karl said.
