The signs of climate change appear like pieces of a mosaic, a patchwork of scientific data and observation. Most individual signs don’t carry great significance, but here’s one that does – the persistent rise of the temperature of the oceans over the past 100 years. The research comes from an international team (China, Japan, Australia, USA, Germany) and reported in Nature Climate Change [29 January 2012, paywalled, Enhanced warming over the global subtropical western boundary currents]. The researchers studied ocean surface temperature records since 1900 and found that in certain areas, what they call “subtropical western boundary currents” – such as off the eastern Australian coast, near the Philippines, the Gulf Stream off the eastern U.S., the Brazil current, and the Kuroshio current near Japan – were warming two to three times faster than the oceanic average (which is itself increasing).

These are all major currents that have an impact on the weather in their regions. The increased surface temperature of the ocean over thousands of miles can change the pattern of weather, for example, increasing the occurrence of extreme climate events such as major winter storms. The currents themselves can also affect the global current patterns that impact marine ecosystems. The problem for climatologists is that while the effects of warmer water, such as more dynamic surface winds and greater availability of moisture for precipitation are well documented, the specific events associated with the change are unpredictable and difficult to correlate. This is a very common position for climate change studies and it leads to what some choose to see as ‘uncertainty.’ Climatologists look at the patterns, that mosaic of climate change, and see no uncertainty that the oceans are warming, that some important currents are warming faster than the ocean average, and both of these things will change the weather in many part of the world.

This enhanced warming may reduce the ability of the oceans to absorb anthropogenic carbon dioxide over these regions. However, uncertainties in detection and attribution of these warming trends remain, pointing to a need for a long-term monitoring network of the global western boundary currents and their extensions.
[Source: Abstract]