SST Trends Since 1900.
By Paul Homewood
While we’re on the subject of sea surface temperatures, let’s take a look at the long term changes, as measured by HADSST3.
We can see the step up in 1998, since when things have largely levelled off. What is also noticeable though is the rapid warming from 1920 to 1950, which was a a similar rate to the more recent warming between 1980 and 2000.
As the earlier warming could not have been caused by the small increase in CO2 emissions during those years, clearly some other factor is at play.
Kenneth Richards also points out that Gouretski’s paper, “Near-Surface Ocean Warming Since 1900”, published in 2012, finds that sub surface temperatures (to a depth of 20m) rose more quickly between 1920 and 1950 than in recent decades.
Gouretski also notes that
These maps demonstrate that the first decade of the 21stcentury (2001–2010) was not uniformly warmer than previous decades. Before about 1920, the global ocean was almost everywhere colder than the reference decade of 2001–2010. After 1920, several regions of the global ocean were warmer than in the reference decadeLeaving aside the effect of underwater volcanoes and other seismic activity, the dominant energy source for ocean warming is, of course, the sun. But the ocean’s heat capacity is so huge that the effect of any changes can take decades to appear….
Decadal mean SST and 0–20 m layer anomalies calculated relative to the reference decade 2001–2010 give evidence of the general warming of the global ocean since 1900. However, large regions of the oceans have experienced cooling since the 1990s.
This is hardly the uniformly warming effect that you would expect increased levels of CO2 to produce.
The chart below, from an Indiana University publication, gives a good overview of how ocean currents move warm and cold water around the planet. According to them, a complete run through this current system is estimated to take about 1000 years.
NASA describe the process whereby the cold, bottom water from Antarctica rise to the surface in the Pacific:
The resulting Common Water, also called Antarctic Circumpolar water, flows northward at depth into the three ocean basins (primarily the Pacific and Indian Oceans). These bottom waters gradually warm and mix with overlying waters as they flow northward. They move to the surface at a rate of only a few meters per year.
In other words, the whole process is an extremely slow one. The idea that an increase in GHG over just a few years can make any measurable difference to these enormously powerful oceanic processes is frankly ridiculous.