Source: www.bbc.co.uk
The amount of phytoplankton – tiny marine plants – in the top layers of the oceans has declined markedly over the last century, research suggests. Writing in the journal Nature, scientists say the decline appears to be linked to rising water temperatures. The final tally included 445,237 data points spanning the period 1899-2008.
“This study took three years, and we spent lots of time going through the data checking that there wasn’t any ‘garbage’ in there,” said research leader Daniel Boyce from Dalhousie University in Halifax, Nova Scotia, Canada.
The higher quality data available since 1950 has allowed the team to calculate that since that time, the world has seen a phytoplankton decline of about 40%.
If the trend is real, it could also act to accelerate warming, the team noted. Photosynthesis by phytoplankton removes carbon dioxide from the air and produces oxygen.
In several parts of the world, notably the Southern Ocean, scientists have already noted that the waters appear to be absorbing less CO2 – although this is principally thought to be because of changes to wind patterns – and leaving more CO2 in the air should logically lead to greater warming.
“Phytoplankton… produce half of the oxygen we breathe, draw down surface CO2, and ultimately support all of our fisheries,” said Boris Worm, another member of the Dalhousie team. “An ocean with less phytoplankton will function differently.” The question is: how differently?