From Watts Up With That?
By Paul Homewood
Yet another junk study, which would not see the light of day in any other branch of science:
Abstract
Phytoplankton Primary Production supports most of the marine ecosystem and is highly sensitive to changing environmental pressures. There is much debate about whether marine primary production is increasing or decreasing and what environmental parameters may be driving these changes. We analysed a 21-year time-series of net primary production (NPP) computed from Ocean Colour Climate Change Initiative (OC-CCI) data spanning September 1997-December 2018, focusing on areas of similar phenology, climatology, and annual NPP in the north-east Atlantic Ocean. Across the entire area, NPP increased from 1998 to 2003, followed by a significant decline until 2018. This pattern was predominant in north-western European coastal waters and specific areas of the English Channel, Irish Sea, North Sea and Norwegian Sea, where it was related to changes in sea surface temperature and mixed layer depth.
The press release states:
Detected from space: 20 years of data shows declining photosynthesis in UK and surrounding waters
A new study by scientists at Plymouth Marine Laboratory (PML) has revealed a significant long-term decline in ocean productivity across large parts of the north-east Atlantic. This raises concerns about the future health of marine food webs, fisheries and the ocean’s ability to absorb and sequester carbon dioxide.
Using more than two decades of satellite observations, researchers analysed changes in microalgae net primary production – the process by which microscopic marine plants convert sunlight and carbon dioxide into organic matter, which forms the foundation of marine ecosystems.
The study, led by PML’s Dr Gavin Tilstone and Dr Peter Land, examined satellite data spanning 1997 to 2018 and found that, after a brief period of increasing productivity in the late 1990s and early 2000s, primary production declined steadily across much of the region, particularly in north-west European coastal waters, the Irish Sea, North Sea, western English Channel and parts of the Norwegian Sea.
The research links these declines primarily to changes in sea surface temperature and mixed layer depth – key physical properties that control how nutrients and light are distributed in the upper ocean.
Dr Gavin Tilstone, Bio-optical Oceanographer at PML, said:
“While the ocean may appear to be one giant body of water, it is often divided into layers based on temperature. As the ocean warms, these layers become stronger and less likely to vertically mix – a process known as thermal stratification.”
“This matters because the mixing of ocean waters helps transport nutrients from the depths to the surface, where phytoplankton can use them to grow. When that supply is reduced, microalgae productivity can decline.”
Dr Peter Land, Remote Sensing Scientist at PML, added:
“In many regions, warming surface waters and altered mixing are reducing the conditions phytoplankton need to thrive. This limits the energy entering marine food webs and can have huge knock-on effects for fish stocks and ecosystem services.”
Like so many other climate studies, this one takes a microscopically short period of data, twenty one years, and pretends that trends during that time have any significance whatsoever. As scientific experts in the Atlantic climate have long known, ocean temperatures and currents there regularly undergo massive climatic shifts. During the last century alone, the North Atlantic has swung from cold to warm, warm to cold, and back again to the warmer climate we have enjoyed for the last three decades.
It is not coincidental that the Atlantic Multidecadal Oscillation switched to warm phase in the mid 1990s, just when this latest study began its analysis.
The graph below is key to the study’s findings that plankton production is declining:
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