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January 20, 2006

Global Warming News Keeps Getting Worse Environment

Earlier this week, we had James Lovelock's grim essay on global warming. Now we have this. The news just keeps getting worse. From today's Independent:

The microscopic plants that underpin all life in the oceans are likely to be destroyed by global warming, a study has found.

Scientists have discovered a way that the vital plankton of the oceans can be starved of nutrients as a result of the seas getting warmer. They believe the findings have catastrophic implications for the entire marine habitat, which ultimately relies on plankton at the base of the food chain.

The study is also potentially devastating because it has thrown up a new "positive feedback" mechanism that could result in more carbon dioxide ending up in the atmosphere to cause a runaway greenhouse effect.

Scientists led by Jef Huisman of the University of Amsterdam have calculated that global warming, which is causing the temperature of the sea surface to rise, will also interfere with the vital upward movement of nutrients from the deep sea.

These nutrients, containing nitrogen, phosphorus and iron, are vital food for phytoplankton. If the supply is interrupted the plants die off, which prevents them from absorbing carbon dioxide from the atmosphere. [...]

The sea is one of nature's "carbon sinks", which removes carbon dioxide from the atmosphere and deposits the carbon in a long-term store - dissolved in the ocean or deposited as organic waste on the seabed. The vast quantities of phytoplankton in the oceans absorb huge amounts of carbon dioxide. When the organisms die they fall to the seabed, carrying their store of carbon with them, where it stays for many thousands of years - thereby helping to counter global warming. [...]

Warmer surface water caused by global warming causes greater temperature stratification, with warm surface layers sitting on deeper, colder layers, to prevent mixing of nutrients.

Professor Huisman shows in a study published in Nature that warmer sea surfaces will deliver a potentially devastating blow to the supply of deep-sea nutrients for phytoplankton.

His computer model of the impact was tested on real measurements made in the Pacific Ocean, where sea surface temperatures tend to be higher than in other parts of the world. He found that his computer predictions of how nutrient movement would be interrupted were accurate. [...]

Scientists had believed phytoplankton, which survives best at depths of about 100 metres, is largely stable and immune from the impact of global warming. "This model prediction was rather unexpected," Professor Huisman said. [...]

Microscopic plankton comes in animal and plant forms. The plants are known as phytoplankton. They lie at the base of the marine food chain because they convert sunlight and carbon dioxide into organic carbon - food for everything else.

...Without phytoplankton, the oceans would soon become marine deserts. [...]

Phytoplankton...acts as a carbon "sink" which takes carbon dioxide from the atmosphere and deposits the carbon in long-term stores that can remain undisturbed for thousands of years. If the growth of phytoplankton is interrupted by global warming, this ability to act as a buffer against global warming is also affected - leading to a much-feared positive feedback. [Emphasis added]

It's impossible to overstate the importance of this finding. All sea life ultimately depends on phytoplankton. Without it, the world's oceans will become an enormous dead zone. And the feedback loop set in motion as the phytoplankton dies off (less phytoplankton leads to more atmospheric CO2 which leads to more global warming which leads to less phytoplankton, etc.) is only one of a number of recently discovered feedback loops that are likely to accelerate and amplify global warming. In other words, current computer models are, if anything, understating what we're up against.

Posted by Jonathan at January 20, 2006 06:24 PM  del.icio.us digg NewsVine Reddit YahooMyWeb