Argument: Global warming kills algae, worsens warming; iron fertilization helps

Issue Report: Geoengineering, iron fertilization of algae blooms


Steve Connor. “Warmer Seas Will Wipe Out Plankton”. 20 The Independent. January 2006 – 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.

“Warming Ocean Slows Phytoplankton Growth”. NASA Earth Observatory.

“Disappearing phytoplankton”. Pacific Views. 9 Dec. 2006 – On Thursday NPR’s Morning Edition had a segment on the bluing of the ocean which scientists have connected with the warming oceans. The color of the ocean is directly related to the amount of phytoplankton in the water. The greener the waters, the more phytoplankton, the bluer indicates less.

So what does this mean? The phytoplankton is an indication of the amount of plant life in the ocean. In fact the phytoplankton is the equivalent of the grass on land. When there is more phytoplankton, the ocean has more food to support the food chain. Furthermore, phytoplankton is essential for enabling the ocean to sequester excess carbon in 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.

What scientists have found is that during the past decade, the amount of phytoplankton has tracked directly to the warming of the oceans. During the late 90s, the amount of phytoplankton increased leading to greener seas. But since then, the oceans have been growing bluer indicating a harsher environment for phytoplankton.

Ocean plant growth increased from 1997 to 1999 as the climate cooled during one of the strongest El Niño to La Niña transitions on record. Since 1999, the climate has been in a period of warming that has seen the health of ocean plants diminish.

The new study also explains why a change in climate produces this effect on ocean plant life. When the climate warms, the temperature of the upper ocean also increases, making it “lighter” than the denser cold water beneath it. This results in a layering or “stratification” of ocean waters that creates an effective barrier between the surface layer and the nutrients below, cutting off phytoplankton’s food supply. The scientists confirmed this effect by comparing records of ocean surface water density with the SeaWiFS biological data.

David Perlman. “Decline in Oceans’ Phytoplankton Alarms Scientists”. San Francisco Chronicle. 6 Oct. 2003 – Plant life covering the surface of the world’s oceans, a vital resource that helps absorb the worst of the “greenhouse gases” involved in global warming, is disappearing at a dangerous rate, scientists have discovered.