The Mystery of Methane -Nature 442:17 August 2006
Methane formation, a gas that is twenty times more effective as a greenhouse heat absorber than carbon dioxide, is usually associated with wet, oxygen-depleted, decaying environments. About 550 million tons a year is emitted.
   In 1988, two scientists found that large amounts of this gas occurred at night in the air over tropical savannahs in Venezuela. In early 2006, another scientist discovered that methane was released by trees. Calculating how much gas might be releas4d by trees in tropical savannahs world-wide annually, both came up with 30 to 60 million tons.
   As yet there is no known mechanism on how healthy trees can produce methane but by growing plants in closed chambers, tiny amounts do appear, so much so that plant life might account for forty percent of all methane released into the atmosphere.   Methane in the atmosphere stopped rising in the 1080’s. One speculation is that this could have been done by tropical deforestation.
   Not all scientists are convinced. Unpublished data shows that methane emissions among plants varies widely by species. Others claim the numerical models used are incorrect. The rub in all this is that if plant release of methane has been underestimated then perhaps human-induced sources have been overestimated.

2006 - April

More Green in Greenhouse -Science 311, p.159 et seq.
Of the many gases that have been involved in global warming, methane is one of the more significant culprits. Bacteria produce it as do termites and cows. Scientists have recently found a more ubiquitous source-plants. Not dead, decaying matter but live vegetation.
Current estimates of world plant output range from 10 to 30 percent of all methane produced, between 60 and 180 million metric tons annually. Methane in the air is either absorbed by soil, lost into space or, mainly, oxidized in the upper atmosphere. These new findings have led scientists to believe that another important “sink” for methane has been overlooked.

Global Conveyor Belt - Nature 439, pp.256-260
If you have seen the wildly improbable film “The Day After Tomorrow”, you are at least aware that a change in oceanic circulation can have dire consequences on the earth’s climate.
In the north Atlantic, surface ocean currents carry heat northward. This heat is transferred via westerly winds to northern Europe creating a mild climate. That cooled, salty water then sinks and returns southward. If this thermohaline conveyor belt shifts, Western Europe would suffer a mini ice age. The southerly shift of the belt could occur as the result of excessive fresh water entering the north Atlantic and mixing with the salty water, preventing it from sinking.
There are counter arguments to this concern but all agree there is a paucity of data. Just recently, twenty-two profilers were moored in the north Atlantic, and already initial data suggests changes are occurring. Indeed, one oceanographer , in a recently published study using other criteria, suggests that circulation system has already dramatically slowed down.

2005

Disappearing Ice - Nature 438, p681-5
    In March 2002, in the northwestern corner of the Weddell Sea (Antarctica), the Larsen Ice Shelf , over 12,500 kilometers in extent, broke loose and its pieces drifted into the Southern Ocean. Because it was floating ice it made little change in the world’s sea level. However, a great deal of land-based ice is now slipping toward the sea and it will raise sea levels.
    The collapse of the shelf, which has existed over the past 11,000 years, is the end result of thinning over a long time and an increase in air temperature in the past 30 to 50 years.
    The authors of the study state that recent air temperatures “have exceeded natural variation of regional climate during the Holocene interglacial”.

Big Nitrogen Fix - Nature 436 pp.786-7
The major limit to biological productivity in the open ocean is either inadequate light or insufficient fixed nitrogen.. Over much of subtropical and tropic seas fixed nitrogen is lost to the abyssal depths by sinking dead organisms. Until recently, it was thought the only replenishment was by upwelling. However biological productivity can be relatively high over large areas where upwelling is insignificant.
Recent work has discovered that nitrogen-fixing bacteria can supply as much or more fixed nitrogen as can upwelling. The organism Trichodesmium, a cyanobacterium, is widespread and adds an order of magnitude more fixed nitrogen than all other natural processes over the whole earth. This discovery also suggests that scientists have understated the amount of denitrification in the sea. (Certain bacteria convert fixed nitrogen back to the simple gas ).

Moving North - Science 308 pp.1912-5
    As climate warms so to the seas and the fish within them move to waters more in line with their past preferences. For the fishes of the North Sea this means north. In the past twenty-five years , cold water species have moved as much as 800 kilometers northward.
    A study of bottom-dwelling fishes (about 90 species) by Perry et al they have responded to a temperature increase of one degree centigrade that has occurred between 1977 and 2001. Both exploited and unexploited species have made the move. If the temperature trend continues a number of species will be completely out of the North Sea by 2050.

2004

Methane Hydrate - a new source of fuel, or a greenhouse gas time bomb?

Back to Where We Came From - or Not? - Reefnotes

A couple articles on global(1) warming(2), not totally recent, but with some good links.

How much control over their life do larval fish have? Maybe more than we might think, as discussed in the Home Reef article.

Dust storms in Sahara puts dust in the atmosphere which takes a long time to settle out. The Picture on the World Wide Winds page also takes a long time to download, but it's worth it.

The otolith "acts like a flight recorder , encoding time-specific information about the waters through which the fish passes, from birth to death," - in weakfish.

Is there Something Fishy about that latest batch of seafood? Some hints, ideas, and pointers.

10/22/06 14:52