Tuesday, August 17, 2010
It turns out that critters so small that they can't be seen with the naked eye might affect the weather, and perhaps even climate.
As I pointed out last year, spacefaring bacteria might affect rainfall:
Now, NOAA scientists say that phytoplankton affects hurricanes. As New Scientist writes:
In 2002, several scientists claimed that bacteria high in Earth's atmosphere came from space.
Last year, scientists said that bacteria in the upper atmosphere may actually make rain. Specifically, they said that bacteria can freeze at fairly warm temperatures, so that the "biological ice nuclei" form condensation nuclei which triggers rain.
Indeed, some scientists have speculated that bacteria cause rain as a means of transportation, so that they will "rain out" from the upper atmosphere to the surface of a planet.
Now, scientists have discovered a "hibernating" bacteria in a salt mine in Utah which they believe has been in suspended animation for 250 million years. There is evidence that this ability to hibernate for long periods of time is also useful for travel through space by the bacteria:Indeed, there is a more down-to-earth analogy to the idea of spacefaring bacteria: the humble coconut. Coconuts can float across long distances of water in the ocean, and when they land on a hospitable island, start growing.
Bacteria have the ability to go into a kind of semi-permanent hibernation, but survival for this long was unheard of. After lying dormant in the salt crystal for 250 million years, the scientists added fresh nutrients and a new salt solution, and the ancient bacteria "re-animated."
Dr. Russell Vreeland, one of the biologists who found the bacteria, pointed out that bacteria can survive the forces [of] acceleration via rubble thrown into space via a meteor impact. If it is possible for a bacteria to survive being [thrown] off the planet and to stay alive within a salt chunk for 250 million years, then in a sort of "reverse-exogenesis" it may be possible that earth's own microbes are already out there.
Using a computer weather simulator, [NOAA's Anand Gnanadesikan] compared the formation of tropical storms in the Pacific under today's phytoplankton concentrations to conditions without any phytoplankton at all. What he found was an overall decrease in tropical storms in a phytoplankton-free digital Pacific.
The mechanism for this shift lies in phytoplankton's ability to absorb sunlight, which heats up the water around it. Without phytoplankton, the sun's rays penetrate deep into the ocean, leaving the surface water cold. Cool water has less energy than warm water, produces less of the moist air needed to build up tropical storms, and allows for stronger winds that can dissipate thunderstorms before they turn into typhoons (what hurricanes are called in the Pacific Ocean). All of this adds up to a Pacific Ocean that is less exciting and deadly than the one we currently have.
Because phytoplankton levels have dropped 40 percent since the 1950s, that may mean that hurricane frequency and/or intensity may decline.
Rain can provide transportation to bacteria, which provides an obvious evolutionary advantage: it gives them a free ride out of space down to a planet's surface.
But could there also be an advantage to phytoplankton from hurricanes? Believe it or not, there is.
As NASA wrote in 2004:
Whenever a hurricane races across the Atlantic Ocean, chances are phytoplankton will bloom behind it. According to a new study using NASA satellite data, these phytoplankton blooms may also affect the Earth's climate and carbon cycle.
The satellite images showed tiny microscopic ocean plants, called phytoplankton, bloomed following the storms.
"Some parts of the ocean are like deserts, because there isn't enough food for many plants to grow. A hurricane's high winds stir up the ocean waters and help bring nutrients and phytoplankton to the surface, where they get more sunlight, allowing the plants to bloom," Babin said.
Bigger storms appear to cause larger phytoplankton blooms. Larger phytoplankton should have more chlorophyll, which satellite sensors can see.
Hurricane-induced upwelling, the rising of cooler nutrient-rich water to the ocean surface, is also critical in phytoplankton growth. For two to three weeks following almost every storm, the satellite data showed phytoplankton growth. Babin and his colleagues believe it was stimulated by the addition of nutrients brought up to the surface.
By stimulating these phytoplankton blooms, hurricanes can affect the ecology of the upper ocean. Phytoplankton is at the bottom of the food chain. The factors that influence their growth also directly affect the animals and organisms that feed on them.