JOIN USRecent massive volcanic eruptions like those at El Chicon, in Mexico in 1982, and Mount Pinatubo, in the Philippines in 1991, undoubtedly caused at least short-term global cooling, said Nadine Unger, a research scientist at the Center for Climate Systems Research at Columbia University.
The reason, she said, is not a cloud of dust but the fact that sulfur dioxide gas released in the explosions forms sulfate aerosol particulates that are injected high up into the atmosphere, where they act as a shiny shield and reflect solar radiation back to space. This mechanism, she said, “is the exact basis of the geoengineering proposal as a solution to global warming in which President Obama has expressed interest.”
After the Pinatubo eruption the Earth’s global average surface temperature dropped by 0.9 degrees Fahrenheit, Unger said.
Sulfate aerosol has a fairly short lifetime in the atmosphere, so the Earth system recovers in one to two years, Unger said, concluding that based on observations, the cooling effects of sulfate particulates outweigh any potential warming effects of carbon dioxide released in the explosion. Still, she added, the carbon dioxide released from volcanoes is dwarfed by the annual emissions from the burning of fossil fuels by humans.
Claiborne Ray
NYT News Service
Of human bioluminescence
Amazing pictures of “glittering” human bodies have been released by Japanese scientists who have captured the first ever images of human “bioluminescence”.
Although it has been known for many years that all living creatures produce a small amount of light as a result of chemical reactions within their cells, this is the first time light produced by humans has been captured on camera.
Writing in the online journal PLoS ONE, the researchers describe how they imaged volunteers’ upper bodies using ultra-sensitive cameras over a period of several days. Their results show that the amount of light emitted follows a 24-hour cycle, at its highest in late afternoon and lowest late at night, and that the brightest light is emitted from the cheeks, forehead and neck.
Strangely, the areas that produced the brightest light did not correspond with the brightest areas on thermal images of the volunteers’ bodies.
The light is a thousand times weaker than the human eye can perceive.
At such a low level, it is unlikely to serve any evolutionary purpose in humans – though when emitted more strongly by animals such as fireflies, glow-worms and deep-sea fish, it can be used to attract mates and for illumination.
Bioluminescence is a side-effect of metabolic reactions within all creatures, the result of highly reactive free radicals produced through cell respiration interacting with free-floating lipids and proteins.
The “excited” molecules that result can react with chemicals called fluorophores to emit photons.
Human bioluminescence has been suspected for years, but until now the cameras required to detect such dim light sources took over an hour to capture a single image and so were unable to measure the constantly fluctuating light from living creatures.
While the practical applications of the discovery are hard to imagine, one can't help wondering what further surprises the human body has in store for us.
The Guardian