Hydrogen Poses Risks to Ozone Layer; Atmospheric Mercury Declining; Where Have All the Flowers Gone?

Hydrogen Poses Risks to Ozone Layer

A report in the June 13 issue of Science entitled "Potential Environmental Impact of a Hydrogen Economy on the Stratosphere" suggests that hydrogen fuel cells could pose environmental risks.

The study theorizes that systems of molecular hydrogen (H2) production, storage, and transport will almost certainly involve some of the hydrogen escaping into the atmosphere. Current losses suggest that 10-20% of all H2 will escape, which implies that if all oil or gasoline combustion technologies were replaced with hydrogen fuel cells, anthropogenic H2 emissions would increase four to eight times.

The researchers suggest that the H2 would move up to mix with air in the stratosphere, where it would oxidize to form water vapor. This would result in a cooling of the lower stratosphere and would also enhance the chemical practices that destroy ozone. A fourfold increase in the amount of H2 in the stratosphere would lead to a stratospheric temperature decrease of about 0.25 C and ozone depletion of around five percent. These effects would rise to a 1 decrease and over 15 percent depletion with a sevenfold increase in H2.

The researchers also suggest that an increase in water vapor in the mesosphere could lead to an increase in noctilucent clouds, potentially affecting the earths albedo.

Atmospheric Mercury Declining

A new study published in Geophysical Research Letters (May 22) has found that total gaseous mercury levels have declined since their peak in the early 1980s. Researchers at the Max Planck Institute for Chemistry measured mercury levels in eight locations in both hemispheres as well as eight trans-Atlantic cruises over the course of more than twenty years. The study found that total gaseous mercury levels have declined since their peak in the early 1980s.  The findings correlate well with earlier research that found decreasing levels of mercury deposition dating back as far as fifty years. 

The study called into question the reliability of mercury models, saying that either "the area of man-made to natural emissions (including re-emissions) has been underestimated or the natural emissions undergo large temporal variations."  If the discrepancy were natural, it would indicate a far greater degree of natural fluctuation than previously believed.

Where Have All the Flowers Gone?

A June 17 story in the Independent of London was headlined, "Global warming may wipe out a fifth of wild flower species, study warns." The actual study (published in the Proceedings of the National Academy of Sciences), however, suggested rather less.

The scientists looked at the effects of increased temperature, CO2, precipitation, and nitrogen on a small patch of California meadow, divided into plots of approximately one square yard. They found that under certain conditions, including increases in all four factors, the average number of forb species in the plots (small flowering plants like buttercups) decreased from about 4 to 3.2 over three years. This did not mean that the plots became less diverse, however, as other plant species took their place, leading in some cases to an increase in biodiversity.

The studys authors acknowledged that not all areas would respond to the effects of climate change like California meadows, something that did not make it through to the Independents coverage.

Global Warming Caused Permian Mass Extinction, Researcher Warns

A new book from Michael Benton, head of earth sciences at Bristol University in England, suggests that the mass extinction at the end of the Permian era, 250 million years ago was caused by a global warming of about 6 C. When Life Nearly Died: The Greatest Mass Extinction of All Time suggests that a series of volcanic explosions caused a runaway greenhouse effect that led to the death of the vast majority of the species alive at the time.

Professor Benton told the Press Association: "The Permian crisis nearly marked the end of life. It's estimated that fewer than one in 10 species survived. Geologists are only now coming to appreciate the severity of this global catastrophe and to understand how and why so many species died out so quickly."

An advisor on the science behind the award-winning TV series Walking with Dinosaurs, Professor Benton is also the author of the Encyclopedia of Awesome Dinosaurs. (Sydney Morning Herald, June 20).

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