On the horizon

News from the frontiers of science.

The sea-level pace race

It's official: Sea-level rise is accelerating - though not exactly at a drag-racer's pace. Measurements by Australian scientists indicate that between 1870 and 2001, global sea levels rose an average of just over 7-1/2 inches. But the pace accelerated each year by an additional 0.0005 inches during that period.

The effort combined satellite and tide-gauge measurements to build trends in sea-level rise. If the acceleration rate remains constant, scientists estimate that between 1990 and 2100 the average sea level will have risen 11 to 13 inches, which falls within projections from the UN's Intergovernmental Panel on Climate Change. The results appeared in the Jan. 6 issue of the Geophysical Review Letters.

Plants turn extra light into heat

Too much of a good thing can be tough on plants, even if it's light. The effect of excessive light gets worse if plants face drought or heat waves. Scientists in Britain appear to have found one of the ways plants adapt to excess light.

Using tiny Arabidopsis plants as botanical guinea pigs, a team led by Peter Horton of the University of Sheffield found that the plants turned unneeded light into heat by changing the shape of a protein in the membranes the plants use for photosynthesis. This process gets a boost from a molecule known as zeaxanthin; the more zeaxanthin a plant has, the more heat it can dissipate. The goal of the work is to improve crops grown in harsh conditions.

Lend me your - gills?

Two paleontologists in Sweden reported in the journal Nature that they've found evidence that the middle ear found in humans and other species may have originated as gills of ancient fish. Scientists from the University of Uppsala examined the skull of a 370-million-year-old fossil of a Panderichthys, a fish closely related to primitive tetrapods - four-limbed vertebrates that have come to include humans. Their examinations found the Panderichthys's gills were much closer to the structure of the middle ear in early tetrapods than they were to other species of fish. They concluded that this "suggests" early tetrapods' middle ears evolved from the structures early fish used for breathing.

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