Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for May 19, 2008

Another Hurricane Model Suggests No Large Increase in Trends

By

Hurricanes and tropical storms will become less frequent by the end of the century as a result of climate change, US researchers have suggested.

But the scientists added their data also showed that there would be a “modest increase” in the intensity of these extreme weather events.

The findings are at odds with some other studies, which forecast a greater number of hurricanes in a warmer world.

The researchers’ results appear in the journal Nature Geoscience.

BBC News website: ‘Fewer hurricanes’ as world warms

Nature Geoscience: Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions

Abstract:

Increasing sea surface temperatures in the tropical Atlantic Ocean and measures of Atlantic hurricane activity have been reported to be strongly correlated since at least 1950 raising concerns that future greenhouse-gas-induced warming could lead to pronounced increases in hurricane activity. Models that explicitly simulate hurricanes are needed to study the influence of warming ocean temperatures on Atlantic hurricane activity, complementing empirical approaches. Our regional climate model of the Atlantic basin reproduces the observed rise in hurricane counts between 1980 and 2006, along with much of the interannual variability, when forced with observed sea surface temperatures and atmospheric conditions. Here we assess, in our model system, the changes in large-scale climate that are projected to occur by the end of the twenty-first century by an ensemble of global climate models, and find that Atlantic hurricane and tropical storm frequencies are reduced. At the same time, near-storm rainfall rates increase substantially. Our results do not support the notion of large increasing trends in either tropical storm or hurricane frequency driven by increases in atmospheric greenhouse-gas concentrations.

Hairy Red Pittosporum

By

Pittosporum.jpg

For the sake of appearance, colour can make a world of difference. In tropical rainforests, a bright upper canopy, rich in blue and UV, and a dark understorey, rich in green and orange, contrasts two distinct light environments.

When discretion is important, bright greens blend better in the upper canopy, whereas dark browns have the advantage in the understorey.

When advertising an invitation to treat, as it were, bright blues glow advantageously in the upper canopy, whilst yellow and red signals optimise conspicuousness in understorey. The Hairy Red Pittosporum P. rubiginosum ssp. Wingii, of Australia’s tropical rainforests, is an excellent example of the latter.