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In the press

Science magazines and journals and the press generally reflect the interest and concerns of the scientific literature and the wider public. Extreme weather events, climate change, the state of the “ozone hole”, dwindling water resources and pollution are some of the favourite topics. In this spirit, the tidbits reproduced here are gleaned from a range of sources. For more detailed information on each of the subject, reference is made to the original articles. A word of caution: the ideas and opinion in no reflect the official position of WMO on these issues.

Corals and global warming—changing partners to survive

The 1997/1998 El Niño event caused the bleaching of coral reefs in many parts of the world including the Seychelles in the Indian Ocean, the Great Barrier Reef of the Pacific Ocean and the Panama coast. Since the 1980s, reefs around the world have suffered from bleaching due to warmer ocean waters. The corals are animals which live in symbiotic relationship with one type of Symbiodinium algae, known as clade C. When the ocean temperature increases by 1°C above the long-term average temperature, the corals expel the photosynthetic algae that supply them with nutrients. The recovery of bleached corals takes several years of congenial conditions. Marine biologists therefore projected that half of all reefs would be lost by 2030.

Photo: International Coral Reef Information Network

The paradox, however, is that coral reefs have survived several periods of warmer climates since they first appeared some 220 millions years ago. Also, the bleaching, though severe, is generally localized. Recent studies along the Panama coast and the around the island of Guam show that those least affected or that had recovered had been befriended another more heat-tolerant algal type clade D. (Nature, 430, 741-742).

Assuming that the time-scale of warming is right and pollution does not overwhelm the reefs, the coral system may adapt to climate change, but the reefs and the associated features around the world might look totally different.

Cosmic rays and climate change

At a recent Western Pacific Geophysics Meeting in Honololu, Hawaii, some scientists brought forward the controversial concept that global warming may be due to cosmic rays that ionize the molecules with which they collide, triggering cloud formation. Fewer cosmic rays would therefore mean a less cloudy sky and a warmer planet. In support of their concept, a scientist from the Danish Space Research Institute has noticed a pattern of global cloud cover varying over a time scale of about 10 years, with correlation to the 11-year sunspot cycle. The implication is that the greater the strength of the Sun’s magnetic field, the greater the deflection of the cosmic rays with fewer rays reaching the Earth and the lower cloud cover.

However, some climatologists believe that the hypothesis is being pushed too far, even though they lack the data to back it up. Several climate scientists have argued that the researchers “applied several adjustments to the data to artificially enhance the correlation” (Eos, 85, 38).

Sea-level rise estimates from coastal fish pens in Italy

The Romans dug fish pens in bedrocks on the Tyrrhenian coast of Italy for a relatively short period some 2 000 years ago leaving useful markers of sea-level change. At that time, the Italian coast was 1.35 m below today’s levels. Taking into account changes in land elevation along the coast due to plate tectonics and the after-effects of ice age, Kurt Lambeck of the Australian National University of Canberra concluded that geological processes pushed the land up by 1.22 m over the last 2 000 years, with a global sea level rise of 13 cm. At the rate of 1-2 mm per year, this amount is equivalent to about 100 years of rise. Based on readings for about last two centuries from tide gauges, it is reckoned that sea level accelerated some 100 years ago. While Lambeck is cautious in imputing the findings to global warming, he notes that the results fit the increase in ocean volume from global warming and melting of glaciers (New Scientist, 183; 2460).

Ocean warming and disruption of food chain

Analysis of nearly half a century of data on the abundance of different plankton groups in the North Sea indicate that those which photosynthesise (diatoms and dinoflagellates) have been largely unchanged as they use the changing lengths of the day as their cue to reproduce. However, the types of plankton higher in the food chain (larvae of copepods, fish and crustaceans) that emerge in response to changing temperatures of each season, are now appearing up to two months earlier each year, even though the North Sea temperatures have increased by less than 1°C (Nature, 430, 881). This could mean that animals at the top of the food chain, such as fish and sea birds have less to eat—with implications for the North Sea ecosystem (New Scientist, 183; 2461).

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