21st July - Today's news

And it's raining again - yesterday having been one of the few entirely dry days all month. Still, a way to go to match 2007's total!

Anyway, a break from the weather today as we catch up on other science news from Science Daily:

Risk of huge Pacific Ocean tsunami on west coast of America greater than previously thought

The new research suggests that future tsunamis could reach a scale far beyond that suffered in the tsunami generated by the great 1964 Alaskan earthquake. Official figures put the number of deaths caused by the earthquake at around 130: 114 in Alaska and 16 in Oregon and California. The tsunami killed 35 people directly and caused extensive damage in Alaska, British Columbia, and the US Pacific region*.

The 1964 Alaskan earthquake – the second biggest recorded in history with a magnitude of 9.2 – triggered a series of massive waves with run up heights of as much as 12.7 metres in the Alaskan Gulf region and 52 metres in the Shoup Bay submarine slide in Valdez Arm.

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The study published in the academic journal Quaternary Science Reviews and funded by the National Science Foundation, NASA, and the US Geological Survey shows that the potential impact in terms of tsunami generation, could be significantly greater if both the 800-km-long 1964 segment and the 250-km-long adjacent Yakataga segment to the east were to rupture simultaneously.

Lead author, Professor Ian Shennan, from Durham University’s Geography Department said: “Our radiocarbon-dated samples suggest that previous earthquakes were fifteen per cent bigger in terms of the area affected than the 1964 event. This historical evidence of widespread, simultaneous plate rupturing within the Alaskan region has significant implications for the tsunami potential of the Gulf of Alaska and the Pacific region as a whole.

Of course that doesn't mean such a quake will occur, or that of it does it'll be any time in the next few hundreds years. Then again, it could hit tomorrow. As could that bus as you cross the road ....

California's Channel islands hold evidence of Clover era comets

A 17-member team has found what may be the smoking gun of a much-debated proposal that a cosmic impact about 12,900 years ago ripped through North America and drove multiple species into extinction.

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"The type of diamond we have found -- Lonsdaleite -- is a shock-synthesized mineral defined by its hexagonal crystalline structure. It forms under very high temperatures and pressures consistent with a cosmic impact," Kennett said. "These diamonds have only been found thus far in meteorites and impact craters on Earth and appear to be the strongest indicator yet of a significant cosmic impact [during Clovis]."

The age of this event also matches the extinction of the pygmy mammoth on the Northern Channel Islands, as well as numerous other North American mammals, including the horse, which Europeans later reintroduced. In all, an estimated 35 mammal and 19 bird genera became extinct near the end of the Pleistocene with some of them occurring very close in time to the proposed cosmic impact, first reported in October 2007 in PNAS.

Interesting stuff. However a comet impact should not be presented as a one size fits all theory - other factors such as overhunting and general climate change are likely to have also contributed to the decline of megafaunal in N America and more especially elsewhere in the world. In Siberia, for example, vegetation changes and increased rainfall look more likely culprits. Of course one may have reduced population sto an extent where they other then finsihed them off. Double whammy. Explaining too why such extinctions do not occur at the end of other glacials. It may though have been the trigger for the Younger Dryas.

Future of Western US water supply threatened by climate change

New research provides insight into ice sheet behaviour

Role of solar radiation in climate change

A special volume of the Journal of Geophysical Research reviews the growing research field of “global dimming” and “global brightening” in over 20 articles. These phenomena, supposedly human-induced, control solar radiation incident at the Earth’s surface and thus influence climate.

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It wasn’t until 1998 that the first global study was conducted for larger areas, like the continents Africa, Asia, North America and Europe for instance. The results showed that on average the surface solar radiation decreased by two percent per decade between the 1950s and 1990.

In analyzing more recently compiled data, however, Wild and his team discovered that solar radiation has gradually been increasing again since 1985.

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It is particularly unclear as to whether it is the clouds or the aerosols that trigger global dimming/brightening, or even interactions between clouds and aerosols, as aerosols can influence the “brightness” and lifetime of the clouds.

New geothermal heat extraction process to deliver clean power generation - it's probably the cleanest, least environmentally damaging source of electricity generation there is. So this has to be good news.

Radioactive material from dying supernova may have spawned our solar system - sing along with me "we are stardust, we are golden ..... "

And finally something a little off topic but very close to my heart - I would so dearly love to see this happen on a big scale across the Highlands: wolf reintroduction proposed in Scottish Highland test case.

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