Guided hurricanes

17/08/2010

Predictions revisited and Climate Change: News and Comments

Guided hurricanes

When speculating four decades ago about the military uses of geophysics, Gordon J.F. MacDonald of UCLA contemplated the triggering of earthquakes or tsunamis, or melting polar ice with nuclear weapons. And he didn’t overlook the idea of steering hurricanes to ravage the enemy’s coasts. Reminding me of that prediction is a report now in press in Geophysical Research Letters, about how natural variations in the colour of the sea help to guide cyclones in the Pacific. A cyclone, remember, is a loosely used generic term that includes the major storms called hurricanes (Atlantic), typhoons (Pacific) or tropical cyclones (Indian Ocean and Australia).

Contributing to Unless Peace Comes, (1968), in a chapter entitled “How to Wreck the Environment”, MacDonald wrote:

… preliminary experiments have been carried out on the seeding of hurricanes. The dynamics of hurricanes and the mechanism by which energy is transferred from the ocean into the atmosphere supporting the hurricane are poorly understood. Yet various schemes for both dissipation and steering can be imagined. Although hurricanes originate in tropical regions, they can travel into temperate latitudes, as the residents of New England know only too well. A controlled hurricane could be used as a weapon to terrorize opponents over substantial parts of the populated world.

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Maps of monsoon history

05/05/2010

Climate Change – News and Comments

Maps of monsoon history

Brendan Buckley cores a tree in Vietnam. Photo: K. Krajick, Earth Institute, Columbia U.

Asian Monsoon Failure and Megadrought During the Last Millennium” is the dramatic title of a report in Science that introduces a new Monsoon Asia Drought Atlas. Edward R. Cook and his colleagues at the Tree-Ring Laboratory of Columbia University’s Lamont-Doherty Earth Observatory have used tree-rings from 300 sites in Asian forests to reconstruct the summer “Palmer Drought Severity Index” (PDSI) across India, China and adjacent regions. PDSI is a fairly complicated reckoning of local deviations from mean conditions, originated in 1965 by Wayne C. Palmer, a climatologist in the US Weather Bureau.

In the following examples, North American data supplement the Asian PDSI, and anomalous sea-surface temperatures (SST) across the Pacific are also reconstructed.

On land, brown is abnormally dry, green is wet. On the oceans, red is abnormally warm, blue is cool. Fig. 4 in E.R. Cook et al, Science, 23 April 2010, distributed by NOAA Paleoclimatology.

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Monsoons and the Sun

01/05/2010

Climate Change: Updating The Chilling Stars

Monsoons and the Sun

Late rains saved most of the 2009 harvest of India, despite a shortfall of 21% in the summer’s rainfall that led to a ban on rice exports, after a 17% loss of production in West Bengal. But 2009 saw the worst deficit in India’s summer monsoon since 1972, while Burma (Myanmar) had its the shortest monsoon season since 1979.

It is chastening to recall that, in April 2009, Reuters reported the Indian Meteorological Department as saying, “IMD’s long range forecast for the 2009 south-west monsoon season (June to September) is that the rainfall for the country as a whole is likely to be near normal.” Even an updated forecast in June expected only a small rainfall deficit. Clearly, the unpredictable monsoons remain a problem for meteorology and climate physics.

Is there a link between reduced monsoon rains and the Sun’s recent sluggish behaviour, shown by the scarcity of sunspots? Probably. But to clarify the solar link well enough to make better regional forecasts, for even a few months ahead, remains an urgent task. Read the rest of this entry »