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the heat so far this June has been exceptional -- and, in some cases, record-breaking.

A strong upper-level high-pressure system, more reminiscent of midsummer than early June, has been responsible for the unusual spike in temperatures, which has extended from the Desert Southwest through the Southern Plains and into the deep South. The heat peaked in the Southwest on Sunday and Monday. The temperature soared to 110 degrees in Las Vegas on Sunday -- the earliest 110-degree reading on record -- and temperatures approached 120 degrees in Death Valley on both Sunday and Monday. The National Weather Service issued excessive-heat warnings and heat advisories for southern Nevada, the deserts of California and portions of Arizona, warning residents of the need to remain hydrated and limit outdoor activity.

In Las Vegas, the high temperature will be close to 105 degrees today and near 100 degrees on Wednesday, which will mark seven consecutive days with 100-plus temperatures.The unusually hot weather has been persistent in the Southern Plains, Missouri Valley and parts of the deep South so far in June as well. Temperatures have averaged five to eight degrees above normal across this region, including a 100-degree temperature in Dallas on Saturday, and heat advisories remain in effect in parts of Louisiana.

long-term monitoring has shown that animal communities living at great depth on the seafloor can change radically over remarkably short periods, and that these events are ultimately driven by climate. Such faunal changes are exemplified by the 'Amperima Event' – the sudden mass occurrence of the sea cucumber (holothurian) Amperima rosea recorded on the Porcupine Abyssal Plain (PAP) situated off the southwest coast of Ireland in the northeast Atlantic. Communities of animals living on the seabed there at depths of nearly 5000 metres have been monitored from 1989 to the present day. A major change occurred in the PAP community between 1996 and 1999 involving a number of animal groups, including sea anemones, segmented worms, sea spiders, sea squirts, brittle stars, and sea cucumbers, all of which increased in abundance. However, the population explosion in the sea cucumber Amperima rosea (hereafter Amperima) was particularly striking – thus the 'Amperima Event'. Before 1996 the sea cucumber was found in only ones or twos. They were very rare. But by 1999, the sea cucumber reached such high densities that if you were able to walk on the deep seafloor, you would have difficulty in avoiding squashing them flat. Dr David Billet and his colleagues showed that the increase abundance and dominance of Amperima occurred over a very wide area, greater than the size of the UK. Changes are also apparent in the abundance of other animals living in the seabed, including the single-celled creatures inhabiting the sediments. The whole deep-sea world had been turned on its head. "What this strongly suggested," says Dr Billett, "is that the 'Amperima Event' did not simply reflect localised, chance changes in the abundances of one or two species. Instead, changes in the whole deep-sea animal community were driven by environmental factors."

"Whether it is the quality or the quality of the organic matter, or both, that matter," says Dr Billett, "it appears that changes in the density of animals such as Amperima are related to phytoplankton productivity in the overlying surface waters, which is affected by climate change."