Are more killer heat waves on the horizon.

• Author: Larsen, Janet
• Position: Ecology

"The top four warmest 12-month periods on record have come in the last six years. The 17 warmest years since record-keeping began in 1867 have occurred since 1980. It is clear that the temperature is rising" and thousands of deaths are the result.

IN AUGUST, 2003, a record heat wave scorched Europe, claiming an estimated 35,000 lives. In France alone, 14,802 people died from the searing temperatures--more than 19 times the death toll from the SARS epidemic worldwide. In the worst heat spell in decades, temperatures in France soared to 104[degrees]F and pretty much stayed in that range for two weeks. During that time, patients suffering from heat-related illnesses lined up for treatment at overcrowded and understaffed hospitals. Paris' morgues were filled past capacity. Excess bodies had to be stored in nearby tents. Those seeking to escape the stifling heat sought out the few public buildings equipped with air conditioning.

Other countries were affected as well. Germany saw some 7,000 perish in the swelter. Spain and Italy each suffered losses of nearly 4,200 lives. At least 1,300 individuals were lost in Portugal and up to 1,400 in the Netherlands.

In London--which on Aug. 10 recorded its first ever triple-digit temperature reading--an estimated 900 citizens were felled. Heat-related fatalities across the United Kingdom reached 2,045. In Belgium, temperatures higher than any in the Royal Meteorological Society's register--dating back to 1833--brought 150 deaths. Since reports are not available for all nations, the actual death toll for the continent likely is higher than what was officially recorded.

Though they rarely are given the same sensational coverage as other natural disasters. heat waves claim more lives each year than floods, tornadoes, and hurricanes combined. In a sense, they are a silent killer, mostly affecting the elderly, very young, or chronically ill. Under normal circumstances, humans maintain a body temperature around 98.6[degrees]F. When subject to extreme heat, the body attempts to maintain this ideal reading by varying blood circulation and perspiring. When the internal temperature rises above 104[degrees], though, vital organs are at risk. If it cannot be reduced, death follows.

The threshold ambient temperature at which more people are at risk for heat-related health complications varies greatly by location. In general, when summer temperatures range 10[degrees] or more above the norm, incidences of heat-related...