Science Now/ Spring 2001 - A Modern Scientist Probes a Mystery of Early Antarctic Exploration

For nearly a century, historians and adventurers have debated about the demise of Robert Falcon Scott's 1912 expedition to the South Pole. Was this tragedy the result of Scott's poor leadership, inadequate planning, extraordinary weather conditions, or a combination of these and other factors? Susan Solomon, an atmospheric chemist and recipient of the Presidents' Medal for Science, has shed light on this mystery by comparing modern Antarctic temperature records to weather data recorded by Scott's team during their fatal expedition.

Being first to the South Pole was Robert Falcon Scott's life-long dream. He first attempted the 1,800-mile round-trip journey from Ross Island to the pole in 1902, accompanied by two companions, 19 dogs, and five loaded sledges. Suffering from inadequate food and scurvy, the men nevertheless pushed on to 82°17' South before turning back.

Scott's final attempt began in 1911. This time, he planned reconnaissance missions to better prepare. During one of these, a team cached supplies and recorded weather data along the route from Ross Island across the Ross Ice Shelf. Measuring winds and temperatures three times a day during July 1911, the Antarctic winter, they recorded values as low as 77° F. The winds blew from south to north, and the coldest temperatures occurred under calm conditions. Scott's meteorologist used weather balloons to measure temperature profiles and then made a forecast of the temperatures the expedition would likely encounter.

In October 1911, retracing the route of the reconnaissance team, Scott and four teammates set out across the ice sheet on their way to the Transantarctic Mountains and onto the 10,000-foot-high Antarctic plateau. At the same time, a Norwegian party led by Roald Amundsen was approaching the pole from another direction.

Scott knew his party would encounter severe weather. They obtained well-insulated felt boots and Siberian horses adapted to cold temperatures. They also designed sails to use on sledges for the return trip, when winds would be from the south. For the first part of the trip, Scott used motorized tracked sledges, forerunners of modern oversnow vehicles, but their air-cooled engines froze in the extreme cold. Relying on horse-drawn sledges, the expedition made slower progress than it might have with dog teams. Nevertheless, it reached within 1° of the South Pole on January 10, 1912.

Scott's men carefully measured the angle between the sun and the horizon as they progressed toward the pole. Upon measuring the same angle above the horizon in all directions throughout the day, Scott knew his team had arrived at the geographic South Pole. There, Scott's party found a tent belonging to Amundsen, who had beaten them to their goal.

While Scott was in the vicinity of the South Pole from January 10 to 23, 1912, daily minimum temperatures averaged 23° F, comparable to the recent average for January of 22.6° F. On his return trip, temperatures stayed in the normal range until the end of February. Using sails on the sledges and with winds at their backs, they made good progress during this time.

Then the weather changed. Between February 25 and March 19, the Scott party recorded daily minimum temperatures between 35°F and 45°F or 15 to 20° F below normal. Some have questioned whether such low temperatures could even occur. By comparing temperatures recorded by Scott's party with weather data from the last 15 years, Solomon found that one year, 1988, also had such severe values. In other years temperatures were as much as 30°F warmer. So, yes, it is possible that normal weather conditions at the beginning of 1912 were followed by a much colder period.

At their last camp, on March 19, 1912, only about 11 miles south of their supply depot, a blizzard prevented Scott's team from going on. Their energy depleted by months of struggle in deep snow and cold, they all died.

Scott's diary states: "No one in the world would have expected the temperature and surfaces which we encountered at this time of the year. . . . it is clear that these circumstances come on very suddenly. . . . our wreck is certainly due to this sudden advent of severe weather." Solomon's work shows that Scott's words were justified.

Activity: Popsicle Toes

Background: The purpose of this activity is to examine the insulating properties of various clothing materials and to demonstrate the cooling effects of evaporating water.

Materials: A variety of pairs of clean socks of different materials (cotton, polypropylene, wool, blends, etc.), a collection of empty and identical 16 oz. bottles over which socks can be pulled, a cork with a hole in the center for each bottle, a thermometer inserted into each cork, hot water, and a large pot of cold water.

Procedure: Have students combine various sock thicknesses and materials. For instance, two pairs of thin cotton socks may equal the thickness of one pair of polypropylene socks. Place a test combination of socks on each bottle as if students are dressing their own feet. Make a duplicate set of bottles for each sock combination to be tested. One set will be tested under wet conditions and another under dry conditions. Fill each of the water bottles with water at body temperature (98.6°F or 37°C), being careful not to wet the socks. Cork the bottles and insert a thermometer into each. Immerse one set of bottles in the pot with cold water for the wet condition test. Then place all bottles outside in the shade. Have students record the temperatures of the bottles every two minutes for one hour. When observations are complete, have students graph the temperatures for the wet and dry conditions.

Discussion: What factors are important to insulating feet in cold weather? Why is it important to look at both wet and dry cooling rates? Why might this be important in choosing socks for a winter trip? How does this experiment relate to Scott's expedition?

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