刘洪波、曹旼炜老师新书《雅思阅读真经3》中收录文章“冰川时期The little ice age”，在上周末雅思考试阅读中重现。

经作者同意，将《雅思阅读真经3》中该文解禁供广大考生参考。

The Little Ice Age: When global cooling gripped the world

The year was 1645, and the glaciers in the Alps were on the move. In Chamonix at the foot of Mont Blanc, people watched in fear as the Mer de Glace (Sea of Ice) glacier advanced. In earlier years, they had seen the slowly flowing ice engulf farms and crush entire villages. They turned to the Bishop of Geneva for help; at the ice front he performed a rite of exorcism. Little by little, the glacier receded. But before long the threatening ice returned, and once again the bishop was summoned. The struggle against the glacier continued for decades. Similar dramas unfolded throughout the Alps and Scandinavia during the late 1600s and early 1700s, as many glaciers grew farther down mountain slopes and valleys than they had in thousands of years. Sea ice choked much of the North Atlantic, causing havoc with fisheries in Iceland and Scandinavia. Eskimos paddled their kayaks as far south as Scotland. These and many similar events, bewildering and disruptive to the societies of the time, are pieces of a global climatic puzzle that scientists and historians today call the "Little Ice Age (LIA)."    

Most of the Little Ice Age occurred well before the Industrial Revolution and the widespread burning of fossil fuels, so scientists are confident that its climatic convulsions had purely natural causes. The event fascinates scientists because it gives them a glimpse of how Earth's climate system operates when left to its own devices. "It's important because we're trying to understand the warming over the past 100 years," says Alan Robock of the University of Maryland's Department of Meteorology. “Some people have said it's just a ‘recovery from the Little Ice Age.’” 

So, what caused the Little Ice Age? Because the sun is the ultimate source of Earth's warmth, some researchers have looked to it for an answer. In the 1970s, solar researcher John Eddy noticed the correlation of sunspot numbers with major ups and downs in Earth's climate. He found that a period of low activity from 1645 to 1715, called the Maunder Minimum, matched perfectly one of the coldest spells of the Little Ice Age. Judith Lean, a solar physicist at the Naval Research Laboratory in Washington, estimates that the sun may have been about a quarter of 1 percent dimmer during the Maunder Minimum. This may not sound like much, but the sun's energy output is so immense that 0.25 percent amount to a lot of missing sunshine -- enough to cause most of the temperature drop, she says.   
 

Other researchers have examined earthly causes. Volcanic eruptions are known to meddle with climate by injecting a veil of sun-blocking aerosols into the atmosphere. The eruption of Mount Pinatubo in 1991 dropped Earth's average air temperature by about 1 degree -- an effect that lasted about two years. Martin Robock points out that there were more frequent eruptions during the Little Ice Age than during the 20th century. Most prominent was the 1815 eruption of Tambora in Indonesia. It pumped into the atmosphere vast amounts of ash -- ten times that of Krakatoa, another famous Indonesian volcano. The following year has been called the "Year without a Summer." In June and July of 1816, New England and northern Europe suffered frost and even snow. Scientists dispute the importance of these two causes, and of other possibilities such as shifts in ocean currents. But it seems possible that during the Little Ice Age Earth's climate was hit by a one-two punch from a dimmer sun and a dustier atmosphere.