Câu hỏi:

The people of Kiribati are afraid that one day in the not-too distant future, their country will disappear from the face of the earth - literally. Several times this year, the Pacific island nation has been flooded by a sudden high tide. These tides, which swept across the island and destroyed houses, came when there was neither wind nor rain. “This never happened before”, say the older citizens of Kiribati. What is causing these mysterious high tides? The answer may well be global warming. When fuels like oil and coal are being burned, pollutants are released; this pollutants trap heat in the earth’s atmosphere. Warmer temperatures cause water to expand and also create more water by melting glaciers and polar ice caps. If the trend continues, scientists say, many countries will suffer. Bangladesh, for example, might lose one-fifth of its land. The coral island nations of the Pacific, like Kiribati and the Marshall Islands, however would have a worse result - they would disappear into the sea. The loss of these coral formations would be everyone’s loss. Coral formations are home to more species than any other place on earth.

According to the passage, this year, the high tides came when ________