More than half of former host cities for the Winter Olympics will be too hot     1     (deal) with such games by the end of this century. That is the     2     (predict) of a recent study.

It’s not just the Olympics that are at risk now. “The world of winter sports is changing as the global climate continues warming,” says Daniel Scott,     3     climate-change researcher in Canada. He led a team of researchers,     4     used math to predict how winter conditions will have changed by February 2050 and 2080. February is the month when the Olympic winter games are     5     (typical) played.

Scott and his team forecast temperatures and snow cover for the 19 cities that have already hosted Winter Olympics, and two     6     (addition) cities: Pyeongchang, South Korea, and Beijing, China, where the 2022 Winter Olympics will be held.

Scott’s team     7     (begin) with looking at historic winter conditions, and then used computer models to predict conditions in the future.     8     (they) model predicted that by 2050, the average February temperatures in past Winter Olympic host cities will rise     9     1.9 to 2.1 degrees Celsius. These temperatures can affect the quality of snow, thus     10     (increase) the chance of accidents.

Stephanie Jenouvrier at the Woods Hole Oceanographic Institution found the future of emperor penguins (帝企鹅)depended on international efforts to manage climate change rather than on their     1     (able)to adapt to new environment. Climate change, if     2    (leave)unchecked, could drive emperor penguins to extinction (灭绝)by the end of the century as sea ice disappears.

Disappearing sea ice affects these penguins     3     (direct) because they rely on it for their living. Sea ice changes are already affecting emperor penguins, with breeding failures for three years in a row at their second     4     (big) living place in the Antarctic.

    5     (examine )the future of emperor penguins, Jenouvirer and her team       6    (model)their population under three scenarios (设想)：global temperature increases by 1.5°C; global temperature increases by 2°C; no action     7     (take) to reduce emissions(排放物). They wanted to see     8     would happen if emissions kept rising. They found that global warming of 1.5°C would cause a 31 percent fall,     9    2°C a 44 percent fall. "The result was     10     81 to 86 per cent fall in population by 2100 under the third scenario, "said Jenouvrier.

All scientists subscribe to the view that it is human activity     1     has caused the global warming. This activity is burning fossil fuels to produce energy. As     2     result, a natural phenomenon     3     (call) the “greenhouse effect” has come about. Without this phenomenon, the earth would be about thirty three degrees Celsius     4     (cool) than it is. So, we need those gases.     5     , the global temperature will rise when we add huge     6     (quantity) of extra carbon dioxide into the atmosphere. We know that the levels of carbon dioxide     7     (increase) greatly over the last 100 to 150 years. The attitudes of scientists towards this rise are     8     (complete) different. Some think that the trend would be a catastrophe while     9     are opposed to this view, and they predict that any warming will be mild     10     few bad environmental consequences.