What will our world be like in 2050?

There are two features in the growth of world population. First, the annual increase in population in 15 European countries, in the past few years, has been only 300,000. The United Nations estimates (估计)that by 2050, the population of European countries will decrease from the current 0.72 billion to 0.63 billion. Second, the population in developing countries is growing rapidly. By 2050，the population of Africa is expected to reach 1.8 billion, 0.9 billion more than its current population.

A recent research report published by the United Nations indicates that it is quite possible that the Earth's temperature is rising well above the previous estimate. The Antarctic ice sheet, which contains 90% of the world's ice, has lost significant mass in the past few years. The discovery comes as a surprise to scientists, who thought that the continent would gain ice this century because of increased snowfall in a warming climate. A research team from the University of Colorado used satellite data to estimate that the ice sheet will lose up to 48 cubic miles by 2050.

Africa's rivers face great change that will leave a quarter of the continent severely short of water by the middle of the century, according to a global warming study published today. Even modest decreases in rain in western Africa will see rivers lose as much as 80% of their water and a rise of what the scientists call "water refuges(难民)”. "In those areas where there is already a water shortage, it's going to have a destructive effect," the study says,.“If you're already walking 5 km to the nearest stream, by 2050,it's going to mean walking 30 km or moving your whole household closer to the water source."

For years, planet-hunters have been searching for a planet other than Earth that can support life. They may have found one.

The planet is the sixth found orbiting a star called Gliese 581. Steven Vogt, one of the scientists involved, expects the new planet to have water. On Earth, when we find water, we find life. 【小题1】

A planet that can support life has to be just the right size for its system and just the right distance from its star. Some planets orbit so close to their stars that they’re much too hot for liquid water—or for life as we know it. 【小题2】

But a right-sized planet that's neither too close nor too far might be just right for water. Gliese 581 is probably just right. It is about three times as huge as Earth. 【小题3】 Because it’s so close, one side of it always faces its star, and the other side is always dark.

The new planet is 20 light years away, which is as far as 250 million trips to the Moon and back. 【小题4】 Only light can go that fast. So even at the fastest speed we could manage, it would take a spaceship from Earth more than 200 years to go that far. 【小题5】 But that doesn’t mean we can’t study it. Thanks to powerful new telescopes and new techniques for searching the skies, scientists can learn a lot about distant planets without even leaving Earth.

Gliese 581 is an exciting discovery—and astronomers are likely to find more soon, thanks to new, powerful telescopes specifically designed to look for planets.

Experts say farmers will need to produce about 70 percent more food by the middle of the century. They predict that 9 billion people will need to be fed worldwide by 2050. The prediction means experts will need to develop more effective farming methods that cause less harm to the environment to produce more food. Experts say living things called bacteria could help achieve that goal. A bacterium is an organism.It is so small that it can be seen only with a microscope.

Researchers are finding extremely small organisms in the ground. One gram of soil contains between 100 million and one billion bacteria. Bacteria are taking part in a healthy ex- change with the plants that share the soil. Around plant roots, bacteria change chemicals in the air and soil into food for the plants. The bacteria include the material known as fungi(真菌). Some bacteria act as bodyguards. They produce anti-bodies and other chemicals to fight harmful bacteria.

Plants make sugar through a process called photosynthesis (光合作用).This happens when a plant receiving light changes water and carbon dioxide into food. Much of the sugar is pumped down through the roots. There, it is turned into sugar-based food and released into the soil. That is done to get bacteria to help the plants grow better. Some of the organisms turn chemicals in the air and soil into food that the plants can eat.

The biosciences company Novozymes already sells one kind of fungi. It has found a way to produce it in very large quantities and offer it to farmers as.a bio-pesticide (生物农药).A bio-pesticide protects crops from animals and bacteria. If so, farmers can harvest more crops.