48 Climate Change-High

Climate Change FOCUS Question How is Earth's climate changing?

气候变化焦点问题地球的气候是如何变化的?

Warming Up In recent years, severe weather has become more powerful and frequent. The strongest cyclone ever recorded slammed into the Philippines. A drought dried out Australia, and dust storms choked the city of Sydney. Meanwhile, record snowfalls blanketed eastern Canada and the United States. Does this extreme weather mean Earth's entire climate is changing? Yes, and it's just getting started. This is the new reality of climate change. Weather Versus Climate Weather describes the daily conditions in the atmosphere, such as temperature, clouds, rain, or wind. It also includes seasonal trends, such as a very snowy winter or a very hot summer. Climate is the average temperature, wind speed, and rainfall in a region over many years. Climate helps define the average weather in an area, but the day-to-day weather can vary.

近年来，恶劣天气变得更加强大和频繁。 有史以来最强的气旋袭击了菲律宾。 干旱使澳大利亚干旱，沙尘暴使悉尼城市窒息。 与此同时，创纪录的降雪覆盖了加拿大东部和美国。 这种极端天气是否意味着地球的整个气候正在发生变化? 是的，这才刚刚开始。 这是气候变化的新现实。 天气与气候天气描述的是大气中的日常情况，如温度、云、雨或风。 它还包括季节趋势，比如一个大雪纷飞的冬天或一个非常炎热的夏天。 气候是指一个地区多年来的平均温度、风速和降雨量。 气候有助于确定一个地区的平均天气，但每天的天气可能会有所不同。

The Greenhouse Effect Earth's atmosphere acts like a blanket. The Sun shines on Earth's surface, warming the land and water. Heat that was absorbed by the surface is then released, and some of it is trapped by the atmosphere, keeping Earth warm. This process is called the greenhouse effect. Without it, Earth would be cold and lifeless like the Moon. Some gases in Earth's atmosphere, called greenhouse gases, trap heat better than others— just as some materials, such as wool, make warmer blankets. Carbon dioxide (CO2) is an important natural greenhouse gas. It is the gas you breathe out and the gas plants take in. But too much of it can cause problems. Large amounts of CO2 in the atmosphere trap more heat, causing Earth to heat up even more.

温室效应地球的大气层就像一张毯子。 太阳照射在地球表面，使陆地和水变暖。 被地表吸收的热量被释放出来，其中一些被大气层捕获，使地球保持温暖。 这个过程被称为温室效应。 没有它，地球就会像月球一样冰冷而没有生命。 地球大气中的一些气体，被称为温室气体，比其他气体更能吸收热量——就像一些材料，如羊毛，可以制作更温暖的毯子一样。 二氧化碳(CO2)是一种重要的天然温室气体。 它是你呼出的气体和工厂吸收的气体。 但过多会导致问题。 大气中大量的二氧化碳会捕获更多的热量，导致地球温度更高。

Changing Atmosphere Excess CO2 in the atmosphere comes from burning fuels. Since the early 1900s, cars, airplanes, factories, and power plants have pumped out tons of extra CO2. Adding CO2 to the atmosphere is like adding blankets to a bed. Many of the warmest years in history have occurred in the twenty-first century. Different places on Earth have warmed up at different rates. A few places have even cooled off, but Earth as a whole has warmed. This is known as global warming. Scientists predict that the global average temperature will rise between 2° and 6°C (3.6-10.8°F) by the year 2115. That may not sound like a lot, but even small changes in temperature can mean big changes for Earth.

大气中过量的二氧化碳来自燃烧燃料。 自20世纪初以来，汽车、飞机、工厂和发电厂排放了大量额外的二氧化碳。 向大气中添加二氧化碳就像在床上加毯子一样。 历史上许多最温暖的年份都发生在21世纪。 地球上不同的地方升温的速度不同。 一些地方甚至变冷了，但整个地球变暖了。 这就是全球变暖。 科学家预测，到2115年，全球平均气温将上升2°到6°C(3.6-10.8°F)。 这听起来可能不多，但即使温度的微小变化对地球来说也意味着巨大的变化。

Changing Ice Normally, about 10 percent of Earth's surface is covered with some form of ice. As Earth warms up, this ice is melting rapidly. Ice sheets are massive slabs of frozen water that cover land. These ice sheets are losing billions of tons of ice per year. Glaciers are rivers of slow-moving ice, often found on mountaintops. It is natural for glaciers to melt a bit in the spring and summer. But now, thousands of glaciers have shrunk quickly, and hundreds of them have vanished entirely. Sea ice is frozen ocean water that floats on the surface. It, too, is shrinking. Do You Know? White ice and snow reflect sunlight back into space. As ice melts, more dark land and water are exposed. This causes Earth's surface to absorb even more heat.

通常情况下，大约10%的地球表面覆盖着某种形式的冰。 随着地球变暖，这些冰正在迅速融化。 冰原是覆盖在陆地上的巨大的冻结水板。 这些冰原每年损失数十亿吨冰。 冰川是由缓慢移动的冰组成的河流，通常在山顶上发现。 冰川在春天和夏天融化一点是很自然的。 但现在，成千上万的冰川迅速缩小，数百座冰川已经完全消失。 海冰是漂浮在海面上的冻结海水。 它也在萎缩。你知道吗? 白色的冰雪将阳光反射回太空。 随着冰的融化，更多黑暗的土地和水暴露出来。 这导致地球表面吸收更多的热量。

Changing Seas The Arctic Ocean is usually covered with sea ice year round, but in recent summers, scientists have spotted open water, even at the North Pole. Water from melting sea ice, glaciers, and ice sheets is filling the ocean. All that extra water increases the sea level. Since the early 1900s, the sea level has risen 19 centimeters (7.5 in.). This rise has caused flooding in many areas, especially during storms. The sea level is rising for another reason, too. The warmer atmosphere is warming up our oceans, and water expands as it heats up. Warmer waters also change sea life. Fragile coral reefs struggle in water that is too warm. Fish and other animals are moving closer to the poles to find cooler water.

北冰洋通常一年四季都被海冰覆盖，但在最近的夏天，科学家们甚至在北极也发现了开阔的水域。 来自融化的海冰、冰川和冰原的水充满了海洋。 所有这些额外的水增加了海平面。 自20世纪初以来，海平面上升了19厘米(7.5英寸)。 这一上升已经在许多地区引发了洪水，尤其是在暴风雨期间。 海平面上升还有另一个原因。 变暖的大气使我们的海洋变暖，水在升温时膨胀。 温暖的海水也改变了海洋生物。 脆弱的珊瑚礁在过于温暖的水中挣扎。 鱼类和其他动物正在向两极靠近，以寻找更凉爽的水域。