根据短文内容填空。

      A seabird named Lydia recently made a 26-day nonstop(不间断的)journey of about 2,500 mi­les, just to search for food for her baby. She is fitted with a satellite tracking device (卫星跟踪仪). Her trip started on Oct. 18 from Christmas Island in the Indian Ocean. The trip is known as the lon­gest nonstop journey by one of these endangered seabirds.

      Before that, this kind of birds was known only to fly a few hundred miles from where they live, staying away for just a few days at a time. They usually fly over the sea.

      The scientists feel it strange that Lydia made such a long, nonstop journey and flew overland. So the above facts raise some serious questions about efforts to stop the decline(减少)of the birds. The number of the birds has fallen by 10 percent over the past 20 years.

Besides, the scientists are surprised that she was away from her baby for such a long time. They wonder why she needed to go that far. Maybe it shows that fish resources (资源)around Christmas Island are not large enough now. That might explain the slow decline of the bird 一 sea pollution(污染) is serious.

概括下面一段话的主要信息。（不超过20个字）

    联合国政府气候变化专门委员会在公布的最新报告中指出，全球变暖速度近来有所放缓。尽管全球温度在20世纪50年代到90年代期间每十年上升约0．2华氏度（约合0．11摄氏度），但在1998年气温达到创纪录的高度之后，变暖速度下降了一半。该委员会的科学家认为，20世纪70年代以来，人类通过温室气体排放向大气层输送的部分热量已被海洋吸收。权威的《科学》杂志也刊文称，从更长时间范围看，海洋消化人类碳排放产生的热量的能力可能比目前科学家所认为的还要强，该文首席作者、拉特格斯大学气候学家亚伊尔·罗森塔尔说：“我们可能低估了海洋储藏热量的效率，它可能为我们应对全球变暖这个难题争取了一些时间。”

阅读下列材料：

1956年元旦，北京市各行各业工商业者申请实行全行业公私合营，得到北京市人民政府批准 … … 1月底，全国所有大城市和五十多个中等城市的资本主义工商业者都实行了全行业公私合营。

 请回答：

（1）这则材料反映的是20世纪50年代的什么历史事件？

（2）这一历史事件什么时间结束？其重要的作用是什么？