Two Christmas traditions have come under attack in recent years from environmentalists: Christmas cards and Christmas trees. Paper cards are seen as wasteful and, for some people, going card-free is another way of going green. They also argue that in a world of e-mail, Skype, Facebook and Twitter, people are in touch all the time anyway; they no longer need the yearly card that connects them with long lost friends. If you want to send Christmas greetings, there are free e-cards, which get the job done with no postage or wasted paper. However, especially for people who didn't grow up with e-mail, there is something missing from a Christmas e-mail. The first Christmas cards appeared in London in 1843 and were designed by the same man who had introduced the world's first postage stamp three years earlier. His name was Sir Henry Cole. They rose in popularity throughout the 20th century. Many people sent cards that were sold for charity. The most famous of these are the ones sold for UNICEF. In the UK this year, in the three weeks before Christmas, the post office expects to handle 100 million cards every day. Environmental awareness also means that nowadays many people recycle their cards; this helps raise money to plant more trees, as well as recreating more paper. When we think of trees at Christmas, there is one that immediately springs mind---the evergreen tree that people decorate with ornaments and place their presents under. The custom dates back almost a thousand years to Germany. Nowadays 33 to 36 million Christmas trees are produced in America and 50 to 60 million in Europe each year. Some trees are sold live with roots and soil so people can plant them later and reuse them next year. Some people prefer artificial trees as they are reusable and much cheaper than their natural alternative. However, environmentalists point out that they are made from petroleum   products and so have many pollution issues. What is the main idea of the article?
To introduce the history of two typical Christmas traditions. To explain the debate about some Christmas traditions. To analyze how two Christmas traditions grew in popularity. To point out the problems caused by celebrating Christmas.