While he was growing up, the philosopher Aristotle was his teacher. Alexander became interested in science, medicine, philosophy, and literature.While his father Philip was attending his daughter’s wedding, a young nobleman murdered him. Alexander became king of Macedonia at the age of 20.While he was fighting his enemies in the north, the Greeks in the south started a rebellion. He destroyed all their cities.He led his army against the Persian Empire through what is now Turkey. While he was staying in the ancient city of Gordium, he undid the Gordian knot. A legend said that only a future king of Asia could do this.While his army was marching through Persia, it defeated Darius, the king of Persia.He founded the city of Alexandria at the mouth of the Nile while he was visiting Egypt.While he was traveling with his army, he gave his name to many other towns.He killed his friend Clitus in a quarrel while they were having dinner.While he was attacking the city of Mali in India, he received a serious wound from an arrow.While he was attending a banquet in Babylon in 323 BC, he fell ill and died.

At the moment, scientists agree that the world’s climate has become warmer over the past 50 years, but they disagree about the causes. Some believe that human activities have caused climate change. They argue that for 1,000 or 2,000 years before 1850, when records began, the temperature was more or less stable. Short warm or cold periods occurred during that time, but the climate always returned to the same level. However, since the Industrial Revolution, human beings have burned more and more fossil fuels, such as coal and oil. In 1800 the atmosphere contained around 280 parts per million of carbon dioxide (CO₂). Since then, there has been an increase of about 31%.