Rock art from Gilf Kebir in the present day Libyan Desert, part of the Sahara. Painted between 8000 and 4000 BC, it depicts...Read More >>Rock art from Gilf Kebir in the present day Libyan Desert, part of the Sahara. Painted between 8000 and 4000 BC, it depicts giraffes and ostriches, along with people herding longhorned cattle—evidence for a much wetter climate in that period. Since the end of the Ice Ages, around 10–12,000 years ago, there have been periods when the Earth's climates have varied. Up to around 6000 years ago, northern Africa was much wetter than it is today. The Sahara was not desert at all, but "Green Sahara", a region of savanna grasslands and forested mountains, dotted with lakes and inhabited by animals such as giraffe, hippos and crocodiles—and humans. The Sahara's climate at the time was similar to that of those regions of the world, such as the Indian subcontinent, that experience monsoons today: warm winds blowing over the ocean bringing heavy rainfall at a certain time of the year.
Medieval Warm Period
Between about AD 800 and 1300, during the European Middle Ages, the average temperatures were higher across the world. The Vikings took advantage of ice-free seas to explore the North Atlantic Ocean. Norse sagas describe how they settled Greenland in the 9th century AD, farming land now totally unsuitable for cultivation. In an area called Vinland, probably Newfoundland, the Vikings reported grape vines growing. This is known as the Medieval Warm Period.
Records suggest that average temperatures during the Medieval Warm Period were still cooler than those of the late 20th century, when the effects of global warming caused by human activity were felt.
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