Wet climate helped Genghis Khan conquer Asia The early 13th Century marked the beginning of the conquests of Genghis Khan and his Mongol hordes. Similar agricultural expansion occurred in some parts of North America, but also in central Asia where farmers spread into the northern region of Russia, into Manchuria, the Amur Valley, and northern Japan. At the time, England was warm enough to support vineyards, centralised governments in Europe were becoming stronger, people no longer needed fortifications to protect their once limited arable lands, and many people left seeking new lands. Unequal consequences for people and environmentsįor about 300 years, these new climate conditions changed ecosystems and radically altered human societies.Īs northern Europe became warmer, agriculture spread and generated food surpluses. These conditions also affected the winter weather in Greenland, north Africa and northern Asia. The increase in solar radiation also modified the atmospheric pressure system over the north Atlantic Ocean ( North Atlantic Oscillation), which brought warmer winters and wetter conditions over northern Europe and most of north-eastern part of the North American continent. Stronger trade winds pushing more warm water towards Asia created wetter conditions in Australasia, droughts in the southern US and South and Central America, and heavy rains and flooding in the Pacific Northwest and Canada. It usually brings clouds and rain in the western tropical Pacific while making regions in the eastern tropical Pacific relatively drier and cooler.ĭuring the Medieval warm period, an increase in solar radiation and decrease in volcanic eruptions created a La Niña-like event that changed the usual patterns. This recurring climate pattern of winds and sea-surface temperatures over the tropical eastern Pacific affects the climate and weather of much of the tropics and subtropics. The most likely cause of the regional changes in temperature was related to a modification of the El Niño–Southern Oscillation. Its presence or absence reflects a redistribution of heat around the planet, and this suggests drivers other than a global increase in atmospheric greenhouse gases such as carbon dioxide. The Medieval warm period was by and large a regional event. Mechanisms driving the Medieval warm period While the northern hemisphere, South America, China and Australasia, and even New Zealand, recorded temperatures of 0.3-1.0 ☌ higher than those of 1960-1990 between the early ninth and late 14th centuries, in other areas such as the eastern tropical Pacific Ocean, it was much cooler than today. But the temperature increase was not universal, varying across regions of the world, and did not happen simultaneously everywhere. The available evidence suggests that at times, some regions experienced temperatures exceeding those recorded during the period between 19.ĭespite being predominantly recorded in Europe, south-western North America and in some tropical regions, the Medieval warm period affected both the northern and southern hemispheres. This Medieval period of warming, also known as the Medieval climate anomaly, was associated with an unusual temperature rise roughly between 7 AD (the European Middle Ages). And it does not really matter because if we survived one in the past, then we can surely survive one now.Ģ,000 years of records show it's getting hotter, faster This evokes the idea that if natural global warming and all its effects occurred in the past without humans causing them, then perhaps we are not responsible for this one. The often mentioned Medieval warm period seems to fit the bill. We are living in a world that is getting warmer year by year, threatening our environment and way of life.īut what if these climate conditions were not exceptional? What if it had already happened in the past when human influences were not part of the picture? If you have a question you’d like an expert to answer, please send it to was the Medieval warm period? What caused it, and did carbon dioxide play a role? Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
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