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. Credit: Wikimedia, CC BY-SA Mechanisms driving the Medieval warm period The last written records of the Norse Greenlanders are from an Icelandic marriage in 1408, which was recorded later in Iceland, at Hvalsey Church, the best-preserved of the Norse ruins. 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. 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?
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