- Also called:
- medieval warm epoch or little climatic optimum
Medieval warm period
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What was the Medieval Warm Period?
The Medieval Warm Period (MWP) is a hypothesized climate interval from approximately 900 to 1300 CE, during the Middle Ages in Europe. During this time, relatively warm conditions prevailed in various parts of the world, mainly in the Northern Hemisphere from Greenland eastward through Europe and parts of Asia.
The notion of the MWP is controversial. Some paleoclimatologists claim there is documented evidence in the North Atlantic region, while others believe it was a global phenomenon. Some scientists insist their data do not show changes in average temperature anywhere during the interval.
Many studies reveal that the amount of warming during the MWP varied by season and region. Some show relatively warm temperatures in the North Atlantic, Northern Europe, China, and parts of North America, as well as the Andes, Tasmania, and New Zealand.
4 Britannica Sources- Climate Change: Con 2: Earth’s climate has always warmed and cooled, and the 20th century rise in global temperature is within the bounds of natural temperature fluctuations over the past 3,000 years.
- medieval warm period
- North Atlantic Oscillation: The NAO and shifting climate
- climate change: Centennial-scale variation
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When did the Medieval Warm Period happen?
The Medieval Warm Period (MWP) is hypothesized to have occurred from approximately 900 CE to 1300, roughly coinciding with the Middle Ages in Europe. During this time, relatively warm conditions prevailed in various parts of the world, predominantly in the Northern Hemisphere from Greenland eastward through Europe and parts of Asia.
Many scientists suggest that the MWP was characterized by increased incoming solar radiation and a relative absence of volcanic activity, which contributed to warmer air temperatures. Some have attributed warmer air temperatures in the North Atlantic region to warmer seawater delivered by the Gulf Stream and other currents.
The notion of a Medieval Warm Period is controversial. While many paleoclimatologists claim that well-documented evidence for the phenomenon appears across the North Atlantic region, others maintain that the phenomenon was global, occurring all over the world. Still other scientists insist that their data do not show appreciable changes in average temperature anywhere over the course of the interval.
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What was the climate like during the Medieval Warm Period?
The medieval warm period (MWP), a climatic interval from approximately 900 to 1300 CE, is hypothesized to have brought relatively warm conditions to various parts of the world, mainly in the Northern Hemisphere from Greenland through Europe and parts of Asia.
During the MWP, Europe experienced mild summers and winters, which led to good harvests. Wheat cultivation and vineyards flourished at far higher latitudes and elevations than today. Norse colonies in Iceland and Greenland prospered, and Norse parties fished, hunted, and explored the coast of Labrador and Newfoundland.
However, the notion of a medieval warm period is highly controversial. There is little evidence that such conditions prevailed on a global scale. Some climate proxies point to periods of extended drought in some locations, such as the Sierra Nevada mountains, parts of Australia, and the Asian steppe, while other areas, such as northern China, experienced a mix of heavy rainfall and drought.
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How did the Medieval Warm Period affect people and agriculture?
The Medieval Warm Period (MWP), a climatic interval from approximately 900 to 1300 CE, is hypothesized to have brought relatively warm conditions to various parts of the world.
During this time, Norse colonies in Iceland and Greenland prospered. Norse parties were able to fish, hunt, and explore the coasts of Labrador and Newfoundland. Mild summers and winters led to good harvests in much of Europe, and wheat cultivation and vineyards flourished at higher latitudes and elevations than today.
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What evidence do scientists use to learn about the Medieval Warm Period?
Scientists use a combination of historical records and climate proxies to study the Medieval Warm Period (MWP), a climatic interval from approximately 900 to 1300 CE.
These proxies include tree rings, ice cores, and sediment cores, which help reconstruct past climatic conditions. Historical documents noting food production, growing seasons, and ice cover on water bodies also offer insights.
These records suggest generally pleasant conditions in Europe, but there's little evidence these conditions were global. Some proxies indicate droughts in areas like the Sierra Nevada, while others show heavy rainfall in places such as northern China.
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How does the Medieval Warm Period compare to today’s climate changes?
The Medieval Warm Period (MWP), a climatic interval from approximately 900 to 1300 CE, is hypothesized to have brought relatively warm conditions, mainly in the Northern Hemisphere. The notion of the MWP is controversial, with some scientists claiming evidence in the North Atlantic region, others arguing it was global, and some finding no significant temperature changes.
Comparisons to today's climate changes are complex. Some studies suggest the MWP saw temperatures similar to the early 20th century. However, modern climate change is largely attributed to human activities, especially greenhouse gas emissions. The Intergovernmental Panel on Climate Change (IPCC) reports indicate that scenarios with immediate reductions in greenhouse gas emissions could potentially limit global surface warming by 2100 to below 2.0 °C (3.6 °F), a threshold considered critical to avoid severe climatic effects.
5 Britannica Sources- global warming: Precipitation patterns
- Climate Change: Con 2: Earth’s climate has always warmed and cooled, and the 20th century rise in global temperature is within the bounds of natural temperature fluctuations over the past 3,000 years.
- medieval warm period
- North Atlantic Oscillation: The NAO and shifting climate
- climate change: Centennial-scale variation
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Medieval warm period (MWP), brief climatic interval that is hypothesized to have occurred from approximately 900 ce to 1300 (roughly coinciding with the Middle Ages in Europe), in which relatively warm conditions are said to have prevailed in various parts of the world, though predominantly in the Northern Hemisphere from Greenland eastward through Europe and parts of Asia.
The notion of a medieval warm period is highly controversial. Many paleoclimatologists claim that well-documented evidence for the phenomenon appears across the North Atlantic region, while others maintain that the phenomenon was global, occurring all over the world. Still other scientists insist that their data do not show appreciable changes in average temperature anywhere over the course of the interval. Meanwhile, global warming skeptics have used the MWP to bolster their position in the debate over the nature and effects of climate change.
Level and extent of warming
Direct measurements of climate conditions collected by thermometers, barometers, rain gauges, and other equipment have been available since the 19th century. The climatic conditions of older periods, however, have to be “reconstructed” with the help of historical documents (which contain figures on food production, the length of growing seasons, and the duration of ice on bodies of water) and other indirect measures of climate (including “climate proxies” such as tree rings, ice cores, and sediment cores). Many such studies suggest that Europe’s Middle Ages did see several multiyear stretches of relatively pleasant conditions and reliable weather. There is little evidence that such conditions prevailed on a global scale, however. Indeed, some climate proxies point to several periods of extended drought during the MWP in some locations, such as the Sierra Nevada mountains of North America, parts of Australia, and the Asian steppe, whereas other areas, such as northern China, experienced a mix of heavy rainfall and drought.
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Many studies show that the amount of warming occurring during the MWP varied by season and region. Some provide evidence of relatively warm temperatures (most pronounced during the summer months) in several regions, including the North Atlantic, northern Europe, China, and parts of North America, as well as the Andes, Tasmania, and New Zealand. Other studies maintain that the temperature conditions of certain regions, such as the Mediterranean, South America, and other locations in the Southern Hemisphere, were essentially no different from those of the present day.
Only a few studies have attempted to assign a specific value to changes in average global temperatures during the MWP. In 1965 British climatologist Hubert Horace Lamb examined historical records of harvests and precipitation, along with early ice-core and tree-ring data, and concluded that the MWP was probably 1–2 °C (1.8–3.6 °F) warmer than early 20th-century conditions in Europe. Attempts to calculate global temperature changes during the MWP, even using modern instrumental and ice-core sampling techniques, have been inconclusive.
It is frequently pointed out that the MWP was a prosperous time in European history. The interval was concurrent with Norse explorations of the New World, the founding of Norse settlements in Iceland and Greenland, and increased agricultural productivity and crop diversity in northern Europe. Some paleoclimatologists and historians claim that the pleasant conditions of the MWP allowed the settlements in Iceland and Greenland to prosper and Norse explorers to venture to the coasts of Labrador and Newfoundland to hunt and fish. They interpret records of bountiful harvests over much of Europe to mean that the region benefited from a series of extended summers and mild winters. As proof of warmer average temperatures in northern Europe, they cite the existence of wheat cultivation and vineyards at latitudes and elevations that were far higher than today.
Possible causes
Many scientists arguing for the existence of the MWP have noted that the interval was characterized by an increase in incoming solar radiation paired with a relative absence of volcanic activity. (Aerosols expelled from volcanic eruptions have been shown to block a portion of incoming sunlight.) The combination of both phenomena would contribute to an increase in air temperatures. Some scientists have also attributed warmer air temperatures in the North Atlantic region to the delivery of warmer seawater (heated by solar radiation unimpeded by volcanic aerosols) by the Gulf Stream and other currents.
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Role in the modern climate debate
The climate conditions of the MWP are often compared to those of the late 20th and early 21st centuries in arguments over the causes and potential effects of modern climate trends. The MWP is frequently cited by global warming skeptics as evidence that the consequences of global warming are not all negative, especially as they relate to agricultural production. Because several sources note that temperatures during the MWP were even warmer than today, many skeptics claim that continued warming in modern times will likely bring increased prosperity at least to northern regions. In contrast, some global warming advocates maintain that analysis of the MWP adds little to the climate debate, since the climate variability of the interval can be explained by changes in large-scale climate patterns, such as El Niño/Southern Oscillation (ENSO) and the NAO, rather than by changes brought on by human beings. Other global warming advocates argue that a return to conditions similar to the MWP would not be a benefit to all, as temperature increases might make some regions more pleasant and prosperous while reducing agricultural productivity in others.