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The Medieval Warm Period (MWP), also known as the Medieval Climate Optimum or the Medieval Climatic Anomaly, was a time of warm
climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...
in the
North Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe a ...
region that lasted from to .
Climate proxy In the study of past climates (" paleoclimatology"), climate proxies are preserved physical characteristics of the past that stand in for direct meteorological measurements and enable scientists to reconstruct the climatic conditions over a longe ...
records show peak warmth occurred at different times for different regions, which indicate that the MWP was not a globally uniform event. Some refer to the MWP as the ''Medieval Climatic Anomaly'' to emphasize that climatic effects other than temperature were also important. The MWP was followed by a regionally cooler period in the North Atlantic and elsewhere, which is sometimes called the Little Ice Age (LIA). Possible causes of the MWP include increased solar activity, decreased volcanic activity, and changes in ocean circulation.


Research

The Medieval Warm Period (MWP) is generally thought to have occurred from –, during the European
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
. In 1965,
Hubert Lamb Hubert Horace Lamb (22 September 1913 in Bedford – 28 June 1997 in Holt, Norfolk) was an English climatologist who founded the Climatic Research Unit in 1972 in the School of Environmental Sciences at the University of East Anglia. Caree ...
, one of the first
paleoclimatologists Paleoclimatology ( British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to ...
, published research based on data from
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
, historical document research, and meteorology, combined with records indicating prevailing temperature and rainfall in England around and around . He proposed, "Evidence has been accumulating in many fields of investigation pointing to a notably warm climate in many parts of the world, that lasted a few centuries around – AD, and was followed by a decline of temperature levels till between and the coldest phase since the last ice age occurred." The era of warmer temperatures became known as the Medieval Warm Period and the subsequent cold period the
Little Ice Age The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Ma ...
(LIA). However, the view that the MWP was a global event was challenged by other researchers. The IPCC First Assessment Report of 1990 discussed the "Medieval Warm Period around 1000 AD (which may not have been global) and the Little Ice Age which ended only in the middle to late nineteenth century." It stated that temperatures in the "late tenth to early thirteenth centuries (about AD 950-1250) appear to have been exceptionally warm in western Europe, Iceland and Greenland." IPCC First Assessment Report Working Group 1 report
Chapter 7
Executive Summary p. 199, Climate Of The Past 5,000,000 Years p.202.
The
IPCC Third Assessment Report The IPCC Third Assessment Report (TAR), ''Climate Change 2001'', is an assessment of available scientific and socio-economic information on climate change by the IPCC. Statements of the IPCC or information from the TAR are often used as a referenc ...
from 2001 summarized newer research: "evidence does not support globally synchronous periods of anomalous cold or warmth over this time frame, and the conventional terms of 'Little Ice Age' and 'Medieval Warm Period' are chiefly documented in describing northern hemisphere trends in hemispheric or global mean temperature changes in past centuries." Global
temperature record The global temperature record shows the fluctuations of the temperature of the atmosphere and the oceans through various spans of time. There are numerous estimates of temperatures since the end of the Pleistocene glaciation, particularly dur ...
s taken from ice cores, tree rings, and lake deposits have shown that the Earth may have been slightly cooler globally (by 0.03 °C) than in the early and the mid-20th century. Palaeoclimatologists developing region-specific climate reconstructions of past centuries conventionally label their coldest interval as "LIA" and their warmest interval as the "MWP." Others follow the convention, and when a significant climate event is found in the "LIA" or "MWP" timeframes, they associate their events to the period. Some "MWP" events are thus wet events or cold events, rather than strictly warm events, particularly in central
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
, where climate patterns that are opposite to those of the North Atlantic have been noticed.


Global climate during the Medieval Warm Period

In 2019, by using an extended proxy data set, the Pages-2k consortium confirmed that the Medieval Climate Anomaly was not a globally-synchronous event. The warmest 51-year period within the MWP did not occur at the same time in different regions. They argue for a regional instead of global framing of climate variability in the preindustrial
Common Era Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Common Era and Before the Common Era are alternatives to the or ...
to aid in understanding.


North Atlantic

Lloyd D. Keigwin's 1996 study of
radiocarbon Carbon-14, C-14, or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and c ...
-dated box core data from marine sediments in the
Sargasso Sea The Sargasso Sea () is a region of the Atlantic Ocean bounded by four currents forming an ocean gyre. Unlike all other regions called seas, it has no land boundaries. It is distinguished from other parts of the Atlantic Ocean by its charac ...
found that its sea surface temperature was approximately cooler approximately 400 years ago, during the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
, and 1700 years ago and was approximately 1 °C warmer 1000 years ago, during the MWP. Using sediment samples from
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
, the
Gulf Coast The Gulf Coast of the United States, also known as the Gulf South, is the coast, coastline along the Southern United States where they meet the Gulf of Mexico. The list of U.S. states and territories by coastline, coastal states that have a shor ...
, and the Atlantic Coast from
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...
to
New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...
, Mann ''et al.'' (2009) found consistent evidence of a peak in
North Atlantic tropical cyclone An Atlantic hurricane, also known as tropical storm or simply hurricane, is a tropical cyclone that forms in the Atlantic Ocean, primarily between the months of June and November. A hurricane differs from a cyclone or typhoon only on the basis o ...
activity during the MWP, which was followed by a subsequent lull in activity.


Iceland

Iceland was first settled between about 865 and 930, during a time believed to be warm enough for sailing and farming. By retrieval and isotope analysis of marine cores and from examination of mollusc growth patterns from
Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its ...
, Patterson ''et al.'' reconstructed a stable oxygen (δ18 O) and carbon (δ13 C) isotope record at a decadal resolution from the
Roman Warm Period The Roman Warm Period, or Roman Climatic Optimum, was a period of unusually-warm weather in Europe and the North Atlantic that ran from approximately 250 BC to AD 400. Theophrastus (371 – c. 287 BC) wrote that date trees could grow in Gre ...
to the MWP and the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
. Patterson ''et al.'' conclude that the summer temperature stayed high but winter temperature decreased after the initial settlement of Iceland.


Greenland

The 2009
Mann Mann may refer to: Arts, entertainment and media * Mann (chess), a variant chess piece which moves as a king * ''Mann'' (film), a 1999 Bollywood motion picture * ''Mann'' (magazine), a Norwegian magazine * Mann Theatres, a theatre chain corp ...
''et al.'' study found warmth exceeding 1961–1990 levels in southern
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland ...
and parts of North America during the MWP, which the study defines as from 950 to 1250, with warmth in some regions exceeding temperatures of the 1990–2010 period. Much of the Northern Hemisphere showed a significant cooling during the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
, which the study defines as from 1400 to 1700, but
Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province , subdivision_name1 ...
and isolated parts of the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
appeared to be approximately as warm as during the 1961–1990 period. The Norse colonization of the Americas has been associated with warmer periods. The common theory is that
Norsemen The Norsemen (or Norse people) were a North Germanic ethnolinguistic group of the Early Middle Ages, during which they spoke the Old Norse language. The language belongs to the North Germanic branch of the Indo-European languages and is the ...
took advantage of ice-free seas to colonize areas in Greenland and other outlying lands of the far north. However, a study from
Columbia University Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
suggests that Greenland was not colonized in warmer weather, but the warming effect in fact lasted for only very briefly. , the climate was sufficiently warm for the Vikings to journey to
Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...
and to establish a short-lived outpost there. In around 985, Vikings founded the Eastern and Western Settlements, both near the southern tip of Greenland. In the colony's early stages, they kept cattle, sheep, and goats, with around a quarter of their diet from seafood. After the climate became colder and stormier around 1250, their diet steadily shifted towards ocean sources. By around 1300, seal hunting provided over three quarters of their food. By 1350, there was reduced demand for their exports, and trade with Europe fell away. The last document from the settlements dates from 1412, and over the following decades, the remaining Europeans left in what seems to have been a gradual withdrawal, which was caused mainly by economic factors such as increased availability of farms in Scandinavian countries.


Europe

Substantial glacial retreat in southern Europe was experienced during the MWP. While several smaller glaciers experienced complete deglaciation, larger glaciers in the region survived and now provide insight into the region’s climate history. In addition to warming induced glacial melt, sedimentary records reveal a period of increased flooding, coinciding with the MWP, in eastern Europe that is attributed to enhanced precipitation from a positive phase North Atlantic Oscillation (NAO). Other impacts of
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
can be less apparent such as a changing landscape. Preceding the MWP, a coastal region in western
Sardinia Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label= Algherese and Catalan) is the second-largest island in the Mediterranean Sea, aft ...
was abandoned by the Romans. The coastal area was able to substantially expand into the lagoon without the influence of human populations and a high stand during the MWP. When human populations returned to the region, they encountered a land altered by climate change and had to reestablish ports.


Other regions


North America

In
Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
(now in
Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean t ...
and
Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
), researchers found large temperature excursions (changes from the mean temperature of that time) during the MWP (about 950–1250) and the
Little Ice Age The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Ma ...
(about 1400–1700, with cold periods persisting into the early 20th century), which are possibly related to changes in the strength of North Atlantic thermohaline circulation. Sediments in
Piermont Marsh Piermont is the name of two places in the United States of America: * Piermont, New Hampshire * Piermont, New York See also * Piedmont * Piedmont (United States) {{Geodis ...
of the lower
Hudson Valley The Hudson Valley (also known as the Hudson River Valley) comprises the valley of the Hudson River and its adjacent communities in the U.S. state of New York. The region stretches from the Capital District including Albany and Troy south to ...
show a dry MWP from 800 to 1300. Prolonged droughts affected many parts of what is now the
Western United States The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the We ...
, especially eastern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
and the west of
Great Basin The Great Basin is the largest area of contiguous endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California. It is noted fo ...
.
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
experienced three intervals of comparable warmth: 1–300, 850–1200, and since 1800. Knowledge of the MWP in North America has been useful in dating occupancy periods of certain Native American habitation sites, especially in arid parts of the Western United States. Droughts in the MWP may have impacted Native American settlements also in the Eastern United States, such as at
Cahokia The Cahokia Mounds State Historic Site ( 11 MS 2) is the site of a pre-Columbian Native American city (which existed 1050–1350 CE) directly across the Mississippi River from modern St. Louis, Missouri. This historic park lies in south- ...
. Review of more recent archaeological research shows that as the search for signs of unusual cultural changes has broadened, some of the early patterns (such as violence and health problems) have been found to be more complicated and regionally varied than had been previously thought. Other patterns, such as settlement disruption, deterioration of long-distance trade, and population movements, have been further corroborated.


Africa

The climate in equatorial eastern
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
has alternated between being drier than today and relatively wet. The climate was drier during the MWP (1000–1270). Off the coast of Africa, Isotopic analysis of bones from the Canary Islands’ inhabitants during the MWP to LIA transition reveal the region experienced a 5 °C decrease in air temperature. Over this period, the diet of inhabitants did not appreciably change, which suggests they were remarkably resilient to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
.


Antarctica

A
sediment core A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The h ...
from the eastern Bransfield Basin, in the
Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...
, preserves climatic events from both the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
and the MWP. The authors noted, "The late Holocene records clearly identify Neoglacial events of the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
and Medieval Warm Period (MWP)." Some Antarctic regions were atypically cold, but others were atypically warm between 1000 and 1200.


Pacific Ocean

Corals in the tropical
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...
suggest that relatively cool and dry conditions may have persisted early in the millennium, which is consistent with a La Niña-like configuration of the
El Niño-Southern Oscillation EL, El or el may refer to: Religion * El (deity), a Semitic word for "God" People * EL (rapper) (born 1983), stage name of Elorm Adablah, a Ghanaian rapper and sound engineer * El DeBarge, music artist * El Franco Lee (1949–2016), American ...
patterns. In 2013, a study from three US universities was published in ''Science'' magazine and showed that the water temperature in the Pacific Ocean was 0.9 degrees warmer during the MWP than during the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
and 0.65 degrees warmer than the decades before the study.


South America

The MWP has been noted in
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...
in a 1500-year lake bed sediment core, as well as in the Eastern Cordillera of
Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...
. A reconstruction, based on ice cores, found that the MWP could be distinguished in tropical South America from about 1050 to 1300 and was followed in the 15th century by the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
. Peak temperatures did not rise as to the level of the late 20th century, which were unprecedented in the area during the study period of 1600 years.


Asia

Adhikari and Kumon (2001), investigating sediments in Lake Nakatsuna, in central
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
, found a warm period from 900 to 1200 that corresponded to the MWP and three cool phases, two of which could be related to the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
. Other research in northeastern Japan showed that there was one warm and humid interval, from 750 to 1200, and two cold and dry intervals, from 1 to 750 and from 1200 to now. Ge ''et al.'' studied temperatures in
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
for the past 2000 years and found high uncertainty prior to the 16th century but good consistency over the last 500 years highlighted by the two cold periods, 1620s–1710s and 1800s–1860s, and the 20th-century warming. They also found that the warming from the 10th to the 14th centuries in some regions might be comparable in magnitude to the warming of the last few decades of the 20th century, which was unprecedented within the past 500 years. Generally, a warming period was identified in China, coinciding with the MWP, using multi-proxy data for temperature. However, the warming was inconsistent across China. Significant temperature change, from the MWP to
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
, was found for northeast and central-east China but not for northwest China and the
Tibetan Plateau The Tibetan Plateau (, also known as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as the Himalayan Plateau in India, is a vast elevated plateau located at the intersection of Central, South and East Asia covering most of the Ti ...
. Alongside an overall warmer climate, areas in
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...
experienced wetter conditions in the MWP southeastern China,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
, and far eastern
Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
.
Peat Peat (), also known as turf (), is an accumulation of partially Decomposition, decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, Moorland, moors, or muskegs. The peatland ecosystem covers and ...
cores from peatland in southeast China suggest changes in the East Asian Summer Monsoon (EASM) and El Niño Southern Oscillation (ENSO) are responsible for increased precipitation in the region during the MWP. The Indian Summer Monsoon (ISM) was also enhanced during the MWP with a temperature driven change to the Atlantic Multi-decadal Oscillation (AMO), bringing more precipitation to India. In far eastern Russia, continental regions experienced severe floods during the MWP while nearby islands experienced less precipitation leading to a decrease in peatland. Pollen data from this region indicates an expansion of warm climate vegetation with an increasing number of broadleaf and decreasing number of
coniferous Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...
forests.


Oceania

There is an extreme scarcity of data from
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
for both the MWP and the
LIA Lia is a feminine given name. In the Spanish-speaking world, it is accented Lía. In America, the name may be a variant of Leah or Lea. Lia may be a diminutive of various names including Julia, Cecilia, Amelia, Talia, Cornelia, Ophelia, Rosal ...
. However, evidence from wave-built shingle terraces for a permanently-full
Lake Eyre Lake Eyre ( ), officially known as Kati Thanda–Lake Eyre, is an endorheic lake in east-central Far North South Australia, some north of Adelaide. The shallow lake is the depocentre of the vast endorheic Lake Eyre basin, and contains ...
during the 9th and the 10th centuries is consistent with a La Niña-like configuration, but the data are insufficient to show how lake levels varied from year to year or what climatic conditions elsewhere in Australia were like. A 1979 study from the University of Waikato found, "Temperatures derived from an 18O/16O profile through a stalagmite found in a
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
cave (40.67°S, 172.43°E) suggested the Medieval Warm Period to have occurred between AD and and to have been 0.75 °C warmer than the Current Warm Period." More evidence in
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
is from an 1100-year tree-ring record.


See also

* Classic Maya collapse – concurrent with the Medieval Warm Period and marked by decades long droughts * * * * * * *


References


Further reading

* * * * * *


External links

{{Commons, Medieval Warm Period
HistoricalClimatology.com
further links, resources, and relevant news, updated 2016
Climate History Network
at
American Geophysical Union The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, atmospheric, ocean, hydrologic, space, and planetary scientists and enthusiasts that according to their website includes 130,000 people (not members). AGU's ...
950 establishments 1250 disestablishments History of climate variability and change 10th century 11th century 12th century 13th century Holocene