AstronomyAstronomy is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroid, asteroid, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere.
Atlantic meridional overturning circulationThe Atlantic meridional overturning circulation (AMOC) is part of a global thermohaline circulation in the oceans and is the zonally integrated component of surface and deep currents in the Atlantic Ocean. It is characterized by a northward flow of warm, salty water in the upper layers of the Atlantic, and a southward flow of colder, deep waters. These "limbs" are linked by regions of overturning in the Nordic and Labrador Seas and the Southern Ocean, although the extent of overturning in the Labrador Sea is disputed.
Early Middle AgesThe Early Middle Ages (or early medieval period), sometimes controversially referred to as the Dark Ages, is typically regarded by historians as lasting from the late 5th or early 6th century through the 10th century. They marked the start of the Middle Ages of European history, following the decline of the Western Roman Empire, and preceding the High Middle Ages ( 11th to 14th centuries). The alternative term late antiquity, for the early part of the period, emphasizes elements of continuity with the Roman Empire, while Early Middle Ages is used to emphasize developments characteristic of the earlier medieval period.
Medieval Warm PeriodThe Medieval Warm Period (MWP), also known as the Medieval Climate Optimum or the Medieval Climatic Anomaly, was a time of warm climate in the North Atlantic region that lasted from 950 to 1250. Climate proxy 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.
Würm glaciationThe Würm glaciation or Würm stage (Würm-Kaltzeit or Würm-Glazial, colloquially often also Würmeiszeit or Würmzeit; cf. ice age), usually referred to in the literature as the Würm (often spelled "Wurm"), was the last glacial period in the Alpine region. It is the youngest of the major glaciations of the region that extended beyond the Alps themselves. Like most of the other ice ages of the Pleistocene epoch, it is named after a river, in this case the Würm in Bavaria, a tributary of the Amper.
Columbian exchangeThe Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, precious metals, commodities, culture, human populations, technology, diseases, and ideas between the New World (the Americas) in the Western Hemisphere, and the Old World (Afro-Eurasia) in the Eastern Hemisphere, in the late 15th and following centuries. It is named after the Italian explorer Christopher Columbus and is related to the European colonization and global trade following his 1492 voyage.
Proxy (climate)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 longer fraction of the Earth's history. Reliable global records of climate only began in the 1880s, and proxies provide the only means for scientists to determine climatic patterns before record-keeping began. A large number of climate proxies have been studied from a variety of geologic contexts.
Global temperature recordThe 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 during the current Holocene epoch. Some temperature information is available through geologic evidence, going back millions of years. More recently, information from ice cores covers the period from 800,000 years before the present time until now.
Spörer MinimumThe Spörer Minimum is a hypothesized 90-year span of low solar activity, from about 1460 until 1550, which was identified and named by John A. Eddy in a landmark 1976 paper published in Science titled "The Maunder Minimum". It occurred before sunspots had been directly observed and was discovered instead by analysis of the proportion of carbon-14 in tree rings, which is strongly correlated with solar activity. It is named for the German astronomer Gustav Spörer.
Year Without a SummerThe year 1816 is known as the Year Without a Summer because of severe climate abnormalities that caused average global temperatures to decrease by . Summer temperatures in Europe were the coldest of any on record between the years of 1766 and 2000. This resulted in major food shortages across the Northern Hemisphere. Evidence suggests that the anomaly was predominantly a volcanic winter event caused by the massive 1815 eruption of Mount Tambora in April in the Dutch East Indies (modern-day Indonesia).
