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One of the hotter periods was the Last Interglacial, around 125,000 years ago, where temperatures were between 0.5 °C and 1.5 °C warmer than before the start of global warming. [40] This period saw sea levels 5 to 10 metres higher than today. The most recent glacial maximum 20,000 years ago was some 5–7 °C colder. This period has sea ...
a warm period during the apex of the Minoan civilization; the Roman Warm Period; the Medieval Warm Period; Modern warming during the 20th century; Certain effects have occurred during these cycles. For example, during the Medieval Warm Period, the American Midwest was in drought, including the Sand Hills of Nebraska which were active sand dunes.
Older Peron warm and wet, global sea levels were 2.5 to 4 meters (8 to 13 feet) higher than the twentieth-century average 3900: 5.9 kiloyear event dry and cold. 3500: End of the African humid period, Neolithic Subpluvial in North Africa, expands Sahara Desert 3000 – 0: Neopluvial in North America 3,200–2,900: Piora Oscillation, cold
From ancient times, people suspected that the climate of a region could change over the course of centuries. For example, Theophrastus, a pupil of Ancient Greek philosopher Aristotle in the 4th century BC, told how the draining of marshes had made a particular locality more susceptible to freezing, and speculated that lands became warmer when the clearing of forests exposed them to sunlight.
It has also been known by many other names, such as Altithermal, Climatic Optimum, Holocene Megathermal, Holocene Optimum, Holocene Thermal Maximum, Holocene global thermal maximum, Hypsithermal, and Mid-Holocene Warm Period. The warm period was followed by a gradual decline, of about 0.1 to 0.3 °C per millennium, until about two centuries ago.
The oxygen isotope ratio obtained from seabed sediment core samples, a proxy for the average global temperature, is an important source of information for changes in Earth's climate. An interglacial optimum, or climatic optimum of an interglacial, is the period within an interglacial that experienced the most 'favourable' climate and often ...
A climate normal is defined as the arithmetic average of a climate element (e.g. temperature) over a 30-year period. A 30-year period is used as it is long enough to filter out any interannual variation or anomalies such as El Niño–Southern Oscillation , but also short enough to be able to show longer climatic trends."
For a period to be considered an interglacial, it changes from Arctic through sub-Arctic to boreal to temperate conditions and back again. An interstadial reaches only the stage of boreal vegetation. [1] The MIS 1 interstadial encompasses the entirety of the present Holocene interglacial, but the Wisconsin glaciation encompasses MIS 2, 3, and 4.