Here ’s a fun fact to pull out out the next particularly hot or cold day : we are technically still dwell in an ice geezerhood that start around3 million yearsago .
What is an ice age?
An ice age is a foresightful period of fourth dimension – from million tohundreds of millionsof class – where global temperatures are lower , and large areas of the major planet are covered in ice sheets and glaciers . There have been at least five crank ages on Earth that we know of , with the long – the Huronian ice age – lasting more than 300 million years .
During an shabu historic period , there are period of time of warmer temperatures where glacier and ice shelves hideaway , known as " interglacial periods " as well as the glacial periods , going back and forth between the two .
As far as we can tell – by comparing our current conditions with those we ’ve found in the yesteryear by studying ice cores , sediment , and our honest-to-goodness friend rocks – it ’s potential we are in an interglacial period right now . The Pleistocene Ice Age start about 2.6 million age ago . With ice still covering Antarctica and Greenland we aretechnicallystill in an ice years .
How do ice ages start?
There are a identification number of ways that chalk years can commence , from changing level of carbon dioxide to the kerfuffle of sea circulation as Continent careen . The Pleistocene was likely triggered by the constitution of the Isthmus of Panama demesne bridge between North and South America , preventing the Atlantic and Pacific Oceans from exchanging tropic body of water .
" By cutting off that exchange and post ardent , piquant ocean water northward , the band increase precipitation at gamy latitudes in the Northern Hemisphere , " the National Oceanic and Atmospheric Administration ( NOAA)explains . " Snow accumulated into glaciers and eventually into meth mainsheet . These monolithic , sun - deflecting ice bodies continued the planet ’s cooling trend . "
Meanwhile , the Huronian ice age – in which the whole planet may have been cover in ice in what is known as " snowball terra firma " – likely had a biological case during the Great Oxygenation Event .
" An evolutionary fortuity , the genesis of oxygenic photosynthesis , spark one of the world ’s big mood disasters , the Paleoproterozoic snowball Earth , " apaperon the topic state in 2005 . According to the team , oxygenic photosynthesis in the sea greatly reduced the amount of nursery gaseous state methane in the standard atmosphere , " and triggered a snowball event on timescales as shortsighted as 1 million years " .
Later , an ice age known as the late Paleozoic icehouse wastriggeredby the evolution of plants on kingdom , and the lead increment in O and diminution in glasshouse gas CO2 .
Smaller work shift in temperatures can be down to shifts in the Earth ’s orbit , which vary – thanks to Jupiter ’s influence – on a96,000 - year rhythm . This , and other changes to Earth’sorbit and tilt , touch theadvanceand retreat of glacial periods .
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