Editing 4th millennium BC (section)

==Environment==
{{Holocene}}
{{Main|Atlantic (period)}}
Based on studies by [[glaciologist]] [[Lonnie Thompson]], professor at [[Ohio State University]] and researcher with the [[Byrd Polar Research Center]], a number of indicators shows there was a global change in climate 5,200 years ago, probably due to a drop in solar energy output.<ref>{{cite web|url=http://www.news-about-space.org/story/2409.html |title=Major Climate Change Occurred 5,200 Years Ago: Evidence Suggests That History Could Repeat Itself |access-date=2004-12-17 |url-status=dead |archive-url=https://web.archive.org/web/20080115112153/http://www.news-about-space.org/story/2409.html |archive-date=2008-01-15 }}</ref>
* The [[Older Peron]] transgression was a period identified in 1961<ref name="Fairbridge 1961">{{cite journal |last1=Fairbridge |first1=Rhodes W. |year=1961 |title=Eustatic Changes in Sea Level |journal=Physics and Chemistry of the Earth |volume=4 |pages=99–185 |doi=10.1016/0079-1946(61)90004-0|bibcode=1961PCE.....4...99F }}</ref> happening between 6,000 and 4,600 years [[Before Present|BP]] when sea levels were 3 to 5 metres higher than today.<ref>{{cite book|first1=Colin |last1=Murray-Wallace |first2=Colin |last2=Woodroffe |title=Quaternary Sea-Level Changes: A Global Perspective |publisher=Cambridge University Press|year=2014 |page=338|isbn=9781139867153 |url=https://books.google.com/books?id=l13BAgAAQBAJ&q=%22Older+Peron%22&pg=PA328}}</ref>
*Plants buried in the [[Quelccaya Ice Cap]] in the Peruvian Andes demonstrate the climate had shifted suddenly and severely to capture the plants and preserve them until now.<ref>{{Cite journal |last1=Thompson |first1=L. G. |last2=Mosley-Thompson |first2=E. |last3=Brecher |first3=H. |last4=Davis |first4=M.| last5=León |first5=B.| last6=Les |first6=D. |last7=Lin |first7=P. -N. |last8=Mashiotta |first8=T. |last9=Mountain |first9=K. |title=Inaugural Article: Abrupt tropical climate change: Past and present |journal=Proceedings of the National Academy of Sciences |volume=103 |issue=28 |pages=10536–10543 |year=2006 |doi=10.1073/pnas.0603900103| pmid=16815970 |bibcode=2006PNAS..10310536T |pmc=1484420 |doi-access=free }}</ref>
*c. [[3750 BC]] – The last North American [[mammoth]]s, on [[Saint Paul Island (Alaska)|Saint Paul Island]], [[Alaska]], go extinct.
*Tree rings from Ireland and England show this was their driest period.<ref name="Science Daily 2004-12-04">{{cite web |url=https://www.sciencedaily.com/releases/2004/12/041219142907.htm |title=Major Climate Change Occurred 5,200 Years Ago: Evidence Suggests That History Could Repeat Itself |work=[[Science Daily]]|access-date=19 December 2010}}</ref>
*Ice core records showing the ratio of two oxygen isotopes retrieved from the ice fields atop Africa's [[Mount Kilimanjaro]], a proxy for atmospheric temperature at the time snow fell.<ref name="Science Daily 2004-12-04" />
*Major changes in plant pollen uncovered from lakebed cores in South America.<ref name="Science Daily 2004-12-04" />
*Record lowest levels of [[methane]] retrieved from ice cores from [[Greenland]] and [[Antarctica]].<ref name="Science Daily 2004-12-04" />
*End of the [[Neolithic Subpluvial]], start of [[desertification]] of [[Sahara]] ([[35th century BC]]). North Africa shifts from a habitable region to a barren desert.<ref name="Science Daily 2004-12-04" />
*c. [[3150 BC]] – a lesser [[Tollmann's hypothetical bolide]] event may have occurred.
*3051 BC – [[Methuselah (pine tree)|The oldest currently (2013) living]] non-clonal organism germinated in the present-day Grove of the Ancients, Inyo County, California.