Age dating middle

The population of Iceland fell by half, but that may have been caused by skeletal fluorosis after the eruption of Laki in 1783.

The Norse colonies in Greenland starved and vanished by the early 15th century, as crops failed and livestock could not be maintained through increasingly harsh winters, but Jared Diamond has suggested they had exceeded the agricultural carrying capacity before then.

The undetermined microfossils represent a majority of the assemblages and thus raise a challenge to determine the nature and role of microorganisms in these changing environments.

Despite the early evolution of the eukaryotic cellular toolkit, early eukaryotic crown group diversification may have been restrained in the Paleoproterozoic by ocean chemistry conditions, but it increased during the late Mesoproterozoic–early Neoproterozoic despite the continuation of similar conditions through the (miscalled) “boring billion”, then amplified significantly (but perhaps within lower taxonomic levels), with the demise of euxinic conditions and increase in ecological complexity.

The Paleoproterozoic (2.5–1.6 Ga) Era is a decisive time in Earth and life history.

The paleobiological record (microfossils, stromatolites, biomarkers and isotopes) illustrates the biosphere evolution during a time of transitional oceanic and atmosphere chemistries.

The emerging picture is one of a changing and more complex biosphere in which the three domains of life, Archaea, Bacteria and Eukarya, were diversifying in various ecological niches marked by the diversification of identified microfossils, stromatolites, increasing abundance of preserved biomarkers, and appearance of macroscopic problematic fossils or trace fossils.

At most, there was modest cooling of the Northern Hemisphere during the period.The winter of 1794–1795 was particularly harsh: the French invasion army under Pichegru was able to march on the frozen rivers of the Netherlands, and the Dutch fleet was fixed in the ice in Den Helder harbour.Sea ice surrounding Iceland extended for miles in every direction, closing harbors to shipping.It states that "when viewed together, the currently available reconstructions indicate generally greater variability in centennial time scale trends over the last 1 kyr than was apparent in the TAR....The result is a picture of relatively cool conditions in the seventeenth and early nineteenth centuries and warmth in the eleventh and early fifteenth centuries, but the warmest conditions are apparent in the twentieth century.

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