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> How did fish manage during the climatic optimum [1] some 8500 to 5500 years ago when it was between 1.5°C and 4°C warmer than it is now From your wikipedia l
by thulle 3y ago
> How did fish manage during the climatic optimum [1] some 8500 to 5500 years ago when it was between 1.5°C and 4°C warmer than it is now
From your wikipedia link:
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A study in 2020 estimated that the average global temperature during the warmest 200 year period of the HCO, around 6,500 years ago, was around 0.7 °C warmer than the mean for nineteenth century AD.
The HCO consisted of increases of up to 4 °C near the North Pole (in one study, winter warming of 3 to 9 °C and summer of 2 to 6 °C in northern central Siberia).[8] Northwestern Europe experienced warming, but there was cooling in Southern Europe.[9] The average temperature change appears to have declined rapidly with latitude and so essentially no change in mean temperature is reported at low and middle latitudes.
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So, the effect then was localized to the waters where there's more oxygen anyway, and having temperature going in different directions in different parts of Europe and at a much slower rate than current changes, would make it easier for the fish to migrate? Unclear how water temperatures behaved at different depths though.
- the_third_wave 3y agoThe same is true for the current warming where the largest increases are seen in the northern winters so that does not affect the comparison. Instead of picking on one section in a Wikipedia article it would be interesting to know what exactly is different "this time" compared to earlier warmer periods, both the climatic optimum as well as e.g. the Viking and Roman warm periods, let alone those during earlier interglacials. Just stating "now it is different" is not very convincing.
- defrost 3y agoIn Scandinavian regions, at the very least, the Viking warm periods were not as warm as today; fresh evidence suggests that they were less warm than many have stated: Tree rings reveal that it has not been this warm in the past 1,200 years AUGUST 3, 2023: https://phys.org/news/2023-08-tree-reveal-years.html https://phys.org/news/2023-08-tree-reveal-years.html Fennoscandian tree-ring anatomy shows a warmer modern than medieval climate https://www.nature.com/articles/s41586-023-06176-4 https://www.nature.com/articles/s41586-023-06176-4