Sediments from a cave in NE Greenland tell a story. It was warm and wetter in the past. However, this is dated half a million years ago. See https://phys.org/news/2021-03-greenland-caves-arctic.html … and has nothing to do with conditions during the medieval period. The big take home of the story is that NE Greenland is firmly within the Arctic as far as climate is concerned. Even a pole movement would not alter that to any great degree. However, half a million years ago the situation was quite different. This was determined by flow stone in the cave. In other words, water was flowing. It was not frozen. Speleothems cannot tell us what vegetation was growing but in this instance, they seem to be able to tell us it was warmer and wetter, as water dripping off the cave roof was liquid rather than ice. The authors also say that water flowed intermittently during more recent periods of Greenland climate but emphasized this was an initial look at the potential of speleothems to record climate change on Greenland in the past, and further research in order to date more recent flow stone accumulation is necessary. They see it as complimentary to ice cores. For the full paper go to https://advances.sciencemag.org/content/advances/7/13/eabe1260.full.pdf
At https://phys.org/news/2021-04-chicxulub-impactor-gave-modern-rainforests… … how the Chicxulub asteroid gave rise to modern rainforests. This is one of those 'what if' they had thought outside the box moments. The research relies on the concept the poles are static. Hence, the anomaly encountered. A pole shift would render the findings irrelevant. Having said that, what they are saying is that the effects of the impact at the K/T bundary led to 45 per cent of plants growing in Columbia being replaced by other plants. In Columbia the forest was dominated by ferns and flowering plants. Conifers, related to the Kauri pine, were common. After the impact conifers disappeared and plant diversity took 10 million years to revive – an extraordinarily long period of time that does not look realistic at face value. They found no evidence of legume plants growing in Columbia prior to the impact but nowadays legumes are a dominant family in tropical rainforest environs. The kauri trees continue to grow – in a different part of the world. New Zealand.
At https://phys.org/news/2021-03-huge-volcanic-eruption-didnt-climate.html … which resolves around a reliance on dating methodologies. Scientists have long realised that extinction events coincide with evidence of volcanism in various parts of the world. Even small extinction events, possibly localised, seem to have a volcanic dimension. However, the big extinctions have roughly contempory 'large igneous provinces' such as the Deccan Traps, or the Siberian Traps etc. The argument made in this piece of research is that smaller extinction events may not have a volcanic connection. This might be difficult if they involved a cosmic impact of some kind, one might think, so perhaps they are looking solely at the idea that volcanism, by itself, was capable of causing extinctions. Then, their research would prove that it was not necessary for volcanic activity to coincide with extinctions and some other causes might be appropriate. Or that large igneous province do not necessary have anything to do with extinctions. They chose to look at a large igneous province in Brazil, dated around 140 million years ago, when South America was still joined to Africa. The igneous signature can be seen both in Brazil and in Namibia. They then claim the igneous intrusions occurred one million years after the extinction event. This is remarkably similar to the claim the Deccan Traps occurred long after the Chicxulub impact rather than strictly at the K/T boudnary. Both have a common error, it could be argued, and that is the dating of the sediments laid down at the impact moment. If they are dated by uniformitarian means the evidence is compromised. If those sediments were laid down instantly, as a result of an impact for example, or volcanism, then there is no problem. It disappears.