User:Cowabunga240/Triassic–Jurassic extinction event

Terrestrial Plants
The extinction event marks a floral turnover as well, with estimates of the percentage of Rhaetian pre-extinction plants being lost ranging from 17% to 73%. Though spore turnovers are observed across the Triassic-Jurassic boundary, the abruptness of this transition and the relative abundances of given spore types both before and after the boundary are highly variable from one region to another, pointing to a global ecological restructuring rather than a mass extinction of plants. Overall, plants suffered minor diversity losses on a global scale as a result of the extinction, but species turnover rates were high and substantial changes occurred in terms of relative abundance and growth distribution among taxa. Evidence from Central Europe suggests that rather than a sharp, very rapid decline followed by an adaptive radiation, a more gradual turnover in both fossil plants and spores with several intermediate stages is observed over the course of the extinction event. Extinction of plant species can in part be explained by the suspected increased carbon dioxide in the atmosphere as a result of CAMP volcanic activity, which would have created photoinhibition and decreased transpiration levels among species with low photosynthetic plasticity, such as the broad leaved Ginkgoales which declined to near extinction across the Tr-J boundary.

Ferns and other species with dissected leaves displayed greater adaptability to atmosphere conditions of the extinction event, and in some instances were able to proliferate across the boundary and into the Jurassic. In the Sichuan Basin, relatively cool mixed forests in the late Rhaetian were replaced by hot, arid fernlands during the Triassic-Jurassic transition, which in turn later gave way to a cheirolepid-dominated flora in the Hettangian and Sinemurian. The abundance of ferns in China that were resistant to high levels of aridity increased significantly across the Triassic-Jurassic boundary, though ferns better adapted for moist, humid environments declined, indicating that plants experienced major environmental stress, albeit not an outright mass extinction. In some regions, however, major floral extinctions did occur, with some researchers challenging the hypothesis of there being no significant floral mass extinction on this basis. In the Newark Supergroup of the United States East Coast, about 60% of the diverse monosaccate and bisaccate pollen assemblages disappear at the Tr–J boundary, indicating a major extinction of plant genera. Early Jurassic pollen assemblages are dominated by Corollina, a new genus that took advantage of the empty niches left by the extinction. Along the margins of the European Epicontinental Sea and the European shores of the Tethys, coastal and near-coastal mires fell victim to an abrupt sea level rise. These mires were replaced by a pioneering opportunistic flora after an abrupt sea level fall, although its heyday was short lived and it died out shortly after its rise. In the Eiberg Basin of the Northern Calcareous Alps, there was a very rapid palynomorph turnover. Polyploidy may have been an important factor that mitigated a conifer species' risk of going extinct.

Comparisons to present climate change
The extremely rapid, centuries-long timescale of carbon emissions and global warming caused by pulses of CAMP volcanism has drawn comparisons between the Triassic-Jurassic mass extinction and anthropogenic global warming, currently causing the Holocene extinction. The current rate of carbon dioxide emissions is around 50 gigatonnes per year, hundreds of times faster than during the latest Triassic, although the lack of extremely detailed stratigraphic resolution and pulsed nature of CAMP volcanism means that individual pulses of greenhouse gas emissions likely occurred on comparable timescales to human release of warming gases since the Industrial Revolution. The degassing rate of the first pulse of CAMP volcanism is estimated to have been around half of the rate of modern anthropogenic emissions. Palaeontologists studying the TJME and its impacts warn that a major reduction in humanity's carbon dioxide emissions to slow down climate change is of critical importance for preventing a catastrophe similar to the TJME from befalling the modern biosphere. If human-induced climate change persists as is, predictions can be made as to how various aspects of the biosphere will respond based on records of the TJME. For example, current conditions such the increased carbon dioxide levels, ocean acidification, and ocean deoxygenation create a similar climate to that of the Triassic-Jurassic boundary for marine life, so it is the common assumption that should the trends continue, modern reef-building taxa and skeletal benthic organisms will be preferentially impacted.