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Abrupt Climate Change and Extinction Events in Earth History

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Abstract

Slowly changing boundary conditions can sometimes cause discontinuous responses in climate models and result in relatively rapid transitions between different climate states. Such terrestrially induced abrupt climate transitions could have contributed to biotic crises in earth history. Ancillary events associated with transitions could disperse unstable climate behavior over a longer but still geologically brief interval and account for the stepwise nature of some extinction events. There is a growing body of theoretical and empirical support for the concept of abrupt climate change, and a comparison of paleoclimate data with the Phanerozoic extinction record indicates that climate and biotic transitions often coincide. However, more stratigraphic information is needed to precisely assess phase relations between the two types of transitions. The climate-life comparison also suggests that, if climate change is significantly contributing to biotic turnover, ecosystems may be more sensitive to forcing during the early stages of evolution from an ice-free to a glaciated state. Our analysis suggests that a terrestrially induced climate instability is a viable mechanism for causing rapid environmental change and biotic turnover in earth history, but the relation is not so strong that other sources of variance can be excluded.
... The given definition of mass extinctions (see Section 1.1) and the brief summary of the Big Five mass extinctions (see Section 1.2) suggest that mass extinctions are induced by strong and relatively fast perturbations of the Earth system which critically disturb the living conditions to which the ecosystems' structure and functions are accustomed (Hull & Darroch, 2013, Hull, 2015. Climate plays a significant role for determining the living conditions and hence, mass extinctions are strongly linked to changes in climate (Crowley & North, 1988, Twitchett, 2006, Feulner, 2009, Fan et al., 2020. The description of the five mass extinctions and their possible causes (Section 1.2) has shown this connection already. ...
... The affected climate variables interact with each other and influence the marine and terrestrial biogeochemical cycles, in particular the carbon cycle. These complex interactions include feedback mechanisms which can amplify or dampen the initial change in climate (Crowley & North, 1988, Twitchett, 2006, Ruddiman, 2013, p.15-16, Alley et al., 2002. The diverse proposed drivers for these changes in climate will be described together with the response of the climate system and possible consequences for the biosphere. ...
... Due to the chaotic and non-linear nature of the climate system, the climate can change abruptly by crossing a threshold driving the climate system in a different climate state at a rate which is faster than the forcing and determined by positive feedbacks and interactions in the climate system (Alley et al., 2002, p.14). There is evidence for abrupt climate transitions in the past in the paleontologic record which sometimes coincide with observed changes in the biosphere or even extinction (Crowley & North, 1988. The low resolution of the paleontologic and paleoclimatic record, before the Cenozoic in particular , together with the challenge of understanding and modeling abrupt transitions, limit the existing information on the link between past abrupt climatic changes and changes in the biosphere. ...
Thesis
The evolution of life on Earth has been driven by disturbances of different types and magnitudes over the 4.6 million years of Earth’s history (Raup, 1994, Alroy, 2008). One example for such disturbances are mass extinctions which are characterized by an exceptional increase in the extinction rate affecting a great number of taxa in a short interval of geologic time (Sepkoski, 1986). During the 541 million years of the Phanerozoic, life on Earth suffered five exceptionally severe mass extinctions named the “Big Five Extinctions”. Many mass extinctions are linked to changes in climate (Feulner, 2009). Hence, the study of past mass extinctions is not only intriguing, but can also provide insights into the complex nature of the Earth system. This thesis aims at deepening our understanding of the triggers of mass extinctions and how they affected life. To accomplish this, I investigate changes in climate during two of the Big Five extinctions using a coupled climate model. During the Devonian (419.2–358.9 million years ago) the first vascular plants and vertebrates evolved on land while extinction events occurred in the ocean (Algeo et al., 1995). The causes of these formative changes, their interactions and their links to changes in climate are still poorly understood. Therefore, we explore the sensitivity of the Devonian climate to various boundary conditions using an intermediate-complexity climate model (Brugger et al., 2019). In contrast to Le Hir et al. (2011), we find only a minor biogeophysical effect of changes in vegetation cover due to unrealistically high soil albedo values used in the earlier study. In addition, our results cannot support the strong influence of orbital parameters on the Devonian climate, as simulated with a climate model with a strongly simplified ocean model (De Vleeschouwer et al., 2013, 2014, 2017). We can only reproduce the changes in Devonian climate suggested by proxy data by decreasing atmospheric CO2. Still, finding agreement between the evolution of sea surface temperatures reconstructed from proxy data (Joachimski et al., 2009) and our simulations remains challenging and suggests a lower δ18O ratio of Devonian seawater. Furthermore, our study of the sensitivity of the Devonian climate reveals a prevailing mode of climate variability on a timescale of decades to centuries. The quasi-periodic ocean temperature fluctuations are linked to a physical mechanism of changing sea-ice cover, ocean convection and overturning in high northern latitudes. In the second study of this thesis (Dahl et al., under review) a new reconstruction of atmospheric CO2 for the Devonian, which is based on CO2-sensitive carbon isotope fractionation in the earliest vascular plant fossils, suggests a much earlier drop of atmo- spheric CO2 concentration than previously reconstructed, followed by nearly constant CO2 concentrations during the Middle and Late Devonian. Our simulations for the Early Devonian with identical boundary conditions as in our Devonian sensitivity study (Brugger et al., 2019), but with a low atmospheric CO2 concentration of 500 ppm, show no direct conflict with available proxy and paleobotanical data and confirm that under the simulated climatic conditions carbon isotope fractionation represents a robust proxy for atmospheric CO2. To explain the earlier CO2 drop we suggest that early forms of vascular land plants have already strongly influenced weathering. This new perspective on the Devonian questions previous ideas about the climatic conditions and earlier explanations for the Devonian mass extinctions. The second mass extinction investigated in this thesis is the end-Cretaceous mass extinction (66 million years ago) which differs from the Devonian mass extinctions in terms of the processes involved and the timescale on which the extinctions occurred. In the two studies presented here (Brugger et al., 2017, 2021), we model the climatic effects of the Chicxulub impact, one of the proposed causes of the end-Cretaceous extinction, for the first millennium after the impact. The light-dimming effect of stratospheric sulfate aerosols causes severe cooling, with a decrease of global annual mean surface air temperature of at least 26◦C and a recovery to pre-impact temperatures after more than 30 years. The sudden surface cooling of the ocean induces deep convection which brings nutrients from the deep ocean via upwelling to the surface ocean. Using an ocean biogeochemistry model we explore the combined effect of ocean mixing and iron-rich dust originating from the impactor on the marine biosphere. As soon as light levels have recovered, we find a short, but prominent peak in marine net primary productivity. This newly discovered mechanism could result in toxic effects for marine near-surface ecosystems. Comparison of our model results to proxy data (Vellekoop et al., 2014, 2016, Hull et al., 2020) suggests that carbon release from the terrestrial biosphere is required in addition to the carbon dioxide which can be attributed to the target material. Surface ocean acidification caused by the addition of carbon dioxide and sulfur is only moderate. Taken together, the results indicate a significant contribution of the Chicxulub impact to the end-Cretaceous mass extinction by triggering multiple stressors for the Earth system. Although the sixth extinction we face today is characterized by human intervention in nature, this thesis shows that we can gain many insights into future extinctions from studying past mass extinctions, such as the importance of the rate of change (Rothman, 2017), the interplay of multiple stressors (Gunderson et al., 2016), and changes in the carbon cycle (Rothman, 2017, Tierney et al., 2020).
... Increased volcanic activity over an extended period and on a large enough scale would lead to the production of immense amounts of acid rain, reduction in alkalinity and pH of the surface ocean, global atmospheric cooling resulting from expelled ash, and ozone layer depletion (Hallam, 1987). Crowley and North (1988) have suggested that terrestrially induced climate instability may be a viable mechanism for causing rapid environmental change and biotic turnover in earth's history. Moses (1989) has reviewed and compared the impact and tectonic explanations. ...
Article
The present paper reviews the current distribution and factors determining the level of biological diversity. Past climate changes causing mass extinctions, lessons drawn from these past events and the impact of future climate change on biological diversity in its broadest sense are also considered. Large scale changes in vegetation zones and composition, over extensive parts of the globe are indicated. Displacement of isotherms due to rise in global temperatures would necessitate very rapid species shifts which may be possible only with human assistance except for plants propagated by spores or dust seeds. Rates of migration and behaviour of the migrating species will determine their range shift capabilities. Differences in migration rates may result in new combinations of species because of dissociation of communities into their component species. Species rigidly associated to a particular set of environmental conditions may well become extinct Characteristics such as large population size, broad geographical distribution and high dispersal potentials will protect species from extinction. Increased pressure from invaders, increased frequency of epidemics and alteration of productivity and species distributions are indicated. Elevated sea water temperatures may badly damage sea flora and fauna as is exemplified by present day El nino effects. Destruction of coastal habitats due to sea level rise may affect birds and fishes using sail marshes, estuaries and islets as breeding ground. Island species will be severely affected both due to reduced area and limitations of latitudinal migration. Changes in precipitation pattern may result in reduced avian and mammalian populations in many parts of the world.
... (Frolich, 1989) Although the magnitude and some effects of the greenhouse effect remain hotly contested, the scale and complexity of potential changes has led to a desperate scrabble to foresee the future. Large-scale extinction have occurred as a result of past major climate changes, cataclysmic disturbances, and human activities (Crowley et al, 1988) Although little scientific consensus has emerged on the impacts of apparent current changes, it appears highly likely that global warming and associated disturbance events, particularly when coupled with human population growth and accelerating rates of resource use, will bring further losses in biological diversity. ...
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An overview of the impact of climate change on the ecosystem and on human health is hereby reported. The debate over the effects of ozone depletion and airborne particulate and indeed the greenhouse gases has produced a number of scientific materials on the subject matter. It therefore becomes necessary that a better understanding is established between the biosphere and climate as this will enable better planning for adapting to the changes that occur though it seems unlikely that climate management will become a reality within the foreseeable future.
... Our time-calibrated tree indicated stem node age of about 53 Ma for Hydrocharis (Fig. 3), which is similar to the previously reported median age of 54.7 Ma [4] and in agreement with the oldest known Hydrocharis fossils [39,40]. Rapid climate change during the Miocene may have contributed to the speciation of Hydrocharis as well as extinctions, given that the fossil diversity is high in comparison to the limited extant diversity [41,42]. Additionally, paleoclimatic changes may have induced such changes in water bodies that some groups were driven to extinction [43]. ...
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Background Hydrocharis L. and Limnobium Rich. are small aquatic genera, including three and two species, respectively. The taxonomic status, phylogenetic relationships and biogeographical history of these genera have remained unclear, owing to the lack of Central African endemic H. chevalieri from all previous studies. We sequenced and assembled plastomes of all three Hydrocharis species and Limnobium laevigatum to explore the phylogenetic and biogeographical history of these aquatic plants. Results All four newly generated plastomes were conserved in genome structure, gene content, and gene order. However, they differed in size, the number of repeat sequences, and inverted repeat borders. Our phylogenomic analyses recovered non-monophyletic Hydrocharis . The African species H. chevalieri was fully supported as sister to the rest of the species, and L. laevigatum was nested in Hydrocharis as a sister to H . dubia . Hydrocharis-Limnobium initially diverged from the remaining genera at ca. 53.3 Ma, then began to diversify at ca. 30.9 Ma. The biogeographic analysis suggested that Hydrocharis probably originated in Europe and Central Africa. Conclusion Based on the phylogenetic results, morphological similarity and small size of the genera, the most reasonable taxonomic solution to the non-monophyly of Hydrocharis is to treat Limnobium as its synonym. The African endemic H. chevalieri is fully supported as a sister to the remaining species. Hydrocharis mainly diversified in the Miocene, during which rapid climate change may have contributed to the speciation and extinctions. The American species of former Limnobium probably dispersed to America through the Bering Land Bridge during the Miocene.
... Based on our results, Hydrocharis mainly diversi ed in the Miocene, which is consistent with the time inferred for many other extant plant species [57,58]. Rapid climate change during the Miocene may have contributed to the speciation of Hydrocharis as well as extinctions, given that the fossil diversity is high in comparison to the limited extant diversity [59,60]. The recent analysis of the distribution patterns of Hydrocharis indicated that the mean annual temperature is the main factor to impact the distribution in this genus [3]. ...
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Background Hydrocharis L. and Limnobium Rich. are small aquatic genera, including three and two species, respectively. The taxonomic status, phylogenetic relationships and biogeographical history of these genera have remained unclear, owing to the lack of Central African endemic H. chevalieri from all previous studies. We sequenced and assembled plastomes of all three Hydrocharis species and Limnobium laevigatum to explore the phylogenetic and biogeographical history of these aquatic plants. Results All four newly generated plastomes were conserved in genome structure, gene content, and gene order. However, they differed in size, the number of repeat sequences, and inverted repeat borders. Our phylogenomic analyses recovered non-monophyletic Hydrocharis. African species H. chevalieri was fully supported as sister to the rest of the species, and L. laevigatum was nested in Hydrocharis as a sister to H. dubia. Hydrocharis-Limnobium initially diverged from the remaining genera at ca. 53.3 Ma, then began to diversify at ca. 30.9 Ma. The biogeographic analysis suggested that Hydrocharis probably originated in Europe and Central Africa. Conclusion Based on the phylogenetic results, morphological similarity and small size of the genera, the most reasonable taxonomic solution to the non-monophyly of Hydrocharis is to treat Limnobium as its synonym. The African endemic H. chevalieri is fully supported as a sister to the remaining species. Hydrocharis mainly diversified in the Miocene, during which rapid climate change may have contributed to the speciation and extinctions. The American species of former Limnobium probably dispersed to America through the Bering Land Bridge during the Miocene.
... The Frasnian-Famennian (F-F) bio-crisis is one of the "Big Five" mass extinctions during the Phanerozoic (Sepkoski et al., 1981;Raup et al., 1982;Crowley and North, 1988;McGhee Jr. and Erwin, 1996;Alroy et al., 2008;Shen and Zhang, 2017;Racki and Wignall, 2020;Song et al., 2021), which severely affected the tropical marine ecosystems, especially shallow-water faunas and metazoan reefs (McGhee Jr., 1996;Huang et al., 2018). The basinal anoxia and toxicity (Algeo and Scheckler, 1998;Kazmierczak et al., 2012), climate and sea-level change (Copper, 1998;Algeo et al., 2001;Ma et al., 2016;Huang et al., 2018;Racki, 2020), and microbial blooming (Wu et al., 2013) were considered to be the possible cause for the F-F extinction. ...
Article
Epibionts and hosts as well as their interactions comprise a special ecosystem in the marine hard-substrate communities which could provide paleoecological implications for the critical events of Earth history. Abundant brachiopod hosts were sampled from the Givetian–Famennian of the Longmenshan region in South China. We describe the encrustation patterns on the brachiopods in terms of epibiont abundance, diversity, relationships between hosts and epibionts, and interaction between epibiont taxa. A total of 3067 brachiopod specimens are examined and identified into seven species, among which 683 specimens are encrusted by epibionts represented by eight taxa. The percentage of encrusted shells and the mean number of epibionts per shell of host brachiopods, are mainly related to the shell morphology of the host and ecological environments. The abundance of epibionts and the number of associations are quite variable among the Middle–Late Devonian stages. Most of epibionts have selective preferences on certain host taxa. The individual size of epibionts is an important factor in choosing the host. During the Givetian and Frasnian time, encrusters were much more abundant on the dorsal valves than on the ventral valves of host brachiopods. However, until the Famennian time, the biconvex spiriferoids have more encrusters on the ventral valves. Such an encrusting change from dorsal valves to ventral valves across the F/F boundary might not be related to ecological environments, yet only the change of host taxa. The epibionts encrusted on host brachiopods did not display a sudden collapse around the F-F boundary interval. The epibiont abundance, diversity, relationships between hosts and epibionts, as well as interaction between epibiont taxa do not show a significant change around the F/F boundary. It may indicate there was no dramatic environmental change in the Frasnian and Famennian boundary interval but long-term ecological damage during the Frasnian in the studied region.
... F ive large-magnitude mass extinctions (the "Big Five") have occurred during the past 450 million years (Myr) 1 , where the estimated extinction of marine animals for each event was over 75% at the species level 2 . A large body of evidence has focused on abrupt climate change (both warming and cooling) as a direct or indirect mechanism that drove many mass and minor extinctions [3][4][5][6][7][8] . Of the Big Five extinctions, for example, the end-Ordovician mass extinction (~443 Ma) was related to a shortlived cooling event accompanied by a glaciation maximum and a major drop in sea level 7,9 . ...
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Climate change is a critical factor affecting biodiversity. However, the quantitative relationship between temperature change and extinction is unclear. Here, we analyze magnitudes and rates of temperature change and extinction rates of marine fossils through the past 450 million years (Myr). The results show that both the rate and magnitude of temperature change are significantly positively correlated with the extinction rate of marine animals. Major mass extinctions in the Phanerozoic can be linked to thresholds in climate change (warming or cooling) that equate to magnitudes >5.2 °C and rates >10 °C/Myr. The significant relationship between temperature change and extinction still exists when we exclude the five largest mass extinctions of the Phanerozoic. Our findings predict that a temperature increase of 5.2 °C above the pre-industrial level at present rates of increase would likely result in mass extinction comparable to that of the major Phanerozoic events, even without other, non-climatic anthropogenic impacts.
... Each of the five major extinction events that have occurred on Earth was characterized by up to 80% or more of the then currently living species being lost. However, life on Earth has always recovered, and dominance over certain ecological niches simply passed from one group of organisms to another [120][121][122][123]. ...
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