Session NP3.1

NP3.1 | Climate Variability Across Scales and Deep-Time Biogeoclimate

Climate Variability Across Scales and Deep-Time Biogeoclimate

Co-organized by CL4, co-sponsored by PAGES 2k

Convener: Raphael Hébert | Co-conveners: Andrej Spiridonov, Sylvia Dee, Shaun Lovejoy, Norbert Marwan, Mara Y. McPartland, Elisa Ziegler

Orals

| Thu, 27 Apr, 10:45–12:30 (CEST)

Room -2.31

Posters on site

| Attendance Mon, 24 Apr, 16:15–18:00 (CEST)

Hall X4

We welcome contributions that improve quantification, understanding, and prediction of climate variability in the Earth system across space and timescales through case studies, idealized or realistic modeling, synthesis, and model-data comparison studies that provide insights into past, present and future climate variability on local to global, and synoptic to orbital timescales. In particular, we welcome contributions making use of paleoclimate data and modelling to understand changes in the climate system dynamics and variability during the last glacial cycle, and the related implications for the future.

This session aims to provide a forum to present work on:
1. Characterization of climate dynamics using a variety of techniques (e.g. scaling and multifractal techniques and models, recurrence plots, variance analyses).

2. Proxy-system modelling to improve paleoclimate reconstructions and model-data comparisons

3. Relationship between mean state changes (e.g. glacial to interglacial or pre-industrial to present to future), and higher-order moments of relevant climate variables, including extreme-event occurrence and predictability.

4. Role of the ocean, atmosphere, cryosphere and land-surface processes in fostering long-term climate variability through linear – or nonlinear – feedbacks and mechanisms.

5. Attribution of climate variability to internal and/or forced dynamics, including natural (e.g. volcanic and solar) and anthropogenic forcing changes.

6. Synchronization and pacing of glacial cycles through dynamical interaction of external forcing (e.g. orbital forcing) and internal variability.

7. Characterization of the probabilities of extremes, including linkage between slow climate variability and extreme event recurrence.

Members of the PAGES working group on Climate Variability Across Scales (CVAS) and the German Climate Modeling Initiative PalMod are particularly welcome.

Orals: Thu, 27 Apr | Room -2.31

Chairpersons: Raphael Hébert, Andrej Spiridonov, Elisa Ziegler

10:45–10:47

Megaclimate and Biogeochemical in Deep Time

10:47–10:57

EGU23-1832

ECS

solicited

On-site presentation

Coupled patterns of foraminiferal species richness and mega-climatic change across the Eocene-Oligocene transition

Zhengbo Lu and Junxuan Fan

The Eocene-Oligocene transition (EOT) is the turning point of Earth’s Cenozoic climate, during which it stepped into the current “icehouse” state. The absence of a high-resolution, global, evolutionary timeline has limited understanding of the linkages between marine biodiversity and this environmental change. Here, we present a new 28-Myr-long foraminiferal species-richness history with an average temporal resolution of ~26 kyr based on a global dataset and quantitative stratigraphic method, CONOP. A significant richness decline accompanied the EOT, eliminating a great number of foraminifera species. The extinction events in planktonic foraminiferal (PF) and larger benthic foraminiferal (LBF) near the EOT appear to be associated with the combination of a rapid decrease in deep ocean temperature, a eustatic sea-level fall and a positive carbon isotopic excursion. In contrast, the much longer richness decline of small benthic foraminifera (SBF) across the EOT occurred in two phases: the first coincided with turnover of marine primary producers, and the second appears to have been temporally coincident with Afar-Arabian LIP activity, which led to expansion of oceanic anoxia and euxinia. Thus, mega-climatic changes are reflected in the species richness of foraminifera during the Eocene-Oligocene “warmhouse-icehouse” transition.

How to cite: Lu, Z. and Fan, J.: Coupled patterns of foraminiferal species richness and mega-climatic change across the Eocene-Oligocene transition, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1832, https://doi.org/10.5194/egusphere-egu23-1832, 2023.

10:57–11:07

EGU23-15117

On-site presentation

Climatic warming changes to Northern European extreme temperature processes over the past 500 years

John Bruun

One of the most telling effects of the weather and climate is the occurrence of rare extreme events. As extremes are typically sudden and climate variability is a slower process, it is important to assess how severe changes have become and to aim to understand why. As the climate dynamics of the mean state are altering, can we also establish accurately if there are systematic changes to the extreme temperature process? One main challenge for assessing such climate dynamic alterations across these time scales is how to analyse records across the pre-industrial paleo and instrumental eras of the past 500 years. This analysis focusses on Northern European temperatures and their mean state and extremes changes. The analysis is done using a form of Dominant Frequency State Analysis where the extreme process (modelled as a Generalised Extreme Value process) can be distinguished from the variation of the mean state. The methods used in this approach are generic and can be applied in any study of extremes provided there is data (instrumental, simulated or paleo-proxies) that is of sufficient quality. This work reports how the extreme temperature process properties for Northern Europe appear to have altered across 500 years and I’ll discuss the climate dynamics interpretation of these results.

How to cite: Bruun, J.: Climatic warming changes to Northern European extreme temperature processes over the past 500 years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15117, https://doi.org/10.5194/egusphere-egu23-15117, 2023.

11:07–11:17

EGU23-15592

ECS

On-site presentation

Recurrence analysis of large-scale dynamical properties of terrestrial mammal evolution

Robertas Stankevič, Simona Bekeraitė, Andrej Spiridonov, and Ivona Juchnevičiūtė

Contrary to ecology, biology and climate science, analysis of nonlinear dynamics in paleontological time series is still relatively uncommon. Palaeontology tend to focus on events such as mass extinctions or radiations over dynamical processes and relationships. However, all parts of the Earth system, including the biota, are interrelated at multiple scales, showing feedback relations and nonlinearity. Nonlinear analysis of global palaeodiversity dynamics and its coupling with abiotic variables could offer a fresh view into a long-running question of the relative importance of biotic and abiotic factors in macroevolution by identifying interactions and responses not amenable to classical methods of time series analysis.
As a part of our inquiry into causal explanation of the drivers of mammal evolution, we present our analysis of the dynamics of Cenozoic land mammal evolution, based on high resolution time series data and methods of recurrence plots and causal inference.
Using PyRate, a Bayesian palaeodiversity analysis framework, we estimate diversification parameters and individual taxon lifetimes of several extinct Paleogene mammal orders and several extant large bodied orders Carnivora, Proboscidea, Artiodactyla and Perissodactyla. We then use recurrence analysis tools developed by the author to investigate dynamics of the evolution of the aforementioned taxons, identifying regime transitions and regions of deterministic and chaotic regimes over multi-million year timescales.
Abrupt changes in species composition are indentified particularly in Perissodactyla recurrence plots. First and the most abrupt change occured at ca. 32 Ma, corresponding to Eocene-Oligocene extinction event. Another prominent change indentified at ca. 17 Ma, corresponding to Middle Miocene disruption. Both concide with changes in δ¹³C and δ¹⁸O isotopic record (Westerhold et al. 2020).
In search of signatures of general synchronisation, we performed joint-recurrence plot analysis between matrices of diversity composition, δ¹³C isotopic record and δ¹⁸O-derived global temperature time series.
Our preliminary results shed light on diversification dynamics of the main terrestrial mammal orders and similarity over time and coupling with the climatic and carbon cycle dynamics of the Earth. We compare them with findings of causal analysis of climate and diversification time series, using the same datasets and transfer-entropy based causal inference tools. The relative degrees of herbivore and carnivore diversity couplings with climate is also discussed.

How to cite: Stankevič, R., Bekeraitė, S., Spiridonov, A., and Juchnevičiūtė, I.: Recurrence analysis of large-scale dynamical properties of terrestrial mammal evolution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15592, https://doi.org/10.5194/egusphere-egu23-15592, 2023.

11:17–11:20

Climate Variability Across Scales

11:20–11:30

EGU23-3231

On-site presentation

Synchronization theory for Pleistocene glacial-interglacial cycles

Takahito Mitsui, Matteo Willeit, and Niklas Boers

11:30–11:40

EGU23-7748

ECS

On-site presentation

Response of atmospheric variability in the Northern Hemisphere winter to past climate conditions and elevated CO2 levels

Arthur Oldeman, Michiel Baatsen, Anna von der Heydt, Aarnout van Delden, and Henk Dijkstra

A specific feature where future climate projections fail to see a consistent response to increasing CO₂ levels is Northern Hemisphere winter atmospheric dynamics and variability. This holds specifically for the Northern Annular Mode (NAM) and its regional expression, the North Atlantic Oscillation (NAO). The lack of consensus in future projections is caused in part due to the large internal variations of these modes of atmospheric variability compared to the response to elevated CO₂.

The response of interannual and decadal climate variability to warm conditions can be isolated in climate simulations equilibrated at elevated CO₂ concentrations. However, we cannot perform a future model-data comparison. Fortunately, we can turn to the past. The last time the Earth saw similar CO₂ concentration as the present day was approximately 3 million years ago, in the mid-Pliocene epoch. The mid-Pliocene is often considered the ‘best analog’ to an equilibrated climate at present or near-future CO₂ levels. However, can the mid-Pliocene be used to assess the response of Northern Hemisphere winter atmospheric variability, such as the NAO and NAM, to a warm climate?

To answer this question, we have performed a set of sensitivity experiments using a global coupled climate model (CESM1.0.5). We have performed sensitivity studies using a pre-industrial and a mid-Pliocene geography, as well as two levels of radiative forcing (280 ppm and 560 ppm), as a part of intercomparison project PlioMIP2. Our mid-Pliocene simulations generally compare well to proxy reconstructions of sea-surface temperature.

We consider the sea-level pressure (SLP) and zonal wind at 200 hPa using 200 years of January-mean data, and perform principal component analysis. In response to the mid-Pliocene boundary conditions (other than CO₂), we find a large increase in the mean SLP along with a decreased variance over the North Pacific Ocean. This is accompanied with a weakened jet stream over the western North Pacific, as well as increased occurrence of a split jet condition over the eastern North Pacific. These findings are connected to a regime shift in the modes of atmospheric variability in the Northern Hemisphere, where the so-called North Pacific Oscillation (NPO) becomes the most dominant mode of variability. We do not see tendencies towards similar behavior in the CO₂ doubling experiment indicating that the Pliocene boundary conditions are the main driver of the observed shifts in variability. This suggests that the mid-Pliocene is not a good analog for a warm future climate when considering Northern hemisphere winter atmospheric variability.

How to cite: Oldeman, A., Baatsen, M., von der Heydt, A., van Delden, A., and Dijkstra, H.: Response of atmospheric variability in the Northern Hemisphere winter to past climate conditions and elevated CO2 levels, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7748, https://doi.org/10.5194/egusphere-egu23-7748, 2023.

11:40–11:50

EGU23-2679

ECS

On-site presentation

Mechanisms behind ocean variability in transient simulations of the early deglaciation

Marie-Luise Kapsch, Marlene Klockmann, and Uwe Mikolajewicz

The last deglaciation was accompanied by a gradual warming with superimposed abrupt climate changes. In transient simulations of the last deglaciation with the comprehensive Max Planck Institute Earth System Model (MPI-ESM) we show that the timing and occurrence of abrupt climate changes are highly dependent on the utilized ice-sheet boundary condition. Simulations with different ice-sheet reconstructions show that the variability of North Atlantic surface temperatures are dominated by the timing and amplitude of meltwater fluxes from ice sheets, as derived from reconstructions. While some abrupt climate events (e.g. the Younger Dryas) only occur under certain boundary conditions in the transient simulations, other climate events such as the Bølling Allerød warming (about 14.7-14.2 ka BP) cannot be simulated with any of the applied and widely used reconstructions. However, in a sensitivity experiment with changing ice sheets but no addition of meltwater into the ocean, the North Atlantic experiences a warming during the time of the Bølling-Allerød. This warming is associated with a reorganization of the ocean circulation and deep-water formation sites. Prior to this reorganization, during the glacial and early part of the deglaciation, a rather zonal jet stream maintains a strong subpolar gyre in the North Atlantic. In addition, salty and dense water masses form in the Arctic. Until about 16.5 ka BP the Arctic freshens significantly and the surface elevation over the Laurentide ice sheet reduces. The latter leads to a shift in the atmospheric circulation at around 14.2 ka BP. The resulting changes in wind stress strongly reduce the eastward extent of the North Atlantic subpolar gyre. Here, we examine the physical mechanisms behind the reorganization and explore additional simulations with fixed deglacial key parameters (e.g. CO2, insolation, ice sheets) to identify the key drivers of the climate changes during the early deglaciation and Bølling Allerød.

How to cite: Kapsch, M.-L., Klockmann, M., and Mikolajewicz, U.: Mechanisms behind ocean variability in transient simulations of the early deglaciation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2679, https://doi.org/10.5194/egusphere-egu23-2679, 2023.

11:50–12:00

EGU23-9455

On-site presentation

Was the 4.2 ka event unusual in context of global Holocene climate variability?

Nicholas McKay, Darrell Kaufman, Stéphanie Arcusa, and Hannah Kolus

Abrupt climate changes are commonly observed between 4500 and 4000 years ago, and particular attention has been paid to the “4.2 ka event”, which now serves as a stratigraphic marker to subdivide the mid and late Holocene globally. However, proxy climate records are commonly marked by large, and often abrupt, changes in temperature and moisture throughout the Holocene, and it remains unclear how abrupt change in the mid-Holocene compares to changes throughout the epoch. Here, we assess how regional and global temperature and moisture changes between 4.5 and 4.0 ka compare with other major climate events across the Holocene, in particular the 8.2 ka event. To conduct this analysis objectively, we assess more than a 1000 previously published paleoclimate datasets that span all continents and oceans and include a wide variety of archive and proxy types. All of the data are open access, and the analyses were conducted using the open-source “Abrupt Change Toolkit in R (actR)” software package to determine the timing and significance of multiple types of abrupt change. These include excursion events (significant short-term deviations from the mean state), regime change events (significant rapid shifts in millennial-scale means) and trend change events (significant changes in the long-term trend). We detect multiple significant abrupt change events throughout the Holocene, and therefore evaluate the spatiotemporal significance of events against a null hypothesis of observed background variability. Events at 8.2 ka stand out as large spatiotemporally coherent excursions of temperature and moisture centered in the North Atlantic and globally significant. In contrast, although we detect multiple types of abrupt change in moisture and temperature during the between 4.5 and 4.0 ka, the event does not significantly exceed the expectation of occurrence from our robust null model nor stand out as a regionally coherent anomaly. These results suggest that local abrupt changes are common throughout the Holocene; many of these are regionally coherent, but few are hemispheric or global in extent.

How to cite: McKay, N., Kaufman, D., Arcusa, S., and Kolus, H.: Was the 4.2 ka event unusual in context of global Holocene climate variability?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9455, https://doi.org/10.5194/egusphere-egu23-9455, 2023.

12:00–12:10

EGU23-17584

solicited

Highlight

On-site presentation

Climate change detection and attribution using proxy system models

Jörg Franke, Mike Evans, Andrew Schurer, and Gabriele Hegerl

Until now, pre-instrumental climate change detection and attribution studies were based on the regression of statistical reconstructions on simulations. This approach is limited by stationarity assumptions and the univariate linear response of the underlying paleoclimatic observations. Here, we present a new procedure, in which we model paleoclimate data observations as a function of paleoclimatic data simulations using a proxy system model. Specifically, we detect and attribute tree-ring width (TRW) observations as a linear function of TRW simulations. These are nonlinear and multivariate TRW simulation driven by climate simulations with single or multiple external forcing.

Temperature- and moisture-sensitive TRW simulations detect distinct patterns in time and space. Northern Hemisphere averages of temperature-sensitive TRW observations and simulations are significantly correlated. We can attribute their variation to volcanic forcing. In decadally smoothed temporal fingerprints, we find the observed responses to be significantly larger and/or more persistent than the simulated responses. The pattern of simulated TRW of moisture-limited trees is consistent with the observed anomalies in the two years following major volcanic eruptions. We can for the first time attribute this spatiotemporal fingerprint in moisture-limited tree-ring records to volcanic forcing. These results suggest that the use of nonlinear and multivariate proxy system models in paleoclimatic detection and attribution studies may permit more realistic, spatially resolved and multivariate fingerprint detection studies and evaluation of the climate sensitivity to external radiative forcing than has previously been possible.

How to cite: Franke, J., Evans, M., Schurer, A., and Hegerl, G.: Climate change detection and attribution using proxy system models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17584, https://doi.org/10.5194/egusphere-egu23-17584, 2023.

12:10–12:20

EGU23-14335

On-site presentation

Multi-annual variability of a new proxy-constrained modeled AMOC from 1450-1780 CE

Eric Samakinwa, Christoph Riable, Ralf Hand, Andrew Friedman, and Stefan Brönnimann

12:20–12:30

EGU23-15090

Highlight

Virtual presentation

Heat extremes in scenario projections: the role of variability

Claudia Simolo and Susanna Corti

Posters on site: Mon, 24 Apr, 16:15–18:00 | Hall X4

Chairpersons: Shaun Lovejoy, Mara Y. McPartland, Sylvia Dee

X4.73

EGU23-1833

Highlight

Coral record from Bicol in the Philippines in 1770-1850 reveals volcanic cooling

Hodaka kawahata, Mayuri Inoue, Mutsumi Chihara, Fernando P. Siringan, and Atsuhi Suzuki

Historical variations of surface temperature in relation to anthropogenic warming has been extensively studied to understand and explain changes in the contemporary climate and to estimate future impacts of climate．Inoue and others (in press) reported 228-year records of SST and salinity based on Sr/Ca and d¹⁸O analyses with monthly time resolution in Porites coral collected from Bicol, the south of Luzon, Philippines. From the record, we investigated the relationship between the reconstructed temperature and the volcanic eruptions in late 18^th and early 19^th centuries. There were three great famines during the Edo period (1603-1868), almost corresponding to the Little Ice Age in Japan. Of these, the two were Tenmei-famine in 1782-88 and Tempo-famine in 1833-1837(1839). Both famines killed more than one million people out of a population of 30 million at the time. Our reconstructed SST anomaly fluctuated between -1.5 degree and 1.0 degree. The age model may have the age error of 1 to 3 years before around 1885. Large minima occurred in 1785-1789, 1815-1819, 1822-25, 1827-1830, 1834-1835, and 1843-45. Although Laki eruption, Iceland in 1783 has not been described as large eruption in previous studies, their impact on climatic conditions around the Northern Hemisphere and the globe was widely reported. Local eruption of Asama, Japan in 1783 released volcanic ash over eastern part of Japanese islands, In addition, El Nino event, which often cooled down Japanese islands, occurred around those days. These factors could have been responsible for the coldest anomaly in 1785-1789 recorded in our coral samples. After Tambora eruption in 1815, sharp cooling of around 2.0˚C was observed in our coral sample and almost all over the world. However, this world-scale cooling event have no or little influence on the climate in Japanese islands based upon the historical documents and agriculture records. This indicates that there are areas that do not become exceptionally cold, even by major volcanic eruptions. Large eruption of Galunggung in 1822 brought appreciable degree of cooling anomaly in our coral record. Just after Agung exploded largely in 1843, reconstructed SST significantly dropped. This might be also influenced by another large eruption of Cosiguina in Nicaragua, central America. Cold climate was reported in Japan, New York in USA, Copenhagen, UK in 1840s. It was most likely global in scale in the northern hemisphere.

How to cite: kawahata, H., Inoue, M., Chihara, M., Siringan, F. P., and Suzuki, A.: Coral record from Bicol in the Philippines in 1770-1850 reveals volcanic cooling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1833, https://doi.org/10.5194/egusphere-egu23-1833, 2023.

X4.74

EGU23-4446

The Fractional Macro Evolution Model: A simple quantitative scaling macroevolution model

Shaun Lovejoy and Andrej Spiridinov

Scaling fluctuation analyses of the marine animal diversity, extinction and origination rates based on the Paleobiology Database occurrence data have opened new perspectives on macroevolution, supporting the hypothesis that the environment (climate proxies) and life (extinction and origination rates) are scaling over the “megaclimate” biogeological regime (from ≈ 1 Myr to at least 400Myrs). In the emerging picture, biodiversity is a scaling “cross-over” phenomenon being dominated by the environment at short time scales and by life at long times scales with a cross-over at ≈40Myrs. These findings provide the empirical basis for constructing the Fractional MacroEvolution Model (FMEM), a simple stochastic model combining destabilizing and stabilizing tendencies in macroevolutionary dynamics. The FMEM is driven by two scaling processes: temperature and turnover rates.

Macroevolution models are typically deterministic (albeit sometimes perturbed by random noises), and based on integer ordered differential equations. In contrast, the FMEM is stochastic and based on fractional ordered equations. Stochastic models are natural for systems with large numbers of degrees of freedom and fractional equations naturally give rise to scaling processes.

The basic FMEM drivers are fractional Brownian motions (temperature, T) and fractional Gaussian noises (turnover rates E₊) and the responses (solutions), are fractionally integrated fractional Relaxation processes (diversity (D), extinction (E), origination (O) and E_- = O - E). We discuss the impulse response (itself a model for impulse perturbations such as bolide impacts) and derive the full statistical properties including cross covariances. By numerically solving the model, we verified the mathematical analysis and compared both uniformly and irregularly sampled model outputs to paleobiology series.

The six series (T, E₊, D, E_-, O, E) had fluctuation statistics that varied realistically with time scales Δt (lags) over the observed range (≈3 Myrs to ≈ 400 Myrs). In addition, the 15 pairwise fluctuation correlations (of the six variables) as functions of Δt were also very close to observations even though only two correlations were specified in the model (TE₊and TD). The ability to simulate the effects of irregular temporal sampling was important since model – data agreement was much better with realistic (irregular) sampling than with uniform sampling. Although the model could easily be made more complex, this may not be warranted until much higher resolution series become available.

How to cite: Lovejoy, S. and Spiridinov, A.: The Fractional Macro Evolution Model: A simple quantitative scaling macroevolution model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4446, https://doi.org/10.5194/egusphere-egu23-4446, 2023.

X4.75

EGU23-6069

An ocean surface paradox: gas equilibrium with atmosphere

Brian Durham and Christian Pfrang

Marine science tells us that the surface of Earth’s oceans is in gaseous equilibrium with its atmosphere (Yingxu Wu et al 2022). In the case of the key atmospheric trace gas CO₂, the partition across the phase boundary is given by Henry constants as established by Li and Tsui 1971 and by Weiss 1974, while outside the laboratory there are extensive datasets for the atmospheric mol fraction (ppm CO₂) embodied in the familiar `Keeling curves’, as measured at oceanic, polar and continental locations (Yuan et al 2019).

Sea surface temperatures are widely available for Earth’s oceans (Kent and Kennedy 2021). We have therefore interpreted the Henry Constants from Li and Tsui (1971) and from Weiss (1974) as headspace mol fractions (ppm CO₂) against temperature, and added representative field data from Mauna Loa (https://gml.noaa.gov/ccgg/trends/).

A disparity is evident, which we address as follows: In case the well-known differential between the two 1970s laboratory curves is somehow attributable to pre-treatment including acid in both cases and a biocide in one, we speculate that the outcomes of both might be different if the seawater samples had been treated as biological fluids.

Expanding therefore our studies of atmospheric gas partitioning at a growing ice surface reported to recent EGU conferences, and building on valued conversations with colleagues at EGU 2022, we will present provisional results from gas equilibration in the headspace above freshly-collected (≈`live’) seawater from UK’s Atlantic coast.

How to cite: Durham, B. and Pfrang, C.: An ocean surface paradox: gas equilibrium with atmosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6069, https://doi.org/10.5194/egusphere-egu23-6069, 2023.

X4.76

EGU23-6870

ECS

A natural history of networks: Modelling higher-order interactions in geohistorical data

Alexis Rojas, Anton Holmgren, Magnus Neuman, Daniel Edler, Christopher Blöcker, and Martin Rosvall

Geohistorical records, either stratigraphic sections, boreholes, ice cores, or archaeological sites, are inherently complex. Despite their limitations, the high-dimensional and spatiotemporally resolved data retrieved from individual geohistorical records allow for evaluation of past biotic responses to natural and human-induced environmental changes. Network analysis is becoming an increasingly popular alternative for modelling the dynamics of geohistorical data. However, the complexity of geohistorical data raises questions about the limitations of standard network models widely used in paleobiology research. They risk obscuring large-scale patterns by washing out higher-order node interactions when assuming independent pairwise links. Recently introduced higher-order representations and models better suited for the complex relational structure of geohistorical data provide an opportunity to move paleobiology research beyond these challenges. Higher-order networks can represent the spatiotemporal constraints on the information paths underlying geohistorical data, capturing the high-dimensional patterns more accurately. Here we describe how to design higher-order network models of geohistorical data, address some practical decisions involved in modeling complex dependencies, and discuss critical methodological and conceptual issues that make it difficult to compare results across studies in the growing body of network paleobiology. We illustrate multilayer networks, hypergraphs, and varying Markov time models through case studies on the fossil record from continental shelf ecosystems and delineate future research directions for current challenges in the emerging field of network paleobiology.

How to cite: Rojas, A., Holmgren, A., Neuman, M., Edler, D., Blöcker, C., and Rosvall, M.: A natural history of networks: Modelling higher-order interactions in geohistorical data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6870, https://doi.org/10.5194/egusphere-egu23-6870, 2023.

X4.77

EGU23-7943

Highlight

Framing origins and dynamics of biodiversity in the paradigm of space and time scaling

Andrej Spiridonov, Shaun Lovejoy, and Lauras Balakauskas

The biodiversity is the fundamental aspect and transitive measure of biota and the evolutionary process itself. The biodiversity is usually understood as the diversity of morphological or structural types, and also as the number of taxa (species, genera, families etc.) or branches of different ranks in evolutionary trees or networks. The biodiversity is hierarchical and universal feature of biological systems. Despite its conceptual simplicity, the origins and patterns of variability of diversity, except the fact that they are based on the evolutionary process, are rather hardly comprehensively understood. Therefore, the determination of origins, and the dynamics of biodiversity through the space and time, is one of the most fundamental open questions of biology.

The theory of evolution reveals a number of possibilities on how biodiversity can change, and also predicts patterns which underlie the mechanism: if the biodiversity is autonomous and self-regulating process, or if opposite is true – the biodiversity is a driven variable dependant on many varying Earth system, and possibly astrophysical components. One of the most promising approaches in characterizing the dynamics of biodiversity, and discriminating between the underlying causes of the dynamics, is the analysis of scaling.

The spatial scaling of biodiversity is a well developed field of science. The dependence of species richness on the geographical area is described by power laws. The values of parameters could be interpreted with respect to possible controlling genealogical and ecological mechanisms of evolution. The scaling of biodiversity in space, also suggests the scaling of biodiversity as a function of time scale. The scaling is time scale symmetry which connects the large and small scales, and it reveals the uniformity of a mechanism in a scaling range. Presented approach allows the summarization of macroevolution in very simple terms.

Here we present a case of global marine animal biodiversity, and based on the revealed crossover-like time scaling pattern, we suggest that two competing time symmetric scaling mechanisms, with opposite effects on biodiversity (stabilizing versus destabilizing), are responsible for the evolution of the biota at the eon scale. The presented results can serve as a null model in understanding global evolution, and also can serve in sharpening and strengthening of our intuitions in exploring and explaining macroevolutionary patterns.

The research was supported by the project S-MIP-21-9 “The role of spatial structuring in major transitions in macroevolution”.

How to cite: Spiridonov, A., Lovejoy, S., and Balakauskas, L.: Framing origins and dynamics of biodiversity in the paradigm of space and time scaling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7943, https://doi.org/10.5194/egusphere-egu23-7943, 2023.

X4.78

EGU23-8513

ECS

Highlight

Exploring evolution of feather function in early birds and dinosaurs

Pierre Cockx and Michael Benton

Feathers are key innovations that underpin the evolutionary success of birds, and biologists have achieved a solid understanding of modern feather types and their functions. Nonetheless, the unexpected recent discoveries of several specialized feather morphologies in extinct birds and related dinosaurs, challenges our views of the overall evolution of feathers. Such discoveries raise large evolutionary questions in a wider group than simply birds (i.e., dinosaurs as well as pterosaurs). These are related, for instance, to the initial function of feathers, subsequent feather diversification and functions, and potential links between such evolution and external factors. We have differentiated and inventoried fossil feather types based on their general morphological structure, and coded these as traits that relate to feather functions. We analyse the dataset through computational phylogenetic comparative methods, including ancestral state reconstructions, to identify the points of origin for each feature and estimate patterns and rates of evolution. Monofilamentous integumentary structures appear synapomorphic to Avemetatarsalia. A loss of monofilamentous integumentary structures occurred within Pennaraptora. While the presence of pennaceous feathers is synapomorphic for Pennaraptora, the presence of pennaceous feathers on the hindlimbs is a synapomorphy of Paraves. There is greater complexity, however, in feather evolution, with uncertainty over convergence and uniqueness of some feather types not seen in modern birds. The analysis allows some connection from feather morphology evolution to the sequence of regulatory gene switches in modern feather ontogenetic development, but the fossils suggest a richness of evolution not directly seen in studies of feather evo-devo.

How to cite: Cockx, P. and Benton, M.: Exploring evolution of feather function in early birds and dinosaurs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8513, https://doi.org/10.5194/egusphere-egu23-8513, 2023.

X4.79

EGU23-11519

ECS

“HespDiv” method allows to quantify the dark matter of biosystems

Liudas Daumantas and Andrej Spiridonov

Bretskyan hierarchy of eco-evolutionary entities is a useful theoretical concept that defines hierarchies of communities of species which reside in the same geographical space and are tied together by ecological interactions and evolutionary history. Bretskyan hierarchy can be employed to define and track the evolving hierarchy of bioregions, allowing all sorts of (paleo)biogeographical investigations to be carried out: from finding the causes why bioregions split or fuse and how this happens at many spatial scales, ie. what drives the internal structure of bioregions in Bretskyan hierarchy. Unfortunately, methodical applications of this concept are challenging due to the hybrid nature of Bretskyan hierarchy entities and fuzziness of their boundaries.

In order to help solve the presented problem of explicit subdivision of contiguous spatial regions, which are in our understanding the units of the Bretskyan hierarchy, we propose a new method, within the newly developed R package “HespDiv” which presents a range of functionalities for the determination of spatial structures/bioregions. The method uses fossil taxa distribution data to subdivide a provided territory into hierarchically related (each bioregion is a strict sub-set of larger bioregion) and topologically contiguous bioregional units. It produces split-lines which are used to subdivide bioregions. This subdivision can be done by employing linear or nonlinear divisor lines inside predetermined area polygons. In a latter case, the inferred bioregions can obtain more realistic shapes. The application of “HespDiv” method to Miocene fauna from the contiguous United States was performed in order to demonstrate the potential of the method. Morisita-Horn similarity index was used to measure differences between fossil taxa communities. The results revealed 25 distinct, topologically contiguous and hierarchically related bioregions had the structure dominated by longitudinal and diagonal boundaries, and the three most distinct bioregions were: West Coast, Central Plains and south-east US.

The numerical analyses of real world paleobiogeographical data with newly developed “HespDiv” method indeed show a high potential of the approach in objectively defining the hierarchical units of the Bretskyan hierarchy of (paleo)bioregions in sufficiently densely sampled regions and time bins.

Presented research is funded by project S-MIP-21-9 “The role of spatial structuring in major transitions in macroevolution”.

How to cite: Daumantas, L. and Spiridonov, A.: “HespDiv” method allows to quantify the dark matter of biosystems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11519, https://doi.org/10.5194/egusphere-egu23-11519, 2023.

X4.80

EGU23-12346

ECS

Do tree-rings match the low-frequency patterns represented in climate models?

Mara McPartland, Raphaël Hébert, and Thomas Laepple

Whether tree-rings faithfully archive the low-frequency variability (LFV) in climate remains debated. In theory, trees are fundamentally limited by being relatively short-lived and therefore unable to capture variations in the climate that are longer than their own lifespans. In addition, near universal practices of “detrending” tree-ring records to remove individualistic age-growth trends place further constraints on the amount of LFV that is maintained in final chronologies. Detrending methods designed to boost LFV may increase low-frequency signals, but how well those patterns reflect true variations in climate as opposed to long growth trends is still unclear. In this study, we first compared the spectral properties of the PAGES North America 2k dataset of temperature-sensitive tree-ring records against long temperature records to determine how much variability is retained in tree-rings after detrending, and how detrending method influences agreement in tree-ring power spectra across space. Then, we compare the spectral properties of tree-rings to the CMIP6 last millennium simulation to validate climate models against long proxy records. This research works to resolve discrepancies between temperature proxies and climate models on long timescales in order to improve our understanding of centennial-scale variability in the Earth’s climate system.

How to cite: McPartland, M., Hébert, R., and Laepple, T.: Do tree-rings match the low-frequency patterns represented in climate models?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12346, https://doi.org/10.5194/egusphere-egu23-12346, 2023.

X4.81

EGU23-17369

Spatial and temporal variations of the precipitation regime and trend of the last century in mainland Spain

Jose Carlos Gonzalez-Hidalgo, Victor Trullenque-Blanco, Dhais Peña-Angulo, and Santiago Beguería

The evolution of the seasonal rainfall regime and trend in mainland Spain (western Mediterranean basin) in the period 1916-2015 has been analyzed with the new high spatial resolution grid of the MOPREDAS_century (10 km²) database, included in CLICES project.

Seasonal rainfall regime changes have been analysed in mainland Spain. Comparison of the seasonal precipitation values in four different periods of 25 years in length were done. The spatial distribution of seasonal rainfall highlights a winter regime to the north and west, autumn to the eastern Mediterranean coastland, and spring predominates in between the aforementioned areas, but the analysis shows that the seasonal distribution of precipitation has undergone remarkable changes between 1916 and 2015. During the first 25 years’ period (1916-1940) winter predominates in 44% of grid, increasing to 55% in 1941-1965 and to 60% in 1966-1990 to decrease in the most recent period (1991-2015) to 38%; in the meantime, spring remain around 30% until 1991-2015 when decrease to 16%, and autumn, initially occupying 33%, decrease in the 2^nd and 3rth period to increase in the most recent ones to 50% of grid. These changes have been produce by the different behaviour of rainfall trends, particularly in spring (mostly related to march) and autumn (particularly October). Global spatial changes show the substitution of areas of winter regime by spring, and on the other hand spring substitution by autumn regime, but the analyses of detailed period discover a more complex pattern.

In general, the seasonal rainfall trend present changes throughout the analyzed period, with clear decreases in spring and increases in autumn in the final decades. However, the analysis of temporal scale allows us to observe that since the mid-1970s the seasonal precipitation trends are not statistically significant in the study area. The analysis in four periods of 25 years of the seasonal average values shows that the dominant seasonal regime of precipitations has undergone changes. Between 1916-2015, a replacement of the winter and spring regime for the autumn regime has been detected in extensive areas of the central western peninsular. The results are in line with previous analyzes carried out in the whole of the Mediterranean basin and especially in its western sector and suggest that they may be partly related to the variations in time of the NAO and WeMO atmospheric variability modes. Possible effects on natural systems and human activities are discussed, as a step prior to the adoption of mitigating measures.

The objectives and results obtained in the CLICES project are available on the website www.CLICES.unizar.es.

How to cite: Gonzalez-Hidalgo, J. C., Trullenque-Blanco, V., Peña-Angulo, D., and Beguería, S.: Spatial and temporal variations of the precipitation regime and trend of the last century in mainland Spain, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17369, https://doi.org/10.5194/egusphere-egu23-17369, 2023.

X4.83

EGU23-13323

Centennial to millennial climate variability across climate states; proxy reconstructions vs. transient model simulations.

Andrew M. Dolman, Marie Kapsch, Uwe Mikolajewicz, Lukas Jonkers, and Thomas Laepple

In previous model-data comparisons, the centennial to millennial scale variance of local climate (e.g., SST) reconstructed from proxies was significantly higher than that simulated by climate models. One possible explanation is the lack of long-term feedback mechanisms, e.g. from the representation of changes in ice-sheets in models. Additionally, proxy records are short, and sparse, and the climate signal is significantly modified during the processes of encoding, archiving, and recovery.

Here we introduce new methods to infer the climate variability of the past from proxy data and compare them to new transient model simulations of the last deglaciation. This will allow us to estimate the amplitude of climate variability and to evaluate whether climate models are capable of capturing changes in climate variability between different climate states (e.g. glacial vs. interglacial periods), which is also relevant for the accuracy of future projections. We compare the variability of marine d¹⁸O reconstructed from proxies with that simulated by a state-of-the-art Earth System Model.

From the proxy side, our analysis is based on a new dataset of marine oxygen isotope data from planktonic foraminifera compiled for the PALMOD project. We use new methods to first calculate power-spectra for the LGM, transition and Holocene and then to correct these spectra by fitting a Bayesian model describing the effects of bioturbation and measurement error on the reconstructed climate signal. From the model side we use marine d¹⁸O variability calculated using temperature and salinity from transient model simulations of the last deglaciation, performed within the PALMOD project, that include changes in the ice sheets.

This combination of new data and methods will allow us to investigate the effect of different ice-sheet configurations and physical parametrizations in the model on their ability to characterise long-timescale climate variability and its dependence on climate state.

How to cite: Dolman, A. M., Kapsch, M., Mikolajewicz, U., Jonkers, L., and Laepple, T.: Centennial to millennial climate variability across climate states; proxy reconstructions vs. transient model simulations., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13323, https://doi.org/10.5194/egusphere-egu23-13323, 2023.

X4.84

EGU23-11039

ECS

New Land- vs. Ocean based Global Mean Temperature Reconstructions reveal high consistency except for early 20th Century Ocean Cold Anomaly

Sebastian Sippel, Nicolai Meinshausen, Erich Fischer, Vincent Humphrey, Robert A. Rohde, Iris de Vries, and Reto Knutti

Global mean surface air temperature (GSAT) is a key diagnostic for understanding and constraining historical climate variability and change, and for climate policy. Yet, global temperature estimates (1) are usually based on blending sea surface temperatures (SST) with near-surface air temperature over land (LSAT), and (2) contain many missing values due to incomplete coverage in the historical record. While these issues are usually accounted for in model-observation comparisons, elucidating the consistency of LSAT and SST records, and their contribution to GSAT variability and change, remains difficult.

Here, we present a set of new GSAT reconstructions based separately on either the historical LSAT or SST record. The method is based on regularized linear regression models trained on climate model simulations to optimally predict GSAT from the climate model’s LSAT or SST patterns, respectively. We then predict GSAT from the HadSST4 and CRUTEM5 observational data, respectively, for each month from January 1850 up to December 2020.

We demonstrate that the land- or ocean based GSAT estimates show very similar variability and long-term changes, both in the early (1850-1900) as well as in the late record (post-1950). For example, GSAT of the past decade (2011-2020) increased by 1.15°C (LSAT-based) and 1.17°C (SST-based) relative to an early reference period (1850-1900), which is both well within IPCC AR6 estimates.However, the GSAT estimates show pronounced disagreement in the early 20th century (1900 up to around 1930), when the SST-based GSAT estimates appear on average around 0.3°C colder than the LSAT-based estimates. Decadal changes in the LSAT-based estimates are well explained by the multi-model mean of CMIP6 simulations driven with historical forcings, thus implying only a small role of unforced decadal global variability. In contrast, the SST-based estimate highlights pronounced variability during the early 20^thcentury cold anomaly, which may be related to concerns about instrumental cold biases in SST measurements, but overall reasons for the disagreement remain unclear. Further analysis based on physical reasoning, climate models, and proxy reconstructions, indicates that the ocean data may indeed be implausibly cold.

In conclusion, our methodology and results may help to constrain the magnitude of early 20th century warming, and thus to better understand and attribute decadal climate variability.

How to cite: Sippel, S., Meinshausen, N., Fischer, E., Humphrey, V., Rohde, R. A., de Vries, I., and Knutti, R.: New Land- vs. Ocean based Global Mean Temperature Reconstructions reveal high consistency except for early 20th Century Ocean Cold Anomaly, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11039, https://doi.org/10.5194/egusphere-egu23-11039, 2023.