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Global annual mean temperature variation of the Earth through time (last 400 million years) predicted by the Hadley Centre Coupled Climate Model version 3 (HadCM3), compared with geologically derived estimates of temperature variability over the same period [the Royer et al. 2004 temperature record, the Zachos et al. 2008; Lisiecki and Raymo 2005 benthic oxygen isotope stack, as well as the EPICA and NGRIP ice core records; Jouzel et al. 2007 and NGRIP Members 2004. Geological epochs include the Devonian (D), Carbon-
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In modern environmental and climate science it is necessary to assimilate observational datasets collected over decades with outputs from numerical models, to enable a full understanding of natural systems and their sensitivities. During the twentieth and twenty-first centuries, numerical modelling became central to many areas of science from the B...
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... use of models to understand the evolution of our planet's climate, environment and life ( Fig. 1), collectively known as past (palaeo) climate modelling, has matured in its capacity and capability since the first simulations using a General Circulation Model (GCM) were published in the 1970s for the Last Glacial Maximum (e.g., Gates 1976). Since then it has become apparent that to fully appreciate the complex interactions between ...
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The cryosphere, which comprises a large portion of Earth’s surface, is rapidly changing as a consequence of global climate change. Ice, snow, and frozen ground in the polar and alpine regions of the planet are known to directly impact atmospheric composition, which for example is observed in the large influence of ice and snow on polar boundary lay...
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... Biome delineation is both less exact and more complex than our models suggest, with some biomes occupying a range of environmental conditions, and groupings of environmental conditions being associated with multiple biomes [2,3]. It is also not well understood how historical contingency can play a role in determining biomes [3,11,64]. Further, disturbances such as herbivorous grazing and fires can 'consume' existing vegetation, accelerating the realization of a new biome [3], while in some cases, anthropogenic changes in fire regimes, whether via hunting-gathering or agriculture, have been found to increase or maintain open woodland and savannah biomes [65]. Gaining more knowledge on how biome transitions take place, and the timescales on which they occur, is an important next step in validating our model projections. ...
Most emissions scenarios suggest temperature and precipitation regimes will change dramatically across the globe over the next 500 years. These changes will have large impacts on the biosphere, with species forced to migrate to follow their preferred environmental conditions, therefore moving and fragmenting ecosystems. However, most projections of the impacts of climate change only reach 2100, limiting our understanding of the temporal scope of climate impacts, and potentially impeding suitable adaptive action. To address this data gap, we model future climate change every 20 years from 2000 to 2500 CE, under different CO2 emissions scenarios, using a general circulation model. We then apply a biome model to these modelled climate futures, to investigate shifts in climatic forcing on vegetation worldwide, the feasibility of the migration required to enact these modelled vegetation changes, and potential overlap with human land use based on modern-day anthromes. Under a business-as-usual scenario, up to 40% of terrestrial area is expected to be suited to a different biome by 2500. Cold-adapted biomes, particularly boreal forest and dry tundra, are predicted to experience the greatest losses of suitable area. Without mitigation, these changes could have severe consequences both for global biodiversity and the provision of ecosystem services.
This article is part of the theme issue ‘Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere’.
... Paleontological models are also beginning to estimate rates of diversification regionally (96)(97)(98), with more work needed to develop our understanding of how spatial bias may affect rate parameters. Simulation models, such as mechanistic spatial algorithms, provide a new avenue to elucidate rate variation regionally over Earth history (15,(99)(100)(101), especially when forced with realistic estimates of how climate, continents, and topography have changed spatially and temporally over time (102). Even without realistic forcers, spatial models may provide null expectations for rate variation in silico (15). ...
The latitudinal diversity gradient (LDG) describes the pattern of increasing numbers of species from the poles to the equator. Although recognized for over 200 years, the mechanisms responsible for the largest-scale and longest-known pattern in macroecology are still actively debated. I argue here that any explanation for the LDG must invoke differential rates of speciation, extinction, extirpation, or dispersal. These processes themselves may be governed by numerous abiotic or biotic factors. Hypotheses that claim not to invoke differential rates, such as 'age and area' or 'time for diversification', eschew focus from rate variation that is assumed by these explanations. There is still significant uncertainty in how rates of speciation, extinction, extirpation, and dispersal have varied regionally over Earth history. However, to better understand the development of LDGs, we need to better constrain this variation. Only then will the drivers of such rate variation - be they abiotic or biotic in nature - become clearer.
... Data from these geological archives for times representing higher-than-present CO 2 worlds have been widely used in Climate Model Intercomparison Projects (CMIPs) to assess the performance of transient GCMs run to equilibrium (e.g. Haywood et al., 2019;Masson-Delmotte et al., 2013). While most CMIPs reconcile global mean temperatures, they poorly reconcile regional climatic patterns such as polar amplification (Naish and Zwartz, 2012;Haywood et al., 2019;Masson-Delmotte et al., 2013;Fischer et al., 2018). ...
... Haywood et al., 2019;Masson-Delmotte et al., 2013). While most CMIPs reconcile global mean temperatures, they poorly reconcile regional climatic patterns such as polar amplification (Naish and Zwartz, 2012;Haywood et al., 2019;Masson-Delmotte et al., 2013;Fischer et al., 2018). This is in part due to the incomplete spatial coverage of the geological data, accuracy and quality of the data, the resolution of GCM grids and their treatment of mid-to high-latitude polar processes. ...
... Such a rise in global sea level implies melting of the Greenland Ice Sheet (Koenig et al., 2015;Batchelor et al., 2019), West Antarctic Ice Sheet (Naish et al., 2009;McKay et al., 2012) and parts of the marine-based East Antarctic Ice Sheet (Cook et al., 2013;Patterson et al., 2014;Bertram et al., 2018). Therefore, the interglacial periods of mPWP are considered to be the most accessible and suitable past analogue, or window, into the future equilibrium response of the Earth system to warming in line with SSP2-4.5 (Naish and Zwartz, 2012;Dowsett et al., 2013;Haywood et al., 2019). Location map for sites used in the south-west Pacific SST reconstruction (north: top of page). ...
Based on Nationally Determined Contributions concurrent with Shared Socioeconomic Pathways (SSPs) 2-4.5, the IPCC predicts global warming of 2.1–3.5 ∘C (very likely range 10–90th percentile) by 2100 CE. However, global average temperature is a poor indicator of regional warming and global climate models (GCMs) require validation with instrumental or proxy data from geological archives to assess their ability to simulate regional ocean and atmospheric circulation, and thus, to evaluate their performance for regional climate projections. The south-west Pacific is a region that performs poorly when GCMs are evaluated against instrumental observations. The New Zealand Earth System Model (NZESM) was developed from the United Kingdom Earth System Model (UKESM) to better understand south-west Pacific response to global change, by including a nested ocean grid in the south-west Pacific with 80 % greater horizontal resolution than the global-scale host. Here, we reconstruct regional south-west Pacific sea-surface temperatures (SSTs) for the mid-Pliocene warm period (mPWP; 3.3–3.0 Ma), which has been widely considered a past analogue with an equilibrium surface temperature response of +3 ∘C to an atmospheric CO2 concentration of ∼350–400 ppm, in order to assess the warming distribution in the south-west Pacific. This study presents proxy SSTs from seven deep sea sediment cores distributed across the south-west Pacific. Our reconstructed SSTs are derived from molecular biomarkers preserved in the sediment – alkenones (i.e. U37K′ index) and isoprenoid glycerol dialkyl glycerol tetraethers (i.e. TEX86 index) – and are compared with SSTs reconstructed from the Last Interglacial (125 ka), Pliocene Model Intercomparison Project (PlioMIP) outputs and transient climate model projections (NZESM and UKESM) of low- to high-range SSPs for 2090–2099 CE. Mean interglacial equilibrium SSTs during the mPWP for the south-west Pacific sites were on average 4.2 ∘C (1.8–6.1 ∘C likely range) above pre-industrial temperatures and show good agreement with model outputs from NZESM and UKESM under mid-range SSP 2–4.6 conditions. These results highlight that not only is the mPWP an appropriate analogue when considering future temperature change in the centuries to come, but they also demonstrate that the south-west Pacific region will experience warming that exceeds that of the global mean if atmospheric CO2 remains above 350 ppm.
... However, to arrive at common balance point of 37°C, an environmental assumption is required since as already indicated, homeothermy is dependent on the temperature of the organism being sufficiently higher than the surrounding temperature. Figure 2 depicts the temperature anomaly modelling from various sources dating back to 400 million years and up to the prediction for 2100 [20]. Since current evidence indicates that the most important evolutionary split occurred between primates with wet and dry noses during the Eocene (~40 million years ago), homeothermy must have developed during this epoch [21][22][23]. ...
The relationship between living things and their respective environments highly dependent on body temperature regulation. The human capacity to effectively thermoregulate evolved at a time when the environmental temperature was likely around 25°C during the Eocene epoch, some ~ 50-60 million years ago. This effectively meant that homeothermy settled on a core temperature balance point of ~ 37°C. When Homo split from chimpanzee around 5 million years ago the Earth was entering a cooling period where the balance point temperature was always well above that of the environment and body heat balance could be maintained. Following this cooling period, the Earth’s rewarming by 7 °C took over approximately 5,000 years, whereas the current estimates indicate 0.7 °C over the past 100 years; ten times the rate of ice-age-recovery warming, or 20 times faster compared with the last 2 million years. As such, if the predicted continued rise in global temperature continues, and surface temperature reaches values where heat load cannot be dumped as the body temperature balance point is at or near the environmental temperature, areas of the Earth would become inhospitable. This effectively means that we will need to deal with both physiological and behavioral limitations since our ability to adapt will be limited by a thermoregulatory strategy that evolved over millions of years for a different kind of environment, not one that is predicted to change rapidly over the next century. This paper outlines the basis on which Homo settled on a thermoregulatory balance point and what limitations this presents for us in the future.
... A basic understanding of the timing and magnitude of natural variability of tropical rainfall in the past is critical to place present trends in context and to validate climate model performance 1 . Much of modern society directly or indirectly relies on the consistency of seasonal rains for agriculture in tropical monsoon settings 2,3 . ...
Speleothem δ¹⁸O is widely used as a proxy for rainfall amount in the tropics on glacial-interglacial to interannual scales. However, uncertainties in the interpretation of this renowned proxy pose a vexing problem in tropical paleoclimatology. Here, we present paired multi-proxy geochemical measurements for stalagmites from southwest Sulawesi, Indonesia, and confirm changes in rainfall amount across ice age terminations. Collectively, the stalagmites span two glacial-interglacial transitions from ~380,000 to 330,000 and 230,000 to 170,000 years ago. Mg/Ca in the slow-growing stalagmites is affected by water moving through the karst and prior calcite precipitation, making it a good proxy for changes in local rainfall. When paired, Mg/Ca and δ¹⁸O corroborate prominent shifts from drier glacials to wetter interglacials in the core of the Australasian monsoon domain. These shifts in rainfall occur 4,000-7,000 years later than glacial-interglacial increases in global temperature and the associated response of Sulawesi vegetation, determined by speleothem δ¹³C.
... Environmental reconstructions based on the proxy data play a central role to validate and improve the ability of climate models to simulate past, present, and future climate change. Luckily, as the number of high-resolution proxy data increases, combined model-data interpretations of the climate system became more accurate [14]. However, a special knowledge on the ecological tolerances of the considered species is required to reasonably estimate the paleotemperatures. ...
In this study, the compiled malacological record of the two most important loess-palaeo-sol sequences (LPS) in Serbia was used to reconstruct the Malacothermometer July Paleotempera-ture (MTJP) of the last nine glacials. The sieved loess samples yielded shells of 11 terrestrial gastro-pod species that were used to estimate the MTJP. Veliki Surduk (covering the last three glacial cycles) and Stari Slankamen (covering the last fourth to ninth glacial cycle) LPSs previously lacked the malacological investigations. After the sieving, a total of 66,871 shells were found, from which 48,459 shells were used for the estimation of the MTJP. Through the studied period, the reconstructed MTJP was ranging from 14.4 °C to 21.5 °C. The lowest temperature was recorded during the formation of the loess unit L5, equivalent to the Marine Isotope Stage (MIS) 12. The second-coldest summers were occurring during the MIS 16 glacial. Although the warmest glacial was L8 (MIS 20) according to MTJP, these July temperatures might be overestimated due to only two samples from the poorly preserved L8 unit. The malacological material derived from the loess units at Veliki Sur-duk and Stari Slankamen LPSs showed great potential for July temperature reconstruction, as the comparison with other regional records showed similar climate changes. Further work is necessary to validate the age scale of the oldest samples, and a higher resolution sampling could lead to more detailed July temperature fluctuations, as was shown for the youngest glacial in this study. Likewise, estimating the July temperature using different proxies (e.g., pollen) from the same LPSs could be used to confirm the observed climate trends.
... This brings the need for a methodology to physically interpolate them at a regional scale. In this view, climate modelling is a complementary approach that is both flexible in terms of spatial and temporal variability, and can be adapted to a wide range of studies (Haywood et al 2019). Data and models play a complementary role in understanding climate change. ...
... The forward approach implies modelling of observables (e.g. biomes, oxygen isotopes of water and air) directly within the climate model (Haywood et al 2019). During the inverse approach, proxies are processed to reconstruct physical climatic variables, analogous to typical climate model outputs (Haywood et al 2019). ...
... biomes, oxygen isotopes of water and air) directly within the climate model (Haywood et al 2019). During the inverse approach, proxies are processed to reconstruct physical climatic variables, analogous to typical climate model outputs (Haywood et al 2019). For example, applying reverse vegetation modelling or statistical modelling approaches (e.g. ...
Climate model simulations are inherently biased. It is a notably difficult problem when dealing with climate impact assessments and model-data integration. This is especially true when looking at derived quantities such as biomes, where not only climate but also vegetation dynamics biases come into play. To overcome such difficulties, we evaluate the performance of an existing methodology to correct climate model outputs, applied here for the first time to long past climate conditions. The proposed methodology relies on the “Cumulative Distribution Function - transform” (CDF-t) technique, which allows to account for climate change within the bias-correction procedure. The results are evaluated in two independent ways: i- using forward modelling, so that model results are directly comparable to reconstructed vegetation distribution; ii- using climatic reconstructions based on an inverse modelling approach. The modelling is performed using the intermediate complexity model iLOVECLIM in the standard global and interactively downscaled over the Europe version. The combined effects of dynamical downscaling and bias correction resulted in significantly stronger agreement between the simulated results and pollen-based biome reconstructions (BIOME6000) for the pre-industrial (0.18 versus 0.44) and mid-Holocene (0.31 versus 0.40). Higher correlation is also observed between statistically modelled global gridded potential natural distribution and modelled biomes (0.36 versus 0.41). Similarly, we find higher correlation between the reconstructed and the modelled temperatures for the mid-Holocene (0.02 versus 0.21). No significant difference is found for the Last Glacial Maximum when using temperature reconstructions, due to the low number of data points available. Our findings show that the application of the CDF-t method on simulated climate variables enables us to simulate palaeoclimate and vegetation distribution in better agreement with independent reconstructions.
... Since the Cretaceous shares many similarities with the modern world, understanding of this part of the Earth's history could be significant for developing dynamic models of the globe (Haywood et al., 2019;Tierney et al., 2020). This understanding demands the reconstruction of critical data such as past depositional environments. ...
A study on depositional environment, diagenetic history, and sequence stratigraphy of the upper Cretaceous successions of the boundary between the Central and Eastern Alborz zones is lacking. This study attempts to tackle this issue by analyzing a succession composed of 120 meters of medium- to thick-bedded limestones. Facies analysis led to the identification of facies associations of terrestrial, inner ramp (proximal, mid, and distal lagoon and shoal), mid ramp, outer ramp, and basin settings. According to the lateral and vertical changes in facies associations indicating gradual facies variations and the absence of large barrier reef organisms, a carbonate platform of ramp type with a bioclastic shoal is suggested for the studied succession. However, regarding the presence of turbidites in the transition of mid and outer ramp facies, a distally steepened ramp better suits the studied succession. Diagenetic study reveals products of eogenesis, mesogenesis, and telogenesis stages. Sequence stratigraphic analysis based on facies analysis and field observation denoted one 3rd-order depositional sequence, which its maximum flooding surface is equivalent to MFS K180 of the Arabian Plate (AP) with middle Maastrichtian age. A disconformity at the topmost of the studied succession correlates with the upper sequence boundary of megasequence AP9 around the Cretaceous–Paleogene boundary.
... Today, one of the main focuses of climate research is on understanding how future increases in atmospheric carbon dioxide concentrations will influence temperature and general climate conditions (Haywood et al. 2019;Lunt et al. 2009). In this context, studies in the field of palaeoclimatology are looking closely at past warm periods, when CO 2 concentrations were analogous to current levels and those projected for the near future (Haywood et al. 2019). ...
... Today, one of the main focuses of climate research is on understanding how future increases in atmospheric carbon dioxide concentrations will influence temperature and general climate conditions (Haywood et al. 2019;Lunt et al. 2009). In this context, studies in the field of palaeoclimatology are looking closely at past warm periods, when CO 2 concentrations were analogous to current levels and those projected for the near future (Haywood et al. 2019). In this regard, the warm Pliocene climate is of great interest due to its similarity with the modelling predictions made for the future environment. ...
... Though these studies share the same goal, the methods and data that they have employed differed. These investigations can be grouped into one modelling and two proxy-based categories: 1) computer simulations of global paleoclimate (e.g., Huber, 2012;Valdes et al., 2017;Haywood et al., 2019;Valdes et al., 2021), 2) quantitative reconstructions of climate parameters using various isotopic and molecular systems (e.g., δ 18 O, clumped isotopes, and TEX 86 ; Royer et al., 2004;Grossman, 2012aGrossman, , 2012bVeizer and Prokoph, 2015;O'Brien et al., 2017;Song et al., 2019;Vérard and Veizer, 2019;Grossman andJoachimski, 2020, 2022), and 3) censored climate estimates from geological and paleontological proxies (Wegener, 1912a(Wegener, , 1912b(Wegener, , 1915Du Toit, 1937;Frakes, 1979;Habicht, 1979;Frakes et al., 1992;Parrish et al., 1982;Sellwood and Price, 1994;Parrish, 1998;Ziegler et al., 1985;Boucot et al., 2013;Cao et al., 2019). Here the term "censored" refers to truncated or limited observations where the value is only partially known (e.g., "greater than 30 • C" or "<500 mm yr − 1 ). ...
