scholarly journals Paleoenvironment of the Quilchena flora, British Columbia, during the Early Eocene Climatic Optimum

2016 ◽  
Vol 53 (6) ◽  
pp. 574-590 ◽  
Author(s):  
Rolf W. Mathewes ◽  
David R. Greenwood ◽  
S. Bruce Archibald
Keyword(s):  
British Columbia ◽  
Leaf Size ◽  
Climatic Conditions ◽  
Mean Annual Precipitation ◽  
Size Analysis ◽  
Mean Annual Temperature ◽  
Leaf Margin ◽  
Early Eocene ◽  
Early Eocene Climatic Optimum ◽  
Climatic Optimum

The Quilchena fossil locality is dated (51.5 ± 0.4 Ma) to the Early Eocene Climatic Optimum, and this locality is reconstructed as the warmest and wettest of the Early Eocene upland sites from the Okanagan Highlands of British Columbia and northern Washington State. Mean annual temperature (MAT) is estimated from leaf margin analysis, using 55 dicot morphotypes, as 16.2 ± 2.1 °C/14.6 ± 4.8 °C. Using bioclimatic analysis of 45 nearest living relatives, a moist mesothermal climate is indicated (MAT 12.7–16.6 °C; cold month mean temperature (CMMT) 3.5–7.9 °C; mean annual precipitation (MAP) 103–157 cm/year. Leaf size analysis estimates MAP at 121 ± 39 cm/year. Estimates from the climate leaf analysis multivariate program corroborate these results, although with a slightly cooler MAT (13.3 ± 2.1 °C). Plants that support an interpretation of warm winters with minimal or no frost include Azolla, Glyptostrobus, Taxodium, Keteleeria, Pseudolarix, Eucommia, Dipteronia, Hovenia, Ternstroemia, and others. These thermophilous elements occur together with temperate genera such as Alnus, Betula, Ulmus, Calocedrus, and Fraxinus. Palynological assemblages at Quilchena are dominated by bisaccate conifers and Cupressaceae. Common angiosperms include Ulmus type, triporates, Pterocarya, and Alnus. Insect fossils at Quilchena that today inhabit tropical and subtropical regions also support warm and equable climate without significant frost, and include obligate palm-feeding beetles (Pachymerina), which indicate CMMT perhaps as high as 8 °C. These are found together with temperate aphids, wasps, giant lacewings, brown lacewings, and a panorpoid scorpionfly, supporting an interpretation of equable climatic conditions during the Early Eocene Climatic Optimum.

Depositional setting, fossil flora, and paleoenvironment of the Early Eocene Falkland site, Okanagan Highlands, British Columbia

2009 ◽  
Vol 46 (11) ◽  
pp. 811-822 ◽  
Author(s):  
Robin Y. Smith ◽  
James F. Basinger ◽  
David R. Greenwood
Keyword(s):  
British Columbia ◽  
Climatic Conditions ◽  
Mean Annual Precipitation ◽  
Fossil Flora ◽  
Mean Annual Temperature ◽  
Leaf Margin ◽  
Early Eocene ◽  
Similarity Coefficients ◽  
Okanagan Highlands ◽  
Depositional Setting

The fossil flora and depositional setting of the Early Eocene Falkland site in the southern interior of British Columbia, Canada, is reported in detail for the first time, using a census sampling approach. The Falkland site is part of the series of Okanagan Highlands fossil localities in British Columbia and Washington State that represent relatively cool upland environments within the context of the greenhouse world of the Early Eocene, providing microthermal (mean annual temperature (MAT) < 13 °C) climatic conditions for the establishment of cool-adapted plants geographically adjacent to subtropical elements from lowland floras. Plant community composition of the Falkland flora is most similar to the Republic (Washington) and McAbee (British Columbia) floras based on high Sørenson similarity coefficients, together forming a southern cluster of Okanagan Highlands sites. The site is a lacustrine deposit that formed in a volcanically active landscape. Paleoclimate reconstructions based on leaf physiognomy characterize the site as microthermal (MAT 8.9 ± 2.0 °C by leaf margin analysis or 11.9 ± 2.0 °C by climate leaf analysis multivariate program (CLAMP)), mesic (mean annual precipitation (MAP) 114 [Formula: see text]cm/year), and equable (cold month mean temperature (CMMT) 3.0 ± 2.0 °C). Paleoelevation of the site is estimated to be similar to or slightly higher than modern levels (>1.3 km) during the Early Eocene. The Falkland locality adds new data to the temporal, latitudinal, and altitudinal gradients of the Okanagan Highlands series, reflecting the regional landscape of northwestern North America during the warmest period of the Cenozoic.

scholarly journals Paleoclimate and precipitation seasonality of the Early Eocene McAbee megaflora, Kamloops Group, British Columbia

2016 ◽  
Vol 53 (6) ◽  
pp. 591-604 ◽  
Author(s):  
Cale A.C. Gushulak ◽  
Christopher K. West ◽  
David R. Greenwood
Keyword(s):  
British Columbia ◽  
North American ◽  
Leaf Size ◽  
Early Eocene ◽  
Precipitation Seasonality ◽  
Two Samples ◽  
Fossil Site ◽  
Fossil Floras ◽  
Climate Analysis ◽  
Early Cenozoic

Early Eocene fossil floras from British Columbia are a rich resource for reconstructing western North American early Cenozoic climate. The best known of these floras reflect cooler (MAT ≤ 15 °C) upland forest communities in contrast to coeval (MAT ≥ 18 °C) forests in lowland western North American sites. Of particular interest is whether Early Eocene climates were monsoonal (highly seasonal precipitation). The McAbee site is a 52.9 ± 0.83 Ma 0.5 km outcrop of bedded lacustrine shale interbedded with volcanic ash. In this report two historical megaflora collections that were collected independently from different stratigraphic levels and (or) laterally separated by ∼100–200 m in the 1980s (University of Saskatchewan) and 2000s (Brandon University) are investigated to (i) assess whether they represent the same leaf population, (ii) assess whether a combined collection yields more precise climate estimates, and (iii) reconstruct paleoclimate to assess the character of regional Early Eocene precipitation seasonality. Combined, the two samples yielded 43 dicot leaf morphotypes. Analysis of leaf size distribution using ANOVA showed no difference between the two samples, and thus they were combined for climate analysis. Climate analysis using leaf physiognomy agrees with previous estimates for McAbee and other regional megafloras, indicating a warm (MAT ∼8–13 °C), mild (CMMT ∼5 °C), moist (MAP > 100 cm/year) ever-wet, non-monsoonal climate. Additionally, we recommend that climate analyses derived from leaf fossils should be based on samples collected within a stratigraphically constrained quarry area to capture a snapshot of climate in time rather than time-averaged estimates derived from multiple quarry sites representing different stratigraphic levels within a fossil site.

scholarly journals Temperature seasonality in the North American continental interior during the early Eocene climatic optimum

2018 ◽  
Author(s):  
Ethan G. Hyland ◽  
Katharine W. Huntington ◽  
Nathan D. Sheldon ◽  
Tammo Reichgelt
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Early Eocene ◽  
Early Eocene Climatic Optimum ◽  
The North ◽  
Annual Range ◽  
Climatic Optimum ◽  
Temperature Records ◽  
Model Ensembles ◽  
Continental Interior

Abstract. Paleogene greenhouse climate equability has long been a paradox in paleoclimate research. However, recent developments in proxy and modeling methods have suggested that strong seasonality may be a feature of at least some greenhouse periods. Here we present the first multi-proxy record of seasonal temperatures during the Paleogene from paleofloras, paleosol geochemistry, and carbonate clumped isotope thermometry in the Green River Basin (Wyoming, USA). These combined temperature records allow for the reconstruction of past seasonality in the continental interior, which shows that temperatures were warmer in all seasons during the peak early Eocene climatic optimum and that the mean annual range of temperature was high, similar to the modern value (~ 26 °C). Proxy data and downscaled Eocene regional climate model results suggest amplified seasonality during greenhouse events. Increased seasonality reconstructed for the early Eocene is similar in scope to the higher seasonal range predicted by downscaled climate model ensembles for future high-CO2 emissions scenarios. Overall, these data and model comparisons have substantial implications for understanding greenhouse climates in general, and may be important for predicting future seasonal climate regimes and their impacts in continental regions.

Exploring the possible meridional temperature gradient of Early Eocene Climatic Optimum with an energy balance model

2021 ◽  
Author(s):  
Fanni Dora Kelemen ◽  
Bodo Ahrens
Keyword(s):  
Energy Balance ◽  
Temperature Gradient ◽  
Entropy Production ◽  
Maximum Entropy ◽  
Early Eocene ◽  
Meridional Temperature Gradient ◽  
Proxy Data ◽  
Maximum Entropy Production ◽  
Early Eocene Climatic Optimum ◽  
Climatic Optimum

&lt;p&gt;Early Eocene Climatic Optimum (EECO, ~53-51 million years) is one of the past warm periods, associated with high CO&lt;sub&gt;2&lt;/sub&gt; concentrations (~900-2500 ppmv), which can serve as an analogue for our possible future, high C0&lt;sub&gt;2 &lt;/sub&gt;climate. One notable feature of this hothouse climate state is the weaker meridional temperature gradient relative to pre-industrial values. This have been confirmed by both proxies and models, but the extent of the temperature gradient still requires more research. Models are challenged to reproduce the stronger than present day polar amplification signal, and it is also shown that high latitude proxy data are often influenced by seasonal bias. Thus, there is an uncertainty regarding both the observed and modelled meridional gradient and the mentioned issues complicate also the comparison between modeled and proxy data.&lt;/p&gt;&lt;p&gt;In our work we aim to investigate the EECO period with a simple energy balance box model and apply the maximum entropy production principle to explore the possible scenarios of meridional temperature gradients. We find that the maximum entropy production principle could be beneficial in the paleoclimate context since it has the utility to give an accurate prediction for non-equilibrium systems with the minimal amount of information. We also assess the heat transport signaled by proxy data and by state-of-the-art model outputs in accordance to our theoretical constrains based on the idealized test case.&lt;/p&gt;

scholarly journals Stable isotope paleoclimatology of the earliest Eocene using kimberlite-hosted mummified wood from the Canadian Subarctic

2015 ◽  
Vol 12 (20) ◽  
pp. 5899-5914 ◽  
Author(s):  
B. A. Hook ◽  
J. Halfar ◽  
Z. Gedalof ◽  
J. Bollmann ◽  
D. J. Schulze
Keyword(s):  
Stable Isotopes ◽  
Tree Ring ◽  
Transfer Functions ◽  
Ring Width ◽  
Growth Patterns ◽  
The Arctic ◽  
Mean Annual Temperature ◽  
Leaf Margin ◽  
Early Eocene ◽  
Intrinsic Water Use Efficiency

Abstract. The recent discovery of well-preserved mummified wood buried within a subarctic kimberlite diamond mine prompted a paleoclimatic study of the early Eocene "hothouse" (ca. 53.3 Ma). At the time of kimberlite eruption, the Subarctic was warm and humid producing a temperate rainforest biome well north of the Arctic Circle. Previous studies have estimated that mean annual temperatures in this region were 4–20 °C in the early Eocene, using a variety of proxies including leaf margin analysis and stable isotopes (δ13C and δ18O) of fossil cellulose. Here, we examine stable isotopes of tree-ring cellulose at subannual- to annual-scale resolution, using the oldest viable cellulose found to date. We use mechanistic models and transfer functions to estimate earliest Eocene temperatures using mummified cellulose, which was well preserved in the kimberlite. Multiple samples of Piceoxylon wood within the kimberlite were crossdated by tree-ring width. Multiple proxies are used in combination to tease apart likely environmental factors influencing the tree physiology and growth in the unique extinct ecosystem of the Polar rainforest. Calculations of interannual variation in temperature over a multidecadal time-slice in the early Eocene are presented, with a mean annual temperature (MAT) estimate of 11.4 °C (1 σ = 1.8 °C) based on δ18O, which is 16 °C warmer than the current MAT of the area (−4.6 °C). Early Eocene atmospheric δ13C (δ13Catm) estimates were −5.5 (±0.7) ‰. Isotopic discrimination (Δ) and leaf intercellular pCO2 ratio (ci/ca) were similar to modern values (Δ = 18.7 ± 0.8 ‰; ci/ca = 0.63 ± 0.03 %), but intrinsic water use efficiency (Early Eocene iWUE = 211 ± 20 μmol mol−1) was over twice the level found in modern high-latitude trees. Dual-isotope spectral analysis suggests that multidecadal climate cycles somewhat similar to the modern Pacific Decadal Oscillation likely drove temperature and cloudiness trends on 20–30-year timescales, influencing photosynthetic productivity and tree growth patterns.

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