Marine rapid environmental/climatic change in the Cretaceous greenhouse world (original) (raw)
Special Topic: Cretaceous greenhouse palaeoclimate and sea-level changes
Science China Earth Sciences, 2016
Earth's climate has oscillated between greenhouse (warm) and icehouse (cold) modes throughout Earth history. At present, Earth is in the midst of an icehouse climate interval, despite the anthropogenic contribution to global warming and sea-level rise due to industrialization during the past two centuries. This led to a dramatic increase in atmospheric CO 2 , mainly caused by the extensive burning of fossils fuels. The Cretaceous (145 to 66 million years ago) is the youngest prolonged greenhouse climate interval in the Phanerozoic, marked by very high global mean temperatures with some extreme warming peaks ('hothouse' or 'supergreenhouse'), largely absence of permanent continental ice sheets, a mean global sea-level having been some 250 m higher than that of today, and levels of carbon dioxide 4 to 10 times higher than those of the pre-industrial era. If temperature will continue to rise as quickly as in the last three decades, we are close to being at the cusp to a new greenhouse climate interval facing quickly rising global sea-level and reaching atmospheric CO 2 levels of the 'Cretaceous supergreenhouse' in about the years 2190-2260 (Hay, 2011). Evidence from Earth's history indicates that glacial-interglacial climate mode changes as well as past sea-level changes such as in the Cretaceous greenhouse occurred at rates orders of magnitude slower than observed at present. The recent rise in global sea-level in response to rising levels of atmospheric greenhouse gases, the associated global warming, and the waning of continental ice shields is a primary concern for human society. To predict future sea-levels we need a better understanding of the record of past sea-level changes, especially in the greenhouse palaeoclimate modes. Therefore, understanding the Cretaceous palaeoclimate is essential for a more accurate prediction of future global climate, sea-level rise and environmental changes in a prospective 'Cretaceous-like' greenhouse Earth.
Geological Magazine, 1992
From the unique perspective of the geological record, it appears that the ' Greenhouse Earth' was a feature of climate for up to 80 % of the last 500 Ma, and that therefore our present glacially dominated climate is an anomaly. The Cretaceous in particular was a time of global warmth, an extreme greenhouse world apparently warmer than our current Earth. The geological record provides perspective and constraints against which the success of climate models can be evaluated. At present there are no ways of evaluating model predictions for the future of our ' Greenhouse Earth' until after the event. Retrodicting the past is therefore a very useful way of testing model sensitivity and robustness. The geological record tells us that the characteristics of the Cretaceous greenhouse world were a shallower equator-to-pole temperature gradient, shallow, well-stratified epicontinental seas with a tendency towards periodic dysaerobism, and a well-developed terrestrial flora extending to the high latitudes. Both marine and non-marine data show a global cooling trend throughout Late Cretaceous time, a trend that seems to correlate with declining atmospheric carbon dioxide.
Geophysical Research Letters, 2000
in temperature and precipitation due to the impact-related release of CO2. We evaluate the effects of these long-term changes in the global environment on terrestrial ecosystems using a vegetation-biogeochemistry model forced with a 'best guess' modified latest Cretaceous climate simulation by the GENESIS atmospheric general circulation model. The imposition of long-term global environmental changes after the K/T impact resulted in spatially heterogeneous increases in canopy leaf area index, net primary productivity, and soil carbon concentrations, relative to the latest Cretaceous preimpact situation. Terrestrial carbon storage increased by circa 2000 Gt. Model simulations of Cretaceous climates: the role of geography and carbon dioxide, Phil. Trans. R. Soc., B341, 307-316, 1993. Beerling, D.J., The influence of vegetation cover on soil organic matter preservation in Antarctica during the Mesozoic, Geophys. Res. Lett., 27, 253-256, 2000a. Beerling, D.J., Increased terrestrial carbon storage across the Paleocene-Eocene boundary, Palaeogeogr. Palaeoclimatol. Palaeoecol., 2000b. Beerling, D.J., Atmospheric carbon dioxide, past climates and the plant fossil record, Bot. d. Scot., 51, 49-68, 1998. Beerling, D.J., Woodward, F.I., Lomas, M., and Jenkins, A.J., Testing the responses of a dynamic global vegetation model to environmental change: a comparison of observations and predictions, Global Ecol. Biogeogr. Lett., 6, 439-450, 1997. Bemer, R.A., The carbon cycle and CO2 over Phanerozoic time: the role of land plants, Phil. Trans. R. Soc., B353, 75-82, 1998. Boersma, A., and Shackleton, N.J., Oxygen and carbon isotope variations and planktonic foraminfera depth habits, late Cretaceous to Paleocene. Init. Rep. Deep. Sea Drill. Prog., 62, 513-526, 1981. ., Oceanic primary productivity and dissolved oxygen levels at the Cretaceous/Tertiary boundary: their decrease, subsequent warming, and recovery, Paleoceanography, 14, 511-524, 1999. Kothavala, Z., Oglesby, R.J., and Saltzman, B., Sensitivity of equilibrium surface temperature of CCM3 to systematic changes in atmospheric CO2, Geophys. Res. Lett., 26, 209-212, 1999. Lehman, T.M., Paleosols and the Cretaceous/Tertiary transition in the Size and morphology of the Chicxulub impact crater, Nature, 153-156, 1990. Wolfe, J.A., and Upchurch, G.R., Vegetation, climatic and floral changes at the Cretaceous-Tertiary boundary, Nature, 324, 148-152, 1986. Woodward, F.I., Smith, T.M., and Emanuel, W.R., A global land primary productivity and phytogeography model, Global Biogeochem. Cycles, 9, 471-490, 1995. Zachos, J.C., Arthur, M.A., and Dean, W.E., Geochemical evidence for suppression of pelagic marine productivity at the Cretaceous/Tertiary boundary, Nature, 337, 61-64, 1989. Horrell, M.A., Phytogeography and paleoclimatic interpretation of San Marcos, Texas, TX 78666, USA the Maestrichtian, Palaeogeogr. Palaeoclimatol. Palaeoecol., B.L. Otto-Bliesner 86, 87-138, 1991.
Review: Short-term sea-level changes in a greenhouse world — A view from the Cretaceous
This review provides a synopsis of ongoing research and our understanding of the fundamentals of sea-level change today and in the geologic record, especially as illustrated by conditions and processes during the Cretaceous greenhouse climate episode. We give an overview of the state of the art of our understanding on eustatic (global) versus relative (regional) sea level, as well as long-term versus short-term fluctuations and their drivers. In the context of the focus of UNESCO-IUGS/IGCP project 609 on Cretaceous eustatic, short-term sea-level and climate changes, we evaluate the possible evidence for glacio-eustasy versus alternative or additional mechanisms for continental water storage and release for the Cretaceous greenhouse and hothouse phases during which the presence of larger continental ice shields is considered unlikely. Increasing evidence in the literature suggests a correlation between long-period orbital cycles and depositional cycles that reflect sea-level fluctuations, implying a globally synchronized forcing of (eustatic) sea level. Fourth-order depositional sequences seemto be related to a ~405 ka periodicity,whichmost likely represents long-period orbital eccentricity control on sea level and depositional cycles. Third-order cyclicity, expressed as time-synchronous sea level falls of ~20 to 110 m on ~0.5 to 3.0 Ma timescales in the Cretaceous, are increasingly recognized as connected to climate cycles triggered by longterm astronomical cycles that have periodicity ranging from ~1.0 to 2.4 Ma. Future perspectives of research on greenhouse sea-level changes comprise a high-precision time-scale for sequence stratigraphy and eustatic sealevel changes and high-resolution marine to non-marine stratigraphic correlation.
Southern high latitude climate variability in the Late Cretaceous greenhouse world
Global and Planetary Change v. 60, p. 351–364, 2008
A palynological study of oil exploration wells in the Gippsland Basin southeastern Australia has provided a record of southern high latitude climate variability for the last 12 million years of the Cretaceous greenhouse world. During this time, the vegetation was dominated by a cool to temperate flora of Podocarpaceae, Proteaceae and Nothofagidites spp. at a latitude of 60°S. Milankovitch forced cyclic alternations fromdrier towetter climatic periods caused vegetation variability from72 to 77Ma. This climate change was probably related to the waxing and waning of ephemeral (100 ky) small ice sheets in Antarctica during times of insolation minima and maxima. Drying and cooling after 72Ma culminated from 68 to 66Ma, mirroring trends in global δ18O data. Quantitative palynofloral analyses have the potential to provide realistic proxies for small-scale climate variability in the predominantly ice-free Late Cretaceous.
CO2 and temperature decoupling at the million-year scale during the Cretaceous Greenhouse
Scientific reports, 2017
CO2 is considered the main greenhouse gas involved in the current global warming and the primary driver of temperature throughout Earth's history. However, the soundness of this relationship across time scales and during different climate states of the Earth remains uncertain. Here we explore how CO2 and temperature are related in the framework of a Greenhouse climate state of the Earth. We reconstruct the long-term evolution of atmospheric CO2 concentration (pCO2) throughout the Cretaceous from the carbon isotope compositions of the fossil conifer Frenelopsis. We show that pCO2 was in the range of ca. 150-650 ppm during the Barremian-Santonian interval, far less than what is usually considered for the mid Cretaceous. Comparison with available temperature records suggest that although CO2 may have been a main driver of temperature and primary production at kyr or smaller scales, it was a long-term consequence of the climate-biological system, being decoupled or even showing inve...
Proceedings of The National Academy of Sciences, 2003
Terrestrial climates near the time of the end-Cretaceous mass extinction are poorly known, limiting understanding of environmentally driven changes in biodiversity that occurred before bolide impact. We estimate paleotemperatures for the last Ϸ1.1 million years of the Cretaceous (Ϸ66.6 -65.5 million years ago, Ma) by using fossil plants from North Dakota and employ paleomagnetic stratigraphy to correlate the results to foraminiferal paleoclimatic data from four middle-and high-latitude sites. Both plants and foraminifera indicate warming near 66.0 Ma, a warming peak from Ϸ65.8 to 65.6 Ma, and cooling near 65.6 Ma, suggesting that these were global climate shifts. The warming peak coincides with the immigration of a thermophilic flora, maximum plant diversity, and the poleward range expansion of thermophilic foraminifera. Plant data indicate the continuation of relatively cool temperatures across the Cretaceous-Paleogene boundary; there is no indication of a major warming immediately after the boundary as previously reported. Our temperature proxies correspond well with recent pCO2 data from paleosol carbonate, suggesting a coupling of pCO2 and temperature. To the extent that biodiversity is correlated with temperature, estimates of the severity of end-Cretaceous extinctions that are based on occurrence data from the warming peak are probably inflated, as we illustrate for North Dakota plants. However, our analysis of climate and facies considerations shows that the effects of bolide impact should be regarded as the most significant contributor to these plant extinctions.
Vegetation-atmosphere interactions and their role in global warming during the latest Cretaceous
1998
Forest vegetation has the ability to warm Recent climate by its e¡ects on albedo and atmospheric water vapour, but the role of vegetation in warming climates of the geologic past is poorly understood. This study evaluates the role of forest vegetation in maintaining warm climates of the Late Cretaceous by (1) reconstructing global palaeovegetation for the latest Cretaceous (Maastrichtian); (2) modelling latest Cretaceous climate under unvegetated conditions and di¡erent distributions of palaeovegetation; and (3) comparing model output with a global database of palaeoclimatic indicators. Simulation of Maastrichtian climate with the land surface coded as bare soil produces high-latitude temperatures that are too cold to explain the documented palaeogeographic distribution of forest and woodland vegetation. In contrast, simulations that include forest vegetation at high latitudes show signi¢cantly warmer temperatures that are su¤cient to explain the widespread geographic distribution of high-latitude deciduous forests. These warmer temperatures result from decreased albedo and feedbacks between the land surface and adjacent oceans. Prescribing a realistic distribution of palaeovegetation in model simulations produces the best agreement between simulated climate and the geologic record of palaeoclimatic indicators. Positive feedbacks between high-latitude forests, the atmosphere, and ocean contributed signi¢cantly to high-latitude warming during the latest Cretaceous, and imply that high-latitude forest vegetation was an important source of polar warmth during other warm periods of geologic history.