Archives de catégorie : climate and geology

Molecular fossils from phytoplankton reveal secular Pco2 trend over the Phanerozoic

by C.R. Witkowski et al., November28,  2018 in SciAdvances


Here, we reconstructed Phanerozoic PCO2 from a single proxy: the stable carbon isotopic fractionation associated with photosynthesis (Ɛp) that increases as PCO2 increases. This concept has been widely applied to alkenones, but here, we expand this concept both spatially and temporally by applying it to all marine phytoplankton via a diagenetic product of chlorophyll, phytane. We obtained data from 306 marine sediments and oils, which showed that Ɛp ranges from 11 to 24‰, agreeing with the observed range of maximum fractionation of Rubisco (i.e., 25 to 28‰). The observed secular PCO2 trend derived from phytane-based Ɛp mirrors the available compilations of PCO2over the past 420 Ma, except for two periods in which our higher estimates agree with the warm climate during those time periods. Our record currently provides the longest secular trend in PCO2 based on a single marine proxy, covering the past 500 Ma of Earth history

Fig. 2Ɛp calculated from phytane in Witkowski et al., 2018

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Human ancestors not to blame for ancient mammal extinctions in Africa

by University of Utah, November23, 2018 in ScienceDaily


New research disputes a long-held view that our earliest tool-bearing ancestors contributed to the demise of large mammals in Africa over the last several million years. Instead, the researchers argue that long-term environmental change drove the extinctions, mainly in the form of grassland expansion likely caused by falling atmospheric carbon dioxide (CO2) levels.

The study is published today in the journal Science.

“Despite decades of literature asserting that early hominins impacted ancient African faunas, there have been few attempts to actually test this scenario or to explore alternatives,” Faith says. “We think our study is a major step towards understanding the depth of anthropogenic impacts on large mammal communities, and provides a convincing counter-argument to these long-held views about our early ancestors.”

To test for ancient hominin impacts, the researchers compiled a seven-million-year record of herbivore extinctions in eastern Africa, focusing on the very largest species, the so-called ‘megaherbivores’ (species over 2,000 lbs.) Though only five megaherbivores exist in Africa today, there was a much greater diversity in the past. For example, three-million-year-old ‘Lucy’ (Australopithecus afarensis) shared her woodland landscape with three giraffes, two rhinos, a hippo, and four elephant-like species at Hadar, Ethiopia.

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Volcanoes and glaciers combine as powerful methane producers

by Lancaster University, November 20, 2018 in ScienceDaily


The Lancaster university-led research, which is featured in Scientific Reports, is the first published field study to show methane release from glaciers on this scale.

“This is a huge amount of methane lost from the glacial meltwater stream into the atmosphere,” said Dr Peter Wynn, a glacial biogeochemist from the Lancaster Environment Centre and corresponding author of the study. “It greatly exceeds average methane loss from non-glacial rivers to the atmosphere reported in the scientific literature. It rivals some of the world’s most methane-producing wetlands; and represents more than twenty times the known methane emissions of all Europe’s other volcanoes put together.”

‘True polar wander’ may have caused ice age

by Rice University, November 19, 2018 in ScienceDaily


Their study in the journal Geophysical Research Letters is based on an analysis of fossil signatures from deep ocean sediments, the magnetic signature of oceanic crust and the position of the mantle “hot spot” that created the Hawaiian Islands. Co-authors Richard Gordon and Daniel Woodworth said the evidence suggests Earth spun steadily for millions of years before shifting relative to its spin axis, an effect geophysicists refer to as “true polar wander.”

“The Hawaiian hot spot was fixed, relative to the spin axis, from about 48 million years ago to about 12 million years ago, but it was fixed at a latitude farther north than we find it today,” said Woodworth, a graduate student in Rice’s Department of Earth, Environmental and Planetary Sciences. “By comparing the Hawaiian hot spot to the rest of the Earth, we can see that that shift in location was reflected in the rest of the Earth and is superimposed on the motion of tectonic plates. That tells us that the entire Earth moved, relative to the spin axis, which we interpret to be true polar wander.”

Paleoclimatological Context and Reference Level of the 2°C and 1.5°C Paris Agreement Long-Term Temperature Limits

by S. Lüning & F. Vahrenholt, December12, 2017 in FrontEarthSci


The Paris Agreement adopted in December 2015 during the COP21 conference stipulates that the increase in the global average temperature is to be kept well below 2°C above “pre-industrial levels” and that efforts are pursued to limit the temperature increase to 1.5°C above “pre-industrial levels.” In order to further increase public acceptance of these limits it is important to transparently place the target levels and their baselines in a paleoclimatic context of the past 150,000 years (Last Interglacial, LIG) and in particular of the last 10,000 years (Holocene; Present Interglacial, PIG). Intense paleoclimatological research of the past decade has firmed up that pre-industrial temperatures have been highly variable which needs to be reflected in the pre-industrial climate baseline definitions …

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Discovery Of Massive Volcanic CO2 Emissions Puts Damper On Global Warming Theory

by J.E. Kamis, November 6, 2018 in ClimateChangeDispatch


Recent research shows that the volume of volcanic CO2 currently being emitted into Earth’s atmosphere is far greater than previously calculated, challenging the validity of the man-made global warming theory.

he cornerstone principle of the global warming theory, anthropogenic global warming (AGW), is built on the premise that significant increases of modern era human-induced CO2 emissions have acted to unnaturally warm Earth’s atmosphere.

A warmed atmosphere that directly, or in some cases indirectly fuels anomalous environmental disasters such as ocean warming, alteration of ocean chemistry, polar ice sheet melting, global sea level rise, coral bleaching and most importantly dramatic changes in climate.

There are numerous major problems with the AGW principle.

Identification of Volcanic vs. Man-made CO2

Solar forcing and climate variability during the past millennium as recorded in a high altitude lake: Lake Salda (SW Anatolia)

by I.B. Bauhi & S. Akçer-Ön, August 30, 2018 in QuaternaryInternational


Abstract

Climate variability is a well-known phenomenon and has been frequently, though complex, linked to solar forcing on different time scales. The importance of solar forcing related climate variability is crucial in our understanding of paleoclimate and future climate changes, as well as building climate models. Here in, we present the late Holocene (last ca 1400) climate records from Lake Salda in SW Anatolia using high-resolution micro X-ray Fluorescence (μ-XRF), magnetic susceptibility (MS), stable isotopes13C and δ18O) and TOC-TIC measurements. The age model is constructed by using radionuclide (210Pb, 137Cs and 14C) dating methods. The lake’s high-resolution multiproxy results revealed lake water level fluctuations associated with humid and dry spells during the last 1400 years. Periods of higher lake levels are consistent with solar maxima in total solar irradiance and vice versa. Moreover, the Lake Salda records clearly show dry Dark Ages Cold Period (DACP), humid Medieval Climatic Anomaly (MCA), dry Little Ice Age (LIA), and humid Modern Warm Period (MoWP). These records suggest that the solar forcing, through its influence on the atmospheric circulation, is the main mechanism of climate change during the DACP, MCA, LIA and MoWP in this region.

500 Million Years of Unrelatedness between Atmospheric CO2 and Temperature

by Davis W.J., 2017 in CO2Science


Davis, W.J. 2017. The relationship between atmospheric carbon dioxide concentration and global temperature for the last 425 million years. Climate 5: 76; doi: 10.3390/cli5040076.

Writing by way of introduction to his work, Davis (2017) notes that “a central question for contemporary climate policy is how much of the observed global warming is attributable to the accumulation of atmospheric CO2 and other trace greenhouse gases emitted by human activities.” If you talk to a climate alarmist, the answer you receive from such an inquiry will likely be “almost all.” A climate skeptic, on the other hand, will likely respond that the answer is “likely none.”

Hoping to provide some crucial information on this topic, Davis analyzed the relationship between historic temperature and atmospheric CO2 using the most comprehensive assemblage of empirical databases of these two variables available for the Phanerozoic period (522 to 0 million years before present; Mybp). In all, 6680 proxy temperature and 831 proxy CO2 measurements were utilized, enabling what Davis described as “the most accurate quantitative empirical evaluation to date of the relationship between atmospheric CO2concentration and temperature.” Multiple statistical procedures and analyses were applied to the proxy records and the resultant relationship is depicted in the figure below.

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Study: climate was more variable during the last inter-glacial period

by Anthony Watts, October 12, 2018 in WUWT


Century-scale climate variability was enhanced when the Earth was warmer during the Last Interglacial period (129-116 thousand years ago) compared to the current interglacial (the last 11,700 years), according to a new UCL-led study.

The findings, published today in Nature Communications and funded by the Natural Environment Research Council (NERC) and the Australian Research Council (ARC), reveal that the Last Interglacial period was punctuated by a series of century-scale arid events in southern Europe and cold water-mass expansions in the North Atlantic.

Addressing on Abrupt Global Warming, Warming Trend Slowdown and Related Features in Recent Decades

by Indriani Roy, September28,  2018 in FrontiersinEarthScience


  • College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, United Kingdom

The puzzle of recent global warming trend slowdown has captured enough attention, though the underlying cause is still unexplained. This study addresses that area segregating the role of natural factors (the sun and volcano) to that from CO2 led linear anthropogenic contributions. It separates out a period 1976–1996 that covers two full solar cycles, where two explosive volcanos erupted during active phases of strong solar cycles. The similar period also matched the duration of abrupt global warming. It identifies that dominance of Central Pacific (CP) ENSO and associated water vapor feedback during that period play an important role. The possible mechanism could be initiated via a preferential alignment of NAO phase, generated by explosive volcanos. Inciting extratropical Rossby wave to influence the Aleutian Low, it has a modulating effect on CP ENSO. Disruption of Indian Summer Monsoon and ENSO during the abrupt warming period and a subsequent recovery thereafter can also be explained from that angle. Interestingly, CMIP5 model ensemble, and also individual models, fails to comply with such observation. It also explores possible areas where models miss important contributions due to natural drivers.

Geologists: No Link Between Climate Warming And Rock Slides in European Alps!

by P. Gosselin, September 23, 2018 in NoTricksZone


Last year, August, 2017, a massive rockslide occurred on the north flank of the Piz Cengalo (3369 m) in the Swiss Alps, above the village of Bondo, located near the border to Italy.

No data suggesting warming is behind rock slides

In total some 4 million tonnes of rock and mud came tumbling down. The dramatic incident highlighted the hazards posed by rock slides for villages located near the picturesque mountains of the European Alps.

Though rockslides are not unusual, there has been growing scrutiny behind their causes lately. Unsurprisingly climate alarmists are opportunistically pointing the finger at climate warming.

 

 

A Geological Feud Over the Meghalayan? Or Just More Rubbish Published by the American Association for the Advancement of Science of America?

by David Middleton, September 24, 2018 in WUWT


Alternate Title: Yes, We Have No Anthropocene, We Have No Anthropocene Today! (Sung to the tune of Yes, We Have No Bananas)

 

Figure 4 from Finney & Edwards.  “Workflow for approval and ratification of a Global Standard Stratotype Section and Point (GSSP) proposal. Extensive discussion and evaluation occurs at the level of the working group, subcommission, and International Commission on Stratigraphy (ICS) Bureau. If approved at these successive levels, a proposal is forwarded to the International Union of Geological Sciences (IUGS) for ratification. This process is also followed for other ICS decisions on standardization, such as approval of names of formal units, of revisions to the units, and to revision or replacement of GSSPs.”

500 Million Years of Unrelatedness between Atmospheric CO2 and Temperature

by Davis W.J., 2017 in Climate/CO2Science


One final gem from Davis’ work is a pronouncement that follows a discussion on the lack of correlation between CO2 and temperature across the historical record, where he aptly reminds us that “correlation does not imply causality, but the absence of correlation proves conclusively the absence of causality.” Consequently, there should be no more doubt regarding the ineffectiveness of atmospheric CO2 to control or drive climate change. It is simply nothing more than a bit player, whose influence has been continually overestimated by climate alarmists. The big question now is whether or not 500 million years of these data will convince them otherwise!

from Davis 2017

Egalement: Le changement climatique : la règle en géologie