Archives de catégorie : climate and geology

Porewater salinity reveals past lake-level changes in Lake Van, the Earth’s largest soda lake

by Yama Tomonaga et al., March 22, 2017, Nature


In closed-basin lakes, sediment porewater salinity can potentially be used as a conservative tracer to reconstruct past fluctuations in lake level. However, until now, porewater salinity profiles did not allow quantitative estimates of past lake-level changes because, in contrast to the oceans, significant salinity changes (e.g., local concentration minima and maxima) had never been observed in lacustrine sediments. Here we show that the salinity measured in the sediment pore water of Lake Van (Turkey) allows straightforward reconstruction of two major transgressions and a major regression that occurred during the last 250 ka.

A paleo-perspective on ocean heat content: Lessons from the Holocene and Common Era

by Yair Rosenthal et al., January 1, 2017


 

Here we review proxy records of intermediate water temperatures from sediment cores in the equatorial Pacific and northeastern Atlantic Oceans, spanning 10,000 years beyond the instrumental record.

These records suggests that intermediate waters were 1.5–2 °C warmer during the Holocene Thermal Maximum than in the last century.

Intermediate water masses cooled by 0.9 °C from the Medieval Climate Anomaly to the Little Ice Age.

 

Shelf sediments reveal climate shifts through the eons

by University of Queensland, May 10, 2017, in DailyScience


Ms Korpanty said global climate underwent significant change about 14 million years ago when the Antarctic ice sheet expanded.

“The new study presents shallow-marine sediment records from the Australian continental shelf, providing the first empirical evidence linking high-altitude cooling around Antarctica to climate change in the subtropics during the Miocene era,” she said.

Taking The Economist to Task for Unfounded Climate Catastrophe Fearmongering

by   Dr. John D. Harper, FGSA,FGAC, PGeol., former director of the Geological Survey of Canada © May 2017


I have recently been asked to comment on three articles published in The Economist. My background for such a response is as a Professor of Petroleum Geology and Sedimentology (ret.), a former Director-Energy for the Geological Survey of Canada, a former researcher in industry, and as an academic researcher on sea level changes and climate documentation through geologic time, Natural Resources of the Future and a couple of decades of studies in the Arctic.

1) Skating on thin ice: The thawing Arctic threatens an environmental catastrophe. Apr 27, 2017

2) The Arctic as it is known today is almost certainly gone. April 29, 2017

3) Thaw point: As the Arctic melts the world’s weather suffers. April 29, 2017

Battered Earth revived by mineral weathering after mass extinction

by University of Tromso, May 5, 2017 in ScienceDaily


Bedrock of Earth got severely beaten up by hothouse climate conditions during one of planet’s mass extinctions some 200 million years ago. But the process also allowed life to bounce back.

The hothouse conditions of this mass extinction caused oceans to eventually become depleted of oxygen, and thus become unbearable to live in. But weathering of silicate in the bedrock of Pangea, and subsequent formation of carbonate, tied up the CO2 into the minerals, slowly removing the greenhouse gas from the atmosphere.

Onset and ending of the late Palaeozoic ice age triggered by tectonically paced rock weathering

by Yves Goddéris et al., April 10, 2017, Nature Geoscience


The onset of the late Palaeozoic ice age about 340 million years ago has been attributed to a decrease in atmospheric CO2 concentrations associated with expansion of land plants, as plants both enhance silicate rock weathering—which consumes CO2—and increase the storage of organic carbon on land. However, plant expansion and carbon uptake substantially predate glaciation

Methane seeps in the Canadian high Arctic

by Geological Society of America, April 13, 2017

in ScienceDaily


Cretaceous climate warming led to a significant methane release from the seafloor, indicating potential for similar destabilization of gas hydrates under modern global warming. A field campaign on the remote Ellef Ringnes Island, Canadian High Arctic, discovered an astounding number of methane seep mounds in Cretaceous age sediments.

Quelles énergies dans le monde pour 2050 ?

by  Jean-Louis Schilansky, Président du Centre Hydrocarbures Non Conventionnels, 3 Avril 2017


Le début du XXIe siècle connaît une période inédite d’abondance et de diversité énergétique, marquée par d’importantes avancées technologiques dans la production d’énergie. Les développements les plus notables concernent l’essor des énergies renouvelables et des ressources d’hydrocarbures non conventionnels, en particulier de pétrole et de gaz de schiste en Amérique du Nord

China and Pakistan Join Forces For World’s Biggest Brown Coal Programme

by Dr. Benny Peiser, April 3, 2017


Chinese engineer and inventor Feng Weizhong has an easy ­answer to how China plans to keep slashing coal use and power-­station emissions while relying on coal to provide at least 55 per cent of its massive energy demand for decades to come. The effervescent Professor Feng, who is also general manager of a large Shanghai power plant, explained to The Australian how the country can contrive to do both at the same time. “Simple! It’s clean coal!”

Greenland was nearly ice-free for extended periods during the Pleistocene

by JM Schaefer et al., Nature, December8, 2016


Here we show that Greenland was deglaciated for extended periods during the Pleistocene epoch (from 2.6 million years ago to 11,700 years ago), based on new measurements of cosmic-ray-produced beryllium and aluminium isotopes (10Be and 26Al) in a bedrock core from beneath an ice core near the GIS summit.

Recent Sea-Level Change at Major Cities

by Rich Taylor, March 29, 2017


Where the ground is stable, typical change appears to be a rise of 1- to 2-mm/y. Rates above 3 mm/y seem to have a substantial component of natural and/or anthropogenic subsidence. Rates above 10 mm/y appear to be a primarily a consequence of human activity, which implies they should be manageable to some degree.

All records in this review are from the website www.psmsl.org of the Permanent Service for Mean Sea Level.