“It is absolutely critical to recognize that I am NOT claiming that humans haven’t done great damage to marine and terrestrial [ecosystems], nor that many extinctions have not occurred and more will certainly occur in the near future. But I do think that as scientistswe have a responsibility to be accurate about such comparisons.”
Many popular science articles take this as a given, and indeed, there’s something emotionally satisfying about the idea that humans’ hubris and shortsightedness are so profound that we’re bringing down the whole planet with us.
In previous posts (here, here and here), we have shown reconstructions for the Antarctic, Southern Hemisphere mid-latitudes, the tropics, the Northern Hemisphere mid-latitudes, and the Arctic. Here we combine them into a simple global temperature reconstruction. The five regional reconstructions are shown in figure 1. The R code to map the proxy locations, the references and metadata for the proxies, and the global reconstruction spreadsheet can be downloaded here
As we did in the previous two posts, we will examine each proxy and reject any that have an average time step greater than 130 years or if it does not cover at least part of the Little Ice Age (LIA) and the Holocene Climatic Optimum (HCO). We are looking for coverage from 9000 BP to 500 BP or very close to these values. Only simple statistical techniques that are easy to explain will be used.
by Arthur Viterito, April 25, 2016 in J. of Earth Sc. & Climatic Change
Earth’s climate is a remarkably “noisy” system, driven by scores of oscillators, feedback mechanisms, and radiative forcings. Amidst all this noise, identifying a solitary input to the system (i.e., HGFA MAG4/6 seismic activity as a proxy for geothermal heat flux) that explains 62% of the variation in the earth’s surface temperature is a significant finding. Additionally, the 1997/1998 SIENA was a strong signal for subsequent global warming, and this type of seismic jump may provide valuable predictive information
High latitude ocean gateway changes are thought to play a key role in Cenozoic climate evolution. However, the underlying ocean dynamics are poorly understood. Here we use a fully coupled atmosphere-ocean model to investigate the effect of ocean gateway formation that is associated with the subsidence of the Greenland–Scotland Ridge. We find a threshold in sill depth (∼50 m) that is linked to the influence of wind mixing.
In the last post (see here) we introduced a new Holocene temperature reconstruction for Antarctica using some of the Marcott, et al. (2013) proxies. In this post, we will present two more reconstructions, one for the Southern Hemisphere mid-latitudes (60°S to 30°S) and another for the tropics (30°S to 30°N)
The Marcott, et al. 2013 worldwide reconstruction has its problems, but many of the proxies used in the reconstruction are quite good and very usable.
The Antarctic reconstruction created here is comparable to previous temperature reconstructions, especially those focusing on eastern Antarctica. It shows two climatic optima, one from 11500 BP to 9000 BP and another from 6000 BP to 3000 BP. In eastern Antarctica, using our proxies, the later optimum is warmer. But, in other areas the earlier optimum is warmer, however, the difference is small
The relative influences of tectonics, continental weathering and seafloor weathering in controlling the geological carbon cycle are unknown. Here we develop a new carbon cycle model that explicitly captures the kinetics of seafloor weathering to investigate carbon fluxes and the evolution of atmospheric CO2 and ocean pH since 100 Myr ago.
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.
Chronicling Earth’s past temperature swings is a basic part of understanding climate change. One of the best records of past ocean temperatures can be found in the shells of marine creatures called foraminifera
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.
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.
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
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.
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
At the peak of the last ice age, a vast ice sheet covered northern Europe, spanning from the British Isles, across Scandinavia and into Russia in the east and the Barents Sea in the north. A new reconstruction of this ice sheet shows the interaction between climate and glaciers — how the ice sheet grows and retreats
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.
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
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!”
Just a few short years ago, few would have dared to predict that coal could have a future in the energy policies of emerging and developed countries alike. Yet the fossil fuel is undergoing an unexpected renaissance in Asia, buoyed by technical breakthroughs and looming questions about squaring development with energy security.
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.
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.
A paper published in Paleoworld worries that a repeat of the greatest mass extinction event in Earth’s history could be triggered by Anthropogenic CO2. But Cambridge Professor Peter Wadhams, our favourite sea ice alarmist, thinks the attempt to link the Permian extinction to modern events is a bit wild.
A team of academics led by the University of Leicester has responded to criticisms of the proposal to formalise a new geological epoch – the Anthropocene.
Geological critics of a formalised Anthropocene have alleged that the idea did not arise from geology; that there is simply not enough physical evidence for it as strata; that it is based more on the future than on the past; that it is more a part of human history than the immensely long history of the Earth; and that it is a political statement, rather than a scientific one.
Dead zones affect dozens of coral reefs around the world and threaten hundreds more according to a new study. Watching a massive coral reef die-off on the Caribbean coast of Panama, they suspected it was caused by a dead zone — a low-oxygen area that snuffs out marine life — rather than by ocean warming or acidification.
Journal Reference: Andrew H. Altieri, Seamus B. Harrison, Janina Seemann, Rachel Collin, Robert J. Diaz, Nancy Knowlton. Tropical dead zones and mass mortalities on coral reefs. Proceedings of the National Academy of Sciences, 2017; 201621517 DOI: 10.1073/pnas.1621517114
La géologie, une science plus que passionnante … et diverse
