The Greenland ice sheet (GIS) is losing mass at an increasing rate due to surface melt and flow acceleration in outlet glaciers. Currently, there is a large disagreement between observed and simulated ice flow, which may arise from inaccurate parameterization of basal motion, subglacial hydrology or geothermal heat sources. Recently it was suggested that there may be a hidden heat source beneath GIS caused by a higher than expected geothermal heat flux (GHF) from the Earth’s interior.
Climate change is a reality attested by past records. Concerns about preparing and adapting for climate change are real. However, the idea that we can prevent climate change from happening is dangerous and might be anti-adaptive. Certain energy policies that might have no effect on climate change could make us less able to adapt.
Physics shows that adding carbon dioxide leads to warming under laboratory conditions. It is generally assumed that a doubling of CO2 should produce a direct forcing of 3.7 W/m2 [1], that translates to a warming of 1°C (by differentiating the Stefan-Boltzmann equation) to 1.2°C (by models taking into account latitude and season). But that is a maximum value valid only if total energy outflow is the same as radiative outflow. As there is also conduction, convection, and evaporation, the final warming without feedbacks is probably less. Then we have the problem of feedbacks that we don’t know and cannot properly measure. For some of the feedbacks, like cloud cover we don’t even know the sign of their contribution. And they are huge, a 1% change in albedo has a radiative effect of 3.4 W/m2 [2], almost equivalent to a full doubling of CO2.
Que sont les métaux rares ? Des ressources peu connues mais essentielles au fonctionnement de l’espace mondialisé. Insérées au cœur de tout appareil électronique, sans elles aucune de nos technologies numériques n’existerait. Composant également la plupart de nos technologies vertes (éoliennes, panneaux solaires ou voitures électriques), leurs modes de production laissent toutefois perplexe sur leur capacité à s’établir comme alternatives durables aux énergies fossiles. La pollution ne serait pas réduite mais simplement délocalisée… essentiellement en Chine où 95% des terres rares sont produites. Un chiffre qui par ailleurs devrait nous alarmer sur la situation de dépendance à la Chine dans laquelle le reste du monde -dont l’Europe- se trouve depuis les années 1980. Guillaume Pitron nous présente une enquête de six ans, dont les résultats sont à retrouver dans son livre La guerre des métaux rares.
A long-standing question in Earth Science is the extent to which seismic and volcanic activity can be regulated by tidal stresses, a repeatable and predictable external excitation induced by the Moon-Sun gravitational force. Fortnightly tides, a ~14-day amplitude modulation of the daily tidal stresses that is associated to lunar cycles, have been suggested to affect volcano dynamics. However, previous studies found contradictory results and remain mostly inconclusive. Here we study how fortnightly tides have affected Ruapehu volcano (New Zealand) from 2004 to 2016 by analysing the rolling correlation between lunar cycles and seismic amplitude recorded close to the crater. (…)
A few years ago, 10 glaciologists publishing in the journal Nature Geoscience asserted that “large parts of the north-central Greenland ice sheet are melting from below” due to high geothermal heat flux forcing (Rogozhina et al., 2016).
In a new paper published in Scientific Reports, 4 more glaciologists (Rysgaardet al., 2018) report that “hot vents” (or hot springs) of geothermally-heated water underneath the Greenland ice sheet can explain localized rising temperatures and glacial melting.
The researchers published their findings this week in the Proceedings of the National Academy of Sciences.
Scientists frequently look to the Eocene to understand how the Earth responds to higher levels of carbon dioxide. During the Eocene, the concentration of carbon dioxide in the atmosphere was more than 560 parts per million, at least twice preindustrial levels, and the epoch kicked off with a global average temperature more than 8 degrees Celsius – about 14 degrees Fahrenheit – warmer than today, gradually cooling over the next 22 million years. These characteristics make the Eocene a good period on which to test our understanding of the climate system, said Laura Cotton, study co-author and curator of micropaleontology at the Florida Museum of Natural History.
Scientists have found strong evidence that 2018 will see a big uptick in the number of large earthquakes globally. Earth’s rotation, as with many things, is cyclical, slowing down by a few milliseconds per day then speeding up again.
You and I will never notice this very slight variation in the rotational speed of Earth. However, we will certainly notice the result, an increase in the number of severe earthquakes.
Geophysicists are able to measure the rotational speed of Earth extremely precisely, calculating slight variations on the order of milliseconds. Now, scientists believe a slowdown of the Earth’s rotation is the link to an observed cyclical increase in earthquakes.
Vast ranges of volcanoes hidden under the oceans are presumed by scientists to be the gentle giants of the planet, oozing lava at slow, steady rates along mid-ocean ridges. But a new study shows that they flare up on strikingly regular cycles, ranging from two weeks to 100,000 years—and, that they erupt almost exclusively during the first six months of each year. The pulses—apparently tied to short- and long-term changes in earth’s orbit, and to sea levels–may help trigger natural climate swings. Scientists have already speculated that volcanic cycles on land emitting large amounts of carbon dioxide might influence climate; but up to now there was no evidence from submarine volcanoes. The findings suggest that models of earth’s natural climate dynamics, and by extension human-influenced climate change, may have to be adjusted
The 2014-2017 El Nino “warm blob” was likely created, maintained, and partially recharged on two separate occasions by massive pulses of super-heated and chemically charged seawater from deep-sea geological features in the western North Pacific Ocean. This strongly supports the theory all El Ninos are naturally occurring and geological in origin. Climate change / global warming had nothing to do with generating, rewarming, intensifying, or increasing the frequency of the 2014-2017 El Nino or any previous El Nino.
If proven correct, this would revolutionize climatology and key aspects of many interrelated sciences such as oceanography, marine biology, glaciology, biogeochemistry, and most importantly meteorology. Information supporting a geological origin of El Ninos is diverse, reliable, and can be placed into five general categories as follows: (…)
One of the key effects of the end-Permian mass extinction, 252 million years ago, was rapid heating of tropical waters and atmospheres.
How this affected life on land has been uncertain until now.
In a new study published today, Dr Massimo Bernardi and Professor Mike Benton from the School of Earth Sciences at the University of Bristol show how early reptiles were expelled from the tropics.
Though mass extinctions wiped out staggeringly high numbers of species, they barely touched the overall ‘functional’ diversity — how each species makes a living, be it filtering phytoplankton or eating small crustaceans, burrowing or clamping onto rocks.
We evaluate different hypotheses of the origin of the Little Ice Age, focusing on the long-term response of Arctic sea ice and oceanic circulation to solar and volcanic perturbations. We analyze the Last Millennium Ensemble of climate model simulations carried out with the Community Earth System Model at the National Center for Atmospheric Research. We examine the duration and strength of volcanic perturbations, as well as initial and boundary conditions such as the phase of the Atlantic Multidecadal Oscillation, and their impact on decadal to multi-centennial perturbations of the cryospheric, oceanic, and atmospheric components of the climate system.
The scope of our ignorance on the sea floor is really something. There are 1,500 active volcanoes on land, but on the sea floor we are still discovering them all the time. at least 39,000 of them rise one kilometer off the sea floor, but there are suspicions there might be up to 3 million, holey moley. The Hilliers paper estimates that 24,000 submarine volcanoes were not yet discovered in 2007. Wikimedia is trying to list them. Good luck.
In recent years, researchers have identified a small group of stalactites that appear to have calcified underwater instead of in a dry cave. The Hells Bells in the El Zapote cave near Puerto Morelos on the Yucatán Peninsula are just such formations. Scientists have recently investigated how these bell-shaped, meter-long formations developed, assisted by bacteria and algae.
How deep can seawater penetrate through cracks and fissures into the seafloor? By applying a new analysis method, an international team of researchers has now discovered that the water can penetrate to depths of more than 10 kilometers below the seafloor. This result suggests a stronger cooling effect on the hot mantle.
Earth’s Moon had a rough start in life. Formed from a chunk of Earth that was lopped off during a planetary collision, it spent its early years covered by a roiling global ocean of molten magma before cooling and forming the serene surface we know today.
Using a numerical carbon cycle model, we find that two prominent periods of enhanced rifting 160 to 100 million years ago and after 55 million years ago coincided with greenhouse climate episodes, during which atmospheric CO2 concentrations were more than three times higher than today. We therefore propose that continental fragmentation and long-term climate change could plausibly be linked via massive CO2 degassing in rift systems.
Confirms what I’ve been saying all along!
NASA scientists admit that a massive heat source almost as hot as the Yellowstone supervolcano may be melting the Antarctic ice sheet from below.
It seems like a no-brainer to me. I mean, how can lakes and rivers be flowing beneath the ice unless there’s a heat source down there? And if sub-glacial volcanoes can be melting the ice, why couldn’t underwater volcanoes be heating the sea
An asteroid, also known as the Chicxulub Impactor, hit Earth some 66 million years ago, causing a crater 180 km wide. The impact of the asteroid heated organic matter in rocks and ejected it into the atmosphere, forming soot in the stratosphere.
According to the study, soot from hydrocarbon-rich areas caused global cooling of 8-11°C and cooling on land of 13-17°C. It also caused a decrease in precipitation by approximately 70-85 percent on land and a decrease of approximately 5-7°C in seawater temperature at a 50-m water depth, leading to mass extinction of life forms including dinosaurs and ammonites
18O is a rare isotope of oxygen. The ratio of 18O to the normal 16O in foraminifera fossils (“forams”) can be used to estimate paleo-ocean temperatures. Higher values mean lower temperatures. A recent article on geologypage.com (here) led me to Bernard, et al., 2017, which has experimental data that suggest 18O concentrations can be altered in fossils by solid-state diffusion after fossilization. This can corrupt the measurement and the resulting calculated temperature
Predicting the impact of sea-level (SL) rise on coral reefs requires reliable models of reef accretion. Most assume that accretion results from vertical growth of coralgal framework, but recent studies show that reefs exposed to hurricanes consist of layers of coral gravel rather than in-place corals. New models are therefore needed to account for hurricane impact on reef accretion over geological timescales
Anomalous peaks of nickel abundance have been reported in Permian-Triassic boundary sections in China, Israel, Eastern Europe, Spitzbergen, and the Austrian Carnic Alps. New solution ICP-MS results of enhanced nickel from P-T boundary sections in Hungary, Japan, and Spiti, India suggest that the nickel anomalies at the end of the Permian were a worldwide phenomenon.
Life on Earth began somewhere between 3.7 and 4.5 billion years ago, after meteorites splashed down and leached essential elements into warm little ponds, say scientists. Their calculations suggest that wet and dry cycles bonded basic molecular building blocks in the ponds’ nutrient-rich broth into self-replicating RNA molecules that constituted the first genetic code for life on the planet.
La géologie, une science plus que passionnante … et diverse
