Archives de catégorie : climate and geology

Minimal geological methane emissions during the Younger Dryas–Preboreal abrupt warming event

by Vasilii V. Petrenko et al., August 23, 2017 in Nature

Preboreal event was driven by contemporaneous methane from sources such as wetlands; our findings constrain the contribution from old carbon reservoirs (marine methane hydrates8, permafrost9 and methane trapped under ice10) to 19 per cent or less (95 per cent confidence). To the extent that the characteristics of the most recent deglaciation and the Younger Dryas–Preboreal warming are comparable to those of the current anthropogenic warming, our measurements suggest that large future atmospheric releases of methane from old carbon sources are unlikely to occur.

New Antarctic heat map reveals sub-ice hotspots

by  A. Dinar, November 13, 2017 in GeoSpace-AGU

An international team of scientists, led by British Antarctic Survey (BAS), has produced a new map showing how much heat from the Earth’s interior is reaching the base of the Antarctic Ice Sheet. The map is part of a new paper accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The team has produced the most up to date, accurate and high-resolution map of the so called ‘geothermal heat flux’ at the base of the Antarctic Ice Sheet. Of the basic information that shapes and controls ice flow, the most poorly known about is this heat

Potential links between continental rifting, CO2 degassing and climate change through time

by Sascha Brune et al., March 13, 2017 in NatureGeoscience

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.

New map of Antarctic geothermal heat suggests Steig & Mann 2009 weren’t measuring ‘global warming’

by Anthony Watts, November 15, 2017 in WUWT

This is quite interesting. Remember the claim in on the front cover of Nature in 2009 by Steig and Mann that Antarctica was warming, thanks to that “special Mannian PCA math sauce” that was applied to air temperature data to smear surface temperature trends over the entire continent? It was dashed by climate skeptics who wrote a paper. It was accepted for publication and disproved (in my opinion) by a team of credible skeptics that wrote a counter-paper. But, there’s an interesting twist thanks to new and surprising data; Steig and Mann may have captured surface air temperature trends in the exact same areas that have been identified as geothermal hot spots.

NASA – Supervolcano may be melting Antarctic ice sheet from below

by Robert, November 10, 2017 in NASA

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

Site of asteroid impact changed the history of life

by Tohoku University, November 10, 2017 in ScienceDaily

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

Hot News from the Antarctic Underground

by Alan Buis, November, 7, 2017, in JPL, NASA

Study Bolsters Theory of Heat Source Under West Antarctica

A new NASA study adds evidence that a geothermal heat source called a mantle plume lies deep below Antarctica’s Marie Byrd Land, explaining some of the melting that creates lakes and rivers under the ice sheet. Although the heat source isn’t a new or increasing threat to the West Antarctic ice sheet, it may help explain why the ice sheet collapsed rapidly in an earlier era of rapid climate change, and why it is so unstable today.

Oxygen-18 Stability in Foraminifera fossils, implications in paleoclimatology

by Andy May, November 4, 2017

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 (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

Retrograde Accretion of a Caribbean Fringing Reef Controlled by Hurricanes and Sea-level Rise

by P. Blanchon et al., October 12, 2017 in Front.Earth.Sci

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

Tropical explosive volcanic eruptions can trigger El Niño by cooling tropical Africa

by M. Khodri et al., October 3,  2017 in Nature

Stratospheric aerosols from large tropical explosive volcanic eruptions backscatter shortwave radiation and reduce the global mean surface temperature. Observations suggest that they also favour an El Niño within 2 years following the eruption. Modelling studies have, however, so far reached no consensus on either the sign or physical mechanism of El Niño response to volcanism

The Correlation of Seismic Activity and Recent Global Warming

by Arthur Viterio, 2016, in  J Earth Science Climate 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.

See also here