A highly precise method to determine past typhoon occurrences from giant clam shells has been developed, with the hope of using this method to predict future cyclone activity.
A team of researchers led by Tsuyoshi Watanabe of Hokkaido University has discovered that giant clams record short-term environmental changes, such as those caused by typhoons, in their shells. Analyzing the shell’s microstructure and chemical composition could reveal data about typhoons that occurred before written records were available… (…)
The whole Tridacna maxima valve. The shell was cut in two sections along the maximum growth axis.
Credit: Komagoe T. et al., Journal of Geophysical Research: Biogeosciences, April 19, 2018
When marine algae die, they usually float in slow motion to the ocean’s depths. However, during an expedition with the research icebreaker Polarstern to the Arctic in the spring of 2015, scientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) discovered a phenomenon that significantly accelerate this transport: tiny gypsum crystals, which form during the freezing of salt in the porous spaces of Arctic sea ice, weigh down the phytoplankton like heavy ballast, pulling them to the bottom within a matter of hours. The effect is like an express elevator for the carbon they contain. “This mechanism was previously completely unknown,” says marine bio-geologist Dr Jutta Wollenburg … (…)
The research, published in Science Advances, suggests that early animals diversified within a climate similar to that in which the dinosaurs lived.
This interval in time is known for the ‘Cambrian explosion’, the time during which representatives of most of the major animal groups first appear in the fossil record. These include the first animals to produce shells, and it is these shelly fossils that the scientists used.
Data from the tiny fossil shells, and data from new climate model runs, show that high latitude (~65 °S) sea temperatures were in excess of 20 °C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.
SPOTLIGHT: After the Intergovernmental Panel on Climate Change (IPCC) report was released in 2007, its dramatic findings of species extinction were repeatedly emphasized by chairman Rajendra Pachauri.
BIG PICTURE: When it examined the question of species extinction, the 2007 IPCC report relied heavily on a single piece of research – a Naturecover storypublished early in 2004. Written by Chris Thomas and 18 others, this was the source of Pachauri’s claim that climate change threatened 20 to 30% of the world’s species.
The influence of pHsw on both pHcf and the calcification rate of Neogoniolithon is plotted in Figure 1 below. As indicated there, this coralline algal species is able to elevate its pHcf so as to increase its rate of calcification under moderate levels of ocean acidification (pHsw of 7.91 and 8.05), which increase the authors say is “most likely due to CO2-fertilization of [algal] photosynthesis” that is limited in Neogoniolithon at these lower pCO2 conditions. (….)
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.
Essay by Dr. Susan Crockford (republished from her website https://polarbearscience.com )on Retraction request to Bioscience: FOIA emails document another harsh criticism of Amstrup’s 2007 polar bear model
Today I sent a letter to the editors of the journal Bioscience requesting retraction of the shoddy and malicious paper by Harvey et al. (Internet blogs, polar bears, and climate-change denial by proxy) published online last week.
The letter reveals information about the workings of the polar bear expert inner circle not known before now, so grab your popcorn.
(…) And commenting on this latter finding, they acknowledge that “this is an important component of the biological pump and may contribute to CO2 removal from the atmosphere, mitigating anthropogenic increase in greenhouse gases.”
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
Paper Reviewed: McCulloch, M.T., D’Olivo, J.P., Falter, J., Holcomb, M. and Trotter, J.A. 2017. Coral calcification in a changing world and the interactive dynamics of pH and DIC upregulation. Nature Communications8: 15686, DOI:10.1038/ncomms15686
(…) The implications of the above findings are enormous, for they reveal that “pHcf upregulation occurs largely independent of changes in seawater carbonate chemistry, and hence ocean acidification,” demonstrating “the ability of the coral to ‘control’ what is arguably one of its most fundamental physiological processes, the growth of its skeleton within which it lives.
In light of the above findings, it would appear that, given the near-global distribution of this EM fungi and its importance in stimulating ecosystem productivity, the positive impact of elevated CO2 on C. geophilumproduction (~50% increase for a 200 ppm rise) represents a welcomed benefit for the future of Earth’s forests.
Tremendous amounts of soot, lofted into the air from global wildfires following a massive asteroid strike 66 million years ago, would have plunged Earth into darkness for nearly two years, new research finds. This would have shut down photosynthesis, drastically cooled the planet, and contributed to the mass extinction that marked the end of the age of dinosaurs.
The ‘Rise of Algae’ created food webs with more efficient nutrient and energy transfers, driving ecosystems towards larger and increasingly complex organisms. This effect is recorded by the concomitant appearance of biomarkers for sponges and predatory rhizarians, and the subsequent radiation of eumetazoans in the Ediacaran period.
A Triceratops or Tyrannosaurus rex bulling its way through a pine forest likely dislodged flowers that 100 million years later have been identified in their fossilized form as a new species of tree.
The Tethys Sea couldn’t have been a better place for petroleum source rock deposition even if it had been designed for such a purpose. The “Tethyan realm” encompassed much of the Jurassic and Cretaceous periods…
Yes, Arctic sea ice has declined since satellite records began in 1979 but polar bears have adjusted well to this change, especially to the abrupt decline to low summer sea ice levels that have been the norm since 2007. Some polar bear subpopulations have indeed spent more time on land in summer than in previous decades but this had little negative impact on health or survival and while polar bear attacks on humans appear to have increased in recent years (Wilder et al. 2017), the reasons for this are not clear: reduced summer sea ice is almost certainly not the causal factor (see previous post here).
If aliens sent an exploratory mission to Earth, one of the first things they’d notice — after the fluffy white clouds and blue oceans of our water world — would be the way vegetation grades from exuberance at the equator through moderation at mid-latitudes toward monotony at higher ones. We all learn about this biodiversity gradient in school, but why does it exist?
A controlled lab study led by Mote Marine Laboratory and published June 1 in the peer-reviewed journal PLOS ONE revealed that black band disease was less deadly to mountainous star coral (Orbicella faveolata) as water acidified, or decreased in pH.
La géologie, une science plus que passionnante … et diverse
