That’s more than a 25% adjustment (15,000 sq. km to 19,000 sq km). So while chunks the size of Manhattans may break off from time to time, about 300 Manhattans of new ice gets added annually.
The report notes that in the Antarctic Ocean: “the annual maximum and annual mean sea ice extents have shown a long-term trend of increase since 1979”.
Le Précambrien représente 88% de l’histoire de la Terre âgée de 4,567 milliards d’années (Ga).
C’est au cours de cette période peu connue, peu enseignée que se sont déroulés ou mis en place des événements physico-chimiques et biologiques déterminants: différenciation des enveloppes terrestres, tectonique des plaques et premières ‘pangées’ ou supercontinents, champ magnétique, chaînes de montagnes, glaciations, anoxies des bassins, remplacement du CO2-CH4par l’oxygène atmosphérique, formation de gisements (uranium, manganèse, nickel …. et même pétrole), émergence dès 3,8 Ga des procaryotes puis des eucaryotes …
Vu l’absence de fossiles stratigraphiques, et donc de biozones, la stratigraphie du Précambrien est encore très difficile, elle est intialement basée sur la lithostratigraphie. De grands progrès ont récemment été réalisés grâce à la chimiostratigraphie istotopique (C, O, Sr….) en plus de la radiométrie absolue.
L’exposé se consacrera aux événements sédimentaires liés au Grand Evénement de l’Oxygène il y a environ 2,5-2,1 Ga (Paléoprotérozoïque) et à ceux liés à la ‘Terre Boule de Neige’ (Snowball Earth) avec la glaciation marinoenne il y a 0,635 Ga (Néoprotérozoïque), à partir des séries de l’Afrique de l’Ouest.
DDuring a meeting of polar bear range states (Canada, Russia, Greenland, Norway, and the USA) in late January 2018 to discuss conservation issues, Canada — home to ~2/3 of the world’s polar bears — included in its presentation an updated population status and trend map approved by the Polar Bear Technical Committee in its presentation. This 2017 map replaces one from 2014 but is not yet available on the Environment Canada website.
Because trees may only grow within narrowly-defined temperature ranges and elevations above sea level, perhaps the most reliable means of assessing the air temperatures of past climates is to collect ancient treeline evidence. In a new paper, Kullman (2018) found tree remnants at mountain sites 600 to 700 meters north of where the modern treeline ends, strongly implying Early Holocene air temperatures in northern Sweden were 3-4°C warmer than recent decades.
Since the 1950s the number of lives and the amount of money lost to floods have declined, despite little change to the frequency of catastrophic floods, according to the first comprehensive study of European historical records.
Academics at Delft University of Technology in the Netherlands found that the number of flood deaths across Europe has been falling by about 5 per cent a year for the past six decades. Financial losses to flooding have declined by 2 per cent a year, according to their paper in Nature Communications.
There is a continuing debate over sea level rise, especially how much will occur in the future. The most annoying part of the news media reporting on the issue is that they imply sea level rise is all the fault of humans.
This is why the acceleration of sea level rise is what is usually debated, because sea level has been rising naturally, for at least 100 years before humans could be blamed. So, the two questions really are (1) Has sea level rise accelerated?, and (2) how much of the acceleration is due to humans?
Yesterday’s spat between Gavin Schmidt and Willis Eschenbach dealt with the question of whether sea level rise has accelerated or not. Gavin says it has. Willis says not, or at least not by a statistically significant amount. (…)
by Paul Homewood, May 30, 2018 in NotaLotofPeopleknowThat
China’s carbon emissions growth has accelerated since the beginning of the year, leading to warnings that the country could be headed for its largest annual increase in climate pollution since 2011.
Led by increased demand for coal, oil and gas, China’s CO2 emissions for the first three months of 2018 were 4% higher than they were for the same period in 2017, according to an Unearthed analysis of new government figures.
Analysts have suggested the country’s carbon emissions could rise this year by 5% — the largest annual increase in seven years, back when the airpocalypse was at its peak (…)
Corals around Japan are fleeing northwards, according to a new study. One type has been spotted ‘sprinting’ at 14 kilometres a year, thanks to a lift from ocean currents. That means ocean ecosystems could shift rapidly in the face of climate-change impacts such as warming seas, the authors say.
Inspired by Richard Keen’s interesting WUWT post on using eclipses to determine the clarity of the atmosphere, I went to the website of the Hawaiian Mauna Loa Observatory. They have some very fascinating datasets. One of them is a measurement of direct solar radiation, minute by minute, since about 1980.
I thought that I could use that dataset to determine the clarity of the atmosphere by looking at the maximum downwelling solar energy on a month by month basis. I’ve described my method of extracting the maximum solar energy from the minute by minute data in the appendix for those interested.
Most estimates of Chinese regional Surface Air Temperatures since the late-19th century have identified two relatively warm periods – 1920s–40s and 1990s–present. However, there is considerable debate over how the two periods compare to each other. Some argue the current warm period is much warmer than the earlier warm period. Others argue the earlier warm period was comparable to the present. In this collaborative paper, including authors from both camps, the reasons for this ongoing debate are discussed. Several different estimates of Chinese temperature trends, both new and previously published, are considered. A study of the effects of urbanization bias on Chinese temperature trends was carried out using the new updated version of the Global Historical Climatology Network (GHCN) – version 4 (currently in beta production)
Over millennia, the reef has adapted to sudden changes in environment by migrating across the sea floor as the oceans rose and fell.
The study published today in Nature Geoscience, led by University of Sydney’s Associate Professor Jody Webster, is the first of its kind to reconstruct the evolution of the reef over the past 30 millennia in response to major, abrupt environmental change.
The 10-year, multinational effort has shown the reef is more resilient to major environmental changes such as sea-level rise and sea-temperature change than previously thought but also showed a high sensitivity to increased sediment input and poor water quality. (…)
This manntastic event looms large. With the irascible Dr. Mann pitted against Moore and Curry, fireworks are almost guaranteed. Titley is a lightweight and he’ll be overshadowed by Mann’s huge ego and need to control the conversation. Their idea to hear a “collegial and balanced” discussion may very well be a pipe dream, especially after what happened the last time when Mann and Curry were testifying before congress.
BIG PICTURE: The Population Bomb was first published in May 1968 – 50 years ago this month. Page one of my copy, printed in 1970, describes its author as “a qualified scientist.” The back cover provides further detail: (…)
A landmark paper by warmist scientists in Nature Geosciencenow concedes the world has indeed not warmed as predicted, thanks to a slowdown in the first 15 years of this century. One of its authors, Michael Grubb, professor of international energy and climate change at University College London, admits his past predictions of runaway warming were too alarmist.
“When the facts change, I change my mind. We are in a better place than I thought.”
ANOTHER author, Myles Allen, professor of geosystem science at Oxford, confessed that too many of the mathematical models used by climate scientists to predict future warming “were on the hot side” — meaning they exaggerated.
“We haven’t seen that rapid acceleration in warming after 2000 that we see in the models.”
The sun was inactive in April, as we currently find ourselves in the minimum between solar cycle (SC) 24 and the coming solar cycle 25.
The recorded mean sunspot number (SSN) for April was 8.9, which is only 28% of what is usual 113 months into a solar cycle. In April, 16 days were spotless. The following chart shows sunspot activity (…)
In describing their findings, Lovell et al. state that “between 1972 and 2013, 36% of glacier termini in the entire study area advanced and 25% of glacier termini retreated, with the remainder showing no discernible change outside of the measurement error (± 66 m or ± 1.6 m yr-1) and classified as ‘no change'” (see figure below). Although there were some regional differences in glacier termini changes, these regions over the last four decades were more closely linked to non-climatic drivers, such as terminus type and geometry, than any obvious climatic or oceanic forcing.”
By Field Museum, May 24, 2018 in ScienceDaily (CurrentBiology)
Sixty-six million years ago, the world burned. An asteroid crashed to Earth with a force one million times larger than the largest atomic bomb, causing the extinction of the dinosaurs. But dinosaurs weren’t the only ones that got hit hard — in a new study, scientists learned that the planet’s forests were decimated, leading to the extinction of tree-dwelling birds.
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
Scientists claim that the ocean’s global mean surface pH may have declined (i.e., became less alkaline and thus more “acidic”) by -0.08 in the last 265 years — from 8.13 during pre-industrial times to 8.05 today. That’s an overall, long-term pH change rate of -0.0003 per year.
By way of comparison, from one season to the next, or over the course of less than a year, pH levels naturally change by twice that amount (±0.15 pH units). On a per-decade scale, oceanic pH can naturally fluctuate up and down by up to 0.6 units within a span of a decade (as shown in red below).
Writing as background for their study, Duvat et al. (2017) state that “it has commonly been considered that atoll reef islands would disappear under climate change, as a result of sea-level rise and induced accelerating shoreline erosion,” citing the works of Connell (2003), Dickinson (2009) and McAdam (2010). This perception is based on model predictions, which have been hyped all over the globe, especially among politicians and the media, some of whom demand reparations for small island States who they fear will be forced to abandon their islands within decades.
But how much faith should one place in such projections and concerns?
Have you been keeping an eye on Sol lately? One of the top astronomy stories for 2018 may be what’s not happening, and how inactive our host star has become.
The strange tale of Solar Cycle #24 is ending with an expected whimper: as of May 8th, the Earthward face of the Sun had been spotless for 73 out of 128 days thus far for 2018, or more than 57% of the time. This wasn’t entirely unexpected, as the solar minimum between solar cycle #23 and #24 saw 260 spotless days in 2009 – the most recorded in a single year since 1913.
Cycle #24 got off to a late and sputtering start, and though it produced some whopper sunspots reminiscent of the Sol we knew and loved on 20th century cycles past, it was a chronic under-performer overall. Mid-2018 may see the end of cycle #24 and the start of Cycle #25… or will it?
The well has been drilled through the Lower Bowland shale at a depth of approximately 2,700m (8,860 ft) below ground and extends laterally 800m (2,620 ft).
Francis Egan, chief executive officer of Cuadrilla, said the government’s recent announcement underlined the “national importance of shale gas”.
“We are now very close to demonstrating that Lancashire shale gas can be commercially developed in a safe and environmentally responsible manner.”
The firm said drilling on a second horizontal shale gas exploration well at the site is due to be complete soon when it will lodge a second fracking application.
It said it expects to start fracking both wells later this year.
In Figure 29 of that paper, Hansen claims to show that sea level rise has been accelerating, from 0.6 mm/year from 1900 to 1930, to 1.4 mm/year from 1930 to 1992, and 2.6 mm/year from 1993 to 2015.
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 … (…)
La géologie, une science plus que passionnante … et diverse
