...If you ever want to publish your thoughts to a wider audience, let me know.
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When Donnie is a slob to his wife.......THAT effects RussiaGateThe best arguments are those made based on the major issues, if you write a story about how he leaves a plane without his woman, then this is interference, just not really news. However, people take notice of such subtle details, some things do not have to be communicated. Focus on the major issues, such as a climate denier who sued EPA, leads it now, and what he does, what he said - threatening clean air and water, and climate disruption. Now, you get attention from the average Joe. If you focus too much on the details, or too vague claims, small slips, you lose credibility, or let's say you over bombard the attention spans with small stuff. Focus on the big picture.
I would think that is the way to go, because it eliminates the noise from the facts. The evolution of politics, our future .... how long will it take? It would also possibly mean the best possible environment for prosperity.Or stop dividing in terms of the left and right entirely, and just focus on science based policy
Can you imagine a world where policy is based on the best science and policy changes to meet new data? Too bad we are prisoners of the lawyers and their cognitive dissonance based system.
How about we stop running from the labels "liberal" and "progressive", and instead embrace them and let people know that many of the good things they have in life are courtesy of the Left, things which the Right wants to take away?
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To learn more about large-noise events such as ice-climate feedback due to the collapse of a marine ice sheet (like the WAIS) please review my postsAbruptSLR, i currently plan a new video production where i want to summarize some of the most worrying research. Is it possible, can you summarize maybe what you think are the top 5 or top 10 findings in those regards? Or what you think should be communicated to a larger audience of laymen?
We suggest that basal meltwater is activelyhttp://geology.gsapubs.org/content/early/2017/03/27/G38860.1.full.pdf+html
being routed down both the paleofluvial and subglacially formed channel networks to the coast.
Inheritance of the preglacial channel network may have influenced the present-day location
and dynamics of Humboldt Glacier and enhanced selective erosion at its down-glacier end.
The Milo’s logbook of its 1863 voyage is just one of 35 whaling logs that are part of the Old Weather: Whaling project, an online portal that allows volunteers to assist in exploring, marking, and transcribing ship logs, largely from the 19th and early 20th centuries. The initiative, and its sister side Old Weather, were founded by Dr. Philip Brohan at the UK Met Office in 2010 to recover historical marine-meteorological observations that can be used by supercomputers to reconstruct the weather of the past 150 years. Historic ship logs are difficult for computers to transcribe and mark because of their diverse and idiosyncratic handwriting that only humans can read and understand effectively.
Despite their difficulty, ship loggers’ observations on sea ice conditions that whaling ships have sailed through and documented while navigating Arctic waters are vital to informing the foundations of climate science research being done today.
“Old Weather volunteers have recovered millions of new-to-science weather observations,” explains Dr. Kevin Wood, a research scientists at the University of Washington’s Joint Institute for the Study of Atmosphere and the Arctic Lead Investigator for Old Weather.
“For the Arctic, they have also been recovering many thousands of sea-ice observations and other environmental data – the former specifically to validate century-scale sea-ice model hindcast experiments, so we can better know well our models are working, and more fundamentally document what the Arctic sea-ice was like in the past (especially in offshore areas and in some instances in winter).”
Here we present evidence for persistent active drainage networks—interconnected streams, ponds and rivers—on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf’s meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century.https://www.nature.com/nature/journal/v544/n7650/full/nature22048.html
The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present.
The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica—contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.
I find this fascinating, and I think under-represented in the literature on ice-melt and the ecosystem it is unavoidably entangled with.
The researchers say that additional studies are needed to refine the picture of whether the balance of carbon produced by glaciers is weighted more to release of ancient carbon or production by microorganisms.
..we identify 1997 (±5 years) as the year after which the GICs refreezing regime starts to decrease and diverges significantly from the GrIS refreezing regime (black point in Fig. 3c). This marked reduction in refreezing capacity is representative of a deteriorating firn layer, the porous, multiyear snow layer between surface fresh snow (∼350 kg m−3) and the underlying ice (∼900 kg m−3). Decades of increased melt have reduced pore space to such a degree that enhanced refreezing can no longer compensate for increased meltwater production. Because it would take decades to regrow a healthy firn layer, we interpret 1997 as a tipping point in the mass balance of Greenland’s GICs.
Covering a total area of ∼90,000 km2, Greenland’s peripheral glaciers and ice caps (GICs) represent ∼12% of the world’s glacierized area outside of the Antarctic and Greenland ice sheets1. Greenland’s GICs account for 14 to 20% of total current Greenland glacial mass loss2, although they only represent ∼5% of the area and ∼0.5% (∼39 mm SLE) of the volume of the Greenland ice sheet (GrIS). In a scenario of continued global warming, Greenland’s GICs may lose 19–28% (7.5–11 mm) of their volume by 2100 (ref. 3).
Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote sensing data, to identify 1997 (±5 years) as a tipping point for GICs mass balance. That year marks the onset of a rapid deterioration in the capacity of the GICs firn to refreeze meltwater. Consequently, GICs runoff increases 65% faster than meltwater production, tripling the post-1997 mass loss to 36±16 Gt−1, or ∼14% of the Greenland total. In sharp contrast, the extensive inland firn of the GrIS retains most of its refreezing capacity for now, buffering 22% of the increased meltwater production. This underlines the very different response of the GICs and GrIS to atmospheric warming.
..decision makers are fully aware that our combined societal behavior will likely lead to climate catastrophe; which is an example of our stupid collective behavior due to the mental illness of the decision makers
Neanderthal genes' effects on gene expression likely contribute to traits such as height and susceptibility to schizophrenia or lupus, the researchers found.
"Even 50,000 years after the last human-Neanderthal mating, we can still see measurable impacts on gene expression," says geneticist and study co-author Joshua Akey of the University of Washington School of Medicine. "And those variations in gene expression contribute to human phenotypic variation and disease susceptibility."
Read more at: https://phys.org/news/2017-02-neanderthal-dna-contributes-human-gene.html#jCp
When it is human stupidity that has caused climate change, why do so many think that humans will be able to avoid exceeding the 2C target?Humans have not caused climate change per se, more like unknowingly - at least to some degree. Something every evolving species on a habitable planet in the Universe encounters, burning fossil fuels at one point.
Is there a sub-thread at CS where all the relevant pieces would be stored together? What would be the best terms to use to do a search on this topic?
I was curious about this conversation in PIOMAS, and was hoping you all would continue it here.Ofc, would be nice to get some expert opinions on this years projected melt rates and the data.
In recent decades, the Greenland ice sheet has experienced increased surface melt. However, the underlying cause of this increased surface melting and how it relates to cryospheric changes across the Arctic remain unclear. Here it is shown that an important contributing factor is the decreasing Arctic sea ice. Reduced summer sea ice favors stronger and more frequent occurrences of blocking-high pressure events over Greenland. Blocking highs enhance the transport of warm, moist air over Greenland, which increases downwelling infrared radiation, contributes to increased extreme heat events, and accounts for the majority of the observed warming trends. These findings are supported by analyses of observations and reanalysis data, as well as by independent atmospheric model simulations using a state-of-the-art atmospheric model that is forced by varying only the sea ice conditions. Reduced sea ice conditions in the model favor more extensive Greenland surface melting. The authors find a positive feedback between the variability in the extent of summer Arctic sea ice and melt area of the summer Greenland ice sheet, which affects the Greenland ice sheet mass balance. This linkage may improve the projections of changes in the global sea level and thermohaline circulation.http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0391.1
You won't find much of that in the Cryosphere part of the forum...
In 2014, a crack began opening in the Larsen C Ice Shelf—a huge slab of floating ice along the Antarctic Peninsula. By April 2017, only 16 kilometers (10 miles) of ice separated the tip of that crack from the open sea.https://earthobservatory.nasa.gov/IOTD/view.php?id=90021
Predicting when the cracking shelf will set loose an iceberg is a challenge because ice fracturing depends on several factors, some of which are poorly understood. The iceberg, which is likely to be the size of Rhode Island, could break off any time from days to years from now, according to scientists from Project MIDAS, a United Kingdom-based group that is monitoring the event.
Eric Rignot, a NASA and University of California-Irvine scientist who has studied Petermann up close, commented:
The ice shelf is slowly but surely falling apart. It has been stable from 1901 till the 2000s, then started to break up, especially in 2010-2012. We have seen the glacier speed up for the first time around 2014-2015. Whether this new crack is significant or not is hard to tell as of now. It is unusual to see cracks forming from the center, they usually start from the sides. This could indicate that the ice shelf has gotten too thin in the middle.
Since all the primary forcings initiating these events were occurring at 'natural' rates (eg over Milankovitch cycles) then I would imagine that the comparatively high rate of human-caused change could see a correspondingly higher rate of response by those same mechanisms today.
Chris Machens: Since a lot of discussions evolve around the amount of CO2 in the atmosphere, is it yet possible to quantify projected seismic uptake in relation to particular emission scenarios, based on past events or modelling, or is this easier when comparing sea level heights?http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/
Bill McGuire: It is not possible to link the level of seismic response to particular emissions scenarios in any meaningful way. This is because each active fault is in a different state of strain at any given time, so will respond in a different manner to stress and strain changes that accompany the loss of ice cover or increase in sea level. Where a fault is primed, however, its rupture may be triggered by a pressure change that is literally comparable to that exerted by a handshake. In such circumstances, the environmental changes promoted by climate change could be expected to provide such a trigger.
Bølling–Allerød Interstade (BA), is a widespread abrupt warming event in the Northern Hemisphere during the deglacial transition, essentially synchronous in Alaska and Greenland (Praetorius and Mix, 2014).https://www.researchgate.net/publication/306418361_Interaction_between_climate_volcanism_and_isostatic_rebound_in_Southeast_Alaska_during_the_last_deglaciation
The sea-surface warming of ∼3 ◦C in the Gulf of Alaska (GOA) record occurs abruptly (in <90 yrs), consistent with ice-core records that register this transition as occurring within decades (Steffensen et al., 2008).
The question is what causes the abrupt warming at the onset of the Bølling as seen in the Greenland ice cores. There is a clear antiphasing seen in the deglaciation interval between 20 and 10 ka. During the first half of this period, Antarctica steadily warmed, but little change occurred in Greenland. Then, at the time when Greenland’s climate underwent an abrupt warming, the warming in Antarctica stopped. A possible hypothesis can be that a sudden increase of the northward heat transport draws more heat from the south, and leads to a strong warming in the north. This “heat piracy” from the South Atlantic has been formulated by Crowley (1992). A logical consequence of this heat piracy is the Antarctic Cold Reversal (ACR) during the Northern Hemisphere warm Bølling/Allerød.http://epic.awi.de/41137/1/polfor_2016_013.pdf
July 16, 2009 BOULDER—By simulating 8,000 years of climate with unprecedented detail and accuracy, a team led by scientists from the University of Wisconsin–Madison and the National Center for Atmospheric Research (NCAR) has found a new explanation for the last major period of global warming, which occurred about 14,500 years ago.https://www2.ucar.edu/atmosnews/news/809/new-cause-past-global-warming-revealed-massive-modeling-project
In a period called the Bølling-Allerød warming, global sea level rose by 16 feet and temperatures in Greenland soared by up to 27 degrees Fahrenheit over several hundred years. The new study shows how increased carbon dioxide, strengthening ocean currents, and a release of ocean-stored heat could have combined to trigger the warming.
Using a high-resolution TCC-resolved regional model, it is found that this decadal-scale accumulation of OCAPE ultimately overshoots its intrinsic threshold and is released abruptly (~1 month) into kinetic energy of TCC, with further intensification from cabbeling. TCC has convective plumes with approximately 0.2–1-km horizontal scales and large vertical displacements (~1 km), which make TCC difficult to be resolved or parameterized by current general circulation models. The simulation herein indicates that these local TCC events are spread quickly throughout the OCAPE-contained basin by internal wave perturbations. Their convective plumes have large vertical velocities (~8–15 cm s−1) and bring the WSW to the surface, causing an approximate 2°C sea surface warming for the whole basin (~700 km) within a month. This exposes a huge heat reservoir to the atmosphere, which helps to explain the abrupt Bølling–Allerød warming.http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0675.1
Abrupt changes in climate have occurred in many locations around the globe over the last glacial cycle, with pronounced temperature swings on timescales of decades or less in the North Atlantic. The global pattern of these changes suggests that they reflect variability in the Atlantic meridional overturning circulation (AMOC). This review examines the evidence from ocean sediments for ocean circulation change over these abrupt events. The evidence for changes in the strength and structure of the AMOC associated with the Younger Dryas and many of the Heinrich events is strong. Although it has been difficult to directly document changes in the AMOC over the relatively short Dansgaard-Oeschger events, there is recent evidence supporting AMOC changes over most of these oscillations as well. The lack of direct evidence for circulation changes over the shortest events leaves open the possibility of other driving mechanisms for millennial-scale climate variability.http://annualreviews.org/doi/abs/10.1146/annurev-marine-010816-060415
Elucidating the source(s) of Meltwater Pulse 1a, the largest rapid sea level rise caused by ice melt (14–18 m in less than 340 years, 14,600 years ago), is important for understanding mechanisms of rapid ice melt and the links with abrupt climate change. Here we quantify how much and by what mechanisms the North American ice sheet could have contributed to Meltwater Pulse 1a, by driving an ice sheet model with two transient climate simulations of the last 21,000 years. Ice sheet perturbed physics ensembles were run to account for model uncertainties, constraining ice extent and volume with reconstructions of 21,000 years ago to present. We determine that the North American ice sheet produced 3–4 m global mean sea level rise in 340 years due to the abrupt Bølling warming, but this response is amplified to 5–6 m when it triggers the ice sheet saddle collapse.http://onlinelibrary.wiley.com/doi/10.1002/2016GL070356/full
We evaluate the timing and climate context of a deglacial volcanic sequence from Southeast Alaska.http://www.sciencedirect.com/science/article/pii/S0012821X16303892 https://www.researchgate.net/publication/306418361_Interaction_between_climate_volcanism_and_isostatic_rebound_in_Southeast_Alaska_during_the_last_deglaciation
We document an increase in volcanism in response to deglacial ice loss and isostatic rebound.
These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity.
An increase in regional climate variability is associated with the interval of intense volcanism.
This study illustrates a two-way coupling of climate and volcanism across time scales.
The sudden increase in volcanic activity from the MEVF coincides with the onset of Bølling–Allerød interstadial warmth, the disappearance of ice-rafted detritus, and rapid vertical land motion associated with modeled regional isostatic rebound in response to glacier retreat. These data support the hypothesis that regional deglaciation can rapidly trigger volcanic activity. Rapid sea surface temperature fluctuations and an increase in local salinity (i.e., δ18Osw) variability are associated with the interval of intense volcanic activity, consistent with a two-way interaction between climate and volcanism in which rapid volcanic response to ice unloading may in turn enhance short-term melting of the glaciers, plausibly via albedo effects on glacier ablation zones.
Two plausible mechanisms could have linked the interval of isostatic adjustment with enhanced volcanism: 1) increased melt production generated through decompression in the shallow mantle (Maclennan et al., 2002), or 2) reduced storage time of crustal magmas through regional adjustment in crustal stress and enhanced dike formation (Rawson et al., 2016). The near-zero timelag between regional isostatic adjustment and an abrupt increase in volcanic eruptive frequency in Southeast Alaska suggests the latter scenario is more plausible, or at least the dominant mechanism.
Supporting this supposition is the rapid mobilization of differentiated magma through multiple vents. Decompression melting would not likely have produced differentiated magmas on the time-frames observed, while previous work by others has shown that the Mount Edgecumbe magma chamber likely contained cupolas above the main basaltic chamber that already contained the more siliceous material (e.g. Myers and Sinha, 1985; Riehle et al., 1992b).
The rapid response of the Southeast Alaska system contrasts with inferred lags of volcanism several thousand years behind sealevel rise in global compilations (Kutteroff et al., 2013; Watt et al., 2013). It is plausible to think that some volcanic systems may have longer lag times behind local unloading; for example, arc systems in thicker continental crust may have longer response times (Rawson et al., 2016) than relatively isolated volcanic systems with shallow magma chambers, such as in Southeast Alaska (Riehle et al., 1994). Nevertheless, our findings highlight the importance of well-constrained regional studies to understand the rates and sensitivity of interactions between surface processes and volcanic activity.
The δ18Osw reconstruction reveals low values, implying freshening of surface waters, between 14.6 and 14.0 ka. Although the rapid freshening of surface waters coincides with abrupt warming, the interval of freshening is not uniquely linked to the warmest temperatures, as there are intervals within the BA with equivalently high SSTs that do not show an apparent decrease in δ18Osw.
The interval with greatest apparent freshening and high variance in δ18Osw coincides with the interval of deposition of basaltic tephra, which is coeval with the rapid warming and disappearance of ice-rafted debris (IRD) at the onset of the Bølling Interstade (Fig. 5, Fig. S5). Although these initial tephra layers are thin (0.5 cm), the deposition of dark tephra in the ablation zone of glaciers could have reduced albedo of the snow and ice surfaces (Conway et al., 1996), thereby promoting rapid melting and accelerated local meltwater output along with deglaciation. This mechanism would likely have enhanced freshwater runoff into the Alaskan coastal currents during deglaciation, and this influx of low δ18O water would in turn have influenced the isotopic composition of near-surface waters.
Although firm attribution of specific causal relationships is difficult with only a few events, it is plausible that both hemispheric and regional forcings contribute to climate variability in the GOA region. While direct radiative-forcing effects from individual eruptions are unlikely to lead to long-term cooling due to the relatively short residence time of volcanic aerosols in the upper atmosphere (1–3 yrs), a prolonged increase in the frequency of eruptions could lead to either warming or cooling perturbations through ice-albedo, sea-ice, or CO2 feedbacks.
Modeling studies suggest that hemispheric cooling of decades to centuries can be initiated by the effects of multiple eruptions (McGregor et al., 2015; Pollack et al., 1993), or sea-ice feedbacks (Miller et al., 2012).
Sustained intervals of volcanism during the deglaciation may also have contributed to warming through increased CO2 emissions (Huybers and Langmuir, 2009), and ice-albedo feedbacks. Tephra deposited in the ablation zone of glaciers accelerates melting because the tephra (>5 μm) tends to remain at the ice surface as the glacier retreats (Conway et al., 1996).
Tephra that was once covered in the accumulation zone will at some point be uncovered in the ablation zone, where its growing concentration at the ice surface may provide a feedback for glacial melting in models (Peltier and Marshall, 1995).
In some instances thick ash (>10 mm) can act as a short-term insulating layer on glaciers (Dragosics et al., 2016), delaying melting in areas proximal to the vent, but the wider dispersal of finer ash particles will likely more than compensate this localize insulating effect through a greater surface area over which thin tephra layers will act to increase ablation rates.
Given the evidence for rapid retreat of marine terminating glaciers preceding/coinciding with the interval of frequent volcanic tephra deposition from the MEVF, it is plausible that tephra deposited on these regional glaciers would have an nearly immediate impact on melt rates in the already-expanding ablation zones. Thus, rapid responses of Alaskan volcanic systems to initial deglaciation may have accelerated ice losses in the region.
The large number of volcanoes in the Pacific “Ring of Fire”, coupled with the prevailing westerly winds, make deposition of tephra on the Laurentide and Cordilleran ice sheets (Fig. 1) a potential contributor to glacial wasting and ice-sheet instability
Greenhouse gases are considered one of the powerful feedback mechanisms in the ice age cycle. Might deglacial volcanism contribute to this effect? The rise of atmospheric CO2 during the first half of the deglaciation (18–15 ka) was likely sourced primarily from processes related to organic matter, as shown by δ13C (Schmitt et al., 2012; Bauska et al., 2016), plausibly through a decrease in the net strength of the ocean’s biological pump, which yields CO2 depleted in 13C relative to the atmosphere.
Later in the deglaciation (<15 ka), further trends of rising CO2 are not associated with long-term 13C depletion, and therefore could include contributions from either ocean warming or volcanic CO2, which both yield CO2 rise not depleted in 13C relative the background atmospheric values. Superimposed in these larger trends are abrupt (∼10 ppm) rises in atmospheric CO2 near 16–16.5 ka, 14.5–14.7 ka, and 11.5–12 ka (Marcott et al., 2014).
Carbon isotope data from ice core CO2 constrain the youngest and oldest of these abrupt rises to be sourced primarily from organic carbon reservoirs, most likely on land (Bauska et al., 2016), but could allow partial contributions from other sources including volcanic CO2.
The abrupt rise in atmospheric CO2 near 14.7–14.5 ka, however, has no discernable change in atmospheric δ13C (Bauska et al., 2016) implying that it cannot be sourced from oxidation of organic matter and therefore may be consistent with volcanic sources that responded relatively quickly to deglacial unloading.
This finding is consistent with the hypothesis that ice-unloading can trigger volcanism. We find no significant lag between the timing of major ice retreat and the onset of volcanism, suggesting that the volcanic response to deglaciation is rapid in this region. Between 14.6–13.1 ka, the MEVF exhibited an eruption recurrence interval of ∼1.5 events/century based on the macroscopic tephra-fall units identified in this study.
Early in the eruptive sequence, basaltic tephra is associated with surface water freshening (implied by anomalously low δ18Osw), suggesting that in this region, volcanism triggered by deglacial unloading may plausibly accelerate melting and water runoff through an albedo effect of dark tephra on snow and ice. With this insight from a well constrained regional study, re-examination of the integrated sulfate record from the Greenland ice core suggests that sustained early deglacial volcanism could accelerate rapid melting of some northern hemisphere glaciers through a reduction in surface albedo. Regional volcanism may thus play a significant role in century-to millennial scale climate change during the deglaciation.
Since there is no dedicated topic yet, here it is now.
Try the 5 pages of discussions here
The topic has since moved on to discuss other PIG calvings as they happen.
The image shows sea ice breaking away from the Thwaites Ice Shelf; so the image does not indicate any significant iceberg calving.
We've had a calving event. Movement in the ice in front of the glacier.
edit= http://go.nasa.gov/2dXXbMV http://go.nasa.gov/2eaK3Ur
Those two pix show a big berg and a shadow. The shadow is just over two miles from where the berg was and is there several days in a row.
Stefan Rahmstorf October 9th Iceland presentation of recent science confirming AMOC slowdown.Btw. made the same mistake, but per video info from University of Iceland on May 27th 2016 at the conference "The Past, the Future. How Fast, How Far? Threats Facing the Climate System"
further, it is not clear that an abrupt increase in SLR would increase the frequency of earthquakes leading to a possible triggering of the Clathrate Gun Hypothesis on a decadal-time-scale. Nevertheless, the linked Wikipedia article discusses the Clathrate Gun Hypothesis and references Obata & Shibata (2012)
.. increase the frequency of earthquakes leading to a possible triggering of the Clathrate Gun Hypothesis
Methane hydrate destabilisation is clearly a real worry, particularly in the context of warming ocean waters in the East Siberian Continental Shelf. It is also a concern around Greenland, where uplift as the ice continues to melt seems likely to raise submarine deposits around the margins more rapidly than sea level increases, thus having the potential to cause destabilisation of methane hydrates contained therein as a consequence of reduced pressures. I don’t think, however, that warming is likely to directly affect the operation of any tectonic faults within the East Siberian Shelf itself. If anything, as sea levels continue to rise, submarine faults – in general – will become more stabilised beneath the increasing load.http://climatestate.com/2014/10/16/methane-hydrate-destabilisation-is-clearly-a-real-worry-particularly-in-the-context-of-warming-ocean-waters-in-the-east-siberian-continental-shelf/
After the death of wild boar, a report from the Anses had highlighted the strong suspicion as to the hydrogen sulphide emissions (H2S) from the decomposing algae
storm triggered heavy flooding in towns along the La Guajira peninsula of Colombia, but damage overall was minimal. Some officials were even grateful for the rain after a multi-year drought in the poverty-stricken area.https://www.yahoo.com/news/mega-hurricane-matthew-threatens-jamaica-haiti-cuba-040643990.html
"Families that evacuated are returning to their homes," said La Guajira Gov. Jorge Velez. "The dikes and wells filled up, the earth is moist, and this benefits agriculture in an area where it hasn't rained for five years, benefiting the community."
Authorities say that at least 27 houses were damaged and two roads were washed out. One person, a 67-year indigenous man, was carried away to his death by a flash flood in an area where it hadn't rained for four years.
The National Snow and Ice Data Center in Colorado said the sea ice reached its summer low point on Saturday, extending 4.14m sq km (1.6m sq miles). That’s behind only the mark set in 2012, 3.39m sq km.https://www.theguardian.com/environment/2016/sep/16/arctic-sea-ice-shrinks-to-second-lowest-level-ever-recorded
Center director Mark Serreze said this year’s level technically was 10,000 sq km less than 2007, but that’s so close the two years are essentially tied.
... this only raises new questions as to why the ice shelf is lower here, where the water drains, what accounts for the extreme meandering, and why it is not central as at Petermann. The elevated fold, which casts shadows at this high resolution, remains an unexplained oddity as does the point of compression wave refraction.
Recent work has shown that surface-to-bed drainage systems re-form annually on parts of the Greenland ice sheet and some High Arctic glaciers, leading to speed-up events soon after the onset of summer melt. Surface observations and geophysical data indicate that such systems form by hydrologically driven fracture propagation (herein referred to as ‘hydrofracturing’), although little is known about their characteristics. Using speleological techniques, we have explored and surveyed englacial drainage systems formed by hydrofracturing in glaciers in Svalbard, Nepal and Alaska.https://www.igsoc.org/journal/55/191/j08j038.pdf
In Hansbreen, Svalbard, vertical shafts were followed through 60 m of cold ice and 10 m of temperate basal ice to a subglacial conduit. Deep hydrofracturing occurred at this site due to a combination of extensional ice flow and abundant surface meltwater at a glacier confluence. The englacial drainage systems in Khumbu Glacier, Nepal, and Matanuska Glacier, Alaska, USA, formed in areas of longitudinal compression and transverse extension and consist of vertical slots that plunge down-glacier at angles of 558 or less.
The occurrence of englacial drainages initiated by hydrofracturing in diverse glaciological regimes suggests that it is a very widespread process, and that surface-to-bed drainage can occur wherever high meltwater supply coincides with ice subjected to sufficiently large tensile stresses.
Theoretical considerations indicate that hydrologically driven propagation of surface fractures will occur where a combination of tensile stresses and water pressure is large enough to overcome the fracture toughness of the ice (Ro¨thlisberger and Lang, 1987; Van der Veen, 1998, 2007; Alley and others, 2005).
Surface fractures can penetrate all the way to the glacier bed if water supply is great enough to fill the expanding fracture and offset freezing onto the walls. It has been argued that supraglacial ponds play a crucial role in this process, by providing an elevated head of water at the ice surface (Hagen and others, 1991; Boon and Sharp, 2003; Alley and others, 2005).
Once established, fractures provide high hydraulic conductivity pathways through the glacier, which may then be enlarged into moulins by flowing water. If the fracture or moulin does not completely close during the winter months, it may be reactivated in the following melt season.
Surface meltwater that reaches the base of an ice sheet creates a mechanism for the rapid response of ice flow to climate change. The process whereby such a pathway is created through thick, cold ice has not, however, been previously observed. We describe the rapid (<2 hours) drainage of a large supraglacial lake down 980 meters through to the bed of the Greenland Ice Sheet initiated by water-driven fracture propagation evolving into moulin flow.http://science.sciencemag.org/content/320/5877/778.full
Drainage coincided with increased seismicity, transient acceleration, ice-sheet uplift, and horizontal displacement. Subsidence and deceleration occurred over the subsequent 24 hours. The short-lived dynamic response suggests that an efficient drainage system dispersed the meltwater subglacially. The integrated effect of multiple lake drainages could explain the observed net regional summer ice speedup.