A seemingly compelling counterargument, often reused in the media, is that none of the glacial-interglacial transitions of the past 400 kyr shows a sudden, large methane-spike, suggesting that abrupt, large-scale methane outbursts are unlikely. One might appeal to such abrupt events being below the temporal resolution of the rock record in explanation, but absent such spikes the safest answer is to say that large-scale interglacial outbursts did not occur during that time.
This time, however, is different. Anthropogenic warming has interrupted the Glacial-Interglacial cycle of the Quaternary (Ganopolski et al., 2016; Haqq-Misra, 2014) and there will be no coming Ice-Age n-1000 years from now to reseal all of this volatile Carbon, as happened at the end of each previous interglacial. This now-broken cyclicity is one reason why catastrophic reservoir-collapse has never occurred in the past and we should not take any comfort from that lack of precedent as never before has an Interglacial period been combined with annual, planetary-scale thermal forcing.
While high CO₂ levels have been present in Earth's atmosphere before (e.g., during the Cambrian and Archaean) without initiating either the moist or runaway greenhouse state, never has the rate of warming been annual in scale as today. The question is not whether anthropogenic emissions could initiate these greenhouse states, but whether Arctic clathrate release could. The IPCC 3rd Assessment Report (2001) concluded that rapid increase in atmospheric methane from the release of buried clathrate reservoirs would be "exceptionally unlikely", at < 1% chance, a figure revised up to 10% by the following report in 2008.
Yet the Mars observations show that abrupt, cascading devolatilisation occurs readily in nature, and there is nothing about these observations to suggest that this process is not portable or scalable to Earth. That ESAS lacks Mars' mound-density makes the scaling no less valid, the methane-supersaturation of 80% of ESAS bottom waters (Shakhova et al., 2010) showing that frost mounds are not the sole venting pathway, gas migration pathways growing in capacity annually in the areas of greatest emissions (Shakhova et al., 2017).
Destabilisation of the shallow-marine clathrates of ESAS continues to be excluded from every global climate model
Cid_Yama wrote:I think I've come up with a temporary fix that could at least buy us time. Could we not create our own manmade freshwater pulse? I'm sure we could engineer a placement for nukes in the Greenland ice cap for maximum effect.
link
This is something we actually have the means to do. We have the knowledge.
link
This is the first time in a decade I've felt we have a way out.
What do you all think? This is the first time you've seen a hopeful Cid Yama. It may not be over.
(And it's a good way to dispose of all the world's nukes, as this would be a monumental undertaking. Geoengineering on a massive scale requiring perhaps all of them, reengineered for this purpose.)
The ocean apparently circulates in such a way that freshwater released farther northward near the Arctic can much more easily interrupt the sinking of surface waters in the Greenland and Labrador Sea that sets the pace of the Atlantic Meridional Overturning Circulation.
The Younger Dryas event was not like any normal climate change as therefore was bound to have impacts on the world. It is said that temperature fluctuations not only occurred before and after but also during the phenomenon. In England, the glaciers started to form which was caused by extremely low temperatures while in Holland the temperatures were below -20°C when the winter season came. Of all regions affected by the YD, in Greenland, the effects were felt the most with the ice cores recording a temperature drop of 15°C. The trees were also affected in most of Europe and alpines and tundra were dominant after the trees retreated. This period affected even Syria where drought hit the ancient community of Abu Hurerya.
Keeping global warming to within 1.5-2 degrees C may be more difficult than previously assessed, according to researchers.
An international team of scientists has published a study in the Proceedings of the National Academy of Sciences (PNAS) showing that even if the carbon emission reductions called for in the Paris Agreement are met, there is a risk of Earth entering what the scientists call "Hothouse Earth" conditions.
Crossing that threshold "guarantees a climate 4-5 Celsius (7-9 Fahrenheit) higher than pre-industrial times, and sea levels that are 10 to 60 meters (30-200 feet) higher than today," cautioned scientists in the Proceedings of the National Academy of Sciences.
And that "could be only decades ahead," they said.... The impacts would be "massive, sometimes abrupt and undoubtedly disruptive"
"Places on Earth will become uninhabitable if 'Hothouse Earth' becomes the reality," said co-author Johan Rockstrom, executive director of the Stockholm Resilience CentreResearchers suggest the tipping point could come once the Earth warms to 3.6 Fahrenheit (2 Celsius) over pre-industrial times.
The planet has already warmed 1 C over pre-industrial times, and is heating up at a rate of 0.17 C per decade.
"A 2 C warming could activate important tipping elements, raising the temperature further to activate other tipping elements in a domino-like cascade that could take the Earth System to even higher temperatures," said the report.
The authors of the study consider 10 natural feedback processes, some of which are "tipping elements" that lead to abrupt change if a critical threshold is crossed. These feedbacks could turn from being beneficial, by storing carbon, to a source of uncontrollable emission in a warmer world. These feedbacks are permafrost thaw, loss of methane hydrates from the ocean floor, weakening land and ocean carbon sinks, increasing bacterial respiration in the oceans, Amazon rainforest dieback, boreal forest dieback, reduction of northern hemisphere snow cover, loss of Arctic summer sea ice, and reduction of Antarctic sea ice and polar ice sheets.
All of these processes are interconnected, the authors note, and the collapse of one could trigger another.
"The risk of tipping cascades could be significant at a 2 C temperature rise, and could increase sharply beyond that point."
"This cascade of events may tip the entire Earth system into a new mode of operation," said co-author Hans Joachim Schellnhuber, Director of the Potsdam Institute for Climate Impact Research..The "carrying capacity" of a 4 C or 5 C degree world, he has said previously, could drop to a billion people
http://www.pnas.org/content/early/2018/07/31/1810141115
... Some are concerned that the authors' faith in humanity to grasp the serious nature of the problem is misplaced.
"Given the evidence of human history, this would seem a naive hope," said Prof Chris Rapley, from University College London.
"At a time of the widespread rise of right-wing populism, with its associated rejection of the messages of those perceived as 'cosmopolitan elites' and specific denial of climate change as an issue, the likelihood that the combination of factors necessary to allow humanity to navigate the planet to an acceptable 'intermediate state' must surely be close to zero."
Pops wrote:Luckily we got out of that worthless Paris agreement, plant, we're much better off, even better, freezing the unprofitable CAFE standards will help cool the planet, now if only gov.moonbeam would quit diverting rivers to the ocean the fires would go out...
.
Pops wrote: now if only gov.moonbeam would quit diverting rivers to the ocean the fires would go out...
Return to Environment, Weather & Climate
Users browsing this forum: Tuike and 9 guests