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The degree that this is correct is slightly debatable but the severity of it is highly debatable.
3, The earth has not warmed to any measurable way (morethan the accuracy of the instrumentation) since 1998. Perhaps it has already stoped. Surely we can now consider the predictions of the famous hockey stick and IPCC forcasts to be in th ebottom half of their range for 2100.
4. An average shift of +3-4c would drive the ecosystems of the world further towards the poles by 200 to 300 miles or so. Again, surely we can now discount this.... But do you consider the life a few hundred miles south of you to be very bad or is it actually a bit nicer weather wise?
BETWEEN THREE AND FOUR DEGREES OF WARMING The stream of refugees will now include those fleeing from coasts to safer interiors – millions at a time when storms hit. Where they persist, coastal cities will become fortified islands. The world economy, too, will be threadbare. As direct losses, social instability and insurance payouts cascade through the system, the funds to support displaced people will be increasingly scarce. Sea levels will be rampaging upwards – in this temperature range, both poles are certain to melt, causing an eventual rise of 50 metres. “I am not suggesting it would be instantaneous. In fact it would take centuries, and probably millennia, to melt all of the Antarctic’s ice. But it could yield sea-level rises of a metre or so every 20 years – far beyond our capacity to adapt.Oxford would sit on one of many coastlines in a UK reduced to an archipelago of tiny islands. More immediately, China is on a collision course with the planet. By 2030, if its people are consuming at the same rate as Americans, they will eat two-thirds of the entire global harvest and burn 100m barrels of oil a day, or 125% of current world output. That prospect alone contains all the ingredients of catastrophe. But it’s worse than that: “By the latter third of the 21st century, if global temperatures are more than three degrees higher than now, China’s agricultural production will crash. It will face the task of feeding 1.5bn much richer people – 200m more than now – on two thirds of current supplies.” For people throughout much of the world, starvation will be a regular threat; but it will not be the only one. The summer will get longer still, as soaring temperatures reduce forests to tinderwood and cities to boiling morgues. Temperatures in the Home Counties could reach 45C – the sort of climate experienced today in Marrakech. Droughts will put the south-east of England on the global list of water-stressed areas, with farmers competing against cities for dwindling supplies from rivers and reservoirs. Air-conditioning will be mandatory for anyone wanting to stay cool. This in turn will put ever more stress on energy systems, which could pour more greenhouse gases into the air if coal and gas-fired power stations ramp up their output, hydroelectric sources dwindle and renewables fail to take up the slack. The abandonment of the Mediterranean will send even more people north to “overcrowded refuges in the Baltic, Scandinavia and the British Isles. Britain will have problems of its own. As flood plains are more regularly inundated, a general retreat out of high risk areas is likely. Millions of people will lose their lifetime investments in houses that become uninsurable and therefore unsaleable? The Lancashire/Humber corridor is expected to be among the worst affected regions, as are the Thames Valley, eastern Devon and towns around the already flood-prone Severn estuary like Monmouth and Bristol. The entire English coast from the Isle of Wight to Middlesbrough is classified as at ‘very high’ or ‘extreme’ risk, as is the whole of Cardigan Bay in Wales. One of the most dangerous of all feedbacks will now be kicking in – the runaway thaw of permafrost. Scientists believe at least 500 billion tonnes of carbon are waiting to be released from the Arctic ice, though none yet has put a figure on what it will add to global warming. One degree? Two? Three? The pointers are ominous. As with Amazon collapse and the carbon-cycle feedback in the three-degree worldstabilising global temperatures at four degrees above current levels may not be possible. If we reach three degrees, therefore, that leads inexorably to four degrees, which leads inexorably to five? Chance of avoiding four degrees of global warming: poor if the rise reaches three degrees and triggers a runaway thaw of permafrost.
6, Why would we want to? What do you think is the worste thing that is expected to happen?
BETWEEN FIVE AND SIX DEGREES OF WARMING Although warming on this scale lies within the IPCC’s officially endorsed range of 21st-century possibilities, climate models have little to say about what Lynas, echoing Dante, describes as “the Sixth Circle of Hell”. To see the most recent climatic lookalike, we have to turn the geological clock back between 144m and 65m years, to the Cretaceous, which ended with the extinction of the dinosaurs. There was an even closer fit at the end of the Permian, 251m years ago, when global temperatures rose by – yes – six degrees, and 95% of species were wiped out. That episode was the worst ever endured by life on Earth, the closest the planet has come to ending up a dead and desolate rock in space.” On land, the only winners were fungi that flourished on dying trees and shrubs. At sea there were only losers. Warm water is a killer. Less oxygen can dissolve, so conditions become stagnant and anoxic. Oxygen-breathing water-dwellers – all the higher forms of life from plankton to sharks – face suffocation. Warm water also expands, and sea levels rose by 20 metres.” The resulting “super-hurricanes” hitting the coasts would have triggered flash floods that no living thing could have survived. There are aspects of the so-called “end-Permian extinction” that are unlikely to recur – most importantly, the vast volcanic eruption in Siberia that spread magma hundreds of metres thick over an area bigger than western Europe and shot billions of tonnes of CO2 into the atmosphere. That is small comfort, however, for beneath the oceans, another monster stirred – the same that would bring a devastating end to the Palaeocene nearly 200m years later, and that still lies in wait today. Methane hydrate. What happens when warming water releases pent-up gas from the sea bed: First, a small disturbance drives a gas-saturated parcel of water upwards. As it rises, bubbles begin to appear, as dissolved gas fizzles out with reducing pressure – just as a bottle of lemonade overflows if the top is taken off too quickly. These bubbles make the parcel of water still more buoyant, accelerating its rise through the water. As it surges upwards, reaching explosive force, it drags surrounding water up with it. At the surface, water is shot hundreds of metres into the air as the released gas blasts into the atmosphere. Shockwaves propagate outwards in all directions, triggering more eruptions nearby. The eruption is more than just another positive feedback in the quickening process of global warming. Unlike CO2, methane is flammable. Even in air-methane concentrations as low as 5%, the mixture could ignite from lightning or some other spark and send fireballs tearing across the sky. The effect would be much like that of the fuel-air explosives used by the US and Russian armies – so-called “vacuum bombs” that ignite fuel droplets above a target. According to the CIA, those near the ignition point are obliterated. Those at the fringes are likely to suffer many internal injuries, including burst eardrums, severe concussion, ruptured lungs and internal organs, and possibly blindness.” Such tactical weapons, however, are squibs when set against methane-air clouds from oceanic eruptions. Scientists calculate that they could “destroy terrestrial life almost entirely (251m years ago, only one large land animal, the pig-like lystrosaurus, survived). It has been estimated that a large eruption in future could release energy equivalent to 108 megatonnes of TNT – 100,000 times more than the world’s entire stockpile of nuclear weapons. Not even Lynas, for all his scientific propriety, can avoid the Hollywood ending. “It is not too difficult to imagine the ultimate nightmare, with oceanic methane eruptions near large population centres wiping out billions of people – perhaps in days. Imagine a ‘fuel-air explosive’ fireball racing towards a city – London, say, or Tokyo – the blast wave spreading out from the explosive centre with the speed and force of an atomic bomb. Buildings are flattened, people are incinerated where they stand, or left blind and deaf by the force of the explosion. Mix Hiroshima with post-Katrina New Orleans to get some idea of what such a catastrophe might look like: burnt survivors battling over food, wandering far and wide from empty cities. Then would come hydrogen sulphide from the stagnant oceans. “It would be a silent killer: imagine the scene at Bhopal following the Union Carbide gas release in 1984, replayed first at coastal settlements, then continental interiors across the world. At the same time, as the ozone layer came under assault, we would feel the sun’s rays burning into our skin, and the first cell mutations would be triggering outbreaks of cancer among anyone who survived. Dante’s hell was a place of judgment, where humanity was for ever punished for its sins. With all the remaining forests burning, and the corpses of people, livestock and wildlife piling up in every continent, the six-degree world would be a harsh penalty indeed for the mundane crime of burning fossil energy.
Algy,In an attempt to keep it snappy, do you have anyscience that supports a +6c temperature rise? Presmumably by 2100???
Quote from: Tim the Plumber on 12/08/2016 15:21:37Algy,In an attempt to keep it snappy, do you have anyscience that supports a +6c temperature rise? Presmumably by 2100???That is just a what if worst case scenario that maybe might happen (probably after 2100) if everything goes wrong. It is still a possibility though and I'd rather not risk the future of my potential offspring if I can help it.
So can you actually quote any science what so ever that supports your assertion or is it just drivel?
Shouting drivel should not be done on a science forum.
The bad science of CAGW is currently killing loads of people per year. The figure of 200K is the lowest estimate but I put the practice of using food as fuel at killing at least 20 million per year. Poorest billion people paying 70% more than they should be for food.
Surely the University of Cambridge has some sort of responsibility to not have alarmist drivel spouted as science???
There is indeed at least a plausible risk of runaway climate change.... and +6 degrees might even be an understatement.https://en.wikipedia.org/wiki/Runaway_climate_changeFurther +6 degrees could be a worse ecological disaster than when the dinosaurs copped it.inghttp://palaeo.gly.bris.ac.uk/Benton/reprints/2003TREEPTr.pdfIt would be extreme pig headed stupidity to deny research or debate on the topic. Almost as bad as believing that we know for sure the answer ether way.
Why has the earth not gone down this road in the past when the temperature was much higer than now often with very much higher levels of CO"?
6. What are the potential dangers of using geo-engineering techniques to try cooling the earth?
There is another scenario that is not discussed. Say the climate change, we are experiencing is part of a natural cycle of the earth, not dependent on manmade. Instead, we are living during one of those times that has occurred before and will occur again. The end of the last ice age was connected to natural climate change. This cycle of global warming and climate change melted more squares miles of glaciers than we have left, even without man being part of the equation.
The question becomes what does humanity do, if climate change can't be fixed with more taxes and new regulations? For example, countries may not be able to afford bailing out more and more human disasters, due to people wanting to build and remain in places of high risk. This may be due to thinking regulation is fixing the problem, due to spin and propaganda. While the calculated safer zones get so crowded, as to create unanticipated problems. The current stating of thinking; humans did it and humans can fix it, could be placing all our eggs in the wrong basket, wasting time and resources, fooling ourselves into thinking this is all about humans and not about nature. There is comfort in thinking, if we; humans, change our behavior, we can appease the gods of climate. But what if the gods of climate already bought the ticket and are riding to a destination?
The new earth may be for the better, but the transition time would be very unsettled, and would test the instincts of humanity.
One scenario that nobody is talking about, is connected to the discovery of huge deposits of water in the mantle, below the earth's crust. For example, an ocean sized deposit was found under south east Asia. If this deposit breaks the crust and leaks into the oceans, the oceans will warm. Water under the high pressure and temperature conditions of the mantle is not your normal water. Water exists in a state beyond hydrothermal, called super ionic water. Changes in pressure can cause this super sonic phase of water, to explode, fracturing the crust.
Scientists have also found a huge scar, on the floor of the Atlantic ocean, where the mantle is exposed and the crust is gone. This way well be connected to a previous hot water release from the mantle.