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Most of the articles I've read about this refer to a "tipping point": that we're crossing some line where the behavior of the system will change dramatically.

• lsadam0 10y ago
  I believe the tipping point usually refers to the release of Methane trapped in permafrost? Meaning the permafrost melts, releasing methane, and thus triggering a runaway greenhouse effect. Something like Venus.
  • greglindahl 10y ago
    The other Arctic tipping point is because the ocean absorbs a lot more energy than ice... so once the Arctic loses more ice cover, it will go ice-free and remain that way. Nobody knows when/if the methane problem will happen. The ice/ocean thing can be modeled.
  • jamesblonde 10y ago
    These are the methane clathrates trapped mostly in the siberian sea (Arctic ocean), where increasing sea temperatures are causing methane to bubble up to the surface in large patches (sometimes 1 sq km in size). Runaway global warming by melting methane clathrates is known as the Clathrate Gun Hypothesis: https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis https://en.wikipedia.org/wiki/Clathrate_gun_hypothesis In previous mass extinctions, such as the End of the Permian, 251 million years ago, 96% of species were lost - due to a similar event: " A cataclysmic eruption near Siberia blasted CO2 into the atmosphere. Methanogenic bacteria responded by belching out methane, a potent greenhouse gas. Global temperatures surged while oceans acidified and stagnated, belching poisonous hydrogen sulfide. " https://cosmosmagazine.com/palaeontology/big-five-extinctions https://cosmosmagazine.com/palaeontology/big-five-extinction...
  • Tuna-Fish 10y ago
    Release of all the stored methane would not cause the Earth to turn into Venus. We know this because the process has happened several times, and not only did the Earth not become Venus, it did not come anywhere even remotely close. There is no known process by which climate change would render the Earth uninhabitable. This doesn't mean it's okay. Release of methane has always happened at the same time as major mass extinctions, possibly as the cause of it. It would create massive warming which would make large inhabited parts of the planet much less desirable, play havoc with the biosphere possibly making large areas of farmland unproductive, and in general being a massive economic drain and probably killing a lot of people.
    • jamesblonde 10y ago
      If we talk about the 5 great extinctions on Earth to date, with 96% of life dying out after one of the great methane releases, i think our chances of survival in such an event is minimal. I don't think even a tiny group of humans could retain enough resources and technology to survive the millions of years that would be needed before life regenerates itself.
• walkingolof 10y ago
  Its speculated that it could effect the Gulf stream which transport allot of warm water to northern parts of the Atlantic, which gives especially the Northern part of Europe a relatively mild climate considering the latitude. https://en.wikipedia.org/wiki/Shutdown_of_thermohaline_circulation https://en.wikipedia.org/wiki/Shutdown_of_thermohaline_circu...
  • jamesblonde 10y ago
    It has already affected it to the extent that we have a cold spot out in the North Atlantic (it's been there for about 10 years - caused by melting ice in Greenland, probably): https://climatecrocks.com/2016/03/01/mystery-deepens-around-greenland-cold-spot/ https://climatecrocks.com/2016/03/01/mystery-deepens-around-...
• azernik 10y ago
  "Tipping point" refers to positive feedback loops that you get into above a certain level of ice melt. One is potential methane release, as another commenter pointed out. Another is the reduced albedo of the melted water as opposed to ice - the water will absorb heat from sunshine more easily, and conduct that heat to the ice. There may be more. (Of course, there may also be negative feedback effects I'm not aware of.)
• jpeanuts 10y ago
  The discussion is quite abstract - perhaps that's why it's difficult to grasp. As I understand it, the climate can be regarded as a dynamical system currently existing at a stable equilibrium. I.e. small perturbations to the state tend to be damped. If there's a massive volcanic event, we will have a few cold years, but the climate will return to something familiar. It's stable, as when you add up all the positive and negative feedback effects, the result is negative. The most important negative comes from the thermal radiation of the Earth into space, which increases with increasing temperature, resulting in more cooling. Methane in Siberian ice is a hypothesised positive feedback effect: higher temperature => more methane => more warming. If all these effects ever add up to more than 0 (the "tipping point"), the system will no longer be stable, and will travel around until it finds another stable equilibrium. The actual consequences of this are nowhere stated because they are completely unknown. But we're not talking about measuring sea-levels, we're talking a completely different climate (e.g. Venus).
  • gabrielgoh 10y ago
    Interesting! I've never heard climate science explained this way before. Could you point me to a few papers which expound on this view? I'd be interested to see the mathematical models behind this.
    • MooMooMilkParty 10y ago
      Lorenz's Deterministic Nonperiodic Flow is the earliest work on the topic that I can think of. It's relatively accessible too. http://journals.ametsoc.org/doi/abs/10.1175/1520-0469(1963)020%3C0130%3ADNF%3E2.0.CO%3B2 http://journals.ametsoc.org/doi/abs/10.1175/1520-0469(1963)0...
      • mturmon 10y ago
        Nice pointer. And in particular, Figure 2 of the paper you linked, which shows the simple "Lorenz System" orbiting about a state C for a long time, and then transitioning (at a hard-to-predict time) to a far-away state C'.
  • 10y ago
• lossolo 10y ago
  In Paris climate conference we decided not to rise temperature over 2.8 degrees. If global temperature will rise over 5.5 degrees not the melting of ice will be our biggest problem, crops will die, plankton in seas will die (60% of oxygen production). So the real-world effect will be game over.
  • neffy 10y ago
    No, the temperature has been significantly higher before - to the point that the poles had a tropical climate. Climate change isn't the end of the world, just the end of the world as we know it.
    • Daishiman 10y ago
      Yeah, but that happened slowly enough that species adapted. This is going far, far too rapidly.
      • neffy 10y ago
        Some species survived and adapted, some didn't. Hey, evolution! The available evidence on the onset/offset for major climatic swings over the last 1 million years does suggest between a 10 - 100 year switching time, probably linked to the global conveyor belt currents switching between different states. We have a fairly good understanding of the onset of the current inter-glacial. We don't, because ice cores and other information gets progressively harder to read, the further you go back, know all that much about the onset of a glacial period, but it does appear to be fairly quick. (Not Day after Tomorrow quick, but definitely within a lifetime quick.) We're coming to what would normally be the end of the current inter-glacial, we have record C02 levels, and the gulf stream has been slowing down for the last 20 years. Nobody really knows whats going to happen next - but the UK Met office was apparently sufficiently alarmed to issue a blog post saying absolutely nothing if you read it carefully. Interesting times.
  • memracom 10y ago
    I don't understand this statement. How can a conference decide not to raise global temperature over 2.8 degrees? For that matter, is there any scientific evidence that humans can actually take collective action to slow or stop global temperature increases? It's all well and good to say that if I personally generate less CO2 then I personally will have less impact on temperature rise, but collectively, the impact depends on lots of other people's decisions, on population growth, on animal populations particularly cows. And of course if we are already on a trajectory that will increasingly release methane from clathrates, then what if that dwarfs changes in human activity? There does seem to be some evidence that things like carbon taxes are mainly a bureaucratic boondoggle to enrich some people and to hide CO2 production by shifting it to some place that people don't look at too closely. We must never forget that bureaucracy drives corruption no matter what the underlying political system is. So if people are truly serious about collective human action to slow CO2 production or reverse it, we must be even more serious about cleaning out corruption at all levels in all countries.
• kodroid 10y ago
  http://pca.st/m32F http://pca.st/m32F is a good interview with Michael Mann on this very subject
• fencepost 10y ago
  One of the impacts is increased humidity and heat retention in the atmosphere (warmer air holds more water, water holds heat well), with that higher humidity and energy level translating into more severe storms. At this point I'd be very leery of purchasing anything in areas traditionally considered to be in "100 year flood plains" because those hundred years were measured over very different climate conditions and these days it seems like those 1% floods have become more like 10% floods. One way of visualizing the impact of warming is by thinking of it like a speaker system. If you turn up the volume (adding more energy), does the average position of the speaker cone itself change much? Or is it just the extremes that change? Part of the concern with climate change is similar to that - the baseline temperature is changing upwards in amounts that don't sound that scary (really, what's the big deal about a degree or two?), but what's really going to do the most immediately noticeable damage is going to be the increased dynamic range which may include temporary instances of extreme cold (e.g. Siberia right now) or extreme heat. Another concern though it breaks the analogy a bit, is whether there's a point at which a peak is such that it causes a permanent change to the whole system. In a speaker analogy, that's a blown speaker (torn cone, coil separation, etc.). In climate change/global warming, that may be thawing methane clathrates undersea (methane locked in the crystalline lattice of ice) or other underground methane reservoirs (e.g. in permafrost) thawing and injecting a temporary massive amount of methane into the atmosphere similar to what happens with CO2 in exploding lakes (which accumulate CO2 as carbonic acid until some event triggers a mass release). That shock of methane will be temporary since methane breaks down relatively quickly, but it's also a very potent greenhouse gas and even a geologically-quick few years of ongoing release may trigger massive changes in a relatively short time - changes that won't go backwards even after the methane degrades, and changes that will trigger massive political instability while they're going on. Another possible tipping point might be Greenland's ice sheets - melt on them has been accellerating in recent years, and while the sheet is generally more than a mile thick and would take a long time to melt, it doesn't have to all melt to be a problem. In fact, if it all melted, the average sea level change around the world would be somewhere around 20 feet. (edit: By the way, my reference to a methane "shock" was deliberate - if that happens, the impact may be disturbingly similar to the effect of a chlorine "pool shock" that kills off things in the pool then reverts back to a normal chlorine level as the chlorine breaks down into harmless forms.)
• ChuckMcM 10y ago
  Presumably you've gotten your answer from the follow-ups, the system 'tips over' the edge and goes from being stable (always returning to the mean when the stimulus is removed) to unstable (removing the stimulus doesn't increase stability of the system). The problem with it as a theme is that we really don't have a good idea of how the climate system operates long term, and by long term I mean geologically long term, not human long term. Even if we had pre-recorded satellite views of the planet and detailed measurements for the last 2,000 years that would be 2.6% of the 75 ky Ice Age cycle, and less than 0.0004% of the 50 My extinction cycle, or .000005% of the planet lifecycle. For reference, 2.6% of a solar year is 9 days. Humans measure time in terms of lifetime, its a very natural thing to do and since they typically live 70+ years, if you were to come to someone 9 days after you have first shown up on the planet and said "Can't you see, the temperature is a full 5 degrees warmer than it was when I started taking measurements!" And that human would pat them on the head and say, "Yes, you will see much bigger changes than that as the year goes by, it will get so hot you will will die of heat exhaustion if you stand outside all day without protection, and then later it will get so cold that you would freeze to death." And they aren't afraid and they consider it normal, because they have seen it many times before, over their whole life. But when the same person comes to them and says "The temperature is full 5 degrees warmer than it has been in 2000 years!", the fact that 2,000 years represents 100 - 200 generations of people (depending on how you choose a 'generation') it fills them with fear because nobody they know has ever experienced anything like that, its different, its scary, and its unknown. Back in the day (we're talking the 60's) climate scientists would say "Gee, all of these geological records show that the climate changes in cycles, from very warm to very cold. And they noticed we were coming up on a time when the cycles suggest the end of the inter-glacial period was nigh and we should be looking for the leading edge of the next ice age. Anyway, the planet has been warmer than it is now, its been colder, and it has changed with people present and without them present. The tipping point models have the climate becoming irreversibly destabilized after we pass it, what they don't say is what that means. Does it mean the planet gets really hot? does it mean an ice age starts? Nobody knows and the models don't help.
  • JoeAltmaier 10y ago
    Well, since all the ice has been melting in the last decades, even ice that was geological ages old, that seems to indicate this isn't a 'normal' cycle by any means. Its disingenuous to suggest its explained by short human memory - the measurements are real.