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Let me preface this by saying that I believe climate change and decarbonization to be one of the critical challenges of our time. That said… This article’s tit

by zamfi 4y ago

Let me preface this by saying that I believe climate change and decarbonization to be one of the critical challenges of our time. That said… This article’s title and its content are completely at odds. Here’s a critical passage: > As the ice sheet melts, its surface will be at ever-lower elevations, exposed to warmer air temperatures. Warmer air temperatures accelerate melt, making it drop and warm further. Global air temperatures have to remain elevated for hundreds of years or even longer for this feedback loop to become effective; a quick blip of 2 degrees Celsius (3.6 degrees Fahrenheit) wouldn’t trigger it, Höning said. But once the ice crosses the threshold, it would inevitably continue to melt. Even if atmospheric carbon dioxide were reduced to pre-industrial levels, it wouldn’t be enough to allow the ice sheet to regrow substantially. > “We cannot continue carbon emissions at the same rate for much longer without risking crossing the tipping points,” Höning said. “Most of the ice sheet melting won’t occur in the next decade, but it won’t be too long before we will not be able to work against it anymore.” So…we potentially have hundreds of years to bring temperatures back down before the “tipping point” triggers? Forgive me for not being super alarmed. 100 years ago we’d just barely started dumping carbon into the atmosphere. That is a long time. EDIT: to be clear, yes of course it not enough to stop dumping carbon into the atmosphere in the next hundred years, but it does give us (potentially) decades to figure out large-scale carbon capture and sequestration even if we exceed the thresholds described here (1000 gigatons).

deleted 4y ago
[deleted]
Scarblac 4y ago
Well, once the CO2 is in the air and stays there, the warming will happen. Then hundreds of years later the threshold is passed and then even removing it from the air (something we can't do) won't help anymore. Once we've emitted enough CO2 to reach 2 degrees warming, it will almost certainly happen that all the ice melts. And there's a point where that will be certain, even if we learn how to remove all CO2 we emitted from the atmosphere. Is how I read it. The ice on this island is enough to cause about 7m of global sea level rise on its own, iirc.
- gridspy 4y ago
  Fortunately the CO2 does eventually leave our atmosphere, given about 50 years.
  - Scarblac 4y ago
    That's a lot faster than the numbers I usually see (e.g. Google says 300 to 1000 years).
  - folsom 4y ago
    What is the process that removes CO2?
    - JumpCrisscross 4y ago
      > What is the process that removes CO2? Lots of them [1]. (No free lunch, though. Oceans absorbing carbon makes them acidic.) [1] https://en.wikipedia.org/wiki/Carbon_sink https://en.wikipedia.org/wiki/Carbon_sink
    - thechao 4y ago
      The snowball Earth's (both of them) were caused by excess serpentine weathering. Serpentine is one of the most common minerals in the Earth's crust — like 80% of it. The serpentine is covered in limestone (and other things) which prevents warm-saline erosion of the serpentine, directly. If you look at the tailings from the coal mines in the TVA, you could "just" ship those tailings to the Gulf coast (using the old train systems) and cause a major glacial period, quite quickly, by grinding up the tailings & dumping them in a mile wide strip from Corpus Christi to Miami.
      - akiselev 4y ago
        > Serpentine is one of the most common minerals in the Earth's crust — like 80% of it. Serpentines are common but they do not make up 80% of the crust. Feldspars are the most common minerals in the crust and they make up less than 60% of it [1]. [1] https://deq.nc.gov/energy-mineral-and-land-resources/geological-survey/geoscience-education/mystery-minerals-fact-sheet/open https://deq.nc.gov/energy-mineral-and-land-resources/geologi...
gridspy 4y ago
No, the story is that we begin the melting by raising the earth's temperature a little. You'd think that if we reduced our carbon emissions, the ice would stop melting. > But once the ice crosses the threshold, it would inevitably continue to melt Bear in mind that the atmosphere retains carbon dioxide for ~50 years, that other melt events are dumping methane into the atmosphere from permafrost. It's not just one factor heating the planet.
- realworldperson 4y ago
  [dead]
- graeme 4y ago
  >You'd think that if we reduced our carbon emissions, the ice would stop melting. People think of climate change like a river. You reduce emissions, you reduce the size of the emissions, you reduce the size of the problem. But it's more like a bathtub. Emissions are the water filling the tub, but the real problem is the water level already in the tub. If you reduce emissions, you reduce the size of the flow into the tub. But....water is still flowing in and the water is still rising. If we had zero emissions it would take earth systems much much longer than 50 years to bring things back down to where they were.
  - peteradio 4y ago
    Filling a bath tub requires active control, are you saying humans need to actively control the climate of the entire earth?
    - graeme 4y ago
      Suppose a tub was best at two inches of water, got worse for every inch, and overflowed at four feet. And you had turned on the tap and there is now three feet of water. You propose: 1. Reducing the rate of the tap 2. Turning off the tap 3. Turning off the tap and removing water until it gets back to two inches Most people think of climate change prevention as #1. #3 is what actually gets you back to ideal. But if you get back to that level and then leave the tap off, things are fine and no active management is required.
alex_young 4y ago
From the same page: Previous research identified global warming of between 1 degree to 3 degrees Celsius (1.8 to 5.4 degrees Fahrenheit) as the threshold beyond which the Greenland Ice Sheet will melt irreversibly. We're already at 1.2c above pre-industrial levels. Although it will take a long period of exposure to warm air for the ice to melt, we've already been doing that for a long time. It doesn't seem reasonable to say we have hundreds of years to figure out a solution.
- kiliantics 4y ago
  > It doesn't seem reasonable to say we have hundreds of years to figure out a solution. We've also known about the global warming problem in great detail for well over 50 years at this point. Since then we haven't figured it out but made it worse -- most of our cumulative emissions have happened in just the last 50 years. Why do people still think we can figure this out in a matter of decades without having to drastically change our fossil fuel habits?
  - taylodl 4y ago
    Kick the can down the road. Nothing to see here. Let our progeny figure out how to clean up the mess we created. We're doing the same thing with our debt, too. I'm just going to put it out there - our progeny is going to hate our guts. Then again, maybe afterward humanity will hold us up as an example for what not to do, how not to solve global problems. They'll be able to use history to quickly and effectively shut down the naysayers. Of course that's assuming they bother to learn anything from history...I mean we sure as hell haven't!
    - lizard 4y ago
      As a fairly new parent, I'm not thrilled about the world my daughter will inherit. I struggle with a lot of questions like whether I should raise her to be a "good" person or a "successful" person. But, I've heard that studies show that younger generations are more concerned about the environment. Both in that they are showing an interest in the subject at younger ages and they are more likely than older generations to acknowledge it as an issue that affects them. This suggests that our children may not only be better equipped to handle these issues than we are (assuming we continue to advance science and technology without major catastrophe in the meanwhile), but will be more interested in pursuing these problems both personally and professionally and, in the worst case, more willing to make the necessary sacrifices to see actual change. While I certainly hope we can do more and that I can have some confidence my children will actually be better off than myself, changing the way the world thinks is a very slow and difficult thing to do. It may be the case the best we can accomplish is to hold it together the best we can while teaching our children to care about the world around them, and, when the time comes, step aside to let them solve these problems.
lozenge 4y ago
Stopping emissions (which isn't even in the Overton window) means CO2 concentration will slowly reduce. "Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years. The rest is removed by slower processes that take up to several hundreds of thousands of years, including chemical weathering and rock formation. This means that once in the atmosphere, carbon dioxide can continue to affect climate for thousands of years." During the time of elevated CO2 levels, the temperature continues to rise.
Arnt 4y ago
Temperature is a function of elevation. It's saying that if you move the surface down by removing the top layer of material (ice), the temperature at the surface increases, all else being equal including the temperature at sea level. The effect is real, and big enough to feel with the naked skin. One generally says one kelvin per 100m elevation, although the Greenland surface will be different from that rule of thumb.
- saiya-jin 4y ago
  > One generally says one kelvin per 100m elevation That's not true in Europe nor Asia nor South America nor Africa, although I didn't climb mountains specifically in Greenland to be factual. Better value is cca 0.6C per 100m, or 6C per 1km (sorry, no conversion to feet/yard vs F and similar fun games for lazy sunday afternoon... seriously, with all the love, fix this shit guys, we are not living in 15th century when similar stuff was common and accepted). It depends on many factors including humidity and local meteorology. That part discussed about moving surface down doesn't make sense - you can lower glacier only to base rock/soil level. But at this level, where glacier starts, its already the dreaded temperature they want to avoid, so glaciers should be melting from the bottom with this logic. If they mean that once ice melts the rock temperature rises well yeah, that's a no brainer, its a different surface. Ice has surface temperature below/around 0, any rock hit with sun can easily surpass that even during winter. I know reality is more complex out there, one of my todos is to have sleepover (no tent) on nearby Mer de Glace in Chamonix, France. Just me, gazillion stars, mountains crumbling around me and glacier cracking beneath my ass.
  - Arnt 4y ago
    IMO, if you think you need a more precise estimate than 1K/100m, then you should just get a weather forecast for the relevant area and day.
  - czinck 4y ago
    >But at this level, where glacier starts, its already the dreaded temperature they want to avoid, so glaciers should be melting from the bottom with this logic. Yes, that's generally what happens to glaciers even ignoring climate change. The bottom melts, but is replaced by snow/ice that accumulated on top. Glaciers grow top down, not bottom up. But, if you lower the top so it's warmer, less ice accumulates, which can't replace all that melts, and so you get net shrinking.
Belituio 4y ago
100 years is not a lot. Your kids kids will already be affected. It feels very short sides.

by zamfi 4y ago

deleted 4y ago

[deleted]

Scarblac 4y ago

Well, once the CO2 is in the air and stays there, the warming will happen. Then hundreds of years later the threshold is passed and then even removing it from the air (something we can't do) won't help anymore. Once we've emitted enough CO2 to reach 2 degrees warming, it will almost certainly happen that all the ice melts. And there's a point where that will be certain, even if we learn how to remove all CO2 we emitted from the atmosphere. Is how I read it. The ice on this island is enough to cause about 7m of global sea level rise on its own, iirc.

gridspy 4y ago
Fortunately the CO2 does eventually leave our atmosphere, given about 50 years.
- Scarblac 4y ago
  That's a lot faster than the numbers I usually see (e.g. Google says 300 to 1000 years).
- folsom 4y ago
  What is the process that removes CO2?
  - JumpCrisscross 4y ago
    > What is the process that removes CO2? Lots of them [1]. (No free lunch, though. Oceans absorbing carbon makes them acidic.) [1] https://en.wikipedia.org/wiki/Carbon_sink https://en.wikipedia.org/wiki/Carbon_sink
  - thechao 4y ago
    The snowball Earth's (both of them) were caused by excess serpentine weathering. Serpentine is one of the most common minerals in the Earth's crust — like 80% of it. The serpentine is covered in limestone (and other things) which prevents warm-saline erosion of the serpentine, directly. If you look at the tailings from the coal mines in the TVA, you could "just" ship those tailings to the Gulf coast (using the old train systems) and cause a major glacial period, quite quickly, by grinding up the tailings & dumping them in a mile wide strip from Corpus Christi to Miami.
    - akiselev 4y ago
      > Serpentine is one of the most common minerals in the Earth's crust — like 80% of it. Serpentines are common but they do not make up 80% of the crust. Feldspars are the most common minerals in the crust and they make up less than 60% of it [1]. [1] https://deq.nc.gov/energy-mineral-and-land-resources/geological-survey/geoscience-education/mystery-minerals-fact-sheet/open https://deq.nc.gov/energy-mineral-and-land-resources/geologi...

gridspy 4y ago

No, the story is that we begin the melting by raising the earth's temperature a little. You'd think that if we reduced our carbon emissions, the ice would stop melting. > But once the ice crosses the threshold, it would inevitably continue to melt Bear in mind that the atmosphere retains carbon dioxide for ~50 years, that other melt events are dumping methane into the atmosphere from permafrost. It's not just one factor heating the planet.

realworldperson 4y ago
[dead]
graeme 4y ago
>You'd think that if we reduced our carbon emissions, the ice would stop melting. People think of climate change like a river. You reduce emissions, you reduce the size of the emissions, you reduce the size of the problem. But it's more like a bathtub. Emissions are the water filling the tub, but the real problem is the water level already in the tub. If you reduce emissions, you reduce the size of the flow into the tub. But....water is still flowing in and the water is still rising. If we had zero emissions it would take earth systems much much longer than 50 years to bring things back down to where they were.
- peteradio 4y ago
  Filling a bath tub requires active control, are you saying humans need to actively control the climate of the entire earth?
  - graeme 4y ago
    Suppose a tub was best at two inches of water, got worse for every inch, and overflowed at four feet. And you had turned on the tap and there is now three feet of water. You propose: 1. Reducing the rate of the tap 2. Turning off the tap 3. Turning off the tap and removing water until it gets back to two inches Most people think of climate change prevention as #1. #3 is what actually gets you back to ideal. But if you get back to that level and then leave the tap off, things are fine and no active management is required.

alex_young 4y ago

From the same page: Previous research identified global warming of between 1 degree to 3 degrees Celsius (1.8 to 5.4 degrees Fahrenheit) as the threshold beyond which the Greenland Ice Sheet will melt irreversibly. We're already at 1.2c above pre-industrial levels. Although it will take a long period of exposure to warm air for the ice to melt, we've already been doing that for a long time. It doesn't seem reasonable to say we have hundreds of years to figure out a solution.

kiliantics 4y ago
> It doesn't seem reasonable to say we have hundreds of years to figure out a solution. We've also known about the global warming problem in great detail for well over 50 years at this point. Since then we haven't figured it out but made it worse -- most of our cumulative emissions have happened in just the last 50 years. Why do people still think we can figure this out in a matter of decades without having to drastically change our fossil fuel habits?
- taylodl 4y ago
  Kick the can down the road. Nothing to see here. Let our progeny figure out how to clean up the mess we created. We're doing the same thing with our debt, too. I'm just going to put it out there - our progeny is going to hate our guts. Then again, maybe afterward humanity will hold us up as an example for what not to do, how not to solve global problems. They'll be able to use history to quickly and effectively shut down the naysayers. Of course that's assuming they bother to learn anything from history...I mean we sure as hell haven't!
  - lizard 4y ago
    As a fairly new parent, I'm not thrilled about the world my daughter will inherit. I struggle with a lot of questions like whether I should raise her to be a "good" person or a "successful" person. But, I've heard that studies show that younger generations are more concerned about the environment. Both in that they are showing an interest in the subject at younger ages and they are more likely than older generations to acknowledge it as an issue that affects them. This suggests that our children may not only be better equipped to handle these issues than we are (assuming we continue to advance science and technology without major catastrophe in the meanwhile), but will be more interested in pursuing these problems both personally and professionally and, in the worst case, more willing to make the necessary sacrifices to see actual change. While I certainly hope we can do more and that I can have some confidence my children will actually be better off than myself, changing the way the world thinks is a very slow and difficult thing to do. It may be the case the best we can accomplish is to hold it together the best we can while teaching our children to care about the world around them, and, when the time comes, step aside to let them solve these problems.

lozenge 4y ago

Stopping emissions (which isn't even in the Overton window) means CO2 concentration will slowly reduce. "Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years. The rest is removed by slower processes that take up to several hundreds of thousands of years, including chemical weathering and rock formation. This means that once in the atmosphere, carbon dioxide can continue to affect climate for thousands of years." During the time of elevated CO2 levels, the temperature continues to rise.

Arnt 4y ago

Temperature is a function of elevation. It's saying that if you move the surface down by removing the top layer of material (ice), the temperature at the surface increases, all else being equal including the temperature at sea level. The effect is real, and big enough to feel with the naked skin. One generally says one kelvin per 100m elevation, although the Greenland surface will be different from that rule of thumb.

saiya-jin 4y ago
> One generally says one kelvin per 100m elevation That's not true in Europe nor Asia nor South America nor Africa, although I didn't climb mountains specifically in Greenland to be factual. Better value is cca 0.6C per 100m, or 6C per 1km (sorry, no conversion to feet/yard vs F and similar fun games for lazy sunday afternoon... seriously, with all the love, fix this shit guys, we are not living in 15th century when similar stuff was common and accepted). It depends on many factors including humidity and local meteorology. That part discussed about moving surface down doesn't make sense - you can lower glacier only to base rock/soil level. But at this level, where glacier starts, its already the dreaded temperature they want to avoid, so glaciers should be melting from the bottom with this logic. If they mean that once ice melts the rock temperature rises well yeah, that's a no brainer, its a different surface. Ice has surface temperature below/around 0, any rock hit with sun can easily surpass that even during winter. I know reality is more complex out there, one of my todos is to have sleepover (no tent) on nearby Mer de Glace in Chamonix, France. Just me, gazillion stars, mountains crumbling around me and glacier cracking beneath my ass.
- Arnt 4y ago
  IMO, if you think you need a more precise estimate than 1K/100m, then you should just get a weather forecast for the relevant area and day.
- czinck 4y ago
  >But at this level, where glacier starts, its already the dreaded temperature they want to avoid, so glaciers should be melting from the bottom with this logic. Yes, that's generally what happens to glaciers even ignoring climate change. The bottom melts, but is replaced by snow/ice that accumulated on top. Glaciers grow top down, not bottom up. But, if you lower the top so it's warmer, less ice accumulates, which can't replace all that melts, and so you get net shrinking.

Belituio 4y ago

100 years is not a lot. Your kids kids will already be affected. It feels very short sides.