14 ms·

Atlantic Ocean's Circulation Is Weakest in 1,600 Years

183 points by rgbrenner 9y ago

throwaway2048 9y ago
Shutdown of oceanic currents could easily become a civilization ending disaster, this is an extremely concerning sign.
- umanwizard 9y ago
  If you’re only realizing now that climate change will end civilization, you haven’t been paying attention.
  - xor1 9y ago
    On the bright side, we'll have more civilizations after this one. It's not necessarily the end of humanity.
    - mturmon 9y ago
      Not necessarily the end of humanity is a “bright side”?
      - doyoulikeworms 9y ago
        In all seriousness: Yes.
      - Jare 9y ago
        It's brighter than without the "Not"
- acjohnson55 9y ago
  Yeah, the movie The Day After Tomorrow explored this. I'm not looking forward to having to literally outrun waves of freezing ice.
  - taneq 9y ago
    Of all of the disaster movies with terrible physics, The Day After Tomorrow is truly their king. Supercooled air depositing ice crystals on warm surfaces, oh yeah.
- deleted 9y ago
  [deleted]
matte_black 9y ago
Who is to blame for this?
- IAmEveryone 9y ago
  Us, probably. Traditionally, the circulating water gets colder as it reaches the arctic circle and submerges, since cold water has a higher density than warmer water. But: melting ice in the arctic releases freshwater. This reduces the salinity at the surface of the Northern Atlantic. Water with lower salinity is lighter. Therefore, this water no longer submerges, and the circulation is slowed down.
  - bassman9000 9y ago
    The studies differ on the timing of when that weakening began. Thornalley’s record, which spans those 1,600 years, suggests it started at the end of the little ice age, a period from about A.D. 1350 to 1850, when solar and volcanic influences depressed temperatures across the Northern Hemisphere and glaciers and ice sheets expanded. As the little ice age ended and temperatures warmed, ice melted and freshwater flooded into the North Atlantic. The results suggest the current state of the AMOC is the weakest it has been over that whole long record. Whether today’s state is just a continuation of that reaction or whether global warming has also started to chip in is not clear, he says. Caesar, meanwhile, put the turning point toward a weaker AMOC in the mid-20th century, suggesting it is due to the influence of human-caused warming. Her team’s record, however, does not extend as far back. Indications of the process having started (edited) before humans could be responsible for it (few hundred years ago).
    - mirimir 9y ago
      Sure, maybe AMOC has been weakening since the end of the little ice age. But that doesn't matter so much if anthropogenic warming is weakening it now.
    - jonhendry18 9y ago
      It may have started back then but accelerated or been exacerbated because of human activity.
smartbit 9y ago
Two excellent talks from Potsdam Institute for Climate Impact Research (PIK) at 34c3 A hacker's guide to Climate Change - What do we know and how do we know it? An introduction to the basics of climate research and what we can do about climate change https://media.ccc.de/v/34c3-9184-a_hacker_s_guide_to_climate_change_-_what_do_we_know_and_how_do_we_know_it https://media.ccc.de/v/34c3-9184-a_hacker_s_guide_to_climate... Simulating the future of the global agro-food system. Cybernetic models analyze scenarios of interactions between future global food consumption, agriculture, landuse, and the biogeochemical cycles of water, nitrogen and carbon. https://media.ccc.de/v/34c3-8935-simulating_the_future_of_the_global_agro-food_system https://media.ccc.de/v/34c3-8935-simulating_the_future_of_th...
hoodoof 9y ago
Becoming a doomsday prepper edges further away from "flat out crazy" with every day of weird, weird weather. Our climate has been extremely stable for a long time and I'm not expert but it is my understanding that chaotic systems can suddenly flip from stable to extremely unstable. I think there will be a time, hopefully a long time away but possibly close, when the world realises that there' going to be disaster on an unprecedented scale and we all have reason to be very, very concerned. If the entire Antarctic eastern shelf melts, there is enough ice there to raise sea levels by more than 70 meters. Some say this is 100 years away.... but ice doesn't melt all at once. I wouldn't be surprised if it comes alot sooner and what that world/civilization looks like I cannot imagine. And if you have children, then 100 years away sounds very very soon because you know this is the world they will live in.
- knodi123 9y ago
  > we all have reason to be very, very concerned What are you going to do about it? Armed revolution? Hoard enough food to ensure that you survive a few months longer than the rest of humanity?
  - hoodoof 9y ago
    I'm going to try to locate the billionaire bunkers that I am sure they have all built deep into mountains and take refuge with them before battling my way across a post apocalyptic landscape fighting zombies, accompanied by a ragtag bunch of survivors. I figure the Bezos bunker must be part of his 10,000 year clock mountain http://www.10000yearclock.net/learnmore.html http://www.10000yearclock.net/learnmore.html Of course I have no idea what to do because why the heck would you think about that unless you were an actual doomsday prepper? Likely outcomes at that stage is gigantic food crisis and the catastrophe that would follow so you'd need to store quite alot of bags of rice to get through that.
    - prewett 9y ago
      A real doomsday prepper would have bought some land in the middle of nowhere (so hordes don't want/think to come there) and learned how to farm it. Storing six months of food or whatever is preparatory-theater and doesn't address sustainable survivel.
brownbat 9y ago
Additional background on the thermohaline cycle and the Younger Dryas period, which saw a change of 10 degrees Celsius in a decade: https://www.ncdc.noaa.gov/abrupt-climate-change/The%20Younger%20Dryas https://www.ncdc.noaa.gov/abrupt-climate-change/The%20Younge... Some more information on the period here: http://ocp.ldeo.columbia.edu/res/div/ocp/arch/examples.shtml http://ocp.ldeo.columbia.edu/res/div/ocp/arch/examples.shtml
- akvadrako 9y ago
  That's quite interesting. What I can't tell by quickly reading those sources: is this mostly based on the data from a single location? It seems possible that that local climate can change a lot more wildly then the global averages.
  - brownbat 9y ago
    I should have included above, but the wikipedia section on global effects shows how it varied by continent. Massive effects in Europe and South America, but with some evidence the Pacific wasn't as affected. en.m.wikipedia.org/wiki/Younger_Dryas The earlier intro section there lays out the discovery and some types of evidence that led to the conclusion, and a theory based on geology from China that these rapid changes tend to accompany deglaciation. 20 degrees Fahrenheit shift within a decade, even if just for one continent... It's hard to fathom.
purplezooey 9y ago
For a second I thought the headline referred to the circulation of The Atlantic, but then I realized, while a very good magazine, it probably hasn't been around for 1600 years.
jcoffland 9y ago
> The studies differ on the timing of when that weakening began. Thornalley’s record, which spans those 1,600 years, suggests it started at the end of the little ice age, a period from about A.D. 1350 to 1850 So the weakening current started before the industrial revolution could have had an effect and well before any significant human caused CO2 and therefore was not caused by man. https://www.acs.org/content/acs/en/climatescience/greenhousegases/industrialrevolution.html https://www.acs.org/content/acs/en/climatescience/greenhouse...
- DoveBrown 9y ago
  From your link: "These increases in greenhouse gas concentrations and their marked rate of change are largely attributable to human activities since the Industrial Revolution (1800)." and "Data for the past 2000 years show that the atmospheric concentrations of CO2, CH4, and N2O – three important long-lived greenhouse gases – have increased substantially since about 1750." I don't think your link supports the statement "the weaking started well before the industrial revolution."
  - deleted 9y ago
    [deleted]
  - jcoffland 9y ago
    The link clearly shows that significant rise in CO2 did not occur until after 1900 so it could not have caused weakening ocean currents that began, at the latest estimate in 1850. I do not understand where anyone got the idea that a constantly changing climate is abnormal.
    - DoveBrown 9y ago
      I'm not a climatologist but as I understand it when looking at the climate over the long scale there are cycles as the climate changes that are predictable by natural processes (including effects of the Earths orbit and co2 changes). Then from the 19th century the climate has been moving off the known path as understood by these cycles. The difference has been attributed to humans. The worry is that when you put the cyclic natural of climate change together with the human caused climate change then what you may end up with is a climate which is not conducive to food productive for the human population.
dmix 9y ago
> As the little ice age ended and temperatures warmed, ice melted and freshwater flooded into the North Atlantic. The results suggest the current state of the AMOC is the weakest it has been over that whole long record. Whether today’s state is just a continuation of that reaction or whether global warming has also started to chip in is not clear, he says. Caesar, meanwhile, put the turning point toward a weaker AMOC in the mid-20th century, suggesting it is due to the influence of human-caused warming. Her team’s record, however, does not extend as far back. It's always difficult reading climate analysis like these articles where it bounces back and forth between sounding confident of projections in the first half of the article, to how it's all still really speculative without consensus and needing better modeling in the latter half. All I want is to know what the data says and a reasonable estimate of it's probability of being true. Yet it's almost impossible to separate what the scientists hope the data may to point to and what it reasonably does in it's current state. I guess, as a casual reader, it'd be better to not jump on every new study that comes out and wait for future consensus to form.

183 points by rgbrenner 9y ago

throwaway2048 9y ago

Shutdown of oceanic currents could easily become a civilization ending disaster, this is an extremely concerning sign.

umanwizard 9y ago
If you’re only realizing now that climate change will end civilization, you haven’t been paying attention.
- xor1 9y ago
  On the bright side, we'll have more civilizations after this one. It's not necessarily the end of humanity.
  - mturmon 9y ago
    Not necessarily the end of humanity is a “bright side”?
    - doyoulikeworms 9y ago
      In all seriousness: Yes.
    - Jare 9y ago
      It's brighter than without the "Not"
acjohnson55 9y ago
Yeah, the movie The Day After Tomorrow explored this. I'm not looking forward to having to literally outrun waves of freezing ice.
- taneq 9y ago
  Of all of the disaster movies with terrible physics, The Day After Tomorrow is truly their king. Supercooled air depositing ice crystals on warm surfaces, oh yeah.
deleted 9y ago
[deleted]

matte_black 9y ago

Who is to blame for this?

IAmEveryone 9y ago
Us, probably. Traditionally, the circulating water gets colder as it reaches the arctic circle and submerges, since cold water has a higher density than warmer water. But: melting ice in the arctic releases freshwater. This reduces the salinity at the surface of the Northern Atlantic. Water with lower salinity is lighter. Therefore, this water no longer submerges, and the circulation is slowed down.
- bassman9000 9y ago
  The studies differ on the timing of when that weakening began. Thornalley’s record, which spans those 1,600 years, suggests it started at the end of the little ice age, a period from about A.D. 1350 to 1850, when solar and volcanic influences depressed temperatures across the Northern Hemisphere and glaciers and ice sheets expanded. As the little ice age ended and temperatures warmed, ice melted and freshwater flooded into the North Atlantic. The results suggest the current state of the AMOC is the weakest it has been over that whole long record. Whether today’s state is just a continuation of that reaction or whether global warming has also started to chip in is not clear, he says. Caesar, meanwhile, put the turning point toward a weaker AMOC in the mid-20th century, suggesting it is due to the influence of human-caused warming. Her team’s record, however, does not extend as far back. Indications of the process having started (edited) before humans could be responsible for it (few hundred years ago).
  - mirimir 9y ago
    Sure, maybe AMOC has been weakening since the end of the little ice age. But that doesn't matter so much if anthropogenic warming is weakening it now.
  - jonhendry18 9y ago
    It may have started back then but accelerated or been exacerbated because of human activity.

smartbit 9y ago

Two excellent talks from Potsdam Institute for Climate Impact Research (PIK) at 34c3 A hacker's guide to Climate Change - What do we know and how do we know it? An introduction to the basics of climate research and what we can do about climate change https://media.ccc.de/v/34c3-9184-a_hacker_s_guide_to_climate_change_-_what_do_we_know_and_how_do_we_know_it https://media.ccc.de/v/34c3-9184-a_hacker_s_guide_to_climate... Simulating the future of the global agro-food system. Cybernetic models analyze scenarios of interactions between future global food consumption, agriculture, landuse, and the biogeochemical cycles of water, nitrogen and carbon. https://media.ccc.de/v/34c3-8935-simulating_the_future_of_the_global_agro-food_system https://media.ccc.de/v/34c3-8935-simulating_the_future_of_th...

hoodoof 9y ago

Becoming a doomsday prepper edges further away from "flat out crazy" with every day of weird, weird weather. Our climate has been extremely stable for a long time and I'm not expert but it is my understanding that chaotic systems can suddenly flip from stable to extremely unstable. I think there will be a time, hopefully a long time away but possibly close, when the world realises that there' going to be disaster on an unprecedented scale and we all have reason to be very, very concerned. If the entire Antarctic eastern shelf melts, there is enough ice there to raise sea levels by more than 70 meters. Some say this is 100 years away.... but ice doesn't melt all at once. I wouldn't be surprised if it comes alot sooner and what that world/civilization looks like I cannot imagine. And if you have children, then 100 years away sounds very very soon because you know this is the world they will live in.

knodi123 9y ago
> we all have reason to be very, very concerned What are you going to do about it? Armed revolution? Hoard enough food to ensure that you survive a few months longer than the rest of humanity?
- hoodoof 9y ago
  I'm going to try to locate the billionaire bunkers that I am sure they have all built deep into mountains and take refuge with them before battling my way across a post apocalyptic landscape fighting zombies, accompanied by a ragtag bunch of survivors. I figure the Bezos bunker must be part of his 10,000 year clock mountain http://www.10000yearclock.net/learnmore.html http://www.10000yearclock.net/learnmore.html Of course I have no idea what to do because why the heck would you think about that unless you were an actual doomsday prepper? Likely outcomes at that stage is gigantic food crisis and the catastrophe that would follow so you'd need to store quite alot of bags of rice to get through that.
  - prewett 9y ago
    A real doomsday prepper would have bought some land in the middle of nowhere (so hordes don't want/think to come there) and learned how to farm it. Storing six months of food or whatever is preparatory-theater and doesn't address sustainable survivel.

brownbat 9y ago

Additional background on the thermohaline cycle and the Younger Dryas period, which saw a change of 10 degrees Celsius in a decade: https://www.ncdc.noaa.gov/abrupt-climate-change/The%20Younger%20Dryas https://www.ncdc.noaa.gov/abrupt-climate-change/The%20Younge... Some more information on the period here: http://ocp.ldeo.columbia.edu/res/div/ocp/arch/examples.shtml http://ocp.ldeo.columbia.edu/res/div/ocp/arch/examples.shtml

akvadrako 9y ago
That's quite interesting. What I can't tell by quickly reading those sources: is this mostly based on the data from a single location? It seems possible that that local climate can change a lot more wildly then the global averages.
- brownbat 9y ago
  I should have included above, but the wikipedia section on global effects shows how it varied by continent. Massive effects in Europe and South America, but with some evidence the Pacific wasn't as affected. en.m.wikipedia.org/wiki/Younger_Dryas The earlier intro section there lays out the discovery and some types of evidence that led to the conclusion, and a theory based on geology from China that these rapid changes tend to accompany deglaciation. 20 degrees Fahrenheit shift within a decade, even if just for one continent... It's hard to fathom.

purplezooey 9y ago

For a second I thought the headline referred to the circulation of The Atlantic, but then I realized, while a very good magazine, it probably hasn't been around for 1600 years.

jcoffland 9y ago

> The studies differ on the timing of when that weakening began. Thornalley’s record, which spans those 1,600 years, suggests it started at the end of the little ice age, a period from about A.D. 1350 to 1850 So the weakening current started before the industrial revolution could have had an effect and well before any significant human caused CO2 and therefore was not caused by man. https://www.acs.org/content/acs/en/climatescience/greenhousegases/industrialrevolution.html https://www.acs.org/content/acs/en/climatescience/greenhouse...

DoveBrown 9y ago
From your link: "These increases in greenhouse gas concentrations and their marked rate of change are largely attributable to human activities since the Industrial Revolution (1800)." and "Data for the past 2000 years show that the atmospheric concentrations of CO2, CH4, and N2O – three important long-lived greenhouse gases – have increased substantially since about 1750." I don't think your link supports the statement "the weaking started well before the industrial revolution."
- deleted 9y ago
  [deleted]
- jcoffland 9y ago
  The link clearly shows that significant rise in CO2 did not occur until after 1900 so it could not have caused weakening ocean currents that began, at the latest estimate in 1850. I do not understand where anyone got the idea that a constantly changing climate is abnormal.
  - DoveBrown 9y ago
    I'm not a climatologist but as I understand it when looking at the climate over the long scale there are cycles as the climate changes that are predictable by natural processes (including effects of the Earths orbit and co2 changes). Then from the 19th century the climate has been moving off the known path as understood by these cycles. The difference has been attributed to humans. The worry is that when you put the cyclic natural of climate change together with the human caused climate change then what you may end up with is a climate which is not conducive to food productive for the human population.

dmix 9y ago

> As the little ice age ended and temperatures warmed, ice melted and freshwater flooded into the North Atlantic. The results suggest the current state of the AMOC is the weakest it has been over that whole long record. Whether today’s state is just a continuation of that reaction or whether global warming has also started to chip in is not clear, he says. Caesar, meanwhile, put the turning point toward a weaker AMOC in the mid-20th century, suggesting it is due to the influence of human-caused warming. Her team’s record, however, does not extend as far back. It's always difficult reading climate analysis like these articles where it bounces back and forth between sounding confident of projections in the first half of the article, to how it's all still really speculative without consensus and needing better modeling in the latter half. All I want is to know what the data says and a reasonable estimate of it's probability of being true. Yet it's almost impossible to separate what the scientists hope the data may to point to and what it reasonably does in it's current state. I guess, as a casual reader, it'd be better to not jump on every new study that comes out and wait for future consensus to form.