A Nature paper this week suggesting an early collapse of a key ocean current system raised fears of a 'Day after Tomorrow'-style catastrophe. That's overplayed, but the reality is still very worrying
I’m not sure what to make of the conversation around this. If it’s a case of if not when, by all means go ahead and debate. But it seems it’s actually a case of when - so it feels kinda immaterial to be quibbling over whether it’s soon or in a bit or a bit later.
If we have another century or so up our sleeve before we hit this tipping point, we have a much better chance of halting the anthropogenic forcing (ie halt emissions/stop heating the planet) and thus never triggering it, so in that sense the timing is probably quite material....
I agree, even when we are talking next century babies being born in this one will likely be significantly impacted. That is getting very close in real terms.
What drives me crazy in the mainstream response to reports like this one is that the uncertainty element is treated as a mitigating factor -- "well, clearly this may not happen, so..." The uncertainty is one of the scariest aspects of the research! When a serious article like your one can include the line "even as early as 2025", we're at the cliff's edge.
It is still very likely that it won't happen this century! That said, I agree with you on the uncertainty being the scary part. We are entering the 'playing with fire' zone at this point. We should obviously have done a lot more to avoid getting here, but there are still a lot of alternative paths forward from here and it would be a really good idea to pick the most benign one possible!!
Wowzers - 10%! I pack an umbrella if I go out into a day facing a 10% chance of showers... What the hell should the Northern Hemisphere pack for a 10% chance of a complete reinvention of their climate within as little as 2 years?
Right? Even a very small chance of something of that scale happening is quite alarming. A couple of things I would say is that 1) In this study, they found some kind of transition likely around mid-century. The early date, 2025, was the bottom end of the 95% confidence interval, so a very small chance 2) While most scientists thought this kind of modelling exercise was useful, it doesn't include everything we know about ocean circulation systems (which is an incredibly technical subject) and it seems like some of those things make a collapse less likely in the near future. ie the model itself isn't perfect. While it's natural to focus on the most alarming end, the IPCC thought there was less than 10% chance of anything at all happening this century - that's not the same as a 10% chance of the worst possible scenario happening. The chance of that is way, way, way lower.
Thanks for padding that out Cathrine - of course, I was being a little flippant in my comment. However, I tend to think about how weather forecasting works (and most people don't realise this): When forecasters say there is a "10% chance of rain", they are not referring to a '10% chance your house will get rained on', but a 100% chance of rain over 1/10th of the forecast area/time-period... In other words, their forecasting is a guarantee *someone* will get rained on (9/10 times, it just won't be you!).
Obviously the 'Day After Tomorrow' scenario, where whole countries are affected, is silly Hollywood drama. But, in an age of localised, but still hugely damaging, wildfires, storms, and droughts, that 10% might actually be more prescient than it appears.
...Oh, and by the way, I don't think I've said welcome to the Kākā - it's going to be great having your voice in here!
Thank you for making this so rationale and understandable. This issue alone should be making governments, scientists, professors and other teachers use their positions to educate the mainstream. A good set of talking points to use in everyday conversations with the doubters would also be useful. This column will certainly help me around this specific topic - very much appreciated.
Thanks Jenny, I appreciate you taking the time to links here - I was wondering over the weekend if The Workshop had anything but didn't get a chance to look. Their stuff is so useful! I'll check out the other two links as well. Better to channel my irritation over stuff like $6 billion dollars proposed to be spent on more motorways into helping more people realise why we need to act now - we're already years and years late.
100% - and this is a bit of shameless self-promotion, but there'll be a "Vote for Climate 2023" campaign launching in the next few weeks, to drive a coordinated effort to get climate change back in the mainstream election discourse. You can sign on for updates here:
And yet, we'll likely elect a government that will pour petrol on the flames in an attempt to douse the fire. I include Labour in that scenario.
As an indication of how clueless we are as a species, I know of a bowling club that is spending time, money and effort to build a smoking room to literally accommodate those people who smoke! Meanwhile, families are living in cars! What an appalling waste of resources. I fear there is little hope for humanity. The planet will survive but the inhabitants will likely perish and at our own hands.
I have long argued that the IPCC is far too conservative in their findings, as if we're reflecting a degree of uncertainty in something innocuous like the aerodynamic performance of a new racecar, or erosion rates of a limestone headland!
Worth pointing out two further aspects here:
1. With risk being a function of likelihood/impact (net mitigation measures). With the irreversible nature of many climate tipping points, we should be acting to avoid even a 1% chance of such an event materialising. 10% is off the charts extreme risk!
2. The AMOC is one large piece in a highly integrated puzzle of ocean/atmosphere/geophysical systems. What we really talking about is a much greater *cumulative risk* driven by complex interdependencies and positive feedback mechanisms.
What we actually have, is decades of pathetic piecemeal policy and incremental investment in a half-arsed effort to be seen to be doing something...
Great story but it suffers from an ailment common to many climate scientists - it looks at a single causative factor inducing dramatic change within a complex system when the change is likely (certain to be) to be a cascade of compounding drivers.
We blithely overlook the fact that we live at the 99th percentile of the normal climate range of planet earth - to put another way we live (or have lived until recently) in the planet's climate at its most benign = a quick look at the landscapes of the UK or much of North America (and New Zealand) in Google Earth and you see evidence of land gouged by vast ice sheets everywhere - those ice sheets are what is normal for planet earth.
Climate scientist have been obsessing about green house gases over the past few decades without really thinking about where the entire system might be heading =- much of the scientific thinking is that things will continue in a linear manner - ie just keep getting warmer - ignoring the fact that the planet has always (over the past few million years anyway) frozen over just when it gets to its hottest. This might not be as odd a coincidence as might be imagined.
The big problem with obsessing on CO2 etc is that these gases are relatively minor influences on global climate compared to the main actors. The first reason we have a warm climate is that much of the suns warming effect is trapped in the tropical latitudes like a bubble - isolated from dissipation to the poles by the mid-latitude Hadley Cell. The atmosphere is separated into three cells in each hemisphere - the tropic, the mid latitude, and polar cells - the mid latitude cell acts like a thermos - keeping the warm stuff in the tropics and not letting it leak out (to rapidly anyway). If this structure did not exist and the atmosphere circulated freely between poles and tropics all of the water on the planet would be frozen solid.
The next big factor in maintaining a warm planet is water vapour - water vapour is the heavy lifter among green house gases - water vapour doesn't just trap heat it also - unlike the other green houses gases - has considerable thermal mass - it is the primary mechanism for moving heat around the planet - in both the sea and the air - however transport in the atmosphere accounts for 80% of all heat transfers globally so what ever causes an ice age is likely to be an atmospheric phenomenon.
The other interesting feature of an ice age is that most of the ice collects in the northern hemisphere.
An ice age causes some 43 Million cubic kilometres of water to be uplifted from the world's oceans to be deposited on the northern hemisphere as continental ice sheets. This requires a prodigious amount of energy to achieve - the energy is heat - the transfer of mass shifts a vast amount of heat from the topical oceans to the polar regions to be deposited as continental ice - as the ice forms all of this heat is released (the latent heat of change of state if you want to dive into the physics) and this is largely the reradiated into space.
If you want a model for this process go look at your fridge and think about how it works. The atmosphere works in exactly the same way.
At present we are living in a period when the fridge motor is turned off.
A range of drivers may be about to turn it back on. The collapse of the North Atlantic current may be one of them. However for an ice age to occur doesn't necessarily require the poles to get colder - it requires the poles to get WETTER! The poles are desserts because most of the atmospheric moisture condenses out in the mid latitudes - for more moisture to get to the polar regions requires the land and ocean in the mid-latitudes to get warmer so the moisture doesn't precipitate out - just like what is happening right now. Once the poles get wetter the rate of heat transfer from the tropics increases.
Presently the poles get about 10cm of precipitation a year. If that increased to a metre of annual precipitation the rate of heat transfer increases tenfold. And an ice age requires there to be lots more precipitation in the polar regions for ice sheets to form. It is also possible that as the climate warms and events like the the collapse of the north Atlantic ocean current occur this also cause the patterns of atmospheric circulation to change as well. If the hemispheric circulation changed from the present three cell structure to a two cell structure the rate of heat transfer from the tropics to the poles would increase dramatically - as the separation between tropics and polar cells is removed. And from there the heat gets reradiated into space and so a dramatic cooling process begins.
We may be seeing something like this possibility developing now with the jetstream in the northern hemisphere becoming increasingly unstable. So it wont be one thing that causes the next ice age but it might be a number of things that come together in away that we least expect. And some of these things seem to be developing as we watch.
I’m not sure what to make of the conversation around this. If it’s a case of if not when, by all means go ahead and debate. But it seems it’s actually a case of when - so it feels kinda immaterial to be quibbling over whether it’s soon or in a bit or a bit later.
If we have another century or so up our sleeve before we hit this tipping point, we have a much better chance of halting the anthropogenic forcing (ie halt emissions/stop heating the planet) and thus never triggering it, so in that sense the timing is probably quite material....
Yes - time to act. The longer the better.
And welcome, Catherine. Nice to have you around here.
I agree, even when we are talking next century babies being born in this one will likely be significantly impacted. That is getting very close in real terms.
What drives me crazy in the mainstream response to reports like this one is that the uncertainty element is treated as a mitigating factor -- "well, clearly this may not happen, so..." The uncertainty is one of the scariest aspects of the research! When a serious article like your one can include the line "even as early as 2025", we're at the cliff's edge.
It is still very likely that it won't happen this century! That said, I agree with you on the uncertainty being the scary part. We are entering the 'playing with fire' zone at this point. We should obviously have done a lot more to avoid getting here, but there are still a lot of alternative paths forward from here and it would be a really good idea to pick the most benign one possible!!
Wowzers - 10%! I pack an umbrella if I go out into a day facing a 10% chance of showers... What the hell should the Northern Hemisphere pack for a 10% chance of a complete reinvention of their climate within as little as 2 years?
Right? Even a very small chance of something of that scale happening is quite alarming. A couple of things I would say is that 1) In this study, they found some kind of transition likely around mid-century. The early date, 2025, was the bottom end of the 95% confidence interval, so a very small chance 2) While most scientists thought this kind of modelling exercise was useful, it doesn't include everything we know about ocean circulation systems (which is an incredibly technical subject) and it seems like some of those things make a collapse less likely in the near future. ie the model itself isn't perfect. While it's natural to focus on the most alarming end, the IPCC thought there was less than 10% chance of anything at all happening this century - that's not the same as a 10% chance of the worst possible scenario happening. The chance of that is way, way, way lower.
Thanks for padding that out Cathrine - of course, I was being a little flippant in my comment. However, I tend to think about how weather forecasting works (and most people don't realise this): When forecasters say there is a "10% chance of rain", they are not referring to a '10% chance your house will get rained on', but a 100% chance of rain over 1/10th of the forecast area/time-period... In other words, their forecasting is a guarantee *someone* will get rained on (9/10 times, it just won't be you!).
Obviously the 'Day After Tomorrow' scenario, where whole countries are affected, is silly Hollywood drama. But, in an age of localised, but still hugely damaging, wildfires, storms, and droughts, that 10% might actually be more prescient than it appears.
...Oh, and by the way, I don't think I've said welcome to the Kākā - it's going to be great having your voice in here!
Thanks Tim! I'm really enjoying myself already. Bernard has built a really fantastic community here!
Thank you for making this so rationale and understandable. This issue alone should be making governments, scientists, professors and other teachers use their positions to educate the mainstream. A good set of talking points to use in everyday conversations with the doubters would also be useful. This column will certainly help me around this specific topic - very much appreciated.
The Workshop has an excellent resource on how to talk about climate change with people available, highly recommend! https://www.theworkshop.org.nz/publications/how-to-talk-about-climate-change-a-toolkit-for-encouraging-collective-action-2019
Greenpeace also have this one-pager: https://www.greenpeace.org.uk/wp-content/uploads/2020/08/Lets-talk-about-it.pdf
Parents for Climate Action Aotearoa also do this excellent series of free workshops on having better conversations about climate change: https://www.parentsforclimatenz.org/lets-talk-climate
I also hear that there's a climate-specific workshop coming out from Tauiwi Tautoko, which has focussed on anti-racism in the past.
https://www.wgtn.ac.nz/news/2021/12/listening-as-a-martial-art
http://tauiwitautoko.com/
Ohhh, that also sounds good to know about.
Thanks Jenny, I appreciate you taking the time to links here - I was wondering over the weekend if The Workshop had anything but didn't get a chance to look. Their stuff is so useful! I'll check out the other two links as well. Better to channel my irritation over stuff like $6 billion dollars proposed to be spent on more motorways into helping more people realise why we need to act now - we're already years and years late.
100% - and this is a bit of shameless self-promotion, but there'll be a "Vote for Climate 2023" campaign launching in the next few weeks, to drive a coordinated effort to get climate change back in the mainstream election discourse. You can sign on for updates here:
http://climateshift.nz/
Fantastic - I'm so grateful that people like you are working so hard for all of us on this. Will sign up now.
And yet, we'll likely elect a government that will pour petrol on the flames in an attempt to douse the fire. I include Labour in that scenario.
As an indication of how clueless we are as a species, I know of a bowling club that is spending time, money and effort to build a smoking room to literally accommodate those people who smoke! Meanwhile, families are living in cars! What an appalling waste of resources. I fear there is little hope for humanity. The planet will survive but the inhabitants will likely perish and at our own hands.
Great summary thanks Catherine.
I have long argued that the IPCC is far too conservative in their findings, as if we're reflecting a degree of uncertainty in something innocuous like the aerodynamic performance of a new racecar, or erosion rates of a limestone headland!
Worth pointing out two further aspects here:
1. With risk being a function of likelihood/impact (net mitigation measures). With the irreversible nature of many climate tipping points, we should be acting to avoid even a 1% chance of such an event materialising. 10% is off the charts extreme risk!
2. The AMOC is one large piece in a highly integrated puzzle of ocean/atmosphere/geophysical systems. What we really talking about is a much greater *cumulative risk* driven by complex interdependencies and positive feedback mechanisms.
What we actually have, is decades of pathetic piecemeal policy and incremental investment in a half-arsed effort to be seen to be doing something...
Great story but it suffers from an ailment common to many climate scientists - it looks at a single causative factor inducing dramatic change within a complex system when the change is likely (certain to be) to be a cascade of compounding drivers.
We blithely overlook the fact that we live at the 99th percentile of the normal climate range of planet earth - to put another way we live (or have lived until recently) in the planet's climate at its most benign = a quick look at the landscapes of the UK or much of North America (and New Zealand) in Google Earth and you see evidence of land gouged by vast ice sheets everywhere - those ice sheets are what is normal for planet earth.
Climate scientist have been obsessing about green house gases over the past few decades without really thinking about where the entire system might be heading =- much of the scientific thinking is that things will continue in a linear manner - ie just keep getting warmer - ignoring the fact that the planet has always (over the past few million years anyway) frozen over just when it gets to its hottest. This might not be as odd a coincidence as might be imagined.
The big problem with obsessing on CO2 etc is that these gases are relatively minor influences on global climate compared to the main actors. The first reason we have a warm climate is that much of the suns warming effect is trapped in the tropical latitudes like a bubble - isolated from dissipation to the poles by the mid-latitude Hadley Cell. The atmosphere is separated into three cells in each hemisphere - the tropic, the mid latitude, and polar cells - the mid latitude cell acts like a thermos - keeping the warm stuff in the tropics and not letting it leak out (to rapidly anyway). If this structure did not exist and the atmosphere circulated freely between poles and tropics all of the water on the planet would be frozen solid.
The next big factor in maintaining a warm planet is water vapour - water vapour is the heavy lifter among green house gases - water vapour doesn't just trap heat it also - unlike the other green houses gases - has considerable thermal mass - it is the primary mechanism for moving heat around the planet - in both the sea and the air - however transport in the atmosphere accounts for 80% of all heat transfers globally so what ever causes an ice age is likely to be an atmospheric phenomenon.
The other interesting feature of an ice age is that most of the ice collects in the northern hemisphere.
An ice age causes some 43 Million cubic kilometres of water to be uplifted from the world's oceans to be deposited on the northern hemisphere as continental ice sheets. This requires a prodigious amount of energy to achieve - the energy is heat - the transfer of mass shifts a vast amount of heat from the topical oceans to the polar regions to be deposited as continental ice - as the ice forms all of this heat is released (the latent heat of change of state if you want to dive into the physics) and this is largely the reradiated into space.
If you want a model for this process go look at your fridge and think about how it works. The atmosphere works in exactly the same way.
At present we are living in a period when the fridge motor is turned off.
A range of drivers may be about to turn it back on. The collapse of the North Atlantic current may be one of them. However for an ice age to occur doesn't necessarily require the poles to get colder - it requires the poles to get WETTER! The poles are desserts because most of the atmospheric moisture condenses out in the mid latitudes - for more moisture to get to the polar regions requires the land and ocean in the mid-latitudes to get warmer so the moisture doesn't precipitate out - just like what is happening right now. Once the poles get wetter the rate of heat transfer from the tropics increases.
Presently the poles get about 10cm of precipitation a year. If that increased to a metre of annual precipitation the rate of heat transfer increases tenfold. And an ice age requires there to be lots more precipitation in the polar regions for ice sheets to form. It is also possible that as the climate warms and events like the the collapse of the north Atlantic ocean current occur this also cause the patterns of atmospheric circulation to change as well. If the hemispheric circulation changed from the present three cell structure to a two cell structure the rate of heat transfer from the tropics to the poles would increase dramatically - as the separation between tropics and polar cells is removed. And from there the heat gets reradiated into space and so a dramatic cooling process begins.
We may be seeing something like this possibility developing now with the jetstream in the northern hemisphere becoming increasingly unstable. So it wont be one thing that causes the next ice age but it might be a number of things that come together in away that we least expect. And some of these things seem to be developing as we watch.