Ice Ages

[mike Meehan]

According to averages, I understand that we are getting near to the end of an inter glacial period. We don't really know what kicked the ice ages off in the first place but just suppose that the conditions whatever they were were met, say within the next couple of years, what thoughts do you have on how it would progress and how do you expect the climate of the uk to change, considering the most northern parts were under about 2 kms of ice at its worst in the last ice age.

As far as I am aware no plans appear to have made for this eventuallity but it will happen one day.

Any ideas?

[SteveB]

It's something I not really thought that much about. I guess it's because it's unlikely to happen in our life times. But when it does it will have more of an impact on humans than c02 will.

[noggin]

I think there would be big, big trouble and much social unrest. We will have had dire warnings shoved down our throats and in our faces for years about what awaits us as a result of (A)GW, and if the ice-age were to suddenly, and without doubt, come upon us there would be absolute panic. Would the world come together for it's survival or would we all be fighting each other? I don't know, but I would envisage an attempt at the former, which would fail and then it would be every country for itself and finally every man for himself.

The people who live far to the north and south of the equator could migrate to equatorial lands, if such lands remain unaffected by the ice. But even if the equatorial lands were cooled by the ice-age, how could we produce enough food to keep everyone alive?

A lot would depend on how much time we have. If, say, we knew that the north and south would be uninhabitable in, say, 50 years' time, then an attempt at strict birth control could be made, in an effort to drastically reduce the world's population, thereby giving mankind a chance of survival if the equatorial land were to become able to support human life. All of us oldies would have popped off in that time and the birth rate could be made tiny by strict birth control. The trouble is, who would ensure that this is carried out, and what if there were moral objections from those who think birth-control is wrong?

Ah, that brings me on to other animal life and plant life. How would the other animal species survive? They would mostly freeze to death, on land and in the sea. With the food chain and the balance of life on Earth broken, would mankind survive anyway?

If, however, the whole of the world was to be covered in thick ice, then I would say that we would be well and truly stuffed.

[Moomin]

I think there would be big, big trouble and much social unrest. We will have had dire warnings shoved down our throats and in our faces for years about what awaits us as a result of (A)GW, and if the ice-age were to suddenly, and without doubt, come upon us there would be absolute panic. Would the world come together for it's survival or would we all be fighting each other? I don't know, but I would envisage an attempt at the former, which would fail and then it would be every country for itself and finally every man for himself.

The people who live far to the north and south of the equator could migrate to equatorial lands, if such lands remain unaffected by the ice. But even if the equatorial lands were cooled by the ice-age, how could we produce enough food to keep everyone alive?

A lot would depend on how much time we have. If, say, we knew that the north and south would be uninhabitable in, say, 50 years' time, then an attempt at strict birth control could be made, in an effort to drastically reduce the world's population, thereby giving mankind a chance of survival if the equatorial land were to become able to support human life. All of us oldies would have popped off in that time and the birth rate could be made tiny by strict birth control. The trouble is, who would ensure that this is carried out, and what if there were moral objections from those who think birth-control is wrong?

Ah, that brings me on to other animal life and plant life. How would the other animal species survive? They would mostly freeze to death, on land and in the sea. With the food chain and the balance of life on Earth broken, would mankind survive anyway?

If, however, the whole of the world was to be covered in thick ice, then I would say that we would be well and truly stuffed.

If I remember my glaciology lectures correctly, the ice got as far as the southern midlands during the last ice age, so some of the UK would most likely be ice free. However, conditions would be harsh as the land left uncovered by ice would be very similar to the canadian and siberian Tundra, which isn't famous for its crop growing characteristics! Glaciation happens quickly in geological terms but I doubt we would see the maximum ice extent in our lifetime even if it started tomorrow, I would imagine we'd be looking at a couple of hundred years before ice started to impact the arable valley floors.

Moomin

[jethro]

If the Gulf Stream shuts down, it could get rather chilly, rather quickly:

http://www.msnbc.msn.com/id/34242705/ns/technology_and_science-science/

[Guest]

Some thoughts on the posts to date:

With the last Ice Age ending approx 12,000 years ago and the average inter-glacial being 10,000 years, we appear to be into extra time at the moment.

I also wonder about how much topographical features affected the onset of the ice age proper, for example the mountains of Scotland and Scandinavia would have been higher and in today's climate more likely to have permanent glaciers. One chart I saw indicated that the ice sheets, this side of the pond, were mainly over Northern Europe and the UK but Asiatic Russia appears to have been clear. Was this because there was so much more precipitation in the west than the east, making Asiatic Russia a vitual desert?

Could warming have been a trigger? i.e. More warming, more precipitation falling as snow at high altitudes and northern latitudes to such an extent that it was not all melted during the summers, leading to a gradual creep down as the summers gradually became worse leading to an initial forming of an ice sheet which became established and self perpetuating, then once this occurred would there be a general drying out of the atmosphere as sea levels dropped leading to a narrower temperate zone between the ice sheets and the deserts further to the south?

Another trigger could perhaps have been an upsurge of volcanic dust but I would have thought that it would have been possible to detect these from fossil records. However an eruption of Yellow Stone would belikely to have quite a global effect!

I think that the deposits of gravel in Hertfordshire point to the terminal moraine being situated further south than the south Midlands.

Jethro's attachment re the Gulf Stream shutting down seems to hold some weight i.e. the North American and Eurpean Ice sheets melt, depositing fresh water into the Atlantic for the hiccup in warming circ 12,800 years ago.

[noggin]

Could warming have been a trigger? i.e. More warming, more precipitation falling as snow at high altitudes and northern latitudes to such an extent that it was not all melted during the summers,

Genuine question. Why would more warming mean more snow?

[High Altitude]

According to averages, I understand that we are getting near to the end of an inter glacial period. We don't really know what kicked the ice ages off in the first place but just suppose that the conditions whatever they were were met, say within the next couple of years, what thoughts do you have on how it would progress and how do you expect the climate of the uk to change, considering the most northern parts were under about 2 kms of ice at its worst in the last ice age.

As far as I am aware no plans appear to have made for this eventuallity but it will happen one day.

Any ideas?

www.iceagenow.com

[Devonian]

www.iceagenow.com

Yeah, he's been scaremongering about an Ice Age for some times. Good at picking cherries as well he is...

[VillagePlank]

No chance of an imminent ice-age, I'm afraid. Some chance of a return to 1980's style winters, perhaps in the next decade, before the sun starts heating stuff up again. That's my view for what it's worth, anyway.

[Guest]

Noggin,

Warmer conditions mean that there is greater evaporation from the surface of the seas - greater evaporation means more water vapour in the atmosphere - more water vapour means more cloud and more precipitation - both the clouds and the precipitation will act as a cooling agent.

At higher altitudes and latitudes the precipitation will be snow.

Consider the situation where sometimes we have a day, say about +4C air temp at surface level, then it starts to snow really heavily, the effect of the heavy snow after a time can cool the surface level temp down towards 0C air temp, so we end up with snow settling on the ground.

There is a saying that it is too cold to snow - I don't altogether go with this because there is snow at the poles where it gets very nippy, though there is a certain amount of truth in this saying inasmuch as you have to have a certain amount of warmth in order to create the conditions which lead to snow falling.

No chance of an imminent ice-age, I'm afraid. Some chance of a return to 1980's style winters, perhaps in the next decade, before the sun starts heating stuff up again. That's my view for what it's worth, anyway.

Who knows, since we are unsure as to what caused the ices ages in the first instant I think it is impossible to say.

Edited December 7, 2009 by mike Meehan

[Mr Maunder]

If the Gulf Stream shuts down, it could get rather chilly, rather quickly:

http://www.msnbc.msn.com/id/34242705/ns/technology_and_science-science/

Funny you should mention this as, as if you look at the image below, you could suggest that there is some sort of NAD disruption taking place right now.

It does look as if the Labrador current could possibly have "overrun" the NAD, temporarily disrupting its progress north. The strongly positive SST anomalies close to the NE coast of America and the lower(ing) mid-Atlantic anomalies stretching across to the south of the UK could support this view.

I also remember reading (I cannot remember where) that one of the first signs of NAD disruption would be the appearance of positive SST anomalies to the west and north of Iceland. This would occur as "warm pooling" takes place at the usual sink points of the surface warm current, due to the disruption of the return current.

Well, there are positive SST anonmalies developing now in this area - but, equally, these could just be due to local weather conditions in that area right now.

I'm not suggesting I am right or I have uncovered a NAD shutdown! However it will interesting to see how this develops. If this is happening then I would expect the "warm pools" to strengthen for a period (I've no idea how long), before fading.

MM

[Essan]

According to averages, I understand that we are getting near to the end of an inter glacial period.

Based on Milankvitch cycles we're in a 'double interglacial' - a full blown Glacial isnt expected to start for several thousand years.

However, due to changes in N Hemisphere insolation, we are in a cooling phase folling the Holocene Climatic Optimum and can expect summers in the north to continue to cool for some time to come. Which begs the question why they are warming ....

At present ice caps on Baffin and Labrador are at their lowest extent since before the MWP and quite possibly since the height of the Holocene Climatic Optimum 6,000 years ago. So we're currently about as far from a new ice age as it's possible to be. But if glo0bal warming doesn't continue and N Hemisphere summers revert to LIA conditions then we could see a minor stadial event within the next few hundred years - possibly plummeting temps down to 1800 levels.

Worst case scenario is glaciers advancing in New York City sometime around 40,000AD

[Guest]

Based on Milankvitch cycles we're in a 'double interglacial' - a full blown Glacial isnt expected to start for several thousand years.

However, due to changes in N Hemisphere insolation, we are in a cooling phase folling the Holocene Climatic Optimum and can expect summers in the north to continue to cool for some time to come. Which begs the question why they are warming ....

At present ice caps on Baffin and Labrador are at their lowest extent since before the MWP and quite possibly since the height of the Holocene Climatic Optimum 6,000 years ago. So we're currently about as far from a new ice age as it's possible to be. But if glo0bal warming doesn't continue and N Hemisphere summers revert to LIA conditions then we could see a minor stadial event within the next few hundred years - possibly plummeting temps down to 1800 levels.

Worst case scenario is glaciers advancing in New York City sometime around 40,000AD

But is this only a part of the story? - others which would have an effect are plate movements - pollution of the atmosphere by volcanos etc. - the possible varying output of the sun and changes in ocean currents to mention just a few.

Our minds are focused on this coming winter and many of us older ones are recalling the winter of '63 and wondering whether there will be a repeat with a great big fat high sitting over Greenland but this high sitting there was probably one of many causes for this winter, '63 that is, which all came together.

Likewise is it the same for the causation of ice ages i.e. several factors coming together to kick it off and once started it gathers momentum with feed backs until such time as a stronger influence comes into play to dispel it?

The other thing which occurs is that ice caps and glaciers really need two things to grow and they are cold and snow and if there is a shortage of either the ice would retreat.

Edited December 14, 2009 by mike Meehan

[Roger J Smith]

While I do believe that there is some limited AGW going on in the background of recent fluctuations, we need to step back and gain a bigger picture of where we are now in the longer glacial - interglacial fluctuations.

Just as ice cover reaches its least extent in September, after the peak of summer warming, land ice continues to shrink through the past 3,000 years despite the fact that we've passed the "Climatic Optimum" and are now seeing slightly less insolation in the high latitudes in summer. This is probably the normal run of events in an inter-glacial, the temperature peak is probably seen before the ice minimum arrives, and the sharper temperature falls signal the end of the ice ablation.

We may be just about at that point now. Luckily for us, as Essan points out, this next glacial episode to come (as predicted by Milankovitch cycles) is more gradual in onset than the previous one. We probably have 10,000 to 30,000 years of grace before significant glacial advances begin, as the orbital factors change rather slowly in this case. They are changing mainly towards the cold side of the balance, but as I say, luckily for us, not nearly as fast as 120,000 years ago.

However, we are not entirely sure that the Milankovitch cycles are the full story. There could be other factors not yet diagnosed, such as variables in the lunar orbit, as suggested in David Dilley's research. He feels that a somewhat faster onset of the next glacial period is possible. There is also the concept of the singularity, an episode brought on by volcanic dust or even a fluke weather pattern that lays down necessary snow cover in marginal regions, so that the natural processes of albedo and reflectivity kick in prematurely to start glaciation. Once started, in these intermediate insolation conditions, glaciation could become stable at least in a partial ice age configuration. Anyone familiar with the climate of northern Canada would realize that if snowfall was exceptionally heavy in certain subarctic zones, it could persist into July or even early August and "meet" the next winter's snowfall onset. Once that happens for three or four consecutive years, glaciation can quickly accelerate.

In the geological time scale, the current AGW question will probably work itself out simply through depletion of fossil fuels if for no other reason, and the necessary technological change will probably, by 2200 AD or so, remove the excess greenhouse gases, so that whatever happens in the short term, we'll be back to the natural "background" climate, albeit with some massive urban heat islands. Whatever that climate is fated to be, we will be stuck with it unless we learn to modify it (if it proves too cold for our economic well-being).

I would say the odds of an ice age of even modest proportions (land ice advancing half-way to maximum extent of the last glacial period) are something like this:

less than 1% now to 2500 AD

1-5 per cent 2500 to 4000 AD

5 to 25 per cent 4000 to 10,000 AD

25 to 50 per cent 10,000 to 25,000 AD

50-99 per cent after 25,000 AD.

One would have to think that in the distant future, scientists would be talking about ways and means to combat global cooling, and those could involve changing albedo of marginal snow cover regions in late spring, warming the oceans, or using giant mirrors in space to aim more insolation into the subarctic. They might even dust off some old books and discover another way -- drill, baby, drill.

[Guest]

Interesting - I suppose the worst case scenario is a super volcanic eruption triggering off cooling for a few years thus allowing a growth of glaciation - once this is established the albido effect will lead us into a loop with temperatures spiralling down, which I expect could happen in a few decades. If that happens then God help us because with an overpopulated earth we do not have the resources to deal with that situation. On the other hand there would be some survivors and man did manage to manage to survive the last age, although they had nothing like the logistic problems as we would have - it was just case of going out and killing a mammoth every so often.

Now we would have fights and wars over declining food and energy shortages and I expect a good proportion of mankind will succumb to this and the worsening conditions.

On the other hand if the next ice age were to develop well into the future our energy problems may be solved by the development of fusion power for example. I woud anticipate that under an ice age the earth would be generally drier but the power we develop could be used for irrigation of the temperate zones left.

There is an extreme outide chance of a "snowball" earth but as far as I am aware this had only happened once in the world's history.

[Roger J Smith]

I would have to think that at the rate technology is now advancing, we would have a chance of dealing with an ice age within a thousand years or less, so the main danger would be if it came on very soon.