How does an Ice Age form?

[Robbie Garrett]

What are the synoptics of an ice age? Those tell tail signs, would it happen to start over a winter or would it be regular poor winters like we are having now with really wet and cool summers and springs/autumns??

What are the possible weather patterns, seasonal etc?

[knocker]

What are the synoptics of an ice age?

Is that a serious question?

[BARRY]

Is that a serious question?

It's an interesting question

[Robbie Garrett]

Of course it's a serious questions, probably not worded correctly... I am not looking for you to give me full on charts and everything. Just wondering what sort of enviroment the northern hemisphere would be in?

1100mb high over the Arctic I guess....and Greenland!!

[BARRY]

here you go Robbie this is a start

http://iceagenow.info/2011/11/ice-ages/

[BornFromTheVoid]

here you go Robbie this is a start

http://iceagenow.inf...11/11/ice-ages/

Probably best not to stick someone of the track climate science denial, when asking a climate/weather question.

Here are some papers on the synoptic patterns prevalent during the last ice age

Paleometeorology: High resolution Northern Hemisphere wintertime mid-latitude dynamics during the Last Glacial Maximum

Synoptic Reorganization of Atmospheric Flow during the Last Glacial Maximum

Results of PMIP2 coupled simulations of the Mid-Holocene and Last

Glacial Maximum – Part 1: experiments and large-scale features

[knocker]

Very complicated but it's not just the ice ages.

America's Ancient Hurricane Belt and the U.S.-Canada Equator

ScienceDaily (Nov. 15, 2012) — The recent storms that have battered settlements on the east coast of America may have been much more frequent in the region 450 million years ago, according to scientists.

New research pinpointing the positions of the Equator and the landmasses of the USA, Canada and Greenland, during the Ordovician Period 450 million years ago, indicates that the equator ran down the western side of North America with a hurricane belt to the east.

The hurricane belt would have affected an area covering modern day New York State, New Jersey and most of the eastern seaboard of the USA.

http://www.sciencedaily.com/releases/2012/11/121115133754.htm

[Gray-Wolf]

Maybe we should start to list out the changes that help the planet slip into/out of and ice age?

The one we are most familiar with is a change in the amount of energy the planet, or parts of the planet recieve from the sun?

More energy than 'average' must lead to a larger carbon cycle (more biomass able to be produced due to reduction in ice cover/warmer conditions) and so more GHG's in the atmosphere which in turn leads to further warming.

Less ice means a lower albedo for the planet (less ice/snow to reflect energy away) so warmer temps than with a higher albedo.

The rest of the impacts appear far to complex for my little brain! Warmer temps mean the air can hold more moisture so less clouds would form but the extra energy must lead higher evaporation rates so more clouds would form??? Is this a negative forcing (higher aqlbedo due to bright cloud tops) or a positive (water vapour is a powerful GHG so extra saturation of the atmosphere increases it's potential to warm) .

With less energy the opposite happens so the ice cover grows and adds to the cooling due to the increase in albedo and energy lost back to space . Ice cover drowns biomass and cooler temps lead to less vigorous growth and a change to lower maintainance plants.

One recent paper has pointed to the arrival of peat bogs as an important start in our current glacial period with it's ability to consume large amounts of CO2 and hold it in stasis. This has effectively helped shring the carbon cycle so small energy losses have lead to a carbon cycle (and GHG levels) that enable glaciation to begin.

Our destruction of this reserve and climate changes impacts on the conditions needed to produce peat may lead us out of this glacial epoch meaning even low energy conditions (orbital forcings) will no longer be enough to kick start a glacial period due to the extra GHG's no longer held inert by the extensive northern peat bogs..

If our current understandings of the glacial cycles are correct we may find that our increse of GHG's has offset the latest move toward glaciation with the slow cooling of the polar region (past 1,000yrs) now halted and reversed. If this has occurred whilst a potion of our warming has been avoided due to the global dimming phenomina then the future would look increasingly glaciation free as our carbon cycle expands due to warming and further GHG's are made available to the climate system.

It is a very interesting question, i.m.h.o., and may be one that is consigned to the planets history for this geological age with the planet moving , once again, toward a totally ice free planet due to our enabling the full carbon cycle to once again be revealed and the destruction of the 'carbon sinks' that used to deal with the excess carbon (and commit it to the planets rock strata for storage) that the planet produces as it organises itself internally (metal to core, lighter elements/gasses to atmosphere).

[mike Meehan]

My little brain tells me that the ice ages were not caused just by one event but a number dovetailing to create the event, simliar to the recent of flooding of New York being a consequence of both high on shore winds associated with Sandy and a higher than normal high tide making landfall at the same time.

The world climate is controlled first of all by the energy from the sun which can vary especially when you consider that the Earth's orbit is somewhat eliptical meaning that at different periods of time, say the northern hemisphere is more favoured than at others. It is also suggested that through periods of time there are some fluctuations in the actual output of energy from the sun.

With continetal drift we have a gradual changing of the landmasses and here the Antarctic typifies the tendency to be colder than the Arctic because the former consists of a landmass whilst very much of the latter is sea.

In addition to the changes in landmass and energy received we also get changes in the ocean currents which can be further changed by variations of salinity.

On top of this greenhouse gases which do not just mean CO2 but include methane and water vapour also have an effect.

On the other hand water vapour is required to kick start an ice age because this will fall as snow in the hight latitudes and altitudes and without a significant layer of snow I doubt that an ice age as we know it would begin.

So we need moisture to make the snow especially during the winter and colder summers to slow the melt so the areas of snow and ice gradually increase - as they do they will reflect more energy away and become colder - as they become colder these areas will increase in size and this system will feed on itself causing glaciers in high latitude and high altitude regions to form and continue their expansion until they reach the warmer areas at sea level at lower latttitudes until eventually we end up with the limit of ice extending to St Johns Wood in London as it has done in the past.

CO2 is closely associated with the formation of ice ages and less of it means colder conditions and more warmer conditions but we are not totally sure of the mechanics governing this, though there is a suggestion of carbon hungry plant life gulping it out of the atmosphere thus causing cooling.

Volcanic action can also have an effect - a great deal of ash and sulpher dioxide pumped into the atmosphere can shield some of the sun's energy from reaching the surface causing cooling whilst at other times volcanoes can spew out a lot of carbon di-oxide leading to warming.

The interesting thing is that the last encroachment of ice finished pretty quickly about 12000 to 15000 years ago, which is a short time by geological standards, so there must be tipping points in both ice formation and melting.

So I would suggest to kick start, snow and lots of it in the winter coupled with minimal melting in the summer to allow the ice to build up in the first place, then after a time an equilibrium is reached where there are drier periods but the cold does not allow for very much warming and finally a warming period which melts the ice.

[knocker]

In their fine book "Atmosphere, Weather and Climate", Routledge. Roger G. Barry and Richard J. Chorley havea section on The Climate Record which may be of interest so have uploaded it as a PDF.

I had a complete system crash recently so have had to replace what I could afford. Activating Acrobat X! was a bit of a nightmare.

Climate.pdf

Edited November 26, 2012 by knocker

[Gray-Wolf]

Thanks for the trouble Knocker I found it a good overview of past events and the drivers we feel play a role in the ice ages.

Even though from the 'christmas pudding' (EDIT: what the heck did the swear filter see there??...modernera) some areas do appear dated when compared to what most of us now understand from the last 15yrs of related research!

Again we should underscore that GHG's do play their part in both the beginnings and endings of such epochs. It is worth bearing this in mind when looking at how we have inflated the amount of GHG's over the last 60yrs and the current levels of CO2 when compared to past historical levels?

Edited November 26, 2012 by Gray-Wolf

[Robbie Garrett]

Fantastic replies guys, very good read. It does seem to be more than just little things that cause an Ice age...

[PeteB]

IMHO, There has to be some sort of disruption to the Atlantic Conveyor Belt before an Ice Age can establish itself in the Northern hemisphere and probably some sort of chain reaction to the rest of the ocean currents world wide. If you look at the extent of the ice sheet during the last glacial period then there's no way that Ice several kilometres thick could have formed in for example The Irish Sea had the conveyor belt had been running normally. What we have to ask is what factors cause it to switch off, is it a natural cycle or is it linked to dimming of the Sun, volcanic activity or by The Earth passing through interstellar dust?

Pete

[Gray-Wolf]

We see evidence of the opposite happening though with very cold northern areas but mid lats overheating as the waters terminate there due to ice disrupring the northern leg of it's journey?

I think that Arctic cooling pushes south not disruption to the south allowing southerly ice growth?

Some folk might seek to downplay the importance of the current albedo flip but both sides of changes to albedo might be the thing that rapidly alters climate? Once we get 'white' surviving summer then we get impacts instantly, the same applies when we lose that reflectivity over summer.

Current alterations to those critical weeks over summer stand to drive major alterations across the north and reinforce the trend to albedo losses.

In the past this has allowed dormant carbon to leach back into the system and hold onto ever more heat. This time we have already added the GHG's so we instantly are able to hold onto more of the heat.

[PeteB]

I think that Arctic cooling pushes south not disruption to the south allowing southerly ice growth?

That's probably right but there's no real scientific explanation for how they actually start. In fact after reading several articles about this, Ice ages would seem to be impossible but yet they happen..

Pete

[Gray-Wolf]

I'd agree Pete! There seems to be a number of things that need to be 'just so' to allow the initial phase but once ongoing albedo loss sequestration of sections of the carbon cycle (lessening available GHG's) speed things along?