The Feedback mechanism

[Cheviot]

Read this the other day:

http://www.guardian.co.uk/science/2007/aug/07/disasters

which proposes that volcanicity increases with changes in weighting from ice and water on the earth's crust.

To summarise, as ice caps melt the crust under the ice moves and volcanicity increases. This could act as a natural feedback to the GW outlook by reducing global temperatures through increased stratospheric light dispersion due to volcanic particles.

Thought that this was an interesting angle on GW and the earth's inter-relationship with its ecosystems.

[Lettucing Gutted]

Read this the other day:

http://www.guardian.co.uk/science/2007/aug/07/disasters

which proposes that volcanicity increases with changes in weighting from ice and water on the earth's crust.

To summarise, as ice caps melt the crust under the ice moves and volcanicity increases. This could act as a natural feedback to the GW outlook by reducing global temperatures through increased stratospheric light dispersion due to volcanic particles.

Thought that this was an interesting angle on GW and the earth's inter-relationship with its ecosystems.

Alternately the volcanoes could put more CO2 in the atmosphere thus accelerating Global Warming as a positive feedback.

[johnholmes]

Read this the other day:

http://www.guardian.co.uk/science/2007/aug/07/disasters

which proposes that volcanicity increases with changes in weighting from ice and water on the earth's crust.

To summarise, as ice caps melt the crust under the ice moves and volcanicity increases. This could act as a natural feedback to the GW outlook by reducing global temperatures through increased stratospheric light dispersion due to volcanic particles.

Thought that this was an interesting angle on GW and the earth's inter-relationship with its ecosystems.

interesting read, and as you say, yet another slant on GW or AGW.

[Anti-Mild]

Alternately the volcanoes could put more CO2 in the atmosphere thus accelerating Global Warming as a positive feedback.

CO2 doesn't lead the climate, it's the other way around.

[Gray-Wolf]

I keep wondering if the 'human contribution' to the atmospheric composition over the past 150yrs was all condensed into a plume 1mile by 1mile for us all to more easily appreciate the scale of it whether we may change our attitudes a tad towards that that we have,and continue to, be responsible for. The fissure erruptions that resulted in the Deccan plateau (India) continued over a long period of time (compared to normal volcanic 'eruption events' which are generally over within 6 months) and had a major impact upon our global climate ,how are we measuring up to that event?

If the weather leads CO2 then where do we fit into it all with our 'extra', 'un-natural' outputs?

[noggin]

A friend told me that there had been a programme on the History TV channel the other night, about ice ages. I am miserable because I missed it!

However, my friend said that the conclusion of the presentation was that a combination of three things causes ice ages. Volcanic eruptions were one, as the sulphur that was thrown up into the atmosphere reduced the amount of heat coming through from the Sun. Low solar activity was one of the other 3 causes. Don't know what the third was, but the programme concluded that our current situation on Earth was such that another ice age is on the way. Don't know if they meant a little one or a big one though.

Did anyone see the programme? Is this correct about sulphur? Is there much in the way of sulphur around at the moment?

I am going to see if I can find anything on the internet about the programme and if I can, I shall post it.

PS actually, I think the third cause might have been excessive rainfall.

[Guest Mike W]

I thought the tilt and orbit of the Earth was the main cause of Ice Ages, I thought a high anomaly of volcanic eruptions and solar activity was the casues of mini ice age events likr the last Little Ice Age anbd it peak called the maunder minimum. To get a actual ICe Age where ICe sheets advance notably you would need the tilt and orbit to change, called Milancovitch Cycle or simialr isn't it.

[Bobby]

I thought the tilt and orbit of the Earth was the main cause of Ice Ages, I thought a high anomaly of volcanic eruptions and solar activity was the casues of mini ice age events likr the last Little Ice Age anbd it peak called the maunder minimum. To get a actual ICe Age where ICe sheets advance notably you would need the tilt and orbit to change, called Milancovitch Cycle or simialr isn't it.

Yes, that's entirely correct. Ice ages aren't caused by volcanoes or solar activity or anything like that.

[RedShift]

I thought the tilt and orbit of the Earth was the main cause of Ice Ages, I thought a high anomaly of volcanic eruptions and solar activity was the casues of mini ice age events likr the last Little Ice Age anbd it peak called the maunder minimum. To get a actual ICe Age where ICe sheets advance notably you would need the tilt and orbit to change, called Milancovitch Cycle or simialr isn't it.

It’s almost correct. I would argue that the main driver of ice ages is plate tectonics. There have been four, maybe five ice ages that we know of in the Earth’s history. We are currently in one. It seems that when the continents are in a position to block the oceans carrying heat from the equator to the poles you get an ice age. Presently we have a large landmass over the South Pole and an almost land-locked ocean basin over the North Pole.

India colliding with Asia also helped, it threw up a huge amount of rock (i.e. the Himalayas) to be weathered by weakly acidic rainwater. It also started the monsoon with intensified this effect. Rock weathering draws down CO2 from the atmosphere. Milankovitch cycles will cause a regular pattern of glacials and interglacials…(though there is still some debate about their precise timing)…but they also work in an ice-free world too. The geological record is full of cycles which probably correspond to Milankovitch Cycles.

Two of the largest volcanic events of recent history (and I use the word ‘recent’ in a geological context) are the K-T boundary Deccan Traps and the Permian-Triassic Siberian flood basalts…mass extinctions maybe, ice ages no.

[Devonian]

CO2 doesn't lead the climate, it's the other way around.

Co2 is a ghg.

Changing it's atmospheric concentration has a climate changing effect - whatever the cause of a change in concentration.

In the past (pre our influence) it seems likely that a slight warming effect (perhaps orbital variation) triggers the release of CO2 through ocean warming and this causes more warming - temp and CO2 rise through a +ve feedback loop (on a scale of centuries or more).

But, atm, we're releasing CO2, so does that mean the current CO2 doesn't have an climate effect because atm it's not a feedback to some previous warming trigger? Of course not! CO2 is CO2 and CO2 is a ghg. So, atm, the CO2 we are adding to the atmosphere is forcing the climate, an anthropogenic climate forcing.

[SnowBear]

Going back to the original topic of the thread, which discusses the effect of melting ice over land masses.

In parts of the world it is known to have many thousands of metres of ice laying over underlying rock. Once the weight of that ice is removed it must have an effect as per the laws of gravity. Weight off, rock heaves a great sigh of relief at not being squashed any more, but at the same time may release cappings and pressure over previously non-volcanic or long term inactively volcanic areas.

Iceland, if you took all the ice off Iceland I am pretty sure you would have a more volcanically active island than we see today, purely due to the ice "capping" the pressure of the magmas beneath being removed.

This of course does not effect the Arctic so much as the landmasses of Greenland and Antarctica due to the Arctic being a sea ice area rather than a land ice area.

I do think though that the removal of ice over a large land mass would have an effect over a longer period of time and probably wouldn't effect us in this century, take for example the UK after the last ice age, it is still even today slowly finding its equilibrium, the north and western parts rising up after the removal of the ice sheet and the south and east sinking as it is being pushed down due to the effects of those north and western movements.

Now, if you had an area say like Iceland, on a known large faulted area, which has seemed inactive and extinct for some time, suddenly all the ice goes (ice which has the weight of mountains kilometres thick), the faults and volcanism which was once kept in check will almost certainly become active again once the pressure is released.

Combined with the rise in sea level, which would bring to bear a higher possibility of Krakatoa type eruption which can put into the atmosphere large quantities of fine rock and dust particles due to the fact that more craters would be vulnerable to sea water being able to enter them and produce explosive eruptions, the fact that the volcanoes that become active on previously inactive ice locked land masses, we could see a big increase in sun blocking particles in the atmosphere and regardless of atmospheric CO2 content, if enough activity is present, we could quite quickly start to see a volcanic winter phase entered, which might in turn trigger a longer term ice age.

Then we have the tilt of the Earth changes to take into account...

All interesting stuff and all gets very complex really when you think on it!

B)

[Lettucing Gutted]

we could see a big increase in sun blocking particles in the atmosphere and regardless of atmospheric CO2 content, if enough activity is present, we could quite quickly start to see a volcanic winter phase entered, which might in turn trigger a longer term ice age.

B)

The problem is that if the negative forcing from the volcanic eruption (bright sulphuric acid aerosols, dust, ash etc) is too small then we would be lucky for global warming to slow down slightly, let alone cause a long term cooling.

Edited August 31, 2007 by Craig Evans

[Stratos Ferric]

...Now, if you had an area say like Iceland, on a known large faulted area, which has seemed inactive and extinct for some time, suddenly all the ice goes (ice which has the weight of mountains kilometres thick), the faults and volcanism which was once kept in check will almost certainly become active again once the pressure is released.

Combined with the rise in sea level, which would bring to bear a higher possibility of Krakatoa type eruption which can put into the atmosphere large quantities of fine rock and dust particles due to the fact that more craters would be vulnerable to sea water being able to enter them and produce explosive eruptions, the fact that the volcanoes that become active on previously inactive ice locked land masses, we could see a big increase in sun blocking particles in the atmosphere and regardless of atmospheric CO2 content, if enough activity is present, we could quite quickly start to see a volcanic winter phase entered, which might in turn trigger a longer term ice age.

...

Iceland is not so much 'on a large faulted area', so much as a direct product of the divergent American and Eurasian plates. It is the sole example of a sizeable landmass on the earth's surface which is not itself on a continental shelf (these latter being the elements of the earth's crust which are deepest and effectively "float" highest c.f. the ocean surface). Also, the ice on Iceland is not kms thick, and what's there already is absolutely no restraint to the vulcanism on Iceland. There have been several examples of major eruptions beneath the ice, leading to catastrophic releases of melt-water. Iceland, by virtue of its unique location on major divergent plate boundary, will always be volcanically active.

[pottyprof]

Why can't people see that being closer to the sun than we have been for a while, could and will have an effect on our climate?.. Even worse... During our closest approach to the sun, during our now elliptical orbit, the North Pole, during winter, also points closer to the sun due to another wobble.

Now forgive me if I'm wrong here but getting closer to a flame means things get hotter.. I'm sure some will claim that this isn't part of a feedback mechanism and others will just dismiss this outright.

The sun also has a positive and negative phase in its cycles and its magnetic fields. The amount of heat that can be created by magnetic fields being in opposition is quite large on a small scale. This heat generated over the last several very active solar cycles will have taken time to show from the earth's internal furnace. Being closer to the source of the magnetic field will increase this effect... Always a lag on anything with the climate so repeated warming of the core would reach the surface eventually?

Closest approach is about 2012 so hang on to your underwear..

Simplistic but yet obvious..

CO2 lags temperature...

On a slightly different note. Repeated strong opposition on a magnet weakens the fields. This has been observed with our protective shield.

[noggin]

Why can't people see that being closer to the sun than we have been for a while, could and will have an effect on our climate?..

I do see it. I think the Sun and it's juxtaposition with the Earth is the main driver of Earth's climate.

Jack Sparrow. Yum yum.

[Devonian]

Why can't people see that being closer to the sun than we have been for a while, could and will have an effect on our climate?.. Even worse... During our closest approach to the sun, during our now elliptical orbit, the North Pole, during winter, also points closer to the sun due to another wobble.

Now forgive me if I'm wrong here but getting closer to a flame means things get hotter.. I'm sure some will claim that this isn't part of a feedback mechanism and others will just dismiss this outright.

The sun also has a positive and negative phase in its cycles and its magnetic fields. The amount of heat that can be created by magnetic fields being in opposition is quite large on a small scale. This heat generated over the last several very active solar cycles will have taken time to show from the earth's internal furnace. Being closer to the source of the magnetic field will increase this effect... Always a lag on anything with the climate so repeated warming of the core would reach the surface eventually?

Closest approach is about 2012 so hang on to your underwear..

Simplistic but yet obvious..

CO2 lags temperature...

On a slightly different note. Repeated strong opposition on a magnet weakens the fields. This has been observed with our protective shield.

Rather vague I must say, PP. "closer to the sun than we have been for a while" how much time is a pottyproff 'while'? It is simplistic to say being closer to the sun warm us if the amount is trivial - both distance and temperature. You've given no figures so I have to assume you have none? So it's not obvious - it is, as those who have the figure would say, not the explanation for recent warming. How come you know better?

Likewise with CO2 lags temps in the ice cores stuff. Yes it might well have, but so what? In the past CO2 feedback to a warming push, atm we're bypassing that push and just pouring it into the atmosphere and how CO2 gets to the atmosphere doesn't alter it's ghg properties...So, again, not obvious.

[SnowBear]

Iceland is not so much 'on a large faulted area', so much as a direct product of the divergent American and Eurasian plates. It is the sole example of a sizeable landmass on the earth's surface which is not itself on a continental shelf (these latter being the elements of the earth's crust which are deepest and effectively "float" highest c.f. the ocean surface). Also, the ice on Iceland is not kms thick, and what's there already is absolutely no restraint to the vulcanism on Iceland. There have been several examples of major eruptions beneath the ice, leading to catastrophic releases of melt-water. Iceland, by virtue of its unique location on major divergent plate boundary, will always be volcanically active.

Hmmm, I tend to agree there and disagree in another respect.

I will agree Iceland is not the perfect comparison in so far as it is not a continental plate and yes, the thickness's of ice and rock are not the same. I was trying to bring some sort of well known land mass into the post to make it easier for people to understand what I was trying to bring across.

But I do also disagree that the weight of ice on Iceland does not have a capping effect. When we look at a volcano, sometimes it is only a matter of a layer of rock in the volcanoes crater plug, say 100m or so that is holding back the magma underneath. Ice can act the same, allowing a volcano to be capped with a lesser layer of rock than it would be on an ice free land mass. If it takes 100m of rock to cap a certain volcanoes activity, maybe under ice conditions it would only take 40m of rock and 100m of ice to hold back the same volcano. I do believe that Iceland would be even more volcanically active if it was ice free.

Maybe a better comparison would be Greenland, once all the ice is removed, the land would start to move and rise, allowing previously unknown volcanic hotspots to reactivate. All these processes though I believe are over longer periods of time than the article would lead people to believe, its not something that would happen "catastrophically" in my view unless we had a situation whereby a volcanic hotspot like Yellowstone was uncovered in the middle of say Greenland or Antarctica.

All interesting stuff!

[pottyprof]

Rather vague I must say, PP. "closer to the sun than we have been for a while" how much time is a pottyproff 'while'? It is simplistic to say being closer to the sun warm us if the amount is trivial - both distance and temperature. You've given no figures so I have to assume you have none? So it's not obvious - it is, as those who have the figure would say, not the explanation for recent warming. How come you know better?

Likewise with CO2 lags temps in the ice cores stuff. Yes it might well have, but so what? In the past CO2 feedback to a warming push, atm we're bypassing that push and just pouring it into the atmosphere and how CO2 gets to the atmosphere doesn't alter it's ghg properties...So, again, not obvious.

Plenty of info on the net Dev.. I'm sure someone with an interest in the climate knows how to use a search engine. Some of the info is already on NW.

I'm quite impressed BTW. You managed to keep the quote in one piece. Well done..

[Angel15]

Why can't people see that being closer to the sun than we have been for a while, could and will have an effect on our climate?.. Even worse... During our closest approach to the sun, during our now elliptical orbit, the North Pole, during winter, also points closer to the sun due to another wobble.

Now forgive me if I'm wrong here but getting closer to a flame means things get hotter.. I'm sure some will claim that this isn't part of a feedback mechanism and others will just dismiss this outright.

The sun also has a positive and negative phase in its cycles and its magnetic fields. The amount of heat that can be created by magnetic fields being in opposition is quite large on a small scale. This heat generated over the last several very active solar cycles will have taken time to show from the earth's internal furnace. Being closer to the source of the magnetic field will increase this effect... Always a lag on anything with the climate so repeated warming of the core would reach the surface eventually?

Closest approach is about 2012 so hang on to your underwear..

Simplistic but yet obvious..

CO2 lags temperature...

On a slightly different note. Repeated strong opposition on a magnet weakens the fields. This has been observed with our protective shield.

Forgive the question as I am ignorant in these matters - but why are we closer to the sun now? Is is phase that the Earth goes through every so often?

[Devonian]

Forgive the question as I am ignorant in these matters - but why are we closer to the sun now? Is is phase that the Earth goes through every so often?

He wouldn't tell me, perhaps you'll have more luck

[Angel15]

He wouldn't tell me, perhaps you'll have more luck

Well I had a little hunt on the internet and it basically says that coming up to winter the earth is nearer the sun due to its eliptical orbit ..

link below, but not sure if that is the answer ..

http://www.scienceu.com/observatory/articl...ns/seasons.html

another link here - this one says the further we are from the sun, the warmer our planet is!!

http://science.nasa.gov/headlines/y2002/02jul_aphelion.htm

However, this is probs like teaching you all to suck eggs, but I was just curious

Edited September 4, 2007 by Angel15

[pottyprof]

Forgive the question as I am ignorant in these matters - but why are we closer to the sun now? Is is phase that the Earth goes through every so often?

Dev's being lazy.. He knows you know..

http://en.wikipedia.org/wiki/Orbital_forcing

It's one of many theories but I believe that this is playing more of a part than is currently accepted. Human interference with the climate is also playing a part and that part of the complicated picture is something we can do something about.... Perhaps.

[Devonian]

Dev's being lazy.. He knows you know..

http://en.wikipedia.org/wiki/Orbital_forcing

It's one of many theories but I believe that this is playing more of a part than is currently accepted. Human interference with the climate is also playing a part and that part of the complicated picture is something we can do something about.... Perhaps.

I know what I think, I didn't know what you think - I'm clearer now that my guess was right.

My guess was the you were using long term slow changes to the orbit to explain what's happening atm - I don't think there is any way they do. Such changes are simply to slow to explain what's happening atm.

Edited September 4, 2007 by Devonian

[The PIT]

Dev's being lazy.. He knows you know.. :lol:

http://en.wikipedia.org/wiki/Orbital_forcing

It's one of many theories but I believe that this is playing more of a part than is currently accepted. Human interference with the climate is also playing a part and that part of the complicated picture is something we can do something about.... Perhaps.

Interesting read Potty. I've also wondered what effects the position of the land would have on climate and ocean currents. It's something that doesn't seem to come up in climate change arguments.

[Gray-Wolf]

It has certainly been used to help explain why we have had ice ages in the past and so would form an obvious part in any modeling of 'Global Climate' for the future. Maybe they just don't mention the 'obvious' stuff Pit?