[hamza (OP)]

ok.. i was confused about the difference b/w the terms climate change and global warming with special respect to the fact that though global warming means a rise in temp.. but i heard somewhere that our planets movin towards another ice age.. so howcome ice age if the temperature is rising..


[TITLE ALTERED TO RE-FORMAT AS A QUESTION.]

[LeeE]

Although the average planet temperature appears to be rising this doesn't mean that everywhere will just get correspondingly warmer.  If this was the case then we'd have relatively little to worry about.

The problem comes from the weather systems that comprise our climates.  These weather systems are generally considered to be chaotic, insofar as small and seemingly insignificant changes to the initial conditions in a weather system can result in hugely different and unpredictable results.

Thus, although the temperature rise might be small in absolute terms and which, if that was all that mattered, would not amount to much of a problem, what seems almost certain is that the weather systems throughout the world will change from being relatively stable and predictable to being more unstable and unpredictable, with an increasing number of 'freak' weather events.  As the weather becomes more unpredictable, this then further changes the initial conditions for the subsequent weather that follows, and you find yourself in a vicious cycle of increasingly chaotic weather systems and climates.

While our climates are largely due to the weather systems, the weather systems need energy to manifest themselves; the energy that we can harvest from the wind by wind-farm turbines doesn't come from nowhere.  At the very root of the equation are our oceans.

The oceans, which cover the majority of the planet, absorb a lot of heat from the Sun and it is this energy that is transferred from the oceans into the atmosphere and which largely drives the weather (heat energy is also picked up by the atmosphere whilst over land too, but not to the same extent as over the oceans).  However, within the oceans of the world are huge circulating currents that move warm water from the equatorial regions to the poles, whilst at the same time other currents circulate cold water from the poles back down to the equatorial regions.  These currents of water flowing through our oceans are not just driven by the heat energy pumped into the oceans but also, it is believed, by differing relative salinities in in different parts of the oceans, with water from ice melting at the poles being relatively low in salt, whilst the water around the equator is relatively high in it, because of high rates of evaporation.  If the polar ice starts melting more quickly then it's possible that this critical salinity balance will be upset, which in turn is likely to change the ocean currents that circulate the warm and cold water around.

If these ocean current do get disturbed, then for example, instead of Northern Europe enjoying its currently moderate climate, largely due to the warm water brought up from the equator by the Gulf Stream, it might start to experience a much colder climate, more like that of Canada, which is at the same latitude but across the Atlantic, where it doesn't receive warm water via the Gulf Stream.

If it were just increasingly chaotic weather we had to deal with, it would still be pretty easy to survive but the real big problem is food production, as all of our food production, one way or another, ultimately depends upon the weather; we can't make food out of air, mine it from rocks or distill it from oil.  It all has to be grown, and if the weather changes too radically the crops that are usually grown in any particular region of the world will start to fail, and unfortunately, because farming is not a trivial matter, it would not be easy or quick to switch to growing different crops in regions that are still able to grow crops, albeit of different types, let alone being unable to grow crops in regions where it might become impossible.

So ultimately, although the world is getting a little warmer, this in itself is not really the big problem; it is the probable changes to the world's climates, and its subsequent effects upon food production that's really scary.

[hamza (OP)]

so are we or are we not moving towards another ice age? could u make it simpler by telling that climate change is a bigger picture while global warming is just a small part of it though the temperature would not rise for everywhere and even falls at some parts of our earth??

[norcalclimber]

Although the average planet temperature appears to be rising this doesn't mean that everywhere will just get correspondingly warmer.  If this was the case then we'd have relatively little to worry about.

The problem comes from the weather systems that comprise our climates.  These weather systems are generally considered to be chaotic, insofar as small and seemingly insignificant changes to the initial conditions in a weather system can result in hugely different and unpredictable results.

Thus, although the temperature rise might be small in absolute terms and which, if that was all that mattered, would not amount to much of a problem, what seems almost certain is that the weather systems throughout the world will change from being relatively stable and predictable to being more unstable and unpredictable, with an increasing number of 'freak' weather events.  As the weather becomes more unpredictable, this then further changes the initial conditions for the subsequent weather that follows, and you find yourself in a vicious cycle of increasingly chaotic weather systems and climates.

While our climates are largely due to the weather systems, the weather systems need energy to manifest themselves; the energy that we can harvest from the wind by wind-farm turbines doesn't come from nowhere.  At the very root of the equation are our oceans.

The oceans, which cover the majority of the planet, absorb a lot of heat from the Sun and it is this energy that is transferred from the oceans into the atmosphere and which largely drives the weather (heat energy is also picked up by the atmosphere whilst over land too, but not to the same extent as over the oceans).  However, within the oceans of the world are huge circulating currents that move warm water from the equatorial regions to the poles, whilst at the same time other currents circulate cold water from the poles back down to the equatorial regions.  These currents of water flowing through our oceans are not just driven by the heat energy pumped into the oceans but also, it is believed, by differing relative salinities in in different parts of the oceans, with water from ice melting at the poles being relatively low in salt, whilst the water around the equator is relatively high in it, because of high rates of evaporation.  If the polar ice starts melting more quickly then it's possible that this critical salinity balance will be upset, which in turn is likely to change the ocean currents that circulate the warm and cold water around.

If these ocean current do get disturbed, then for example, instead of Northern Europe enjoying its currently moderate climate, largely due to the warm water brought up from the equator by the Gulf Stream, it might start to experience a much colder climate, more like that of Canada, which is at the same latitude but across the Atlantic, where it doesn't receive warm water via the Gulf Stream.

If it were just increasingly chaotic weather we had to deal with, it would still be pretty easy to survive but the real big problem is food production, as all of our food production, one way or another, ultimately depends upon the weather; we can't make food out of air, mine it from rocks or distill it from oil.  It all has to be grown, and if the weather changes too radically the crops that are usually grown in any particular region of the world will start to fail, and unfortunately, because farming is not a trivial matter, it would not be easy or quick to switch to growing different crops in regions that are still able to grow crops, albeit of different types, let alone being unable to grow crops in regions where it might become impossible.

So ultimately, although the world is getting a little warmer, this in itself is not really the big problem; it is the probable changes to the world's climates, and its subsequent effects upon food production that's really scary.

Since the amount of energy in the system seems to be an important issue, shouldn't the increase in amounts of high energy cosmic rays which are bombarding Earth due to our weakening magnetic field and the currently very low magnetic field of the Sun, make a pretty big difference on the unpredictability of our weather system at this point?  After all, these particles have mass and are accelerated to nearly the speed of light, seems to me that is a lot of energy entering the system, and our main line of defense(our magnetic field) seems to be having issues at the moment.  And since the magnetic field is not even, and downright thin at some places, combined with the currents of the oceans; shouldn't we see increased energy throughout the entire system, including areas where the magnetic field is thicker?

[LeeE]

...could u make it simpler...

Nope, because it can't be simplified much beyond what I've already said, which is pretty simple anyway.

[LeeE]

Since the amount of energy in the system seems to be an important issue, shouldn't the increase in amounts of high energy cosmic rays which are bombarding Earth due to our weakening magnetic field and the currently very low magnetic field of the Sun...

I'm not aware of any increase in the amount of cosmic rays bombarding the Earth (where do the increased number of cosmic rays come from?), and nor am I aware of a significant weakening or reduction of the magnetic fields of either the Earth or the Sun.  A change in the magnetic fields of either the Sun or the Earth does not necessarily mean an overall strengthening or weakening of their respective magnetic fields.

[norcalclimber]

Since the amount of energy in the system seems to be an important issue, shouldn't the increase in amounts of high energy cosmic rays which are bombarding Earth due to our weakening magnetic field and the currently very low magnetic field of the Sun...

I'm not aware of any increase in the amount of cosmic rays bombarding the Earth (where do the increased number of cosmic rays come from?), and nor am I aware of a significant weakening or reduction of the magnetic fields of either the Earth or the Sun.  A change in the magnetic fields of either the Sun or the Earth does not necessarily mean an overall strengthening or weakening of their respective magnetic fields.

The cosmic rays are mostly protons but also include heavier nuclei, and come from distant supernovas.  They are massive particles which are traveling at nearly the speed of light.  They are always there, but we have 2 main sources of protection.  The first is the Sun, and it's magnetic field(and solar wind), which fluctuates greatly in strength depending on the solar cycle(look up solar minimum/maximum).  Currently the Sun's magnetic field, which directly correlates with sunspots and in this case the lack of sunspots, is very weak.  The solar wind has slackened as well, which also allows more cosmic rays to pass.  The next source of protection is our own magnetic field, which is weakening and the rate it is weakening is increasing.  Look up the South Atlantic Anomaly, the thinnest part of our magnetic field.  Our magnetic field is by no means uniform around the planet.  Currently I believe the increase in cosmic rays is aprox. 20%, and in the past cosmic rays have been as high as 200% of the "normal" level, but have also been correlated to coincide with ice ages.  There is some evidence which leads us to suspect that clouds actually form around cosmic rays, and an increase could lead to an ice age.

[LeeE]

Whilst there have been bursts of cosmic rays, which have reached levels higher than the norm, these are short term transient phenomenon that can be linked to specific events and do not constitute a trend, which is what is implied by saying that the amount of cosmic rays is increasing.  Claiming that there is an increase is rather like saying that the flow of water from a tap/faucet is increasing when all that has really happened is that someone has just filled their kettle.  Most of the time, of course, there will be no flow of water.

I think you may also be confusing the changing activity of the Sun's magnetic field with it's strength.  You could liken the changing activity of the Sun's magnetic field to the differing height and direction of the waves on a patch of deep ocean where, regardless of which way the wind is blowing and how strong it is, the depth of the water remains essentially the same.

The Earth's magnetic field is getting weaker, although at such a slow rate that the degree of change is negligible.  As with the Sun though, the Earth's magnetic field also varies in its activity, so in addition to the magnetic poles moving around quite a bit, and at varying speeds, it has also flipped many times in the past, and seems set to flip once again, and relatively soon at that.  However, these reversals of the Earth's magnetic field do not amount to a weakening trend.

[norcalclimber]

Whilst there have been bursts of cosmic rays, which have reached levels higher than the norm, these are short term transient phenomenon that can be linked to specific events and do not constitute a trend, which is what is implied by saying that the amount of cosmic rays is increasing.  Claiming that there is an increase is rather like saying that the flow of water from a tap/faucet is increasing when all that has really happened is that someone has just filled their kettle.  Most of the time, of course, there will be no flow of water.

I think you may also be confusing the changing activity of the Sun's magnetic field with it's strength.  You could liken the changing activity of the Sun's magnetic field to the differing height and direction of the waves on a patch of deep ocean where, regardless of which way the wind is blowing and how strong it is, the depth of the water remains essentially the same.

The Earth's magnetic field is getting weaker, although at such a slow rate that the degree of change is negligible.  As with the Sun though, the Earth's magnetic field also varies in its activity, so in addition to the magnetic poles moving around quite a bit, and at varying speeds, it has also flipped many times in the past, and seems set to flip once again, and relatively soon at that.  However, these reversals of the Earth's magnetic field do not amount to a weakening trend.

I am out of town, so I don't have much time to address this, but I have to respectfully disagree at this point.  http://www.tgdaily.com/space-features/44139-cosmic-rays-increase-as-sun-hits-solar-minimum  seems to disagree as well, so if I am misunderstanding something, perhaps you could point out where they are wrong when discussing the sun and cosmic ray intensity.

[LeeE]

I don't think that the current level, being '19% higher' (a percentage of what? - it appears to be a percentage of the total range) than the previous highest level really amounts to very much, being based upon just five previous cycles.  It would be rather surprising if, after only five previous cycles we had established clear maxima and minima.

That article also seems to confuse the magnetic field and the heliosphere...

The sun's magnetic field - the heliosphere - is our first line of defense...

Oops!  The two are entirely different things.  However, it then goes on to say...

Right now, the sun's magnetic field is weak...

When I think they may have meant that the heliosphere is (relatively) weak.

There's then a bit of sensationalist speculation...

We could see cosmic ray fluxes jump all the way to 30 percent above previous Space Age highs

...but then of course, we might not.

Finally though, it does add a bit of perspective...

Indeed, we've weathered storms much worse than this. Hundreds of years ago, polar ice cores show, cosmic ray fluxes were at least 200 percent higher than they are now.

...and then admits...

"The space era has so far experienced a time of relatively low cosmic ray activity," says Mewaldt. "We may now be returning to levels typical of past centuries."

...which really just highlights the fact that five cycles, and fifty years, isn't enough to establish any sort of meaningful trend.

[frethack]

I don't think that the current level, being '19% higher' (a percentage of what? - it appears to be a percentage of the total range) than the previous highest level really amounts to very much, being based upon just five previous cycles.  It would be rather surprising if, after only five previous cycles we had established clear maxima and minima.

Though the space age has seen only five cycles, the current solar cycle is the beginning of the 24th cycle observed.  Using 14C (from tree rings) and 10Be (from glacial cores), solar magnetic activity can be inferred for about the past 24ka.  There are problems with this method, such as estimating the contribution from fluctuations in the earths magnetic field (which contributes comparatively little), or from an abrubt slowing of the overturning circulation and carbon cycle.  There are known cycles at ~11 years (Schwabe cycle), ~22 years (Hale cycle...two Schwabe cycles), ~87 years (Gleissberg cycle), and ~220 years (DeVries/Suess cycle).  There is also good evidence for a 1500 year cycle.

That article also seems to confuse the magnetic field and the heliosphere...

The sun's magnetic field - the heliosphere - is our first line of defense...

Oops!  The two are entirely different things.  However, it then goes on to say...

Not entirely different.  They are both magnetic in nature and well correlated.  The heliosphere is formed mainly by the solar wind, which generally increases/decreases with the solar magnetic field

Right now, the sun's magnetic field is weak...

When I think they may have meant that the heliosphere is (relatively) weak.

Both are weak

There's then a bit of sensationalist speculation...

We could see cosmic ray fluxes jump all the way to 30 percent above previous Space Age highs

...but then of course, we might not.

If we enter another solar grand minimum, which are not rare, then we will see large cosmic ray fluxes.  In the past 1000 years there have been at least 5 grand minima (Oort, Wolf, Sporer, Maunder, Dalton)

Finally though, it does add a bit of perspective...

Indeed, we've weathered storms much worse than this. Hundreds of years ago, polar ice cores show, cosmic ray fluxes were at least 200 percent higher than they are now.

...and then admits...

"The space era has so far experienced a time of relatively low cosmic ray activity," says Mewaldt. "We may now be returning to levels typical of past centuries."

Yes, we have been recovering from the little ice age for a little over 200 years, and have been in a grand maxima since the late 1800's.  There really is no "typical" level of solar activity, as the sun tends to transition from grand maxima to grand minima and back again.

...which really just highlights the fact that five cycles, and fifty years, isn't enough to establish any sort of meaningful trend.

23 full cycles and more than 200 years, with high resolution proxy data for thousands of years.

[frethack]

In answer to the original question:

The earth is currently warming, and we are likely headed toward another glacial period.  There are climate cycles of all time scales...shorter cycles superimposed on longer cycles, superimposed on still longer cycles.

[LeeE]

The solar magnetic field and the heliosphere are entirely different things, even though they might be linked, just as I am entirely different from the building to which I am clearly linked by living in it.  Trying to claim otherwise, to prove a point, is disingenious.

While we may have been observing solar activity for more than fifty years and for more than five cycles we only have direct measurements of solar magnetic activity for those fifty years and those five cycles, and just as five cycles isn't really enough to establish trends and maxima/minima, it is also insufficient to provide a mapping basis for the accurate extrapolation of historical observations where it was not possible to record that data directly.  While the tree ring and ice core data is valuable, inferring conditions with a high degree of accuracy over such long periods of time from such a small overlap is unwise, especially when it is remembered that the conditions during the period when the hard data was collected is known to be different to the period being extrapolated, because of the greenhouse and ozone active pollution which was largely absent in the periods that are being inferred; in trying to do so, you are extrapolating 100% from considerably less than 1% of that total, and when that < 1% is known to be atypical.

I'm not denying that the data is not interesting but drawing meaningful conclusions from it is just wishful thinking at this point in time.  Perhaps it is because we only live for decades, rather than centuries or millennia, that we try to relate everything to our time scales, in what becomes a subjective view, rather than the objective view of the natural time scales of what we're observing.

[norcalclimber]

The solar magnetic field and the heliosphere are entirely different things, even though they might be linked, just as I am entirely different from the building to which I am clearly linked by living in it.  Trying to claim otherwise, to prove a point, is disingenious.

While we may have been observing solar activity for more than fifty years and for more than five cycles we only have direct measurements of solar magnetic activity for those fifty years and those five cycles, and just as five cycles isn't really enough to establish trends and maxima/minima, it is also insufficient to provide a mapping basis for the accurate extrapolation of historical observations where it was not possible to record that data directly.  While the tree ring and ice core data is valuable, inferring conditions with a high degree of accuracy over such long periods of time from such a small overlap is unwise, especially when it is remembered that the conditions during the period when the hard data was collected is known to be different to the period being extrapolated, because of the greenhouse and ozone active pollution which was largely absent in the periods that are being inferred; in trying to do so, you are extrapolating 100% from considerably less than 1% of that total, and when that < 1% is known to be atypical.

I'm not denying that the data is not interesting but drawing meaningful conclusions from it is just wishful thinking at this point in time.  Perhaps it is because we only live for decades, rather than centuries or millennia, that we try to relate everything to our time scales, in what becomes a subjective view, rather than the objective view of the natural time scales of what we're observing.

Good points....can't pretty the exact same things/logic be said about AGW theory?

Which would mean we basically have no clue whether we are headed for an ice age, a meltdown, or anything in between?

[frethack]

The solar magnetic field and the heliosphere are entirely different things, even though they might be linked, just as I am entirely different from the building to which I am clearly linked by living in it.  Trying to claim otherwise, to prove a point, is disingenious.

I havent claimed that the solar magnetic field that produces sunspots and the solar wind (magnetic field that produces the heliosphere) are the same...only that they are well correlated, not unrelated, and that both are magnetic fields.  I wouldnt dream of being disingenuous.

While we may have been observing solar activity for more than fifty years and for more than five cycles we only have direct measurements of solar magnetic activity for those fifty years and those five cycles, and just as five cycles isn't really enough to establish trends and maxima/minima, it is also insufficient to provide a mapping basis for the accurate extrapolation of historical observations where it was not possible to record that data directly.  While the tree ring and ice core data is valuable, inferring conditions with a high degree of accuracy over such long periods of time from such a small overlap is unwise, especially when it is remembered that the conditions during the period when the hard data was collected is known to be different to the period being extrapolated, because...

This is the bread and butter of the paleo-sciences, which most certainly are not exact sciences.  As stated in the previous post, there are many problems encountered when extrapolating proxy data.  But, if you would like to disregard research based on proxy data, then noralclimber is correct...all that we believe we know about the climate system goes out the window.  Also null and void would be plate tectonics, evolution, and the notion of the atom (until, of course, it is actually observed).

...these particles have mass and are accelerated to nearly the speed of light, seems to me that is a lot of energy entering the system, and our main line of defense(our magnetic field) seems to be having issues at the moment. 

This is currently under debate.  Lightening and cloud nucleation have been linked to cosmic radiation, but both ideas are controversial.  If GCRs are indeed involved in cloud nucleation, then they would help modulate the suns input into the system, but their actual direct input is negligible in comparison.

[LeeE]

Actually frethack, you said that they were not entirely different, suggesting that they were, to some degree, the same.

You're also guilty of exaggeration in suggesting that I was disregarding research based upon proxy data when it was pretty clear that I was questioning the accuracy, and therefore the value, of forecasts based upon that proxy data...

...insufficient to provide a mapping basis for the accurate extrapolation...

(my emphasis)

Proxy data gives us an indicator of what probably happened, between probable ranges of error, where we have no hard data, but trying to extrapolate a specific solution from it will almost certainly guarantee that the solution will be wrong; the more tightly you try to constrain the solution, the less accurate it may turn out to be.

Your comments re plate tectonics, evolution and the notion of the atom are not just plain silly but wrong too, for we do not depend upon extrapolated proxy data for them, but correlations of hard data.

[frethack]

Actually frethack, you said that they were not entirely different, suggesting that they were, to some degree, the same.

That would be because they are similar to some degree.  Your original statement:

The sun's magnetic field - the heliosphere - is our first line of defense...

Oops!  The two are entirely different things.  However, it then goes on to say...

Right now, the sun's magnetic field is weak...

When I think they may have meant that the heliosphere is (relatively) weak.

The solar wind that creates the heliosphere contains charged particles moving through space, which in turn creates a magnetic field.  The suns internal magnetic field is also created by charged particles churning around the suns core.  It is not uncommon, even in peer reviewed literature, to interchangeably use the terms "magnetic field" and "heliosphere" when discussing penetration of cosmic radiation.  Why?  Because the heliosphere is a magnetic field created by the atmosphere of the sun.  It weakens and strengthens, depending on the speed and density of the solar wind stream, which allows more or less cosmic ray bombardment of the solar system as a whole.

The sun has at least two magnetic fields, and the sunspots created by the internal magnetic field and the magnitude of the heliosphere are so far well correlated.

You're also guilty of exaggeration in suggesting that I was disregarding research based upon proxy data when it was pretty clear that I was questioning the accuracy, and therefore the value, of forecasts based upon that proxy data...

Yes, I was exaggerating.  I would assume, knowing that you are a very intelligent person, that youre not disregarding everything based on proxy data.  However, I was attempting to point out that there are many theories that are readily accepted and mostly uncontroversial, that are based upon inferences from proxies.  Guilty as charged.

Your comments re plate tectonics, evolution and the notion of the atom are not just plain silly but wrong too, for we do not depend upon extrapolated proxy data for them, but correlations of hard data.

Uhhh...what?  We have known the general speed and direction of plate motion for less than 50 years, and our understanding is constantly refined.  To help determine present/future plate motion we rely on information about past motion from magnetic grains in igneous and sedimentary rocks...isnt this proxy evidence?  Both living and fossilized animals are the basis for the theory of evolution, but we only have hard DNA evidence for the most recent animals.  A very large portion of the phylogenetic tree comes from fossil morphology...proxy data...and not hard DNA evidence.  Weve never seen the internal structure of the atom.  We can only infer the internal structure from its electromagnetic properties...proxy data.  These will all be refined with time, but that does not mean that very useful information cant be found from inferences taken from proxy data.

 

[LeeE]

Let's try another analogy: you bake a cake in an oven.  The cake can't exist without the ingredients and without being baked.  The cake then, requires both the ingredients and the oven, but the cake isn't the oven, nor even part of the oven.  This is like the difference between the the Sun's magnetic field and the Heliosphere.  The fact that peer reviewed literature may use the term interchangeably is just down to sloppy thinking/wording.

Although we may have only known about Plate Tectonics for fifty years it does not depend upon proxy data because the historical data is still there to be sampled, at the bottom of the oceans and in the rock formations on land.  While this data may not be able to give us precise rates of movement, they confirm tectonic action, so while the establishment of the process of Plate Tectonics does not depend upon proxy data, the rates of movement will do, because we weren't there to actually measure them.  The process of Plate Tectonics and the rates of movement are once again, two different things.

Like Plate Tectonics, the theory of evolution does not depend upon our knowledge of DNA, but by using DNA analysis we can establish precise changes i.e. we can measure the changes.  And again, the process and the measurements are not the same thing.

However, if you really want to look at it your way then all data is proxy.  For example, does a thermometer really tell us the temperature of something, or does it just provide proxy data, because all it can really tell us directly is how it is reacting, and not the direct temperature of the thing we are trying to measure?

[frethack]

The fact that peer reviewed literature may use the term interchangeably is just down to sloppy thinking/wording.

I am not a solar physicist and only use their findings for my own research.  Whether its the solar dynamo or the heliosphere, they both are magnetic fields.  I can agree to disagree on this point, and when posting here Ill make sure to specify which solar magnetic field I am talking about.   

Although we may have only known about Plate Tectonics for fifty years it does not depend upon proxy data because the historical data is still there to be sampled, at the bottom of the oceans and in the rock formations on land.  While this data may not be able to give us precise rates of movement, they confirm tectonic action, so while the establishment of the process of Plate Tectonics does not depend upon proxy data, the rates of movement will do, because we weren't there to actually measure them.  The process of Plate Tectonics and the rates of movement are once again, two different things.

Yes, exactly.  Just as the causal relationship between solar magnetic activity (which includes the heliosphere and solar dynamo) and incoming cosmic radiation have been established in the modern, we can use this relationship to make very useful inferences on past solar activity.  The further back in time you go, the larger the error bars, but that is science.  There is always error...Ive never created nor seen a data set without it.

However, if you really want to look at it your way then all data is proxy.  For example, does a thermometer really tell us the temperature of something, or does it just provide proxy data, because all it can really tell us directly is how it is reacting, and not the direct temperature of the thing we are trying to measure?

If taken to the extreme, then yes, this is fundamentally true.  If not taken to the extreme, using magnetic grains as a paleomag indicator, skeletal morphology as a phylogenetic indicator, or using 18O in speleothems/sediment cores/glacial cores as a temperature indicator would all be considered proxies.

The point is, you can get very useful information on solar activity from radiogenic isotopes as long as you are aware that other factors can produce spikes and as long as you know how to tell the difference.

This topic has wandered quite far from its original question.

[LeeE]

The point is, you can get very useful information on solar activity from radiogenic isotopes as long as you are aware that other factors can produce spikes and as long as you know how to tell the difference.

Yes, I agree, but with respect to the original question, in this specific case I still think that the number of samples is far too low to establish a either a trend, or a meaningful proxy dataset, with any real degree of accuracy.

This topic has wandered quite far from its original question.

A very good point.