Record down under

[biffvernon]

In Australia

...the summer of 2012-13 is now the hottest on record. Average temperatures beat the record set in the summer of 1997-98, and daytime maximum temperatures knocked over the 1982-83 record. January 2013 has been the hottest month since records began in 1910.

http://ht.ly/iadJI

[PS_RalphW]

Ironically, antarctica has well above average sea ice area at present. Enough to completely offset the decline in arctic sea ice area.

Sea ice volume, on the the other hand, is still in death spiral in the arctic.

[biffvernon]

Oh don't try comparing Arctic and Antarctic sea ice. Totally different regimes.

[Blue Peter]

Oh don't try comparing Arctic and Antarctic sea ice. Totally different regimes.

But if the question is, What is the current global sea ice extent? then you do have to add the numbers together?


Peter.

Edit: spoolin'

[biffvernon]

It's a silly question. Adding the two lots together gives a silly answer.

Meanwhile it seems to have been snowing in Japan

http://www.bbc.co.uk/news/world-asia-21625702

[Little John]

It's a silly question. Adding the two lots together gives a silly answer.

Meanwhile it seems to have been snowing in Japan

http://www.bbc.co.uk/news/world-asia-21625702

It is not a silly question at all as the two could arguably be linked

Whilst it is true to say that a difference of, say, 4 degrees in the Arctic can be the difference between ice or no ice and that in the Antarctic 4 degrees is merely the difference between freezing temperatures and bollocks freezing temperatures, the rising ice levels in the Antarctic could arguably be the result of the same process that has lowered ice in the Arctic. Namely global warming atmospheric temperatures.

These rising temperatures appear to be pushing the Arctic over a temperature edge that it was already close to. however, those same rising temperatures that have also caused a warming of the lands and seas just north of the Antarctic have led to significantly higher winds over it. So, whilst rising temperatures may have cause the Antarctic to be not quite so ball-achingly cold which should in theory, reduce ice levels, albeit from a very high level, the higher winds passing over it could be causing a sufficient wind-chill factor on those ice levels to completely mitigate, or even overcome the rising temperatures. At least, for the moment.

From a Gaian perspective, this might be seen as self-regulation in action

Given the above, I would certainly be interested to know if, overall, global ice surface area has increased or decreased and so the adding up of total ice coverage is the way to do that

[biffvernon]

I think you've explained why it was a silly question, Steve. There's a much fuller explanation here: http://nsidc.org/cryosphere/seaice/char ... rence.html

It includes this graph:

[Little John]

I think you've explained why it was a silly question, Steve. There's a much fuller explanation here: http://nsidc.org/cryosphere/seaice/char ... rence.html

It includes this graph:

No. what I am specifically objecting to here B is the tendency you seem to have, at least to me, to summarily dismiss out of hand any discussion that goes "off message" in what looks, again to me, like an attempt to close it down. Presumably on the basis that such "off piste" discussions dilute the central "message" of global warming. It is perfectly possible to speculate that the southern pole increasing in ice simultaneously with the north pole decreasing in ice may be not only jointly linked to global warming but, even, that global warming's effects may be being mitigated (or not) by this phenomena, whilst not actually questioning the process of global warming itself. Irespective of whether such speculations are fruitless or not, it's not a "your with us or your against us" propaganda war you know.

Sometimes you do give the distinct impression of being a self appointed thought policeman.

[biffvernon]

No, it's just that the Antarctic sea ice question has been discussed at length before and I couldn't be bothered to go through it all again. I posted a link to a reliable, accessible source of information. It happens to include graphs that show Antarctic and Arctic sea ice extent. If you want to add them together, fine, but I can't see that it will show anything useful.

[RenewableCandy]

I don't think "wind chill" works on objects, only on people (where wind takes the warmth away). Or warm-blooded animals, of course.

[Little John]

I don't think "wind chill" works on objects, only on people (where wind takes the warmth away). Or warm-blooded animals, of course.

I think it may work on non organic objects as well. It's why blast freezers work much more quickly than normal freezers, presumably.

Since ice can exist at any temperature below 0 centigrade, this means that some ice can be relatively warmer than it might otherwise be. That being the case, extremely cold wind should, in principle, be capable of carrying some of that relative warmth away. In other words, as long as a temperature gradient exists in the right direction between the ice and the wind passing over it, then the wind can further reduce the ice's temperature. The reason it superficially seems that wind chill only affects warm blooded animals is because the gradient is so obviously huge that we can see it's effects readily.

[woodburner]

In other words, as long as a temperature gradient exists in the right direction between the ice and the wind passing over it, then the wind can further reduce the ice's temperature. The reason it superficially seems that wind chill only affects warm blooded animals is because the gradient is so obviously huge that we can see it's effects readily.

Inanimate objects with no heat source can reach steady state. Warm blooded animals and heated objects maintain their temperature by heat input. It is a measure of the heat input required to maintain their temperature that gives rise to the wind chill figures.

[Little John]

In other words, as long as a temperature gradient exists in the right direction between the ice and the wind passing over it, then the wind can further reduce the ice's temperature. The reason it superficially seems that wind chill only affects warm blooded animals is because the gradient is so obviously huge that we can see it's effects readily.

Inanimate objects with no heat source can reach steady state. Warm blooded animals and heated objects maintain their temperature by heat input. It is a measure of the heat input required to maintain their temperature that gives rise to the wind chill figures.

Inanimate objects will only achieve a steady state temperature if their temperature matches that of their surrounding environment. That is to say, there is no temperature gradient existing between them and their environment. If there is a temperature gradient in existence, either the environment will lose some heat to the object or the object will lose some heat to the environment until they both reach thermal equilibrium When we say that nature abhors, say, a vacuum we are really only being derivative rather than axiomatic. What we really mean is that nature abhors a gradient.

All of the above means that if a compound gas such as air passes over an object and where the temperature of the air is lower than that of the object, the object will lose heat to the passing air. Or vice-versa, of course.

All other things being equal, the organic versus non organic nature of the object cannot affect that process except insofar as the organic object may actually have the capacity to slow the process of thermal gradient minimization down by being able to regenerate its own heat by turning some of its own mass (for example, stored fat) into heat. Even then, though, there is still no such thing as free lunch because the organic object will have still lost something to the environment. In this case, mass transformed into thermal energy.

In the case of ice, you seem to be implying it has no "heat" in it. If that's the case, then I think you are confused as to what "heat" actually means. "Heat" is just slang for thermal energy and any object with a temperature above zero kelvin has thermal energy. Thus, ice, with a theoretical temperature range from 0 kelvin to 0 celsius contains thermal energy. All that is required for air to reduce the thermal energy of ice (in other words, to make it "colder") is for the temperature of the air to be below the temperature of the ice. Additionally, if the volume of air that passes over the ice is high (in other words, it is very windy), this will carry the thermal energy that has been pulled from the ice away so that it has less chance of being re-absorbed. This, is, presumably, why blast freezers work faster than normal freezers. Also, remember, food that is in a freezer is no longer living and so is no longer able to regulate its heat. To that extent, it is effectively "inorganic" in much the same way as if you put a pebble or other inorganic object in the freezer. At that point, it just comes down to things like density, thermal conductivity of the materials and other factors in determining how fast it loses its heat.

It may be that the term "wind chill" is used exclusively to describe the subjective feeling of getting colder in humans. I don't know. In which case, fair enough and I perhaps need to use a another term to describe the process of wind affecting ice temperature and consequent ice extent in the Antarctic. But, the process itself is materially possible and is physically the same process that causes wind to reduce the temperature of organic objects (with the qualification that warm blooded organic objects can actually mitigate the process by the means I have already described).

[RenewableCandy]

What you describe is more like Convection. Only sideways (due to wind) rather than upwards (due to warm fluid rising). It's an effect that should have a name, but I've only ever heard "wind chill" applied to objects, such as people, which create their own heat. Perhaps I just haven't read enough about windy, icy places. (thinks: it's bad enough having to live in one...)

[Little John]

What you describe is more like Convection. Only sideways (due to wind) rather than upwards (due to warm fluid rising). It's an effect that should have a name, but I've only ever heard "wind chill" applied to objects, such as people, which create their own heat. Perhaps I just haven't read enough about windy, icy places. (thinks: it's bad enough having to live in one...)

Convection is really only a patterned, cyclical form of conduction. In other words, it's all conduction, really. As I said, nature abhors a gradient and thermal conduction leading to eventual thermal equilibrium (in other words, entropy), is an inevitable physical consequence of that abhorrence.