Is There Clear Evidence of Antarctic Global Warming?

[jimmydasaint]

A recent speech has made me wonder about the data from the Antarctic about global warming. There does not seem to be much evidence for an overall temperature rise when I have examined two sources.

The first is a research article:

http://researchnews.osu.edu/archive/anttemps.htm

 

and the other is a paper from 1998:

http://journals.cambridge.org/download.php?file=/ANS/ANS10_02/S095410209800025Xa.pdf&code=3f4f6e8220d6be5c3e3ad43a422129d3

 

Can someone clarify some of the difficulties involved in the temperature data.

[Edtharan]

It's very hard in these polar latitudes to demonstrate a global warming signal. This is in marked contrast to the northern tip of the Antarctic Peninsula that is one of the most rapidly warming parts of the Earth.

First of all, the article says that in polar areas, because of the amount of variability there and that there is not many monitoring stations, it is difficult to detect the signatures of global warming. However, the Northern tip of the Antarctic Peninsula is one of the fastest warming regions in the world.

 

The article is actually saying that: not only do they have evidence of global warming (from else where) but that looking for subtle changes near the poles is not actually a good idea. However, if clear signs are found, near the poles, of global warming, then these signs must be strong enough to exceed the "noise" of the natural variability of these locations.

 

If anything, this article is pro-global warming. The article even ends with them stating that trying to apply a global model to a specific region is not a good idea and will not provide accurate predictions.

 

It is also a mistake to think that Global Warming will mean that temperature, all over the Earth, will go up. Instead Global Warming (which by the way was a catch phrase not invented by the scientists, but by the media who were being dismissive). Instead, "Global Warming" is about energy.

 

Simply put, there is a (relatively) constant amount on energy being input into the Earth climate systems from the sun and a (relatively) constant amount of energy being dissipated from the Earth's climate systems.

 

When sunlight hits the Earth, some of it is reflected, and some of it is absorbed. Eventually, all of the absorbed energy will be re-emitted, usually as infra-red light. However, some of that infra-red light will be absorbed by certain chemicals in the atmosphere, and will be re-emitted back to the Earth (and some out into space too), the rest will just be radiated out into space. Eventually, all of this light too will be emitted back into space, but for a time it is trapped here and while this energy is here it has to go somewhere.

 

The more of these chemicals that can absorb and re-emit this infra-red light there is in the atmosphere, the more infra-red light will be absorbed () and the more that will be trapped here.

 

Now, infra-red light is emitted by hot objects, so the more infra-red light there is the hotter the object (hence the warming bit of global warming).

 

However, the energy in this infra-red light does not ahve to go into making things hotter, it can go into moving things around. Which can include heat, so some parts will get warmer, but others might get cooler.

 

But, in that article, they mentions that the winds surrounding Antarctica are getting faster. Wind is just air being moved around right...

 

The faster the wind is moving the more energy it has. As I said: The energy contained in the infra-red radiation does not just go into making things hotter, but can go into moving things around. It is the energy contained in the sunlight and that is trapped in the climate systems that is causing the winds around to Antarctica to blow, and the more energy the contain, the harder they are blowing.

 

10 to 20 percent increase in the speed of the wind (as per the article) is a massive increase in energy. As energy can't be created or destroyed, then the energy to increase the wind speed has to come from somewhere. If this amount of energy was being taken from somewhere else on the planet then it probably would have been noticed, and not only that, it takes energy to move energy around.

 

So, where is this energy coming from? The best place I can think of (and that fits with the evidence) is that it comes from more energy being trapped in the climate systems of the Earth. This means that the gasses that absorb infra-red radiation in the atmosphere are increasing. These gasses are also know as Greenhouse gasses (as a greenhouse is designed to trap heat in the greenhouse).

 

The increased wind speed, and the warming of the peninsula is pretty clear evidence (especially when you include the rest of the world too) that global warming is occuring.

 

Although this article seems to be pitched against global warming, they actually do a good job in the argument for global warming (it is just that you need to know that Global Warming does not necessarily mean temperature increase, but can mean things like wind speed increase too).

[jimmydasaint]

Thanks for the reply. I am taking the article and the paper together and have found that there are significant fluctuations in temperature in the Antarctic region, except for Antarctic Peninsula. Albeit limited by the material I presented, the data does not seem to show a significant temperature increase as an overall trend in the Antarctic region; it is simply not as clear as the Arctic region. However, I take your point about energy but I though winds were caused by uneven heating of the solid and liquid surfaces on the Earth.

[bascule]

A recent speech has made me wonder about the data from the Antarctic about global warming.

 

A phrase like "Antarctic Global Warming" is meaningless.

 

The term "global warming" applies to an overall warming trend in the global mean surface temperature. You can't use the phrase when talking about a particular region.

 

Are we seeing regional warming in the Antarctic? Not particularly.

[Edtharan]

However, I take your point about energy but I though winds were caused by uneven heating of the solid and liquid surfaces on the Earth.

Yes. That is one way. But winds are generated by High and Low Pressures in the atmosphere. There are several ways they can form.

 

In fact, this difference in Hot/Cold driving some winds is part of the complex systems that scientists are trying to model. In some areas, GW will cause this difference to reduce and so lower wind speeds will be the result, but in other cases it can cause a greater difference between them and so cause more winds.

 

One of the major causes in wind is not so much the temperature differences, but the humidity. When air is over water, the evaporation will increase the amount of humidity in the air. As this rises, the air cools (it doesn't have to be over land for this to occur) and the humidity condenses out into clouds. However, when water condenses from vapour to liquid, it has to get rid of the energy that caused it to evaporate in the first place.

 

Using the knowledge that energy can't just disappear and has to go some place (conservation of energy), then the energy that caused the evaporation must go into the surrounding atmosphere.

 

This causes the air to heat up, and become less dense, so it rises. This cools the air even more and causes more water to condense out, giving more energy to the atmosphere.

 

The result is that you get a strong upwards movement of dense, humid air, and this displaces less dense dryer air. Because of other forces, this mass of rising air starts to spin, and because it is dense it is pushed outwards too.

 

This is what we call a Hurricane/Typhoon/Cyclone (depending where you come from)..

 

Most storms are also created this way too.

 

As you can see, the amounts of energy this process puts into the movement of air is enormous.

[scalbers]

Antarctic ice sheet is melting at an accelerating rate this decade as measured by the GRACE and IceSat satellites.

[bascule]

Antarctic ice sheet is melting at an accelerating rate this decade as measured by the GRACE and IceSat satellites.

 

Do you have a source on that? The only significant melting of the Antarctic ice sheet I am aware of is recent melting of glaciers in West Antarctica, and is attributed to changes in ocean circulation patterns rather than changes in surface temperature.

 

Meanwhile, Antarctic sea ice is generally increasing

[StringJunky]

Do you have a source on that? The only significant melting of the Antarctic ice sheet I am aware of is recent melting of glaciers in West Antarctica, and is attributed to changes in ocean circulation patterns rather than changes in surface temperature.

 

Meanwhile, Antarctic sea ice is generally increasing

 

What's the principle source of the rising sea level if Antarctic ice is generally on the increase...is this a long term trend there?

[bascule]

What's the principle source of the rising sea level if Antarctic ice is generally on the increase...is this a long term trend there?

 

Sea ice does not affect sea levels as it displaces an equal volume of water. However, melting ice sheets, icebergs (which are fresh water), and glaciers will contribute to sea level rise. Right now, the majority of this melting is happening in the Arctic, although as I mentioned earlier there has been some melting of the Antarctic ice sheet in Western Antarctica.

[scalbers]

Do you have a source on that? The only significant melting of the Antarctic ice sheet I am aware of is recent melting of glaciers in West Antarctica, and is attributed to changes in ocean circulation patterns rather than changes in surface temperature.

 

Meanwhile, Antarctic sea ice is generally increasing

 

Here are some links that help to tell the story of the acceleration of overall Antarctic ice sheet loss:

 

http://www.agu.org/pubs/crossref/2009/2009GL040222.shtml

 

http://www.springerlink.com/content/m874025907838v1m/

 

Even if oceans are playing a role, in the long run the oceans would be warming up as part of the global warming trend.

 

Antarctic sea ice is paradoxically gradually increasing, at a rate much lower than the corresponding melt in the Arctic.

 

Another recently published paper documents air temperatures have in fact risen overall in Antarctica over the past 50 years.

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What's the principle source of the rising sea level if Antarctic ice is generally on the increase...is this a long term trend there?

I think 2mm/yr of sea level rise is mostly from thermal expansion and 1mm/yr is from the melting of Greenland and Antarctic ice sheets.

Edited January 10, 2010 by scalbers

[StringJunky]

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I think 2mm/yr of sea level rise is mostly from thermal expansion and 1mm/yr is from the melting of Greenland and Antarctic ice sheets.

 

Yes that makes sense.