Antarctic Ice Melting from Warm Water Below

I will bump this up even though my news refers to Greenland not the West Antarctic Ice Sheet.

New in science a report that the Greenland glaciers are not accelerating as rapidly as some had feared

Increasing speed of Greenland glaciers gives new insight for rising sea level

It stops short of claiming that there will be less than 2 meters sea level rise by 2100. But it does suggest that such high-end estimates are becoming less likely as a result of more detailed analyses.

For your 'moderately good news about climate change' file.

 

I was always skeptical of sea level rise doom predictions.

For one authors of such publications keep forgetting that due to buoyancy melting of all suspended at sea ice results in zero net gain. Only land-bound ice mass melt should have impact on sea levels.

Yes Greenland is in trouble but there wouldn't be significant sea level rise until East Antarctica starts melting,

 

I've spent months under the Arctic ice. It's not all that thick. The profiles usually show variations on about a 10 foot or so average for where I was. Also note that it freezes at 28 F, since it's frozen out of saltwater. It's a factor, just not a significantly big one.

 

It's not necessarily the extra water that's the concern. It's the temperature, and the resulting thermal expansion. There's a massive amount of water in the oceans, and it won't take much of a rise in temperature to make a significant difference to the huge number of people living near coastlines.

It's unfortunate "doom predictions" cause people to close their minds, instead of spurring them to action.

 

Cyclo, I don't agree that folks who study these things disregard the obvious difference between floating and 'grounded' ice. If I am wrong then it should not take more than an email to straighten them out. From my experience, scientists are generally quite open to constructive criticism.

I think that sea level change needs to be viewed in (at least) two timescales. Century: rise will be less than 2 m and mitigating it will be reasonable for economically fit countries. If poor countries look for wealth transfers, it will be politically noisy (it already is)

multi-century: if we warm the ocean waters enough, then further rise in later centuries will not be stoppable at any level of IR absorbing gas control. The ice (notably WAIS and Greenland) will melt at the rate that the warmed water demands. No one could claim to put a tight time frame on it, but these two ice masses have 20 meters of sea level in them. That number may not be quite right but it would be simple to correct it. Depending on the rate, it would or would not be something that (those future) people can mitigate.

Of course the ultimate interglacial is no antarctic ice and +200 m sea level. It seems a bit distracting to talk about that. Instead of talking about how not to add heat to the oceans in this century, so as to avoid those later complications.

 

Around the turn of the 21st century, science surmised that warming seas around Antarctica would place more water vapor into the atmosphere. Furthermore, the water vapor would move onto the generally arid Antarctic ice sheets & fall as snow, ADDING more snow & ice upon the ice sheets which has occurred. This premise was confirmed in 2005 & actual proof of this condition has been observed, in both the Antarctic & Greenland. However, the continually warming oceans would also melt both southern & northern ice sheets at a greater rate than increases in snow quantities, which have been observed by the Grace satellites.

Warmer Air May Cause Increased Antarctic Sea Ice Cover

 

I agree those actually studying the ice understand of these things, but the journalists and politicians talking about them seem to either not understand or are being willfully deceptive. This includes those forecasting doom, as well as my governor that had a passage struck from an impact report because it accurately talked about rising sea levels and that hurt his case that climate change isn't happening.
Texans deserve truth about health of Galveston Bay

 

dumb question ahead (my jury is out as to climate warming being natural or increased by people ... there IS no doubt climate changes ... based off glacier retreat). Put a soda in the freezer and it'll blow apart. Frozen water expands, melted ice contracts. Why don't melting glaciers cause ocean levels to retreat, rather than increase if freezing water expands ... (scratching head)

.

 

Water's minimum volume (per pound) is achieved around 4°C, warmer than that, it expands, colder than that it expands. Ice floats displacing its weight in liquid water. So, warming water (mostly) increases its volume. Melting floating ice doesn't change sea height but makes it absorb more heat, which then increases its volume. Glaciers are generally above sea level on land, so melting those just increases the amount of water in the ocean (plus again subsequent warming).

Concerning whether humans are affecting the climate. Any theory absolving us of blame needs to account for where all the CO2 (et al) we are releasing is going, and why it isn't affecting the weather. Finding another causal factor to such as sun spots, can't absolve us. We would still need to know how what we are doing is NOT affecting the climate.

 

never mind

 

The big change is when ice on land melts and adds to ocean water. If you dive you can find many things that used to be above the sea now submerged.

+1

The melting ice cools the oceans so they warm slower than the land, making thermal expansion likely a minor player in any rapid sea level rise.
The role of ocean thermal expansion in Last Interglacial sea level rise

I don't think any absolving or blaming is needed to predict sea level rises. We don't need to care where the ghg originates to do a model. Certainly in the past ghg rose without any burning of fossil fuels by humans.

That said attribution studies can determine contribution, and they all have determined man contributes to climate change. They only differ in how much

 

I notice you have become coy in your denialism.

 

SageBrush,

You are quite a passive aggressive little poodle. I have never denied climate change, I simply support science over belief. I'm sure you and your buddies prefer some kind of religious, "I believe".

The line of reasoning that "it must be man, what else could it be" is not very scientific. Its like seeing presents under the christmas tree and saying Santa must exist. Who else would put presents under there. But we can put up cameras and see if a fat man is climbing down the chiminey to give us toys

In the case of glacier melt, its pretty easy to see that its mostly natural. The sea level was about 100 meters lower before the ice started melting well before man was here, and has risen a very small percentage since industrialization started burning fossil fuels. In the last interglacial, that link I posted, the sea level was about 6 meters higher than now, think of that higher seas without man. The importance of some of the research is sea surface temperatures were not much different, meaning most of the rise came from melting ice not thermal expansion. Which means even if we put no more ghg out, say we stopped today, the sea levels might rise 6 meters anyway. Those studying the ice through say it will be a slow melt, not a quick thing like that inconvient movie implied. 2 meters is far on the high side of estimates
Coastal Zones and Sea Level Rise | Climate Change - Health and Environmental Effects | U.S. EPA

But we have put that camera up to see if ghg from anthropomorphic sources are causing a contribution to the melt. We call these things attribution studies, and unfortunately they are not exact. Although we don't know exactly how much the average estimate of warming is about 3 degrees for the doubling of co2. Scientists then can estimate how much of that is on the ice, and how much it contributes to it melting. The first link showed that warming seas are melting some of the ice from below. That is why we can say with some confidence that man's ghg are contributing to the rising seas.

 

Then I suppose that makes you a hypocritical Chihuahua.

 

The Santa Claus analogy falls a bit short, when you consider that (most) kids have parents, and the logical ones can say, if not Santa, then maybe mom and dad, perhaps I'll peak through the door latch next Christmas eve,, or install a nanny cam on the fire place.

As for human caused climate change, at some point one can't add ever increasing amounts of insulation to a closed system and with out decreasing the amount of heqt input and not have the temperature rise,, that is science! One can only argue how much the added insulation is causing heisting.

Oh, I forgot,, it is sunspots!

Icarus

 

It seems to me that it is more like:

You watch your parents put presents under the tree. Christmas morning, there are presents under the tree. Someone tells you that Santa brought the presents, and you ask what happened to the ones my parents put under there?

 

The santa analogy is one about scientific method versus belief. Let us assume that you keep trying stay up and see santa, but keep falling asleep. A kid at school tells you he doesn't exist. You parents tell you to look at the cookie plate, one is missing. Who else could have eaten them but santa. You see the evidence of the presents and missing cookie. Does it have to be santa? If you believe you will say yes. If you use scientific method you may want to conduct that experiment with the nanny cam as I suggested, and not realy on your parents set up observations. That is all the story is meant to convey.

We can construct hypothesis and conduct experiments to determine how big the impact is. I guess when I talk about these experiments some here label me a denier. I don't think that is you Icarus.

We don't need to use rhetoric, we can do things for observation. Alley has collected his ice cores, and this seems to get some great information, including large temperature swings with large changes in ghg in the past without man. From these we can refine or reject various hypothesis. My point is we should look. We can even look at genetic information to lend support data about melting ice in previous interglacial periods

Faunal evidence for a late quaternary trans-Antarctic seaway - BARNES - 2010 - Global Change Biology - Wiley Online Library
Antarctic octopus tells story of ice-sheet collapse

We also need to observe these as a proxy for certain wavelenths of solar radiation. Some very smart climate scientists are examining these for impact as well as ghg.
NASA/Marshall Solar Physics

Ah but hill has seen other evidence. Your answer should be that you have seen the evidence for human created ghg contributing to the ice melt. To convince him you should talk about the evidence.

Your answer was sloppy and rhetorical. I was not objecting to your conclusion, but the process. I supported your conclusion in my reply. The head of the IPCC followed that same process of rhetoric to show that human created ghg was going to quickly melt all the Himalayan glaciers. He asked what else could it be. Accepted answer today is that the experiment was not done well. The scientist had taken short cuts and corrupted the experiment. No conclusion could really be drawn.

Corwyn,
The accepted science is that human ghg contribute to melting glaciers. But this is accepted because of data. There are other hypothesis, such as black carbon is a key the melt. Since they have melted before natural cycles also contribute We should not discount the theories, but collect data to confirm or modify or remove them.

 

He has seen Santa? Wow.

 

I'm sure he has. I have. He's been on tv, and movies, and in malls. I even played Santa a couple of times. I don't believe you have actually seen human generated ghg melting ice

Now it may be a good thing to put up that camera to see if that santa on the movie is actually putting presents under the tree. I would want to see evidence it was actually him. If we put up a camera, I might find it was uncle frank in a Santa Suit, grabbing a beer from the fridge, throwing away a cookie, putting presents under that tree. The really cool thing about actually doing the science, creating the experiment, is some times we get unexpected results.

Now I guess at least some members of this forum think talking about that science means you are a denier. That we shouldn't talk about the experiments that are wrong, or that point to other things. I hope you are not one of those.

The biggest case in point as related to ice are Himalayan glaciers. The IPCC working committee said that they were melting at an incredibly fast rate. When the results were questioned, those scientists questioning them were labeled deniers. How could the IPCC make a mistake? It turned out they used a scientist with no knowledge of glaciology as the head of the chapter. They then used a environmental pamphlet not scientific research to come to a conclusion. When finally looked into by those deniers, they found the pamphlet was written from a magazine article, and the scientist interviewed for the article claimed the author made up the high number. This is why there rules for peer review in the IPCC, but they totally ignored them in this case. Now the glaciologist in question did say that ghg were causing Himalayan Glaciers to melt faster than they would normally, but said the rate given in the IPCC working paper had no basis in scientific fact. The ghg baed warming would not support a melt that fast. The IPCC has since put a much smaller melt rate out and lowered its probabilities.

Other theories on ice melt from human causes include black carbon. There is wide scientific agreement that much of the ice melt is natural but man is speeding it up.

On antartic ice the first story here pointed to a mechanism for ghg based warming of sst to melt ice from below. We have also found evidence of antartic ice melts in the last 2 interglacials. IMHO the scientific evidence is that there are tipping points, and the earth has already past the tipping point to add at least a 5 meter rise to sea level. Changing human behavior may be able to slow this down or speed it up, but it is doubtful it can be stopped. The bulk of scientific evidence is that very little of this rise will happen in our lifetimes, with a very high confidence interval of less than 1 meter rise by 2100. The point of the research is to figure out how much, how fast, and how much human changes can change these numbers. In the mean time it seems prudent to cut both ghg and black carbon, and start mitigating for a bad case 2 meter rise in sea level.