Slashdot Mirror
Ice-Free Summers Coming To Arctic
rocketjam writes "CNET reports that researchers from the University of Arizona and other universities have concluded that the Arctic will likely see ice-free summers within a century due to the increasing rate of global warming. The melting will raise ocean levels worldwide, flooding coastal areas where a substantial proportion of the world's population live. The increasing rate of ice melt is already having an impact on people and animals in the Arctic. Currently, researchers cannot foresee any natural forces that will counteract the trend."
Remember, the ability of an object to float is not (directly) related to its density. Its related to its ability to displace water and its mass. The reason submarines float (or sink) is because their shape displaces a greater mass of water than the equivalent mass of water that would fill their volume.
If you take a piece of steel and put it in a bucket, it sinks and raises the volume of the bucket by the volume of the steel. Take that same piece of steel and form it into a boat hull and it will float -- and the volume of the bucket will increase by exactly the same amount even though all of the steel is not submerged.
Karma: SELECT `karma` FROM `users` WHERE `userid`=138474;
OK, so all of you knuckleheads that are responding to the parent post by making glib comments about no hurricanes earlier in history...... Read the post! Although I suppose you are corroborating my suspicions of the prevailing wisdom here, please note that the sea levels and flooding due to storm surge and such are what I was talking about. As the overall temperature increases, sea level rises leading to more problems with flooding. I might also say that more than one climatologist has suggested that more and stronger hurricanes might be expected from global warming as well.
Visit Jonesblog and say hello.
There's a VAST amount suspended above sea level. Melt this, and yes, oceans will rise.
What is it suspended by? If the answer is "more ice", then you're wrong. If the answer is "Greenland", then you're right. But from your wording, it sounded like we're dealing with the "you're wrong" one.
It's a well known fact that Europe (and presumably the rest of the world) went through a cold period in the Dark Ages (approx 500 - 800AD). Such periods are common and known as "mini ice ages".
You link this hurricane to global warming and I'll do a backflip
Start doing backflips sonny. This particular hurricane cannot of course be specifically blamed on global warning. However, one of the most consistent predicitions of modelling over the last decade and a half has been the expectation of an increase in the frequency and strength of extreme weather events. So we can say that this hurrican is not inconsistent with predicted climate change.
Start paying attention over the next decade or two. When you start getting one in a decade hurricanes several times a decade, or you get 4 or 5 hurricanes per season, you should consider yourself put on notice.
Better to be despised for too anxious apprehensions, than ruined by too confident a security. --Edmund Burke
For something to float, it must displace an equal mass of whatever its floating in. By definition, the north polar ice cap is displacing exactly its own mass in water
That's neither "by definition" nor in actual fact; significant parts of the ice in the arctic rest on solid ground. When that ice melts, it will raise the sea level. It won't be anywhere near as dramatic as when the southern polar ice cap melts, but it will have an effect.
However, when taking the different salinity into account, things change. As you know from Archimedes, the ice is displacing exactly enough water to offset its weight (that is, the displaced water weighs as much as the ice). The thing is, it takes less *saltwater* to do that than it would *freshwater*. So when the freshwater in the ice melts, the levels rise.
If you don't believe me, check this article, it includes a picture from an experiment.
(assuming that global warming is fact, which all proven scientific evidence shows it's not)
I see. And of course you have links to back up this assertion from respected peer-reviewed journals?
I could understand if you had asserted "mankind is not the direct cause of current global climate change." That's something that is quite disputed by various climatologists; so one could be forgiven for ill-advisedly "picking" a side. The problem though, is that your assertion that "all proven scientific evidence shows it's not" (i.e. global warming is not occuring) is absolute bunk.
That global climate change is occuring is a forgone conclusion, the data clearly shows trending towards average global warming and increased atmospheric co2. Current science is focused on change rates; specifically problems involving sampling history, techniques, statistics and force modeling. Without solid data and working representative models, it's very difficult to put forth a sound cause-hypothesis.
[Gaffen, D et al - Multidecadal Changes in the Vertical Temperature Structure of the Tropical Troposphere, Science vol 287, 18 Feb. 2000]
[Hegerl, G.C. and J.M. Wallace - Influence of Patterns of Climate Variability on the Difference between Satellite and Surface Temperature Trends, J. Climate vol 15, 2002]
While I appreciate your clever use of basic physics, perhaps you might allow some room for the idea that the earth is not completely described by the science you learned in high school.
One important phenomenon, as described excellently by another poster in this thread, is the the fact that ice is much fresher than ocean water, so the overall density of the ocean will (most likely) go down, and voile, sea level rises.
The second, as others have also elegantly pointed out, is that much ice is not currently displacing any water, so 100% the effect of its melting is to increase sea level.
There are non-sea level issues of vast importance as well. Even simple climate models show vast sensitivity to overall earth albedo (reflectivity) and they all show a feedback loop with accelerating warming when a substantive amount of polar ice is loss. The fact that we're seeing this melting now is pretty strong clue that warming is going to speed up.
Also of great importance is the contribution of this new fresh water (and thanks to decreased albedo a great deal more heat absorbed by the earth) to the hydrologic cycle, as water vapor is also an important greenhouse gas. If the melted ice becomes water vapor, you can expect - again - increased rates of heating.
And yes, the poles get less heat from the sun than does the equator - the transport of that heat is the ultimate source of all weather patterns. So a substantial change in that heat balance can cause vast disruptions in weather patterns. In addition the potential shutoff of the Gulf Stream and general thermohaline circulation, there are potential movements of large high and low-pressure patterns that can bring intense droughts and flooding to numerous places, in the same way that El Nino does. And since climate systems are strongly nonlinear, it's very hard to predict where and when those events might occur. The effect could be anything from a little more sun in places to life-threating droughts. Put it this way: if something like the North Atlantic Oscillation can set conditions for a devastating hurricane season in the tropical Atlantic (as we're poised to get), imagine what a climate change several orders of magnitude larger could involve.
You can argue all you like about whether these changes are majority anthropogenic or not, but it is indisputable that our carbon-loading of the atmosphere is like pressing hard on the accelerator when you're going down a steep incline. Carbon dioxide content is a big, big, lever for global climate, and I'm hard pressed to see value of taking the Wile E. Coyote approach to dealing with this particular change in our world.