CraigD Posted January 13, 2008 Report Share Posted January 13, 2008 One of the speculative “doomsday” scenarios involving artic melting is that release of less dense fresh water will cause the warm northwest flowing Atlantic current to submerge and flow south at a more southern latitude, resulting in the northeast US, Ireland, England, and coastal Europe to become much colder. Already, there has been an unexpected amount of artic melting, but to the best of my knowledge, no evidence of this scenario coming true. This is, I think, very good news.Not such good news! NASA - NASA Examines Arctic Sea Ice Changes Leading to Record Low in 2007The “record low” in this NASA article refers to the area of artic ice, not temperatures in the northeast US or the UK, as was feared in the “doomsday scenario” I mention. It’s an interesting article, offering explanations for some of the underlying causes of the unexpectedly fast rate of artic ice loss, but doesn’t address the effects of increased artic fresh water on the North Atlantic Current important to the feared outcome I described. It appears to me that this particular dreaded possibility is not coming to pass. Quote Link to comment Share on other sites More sharing options...
cyclonebuster Posted January 13, 2008 Author Report Share Posted January 13, 2008 The “record low” in this NASA article refers to the area of artic ice, not temperatures in the northeast US or the UK, as was feared in the “doomsday scenario” I mention. It’s an interesting article, offering explanations for some of the underlying causes of the unexpectedly fast rate of artic ice loss, but doesn’t address the effects of increased artic fresh water on the North Atlantic Current important to the feared outcome I described. It appears to me that this particular dreaded possibility is not coming to pass. If the Gulfsream did slow down the BTU exchange between the two oceans would slow down and the ice would last longer. Sadly,this is not the case. It seems the Arctic Oceans doom is sealed much sooner than thought of by the IPCC. Quote Link to comment Share on other sites More sharing options...
C1ay Posted January 13, 2008 Report Share Posted January 13, 2008 It’s an interesting article, offering explanations for some of the underlying causes of the unexpectedly fast rate of artic ice loss... Considering how fast the Earth has warmed during past ice ages I wonder why the current rate would be unexpected.... Quote Link to comment Share on other sites More sharing options...
InfiniteNow Posted January 13, 2008 Report Share Posted January 13, 2008 Take a look at this for an idea of man's contribution to the problem... C1ay, there are many sources I'd trust far more than "mysite.verizon.net/mhieb...." for information on anthropgenic contributions. Quote Link to comment Share on other sites More sharing options...
freeztar Posted January 14, 2008 Report Share Posted January 14, 2008 Considering how fast the Earth has warmed during past ice ages I wonder why the current rate would be unexpected.... Are you referring to the graph at the bottom of that page? If so, then I'd like to point out that the Y-axis is undefined (or at a minimum, vaguely defined by period). How can we determine the rate from this graph? Are you referring to something else? Quote Link to comment Share on other sites More sharing options...
C1ay Posted January 14, 2008 Report Share Posted January 14, 2008 Are you referring to the graph at the bottom of that page? If so, then I'd like to point out that the Y-axis is undefined (or at a minimum, vaguely defined by period). How can we determine the rate from this graph? Periods are well defined on the Geologic Time-Scale... Quote Link to comment Share on other sites More sharing options...
freeztar Posted January 14, 2008 Report Share Posted January 14, 2008 Periods are well defined on the Geologic Time-Scale... I'm well aware of this, but the curves on the graph are not well defined. How can we quantify the rate from that graph? Did the "switch" happen over a period of 500 years, 5000 years, or 500,000 years? It's not clear from the graph. Quote Link to comment Share on other sites More sharing options...
C1ay Posted January 14, 2008 Report Share Posted January 14, 2008 Look at the dip in the average global temperature that occurred around the middle of the Ordovician period that recovered back to the maximum by the first quarter of the Silurian period. The Ordovician period spanned from 488 - 444 Mya and the Silurian from 444 - 416 Mya. By this it looks like it was approximately 29 Mya. There was an impact at Jämtland, central Sweden dated at approximately 455 Mya that could explain the sudden drop in temperature. More importantly though you should notice that we just had an ice age in the Pleistocene period that brought the average global temperature down to 12°C and the planet is still in a warming phase from that. The Earth Policy Institute reports the average global temperature in 2007 was 14.73°C, still lower than the 17° average of the last 2 billion years. Notice also that each time the Earth has dropped down in global average temperature, because of an impact, volcanic eruption or other atmospheric event, it rebounds to around 22°C. Judging from the history of the planet we are headed back to that average. Quote Link to comment Share on other sites More sharing options...
freeztar Posted January 14, 2008 Report Share Posted January 14, 2008 Look at the dip in the average global temperature that occurred around the middle of the Ordovician period that recovered back to the maximum by the first quarter of the Silurian period. The Ordovician period spanned from 488 - 444 Mya and the Silurian from 444 - 416 Mya. By this it looks like it was approximately 29 Mya. There was an impact at Jämtland, central Sweden dated at approximately 455 Mya that could explain the sudden drop in temperature. More importantly though you should notice that we just had an ice age in the Pleistocene period that brought the average global temperature down to 12°C and the planet is still in a warming phase from that. The Earth Policy Institute reports the average global temperature in 2007 was 14.73°C, still lower than the 17° average of the last 2 billion years. Notice also that each time the Earth has dropped down in global average temperature, because of an impact, volcanic eruption or other atmospheric event, it rebounds to around 22°C. Judging from the history of the planet we are headed back to that average. Ok, I see what you are saying, C1ay, but 29 Mya is a VERY long time compared to what we are able to record "real-time" in a few generations. Likewise, an average temp of 17 degrees over the last 2 Bil. years is hardly a metric with which to judge climate variability over a timespan of 150 years. Recent trends have a much higher temperature *increase rate* than has been seen in paleoclimatic records as far as I'm aware of. (not to discount solar variability and Milankovitch cycles) Does anyone know of any data related to the prehistoric rate of ice cap disappearance? If so, this might help fill the gaps. Quote Link to comment Share on other sites More sharing options...
Chris C Posted January 14, 2008 Report Share Posted January 14, 2008 there is no ice age termination over the ice core record involving a 0.8 C rise in 100 years or so . D-O events are the only thing comparable in rate, but not like today in terms of global scale effects. The rate of change is consideraly rapid on a global and decadal scale, and Milankovitch cycles operate on thousand-of-year timescales, while CO2 and methane feedbacks from warmer temperatures in the glacial-interglacial cycles take hundreds of years as well. Quote Link to comment Share on other sites More sharing options...
Chris C Posted January 14, 2008 Report Share Posted January 14, 2008 Ok, I see what you are saying, C1ay, but 29 Mya is a VERY long time compared to what we are able to record "real-time" in a few generations. Likewise, an average temp of 17 degrees over the last 2 Bil. years is hardly a metric with which to judge climate variability over a timespan of 150 years. Recent trends have a much higher temperature *increase rate* than has been seen in paleoclimatic records as far as I'm aware of. (not to discount solar variability and Milankovitch cycles) Does anyone know of any data related to the prehistoric rate of ice cap disappearance? If so, this might help fill the gaps. You are correct. I'm not very familiar with climates before the ice core record, but neither do the paleo records have time resolution of <100 years. Plate tectonics and the evolution of the air and sea (like plants and cyanobacteria giving oxygen) take a very long time to operate. You need landmass at the poles for glacial periods. I do not know of any time where ice melted at the poles on a decadal to century timescale, but if it happend it must have involved a clear external forcing on the climate system which had an abrupt effect. The glacial to interglacial cycles over the ice core record are fairly clearly slower than today, with much higher CO2 levels today as well. Quote Link to comment Share on other sites More sharing options...
cyclonebuster Posted January 14, 2008 Author Report Share Posted January 14, 2008 Are you referring to the graph at the bottom of that page? If so, then I'd like to point out that the Y-axis is undefined (or at a minimum, vaguely defined by period). How can we determine the rate from this graph? Are you referring to something else? Scary thought when looking at that graph. Modern man only exists in the very top portion of (TODAY) when the climate is cool. Perhaps, when the climate warms up more like in the past we fail to exist at all.:( Quote Link to comment Share on other sites More sharing options...
C1ay Posted January 14, 2008 Report Share Posted January 14, 2008 Likewise, an average temp of 17 degrees over the last 2 Bil. years is hardly a metric with which to judge climate variability over a timespan of 150 years. Recent trends have a much higher temperature *increase rate* than has been seen in paleoclimatic records as far as I'm aware of. (not to discount solar variability and Milankovitch cycles) I think we can see that natural warming cycles are unpredictable, sometimes they are rapid and others are slow. We are facing a warmer future either way and we should adapt. There's nothing wrong with trying to reduce the pollution we create that contributes but it's not going to stop the Earth from warming up. Quote Link to comment Share on other sites More sharing options...
cyclonebuster Posted January 14, 2008 Author Report Share Posted January 14, 2008 I think we can see that natural warming cycles are unpredictable, sometimes they are rapid and others are slow. We are facing a warmer future either way and we should adapt. There's nothing wrong with trying to reduce the pollution we create that contributes but it's not going to stop the Earth from warming up. We can prevent that if we change the BTU content of SSTs as the "TUNNELS" do,also. Quote Link to comment Share on other sites More sharing options...
Zythryn Posted January 14, 2008 Report Share Posted January 14, 2008 There's nothing wrong with trying to reduce the pollution we create that contributes but it's not going to stop the Earth from warming up. Of course we aren't. However we can lessen the impact, or slow it down or speed it up (as we are doing now).Again, this isn't about preventing any change. It is about preventing some of the change. Specifically the change that is going to cause economic and physical hardship to part/most/all of our species. Quote Link to comment Share on other sites More sharing options...
cyclonebuster Posted January 14, 2008 Author Report Share Posted January 14, 2008 Of course we aren't. However we can lessen the impact, or slow it down or speed it up (as we are doing now).Again, this isn't about preventing any change. It is about preventing some of the change. Specifically the change that is going to cause economic and physical hardship to part/most/all of our species. It seems as though the change is escalating more! Sad isn't it? Escalating ice loss found in AntarcticaSheets melting in an area once thought to be unaffected by global warming Escalating ice loss in Antarctica - Washington Post - MSNBC.com Quote Link to comment Share on other sites More sharing options...
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