NOAA's failed sunspot predictions

[Msalgado]

Thread creep again from Sunspot predictions to James Hansen-don't know why I bothered to post in this thread.

Steve

No thread is safe in this forum from Bethesda and Skier talking past one another and turning into one big circle of crap no one else wants to read.

[skierinvermont]

No one has answered me: why does Hansen say 20'/century of sea level rise instead of the .5-2' predicted by the IPCC? Is there any evidence for what he is saying?

He doesn't say 20'/century either.

You are assuming that the 80' in several centuries occurs linearly which a major assumption given he says the sea level will begin slowly and then accelerate, implying the trend is not linear. You are trying to interpret how much sea level rise will occur by 2100 based on his essay when the essay doesn't make any such prediction and is more concerned with multi-century sea level rise. The which hunt continues.

I have told you multiple times that in the peer reviewed journals Hansen generally speaks of 1-2m of SLR this century, which is higher than the IPCC but certainly not out of the realm of possibility given the large uncertainties regarding the high end of their range which are discussed in the text of the IPCC report. Specifically they state that increases in glacial flow rates were not included in their prediction of .5-2'. Any increase in glacial flow rate (as we have observed in Greenland) would increase the .5-2' prediction.

[nzucker]

He doesn't say 20'/century either.

You are assuming that the 80' in several centuries occurs linearly which a major assumption given he says the sea level will begin slowly and then accelerate, implying the trend is not linear. You are trying to interpret how much sea level rise will occur by 2100 based on his essay when the essay doesn't make any such prediction and is more concerned with multi-century sea level rise. The which hunt continues.

I have told you multiple times that in the peer reviewed journals Hansen generally speaks of 1-2m of SLR this century, which is higher than the IPCC but certainly not out of the realm of possibility given the large uncertainties regarding the high end of their range which are discussed in the text of the IPCC report. Specifically they state that increases in glacial flow rates were not included in their prediction of .5-2'. Any increase in glacial flow rate (as we have observed in Greenland) would increase the .5-2' prediction.

So the sea level rise will be 1-2' this century but then suddenly rise to 30'/century to make up for the slow start?

And what about his comments about the NJ Turnpike and NYC restaurants? Even 400 years is an unrealistic amount of time for DC to be underwater, they're not even a coastal city. Does Hansen know his geography? Do I need to send him a map of the US?

Pretty much akin to the Hadley saying it will never snow in the UK and then deliberately hiding their cold winter forecast before the climate conference. Lies, lies, and more lies. The AGW crowd has become almost as bad as the oil industry "manufactured doubt machine" telling us pollution is OK

[nzucker]

He doesn't say 20'/century either.

You are assuming that the 80' in several centuries occurs linearly which a major assumption given he says the sea level will begin slowly and then accelerate, implying the trend is not linear. You are trying to interpret how much sea level rise will occur by 2100 based on his essay when the essay doesn't make any such prediction and is more concerned with multi-century sea level rise. The which hunt continues.

I have told you multiple times that in the peer reviewed journals Hansen generally speaks of 1-2m of SLR this century, which is higher than the IPCC but certainly not out of the realm of possibility given the large uncertainties regarding the high end of their range which are discussed in the text of the IPCC report. Specifically they state that increases in glacial flow rates were not included in their prediction of .5-2'. Any increase in glacial flow rate (as we have observed in Greenland) would increase the .5-2' prediction.

Also, Hansen is saying 80' increase from 5F warming this century. I assume he thinks we'd see greater sea level rises if the temperature continued to climb in the 2100s.

So we are talking 100'+ of SLR

[LakeEffectKing]

Also, Hansen is saying 80' increase from 5F warming this century. I assume he thinks we'd see greater sea level rises if the temperature continued to climb in the 2100s.

So we are talking 100'+ of SLR

From what I've heard, at the temperatures that would cause 100' increase, all the methane in the ground would explode outward....and potentially lead to a 10,000' SLR, which of course would change most of us skeptical minds and at least some deniers' minds......

[skierinvermont]

So the sea level rise will be 1-2' this century but then suddenly rise to 30'/century to make up for the slow start?

A scenario such as 1.5m this century followed by 4m next century and 8m the century after that is certainly possible. I think most scientists are a little more conservative than that, but I don't think that such a scenario could be ruled out. Rapid sea level rise, even more rapid than that, has occurred in geologic history associated with warming events. Our relatively stable sea levels the last few centuries are a geologic anomaly. The Greenland ice sheet melts completely at global temperatures less than 2C warmer than present. That alone is 8m of sea level rise. If temperatures warm 5F this century it is highly likely Greenland will melt within a few centuries.

[nzucker]

A scenario such as 1.5m this century followed by 4m next century and 8m the century after that is certainly possible. I think most scientists are a little more conservative than that, but I don't think that such a scenario could be ruled out. Rapid sea level rise, even more rapid than that, has occurred in geologic history associated with warming events. Our relatively stable sea levels the last few centuries are a geologic anomaly. The Greenland ice sheet melts completely at global temperatures less than 2C warmer than present. That alone is 8m of sea level rise. If temperatures warm 5F this century it is highly likely Greenland will melt within a few centuries.

I think you are just throwing numbers out....IPCC says about .2-.7m of sea level rise this century, and they're generally considered to be aggressive on everything pertaining to global warming. That would be assuming their temperature increases verify, which can't be confirmed given the lack of warming since 1998. I think a wise prediction would be around .1-.2mm this century followed by a bit more, at least that's what I'm thinking sounds reasonable...granted I'm no expert at sea level rise and haven't studied it that carefully. The White study from Geophysical Research Letters found a sea level rise of 1.8mm/yr from 1950-2000, which I believe was the greatest period of warming we're going to see. Even if that rate tripled to 5mm/yr from 2010-2100, we'd be talking about a sea level rise of no more than .5m/century, about in line with the IPCC estimates.

Also, why do you think Greenland would completely melt if we warmed 2C globally? The highest parts of the ice sheet approach 4,000m elevations, which I assume would stay plenty cold even if temperatures up there increased 4-5C due to the amplified effect of warming at higher latitudes. Also, we can't be sure higher latitudes are going to warm more because Antarctica has actually cooled since the 1970s, and Greenland could become an oddball case like that. If I have my data correct, Greenland didn't warm as much in the 1900s as many other places in the Arctic. Here is the forecast for Summit, Greenland from Wunderground...looks as if -40F/-60F is a pretty typical winter day there. If that increased to -30F/-50F, you'd still have an ice sheet:

http://www.wunderground.com/global/stations/04416.html

[skierinvermont]

I think you are just throwing numbers out....IPCC says about .2-.7m of sea level rise this century, and they're generally considered to be aggressive on everything pertaining to global warming. That would be assuming their temperature increases verify, which can't be confirmed given the lack of warming since 1998. I think a wise prediction would be around .1-.2mm this century followed by a bit more, at least that's what I'm thinking sounds reasonable...granted I'm no expert at sea level rise and haven't studied it that carefully. The White study from Geophysical Research Letters found a sea level rise of 1.8mm/yr from 1950-2000, which I believe was the greatest period of warming we're going to see. Even if that rate tripled to 5mm/yr from 2010-2100, we'd be talking about a sea level rise of no more than .5m/century, about in line with the IPCC estimates.

Also, why do you think Greenland would completely melt if we warmed 2C globally? The highest parts of the ice sheet approach 4,000m elevations, which I assume would stay plenty cold even if temperatures up there increased 4-5C due to the amplified effect of warming at higher latitudes. Also, we can't be sure higher latitudes are going to warm more because Antarctica has actually cooled since the 1970s, and Greenland could become an oddball case like that. If I have my data correct, Greenland didn't warm as much in the 1900s as many other places in the Arctic. Here is the forecast for Summit, Greenland from Wunderground...looks as if -40F/-60F is a pretty typical winter day there. If that increased to -30F/-50F, you'd still have an ice sheet:

http://www.wundergro...ions/04416.html

IPCC specifically notes that their numbers are conservative and not complete estimates because they do not include sea level rise due to glacier acceleration. Obviously most scientists agree more with something closer to the IPCC's numbers than Hansen's 1-2m forecast.

However, it is supposed to accelerate rapidly as the Greenland ice sheet destabilizes from around the edges. Most of Greenland is very low elevation it is simply the ice that is at a high elevation because it is so thick. This makes it inherently unstable. As the edges warm they release the floodgates and the ice sheet thins rapidly. As the ice thins, it loses elevation and warms further. This has happened in the past. Rapid declaciation of Greenland has occurred before in response to modest global warming. If the earth warms 2-3C this century then Greenland will melt just as it has in the past.

[Sunny and Warm]

quote name='skierinvermont' timestamp='1294452885' post='241489'

A scenario such as 1.5m this century followed by 4m next century and 8m the century after that is certainly possible.

Possible, but how likely? Would you say it has a 100% chance for verification given CO2 trends? 10%? 1%? Anything is possible. An unknown asteroid could hit my house tomorrow. How likely? You tell me.

I think most scientists are a little more conservative than that, but I don't think that such a scenario could be ruled out.

Why not?? On what basis do you make this claim given the last 10-15 years of data??

Our relatively stable sea levels the last few centuries are a geologic anomaly.

Not during an interglacial, and one where the bottom has been reached. You have to put context into your statement, and when one does so, it falsifies your statement.

The Greenland ice sheet melts completely at global temperatures less than 2C warmer than present. That alone is 8m of sea level rise. If temperatures warm 5F this century it is highly likely Greenland will melt within a few centuries.

Really?? Given current temps on Greenland during its very short summer, do you really believe that can be accomplished in even a few hundred years? If so, please provide proof as to how this happens. And please remember, at warmer temps, it will likely snow more on Greenland.

Honestly, your posts lack any sense of credibility. I know you won't be taking my word for it, but you ape what others say, and have no substance to your quotes. It would help if you added a little reality to your thoughts on occasion.

[nzucker]

IPCC specifically notes that their numbers are conservative and not complete estimates because they do not include sea level rise due to glacier acceleration. Obviously most scientists agree more with something closer to the IPCC's numbers than Hansen's 1-2m forecast.

However, it is supposed to accelerate rapidly as the Greenland ice sheet destabilizes from around the edges. Most of Greenland is very low elevation it is simply the ice that is at a high elevation because it is so thick. This makes it inherently unstable. As the edges warm they release the floodgates and the ice sheet thins rapidly. As the ice thins, it loses elevation and warms further. This has happened in the past. Rapid declaciation of Greenland has occurred before in response to modest global warming. If the earth warms 2-3C this century then Greenland will melt just as it has in the past.

According to the Box study, Southern Greenland temperatures cooled drastically in spring and summer, the area and seasons that would most likely see melting. 1961-1990 saw significant cooling in much of Greenland, and the warmest years for Greenland were 1932, 1941, 1947, and 1960....not the recent years, as many would have you believe.

http://www.astro.uu.nl/~werkhvn/study/Y3_05_06/data/ex6/gl.pdf

I also don't see evidence for how the very edges of the ice sheet warming would cause the high elevation areas to lose all of their ice. What I'd imagine is that icebergs would increasingly calve into the ocean on the edges of the ice sheet causing the sheet to lose mass; at the same time, increased snowfall from the warmer temperatures would load up the top of the ice sheet with more thickness. Aren't the models showing more precipitation for the Greenland Ice Sheet this century? Also, doesn't a -NAO produce excessive snowfall in eastern Greenland? Is the ice sheet just going to slip increasingly into the ocean, or will the coastal areas fall off while the high areas remain ice down to the ground and thus retain their elevation, especially with more snowfall occurring?

You can see from this chart that much of the ice sheet has actually been gaining elevation due to increased snowfall (blue=thinning, brown/grey=thickening):

Also, 2-3C of surface warming is looking like a very generous estimate considering the lack of warming this century. You said yourself you favor .5C-2C of warming, below the threshold for the Greenland Ice Sheet to melt. Also, even if we did warm 3C this century, it would take several centuries to melt the entire ice sheet just due to its mass alone, and that would be sufficient time to find a geoengineering solution to climate change IMO.

[skierinvermont]

Ok you are right.. I completely made up the fact that Greenland has melted in the past with global temperatures less than 2C warmer than present.

[skierinvermont]

Also, even if we did warm 3C this century, it would take several centuries to melt the entire ice sheet just due to its mass alone, and that would be sufficient time to find a geoengineering solution to climate change IMO.

i hope so. This is actually one of the effects of climate change which we can have higher confidence in because we have good data as to what has happened in the past.

[BethesdaWX]

Warmer Greenland means more snowfall....which the same thing is causing more Antarctic Ice......right?

Major Cooling in Greenland coincided with the -AMO phase almost to a tee....warming has matched the +AMO almost to a tee......all AMO dude.

[nzucker]

i hope so. This is actually one of the effects of climate change which we can have higher confidence in because we have good data as to what has happened in the past.

Having an equal rise in global temperature doesn't guarantee the same effects on Greenland's Ice Sheet, though, in either direction. There's still regional climatology to consider, obviously, as the Antarctica analogy demonstrates.

Warmer Greenland means more snowfall....which the same thing is causing more Antarctic Ice......right?

Major Cooling in Greenland coincided with the -AMO phase almost to a tee....warming has matched the +AMO almost to a tee......all AMO dude.

Yeah, Greenland hasn't warmed as much as most of the Arctic except for the recent +AMO extreme. I do suspect there'll be warmer than average, though, in the next 20-30 years with the -NAO pattern. Greenland's temperatures went up during the Maunder Minimum, so even if we had widespread cooling due to a dramatic solar minimum, the -NAO state induced by such minimum could keep them well above average.