Greenland's greenhouse

By: Dr. Jeff Masters , 8:23 PM GMT on February 22, 2006

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Glaciers in southern Greenland are flowing 30% to 210% faster then they were ten years ago, and the overall amount of ice dumped into the sea from Greenland increased from 90 cubic km in 1996 to 224 cubic km in 2005, up 250%. As a result, Greenland's contribution to average annual sea rise increased from .23 mm/year in 1996 to .57 mm/year in 2005, and now accounts for between 20% and 38% of the observed yearly global sea level rise. Two-thirds of Greenland's contribution (.38 mm/yr) was due to glacier dynamics (chunks of ice breaking off and melting), and one-third (.19 mm/yr) from melting. These were the results of a paper called "Changes in the Velocity Structure of the Greenland Ice Sheet" published last Friday in Science magazine. NASA scientist Eric Rignot and University of Kansas researcher Pannir Kanagaratnam used ten years of satellite radar interferometry data to arrive at their conclusions.

The authors attributed the speedier glacier flow in southeast Greenland to climate warming, and noted that there had been a 3° C rise in temperature in the past 20 years at one station there. Widespread glacier acceleration affected just the southern tip of Greenland south of 66° north between 1996 and 2000, then spread rapidly northwards to 70° north by 2005 to cover the southern half of Greenland. The authors anticipated that as glacier acceleration continued to spread northward, Greenland's contribution to global sea level rise would continue to increase in coming years.

Greenland's increase in glacier speed and a corresponding rise in global sea level are reason for great concern, since Greenland holds enough ice to raise global sea level by over 20 feet (6.5 meters), should the ice cap disintegrate. However, the paper does not discuss many complicating factors, and it is uncertain if the paper's findings mean that Greenland's ice cap is in immediate danger. The most worrying aspect of the paper's findings is that we are told that the computer models used to estimate how long it will take Greenland's ice will melt are significantly in error--and in the wrong direction!


Figure 1. Change in sea level from 1993 to the end of 2004 shows a steady increase of about 3 mm/year. No acceleration of sea level rise due to increased input from Greenland or other causes is apparent. Image credit: University of Colorado.

Is the new Greenland melting evident in global sea level trends?
Sea level is a surprisingly difficult thing to measure. Tide gauges are very noisy, and only show sea level trend for the coastal areas they happen to be installed on. Global sea level trends from these gauges show a rise of between 1.5 and 2.1 mm/yr for the period 1950-2000. Satellite data from the TOPEX/POSEIDON and JASON satellites can give a better global picture, and show a rise of 2.9 mm/yr for the period 1993-2004 (Figure 1). This had increased to 3.4 mm/year for the period 1993-2007. The reason for the disagreement between the tide gauges and satellite data is unknown. There is a lot of variability in the data, due to changes in evaporation and precipitation related to such events as El Niño and La Niña. Indeed, sea level is not rising everywhere. In Scandinavia, the land is still rebounding from the Ice Age, and local sea level is receding. Sea level is also not increasing in the South Pacific's Vanuatu Islands, which Michael Crichton focuses on in his State of Fear book. This lack of sea level rise is not well understood, but may in part due to regional ocean current and precipitation patterns that reduce the amount of sea level rise one might expect. Mitrovica et.al. (2001) argue that as an ice sheet melts, the gravitational pull of the ice sheet on the surrounding ocean decreases, so that a substantial melting of the Greenland ice sheet would result in substantial drop in sea level over the North Atlantic, and a major sea level rise over the South Pacific with the maximum rise near the southern part of South America.

Given how noisy the global sea level data is, it should be no surprise that an increasing trend in sea level due to the increased contribution from Greenland is not apparent in Figure 1. According to Rignot and Kanagaratnam, Greenland's contribution to global sea level rise increased from .23 mm/year in 1996 to .57 mm/year in 2005, an increase of .34 mm/year. This is less than the error bounds of .4 mm/yr in the Figure 1 satellite data. It is also worth noting that while Rignot and Kanagaratnam's estimates to contributions to sea level rise due to glacier flow (.38 mm/yr) are not disputed by other studies, their estimate of the amount of melting Greenland is undergoing (.19 mm/yr) is in dispute. For example, Box et al. (2004) came up with a global sea level rise of 1.5 mm/yr due to Greenland's contributions, and Chylek et. al. (2004) say that the ice sheet may not be adding to sea level rise at all.



Figure 2. Average temperatures for the two stations in Greenland with a century-long record. Top: Godthab. Bottom: Angmagssalik. Image credit: NASA Goddard.

Is Greenland's Ice Cap in danger of disintegrating?
Greenland's ice cap is probably not in immediate danger of disintegrating, if temperatures stay at their current levels. Most of Greenland has been in a cooling trend over much of the last 60 years. It is only during the past ten years that we have seen a sharp upward jump in the temperatures at many (but not all) Greenland locations. However, temperatures as warm as Greenland is seeing now were also observed back in the Medieval Warm Period of 800-1300 A.D., and again in the 1930s. We can see the warm period of the 1930's reflected in the temperature records for two Greenland stations with records extending back over a century (Figure 2). Presumably, Greenland's glaciers at that time accelerated to speeds similar to what we are seeing today, without the ice cap suffering significant disintegration. I haven't looked for records of glacier flow and iceberg calving for that time period to check this hypothesis; I doubt reliable records exist.

Natural Variability
The temperature plot of Figure 2 demonstrates that Greenland is subject to large decades-long changes in its climate due to natural variation. The 2-4° C increase in temperature during the 1920s must have been primarily due to natural causes, since human-emitted greenhouse gases were relatively low then. Research results show that the climate of Greenland is dominated by a regional weather pattern called the North Atlantic Oscillation (NAO). The NAO oscillates unpredictably between a negative phase and a positive phase. If the wintertime NAO is negative, the persistent low-pressure area near Iceland called the Icelandic Low moves towards the southern tip of Greenland, bringing a sharp increase in precipitation and warmer temperatures to the island. During the positive phase of the NAO, the Icelandic Low moves back towards Iceland, allowing colder and drier conditions to prevail over Greenland. The wintertime NAO during 1950-2000 was primarily positive, which led to cooling over virtually all of Greenland--the opposite of the global warming trend of most of the rest of the world (Chylek et al., 2004). This cooling reduced the amount of glacier break-up and melting one would have expected due to global warming. To make things more complicated, increased precipitation during the wintertime negative NAO phase tends to add mass to the ice sheet in the interior, and may partially or totally offset the mass loss due to melting from that phase's increased temperatures (Johannessen, 2005). This is a very complicated system with many unknowns! The question--which was not discussed in Rignot and Kanagaratnam's paper--is, how will the expected rise in global temperatures of 1.5 to 4.5° C this century affect the NAO, and thus Greenland's temperature and precipitation? The current consensus from the computer models is that global warming should act to create a more positive NAO, which would keep Greenland cooler and drier.

When will Greenland's Ice Cap be gone?
The consensus view (Gregory et. al, 2004), using computer models that treat the Greenland ice sheet as a static hunk of ice, has been that the Greenland ice sheet will melt in about a thousand years, if atmospheric CO2 doubles. However, the doubling in glacier flow observed in the past ten years comes as a major shock. The models used to come up with the 1000 year estimate do not account for changes in glacier speed at all! The unexpected increase in glacier flow probably occurred in response to the lubrication effect of melt-water penetrating down to the glacial bed, as well as other poorly-understood processes. The paper concluded: "Current models used to project the contribution to sea level from the Greenland Ice Sheet in a changing climate do not include such physical processes and hence do not account for the effect of glacier dynamics." In other words, the models were wrong. Climate change skeptics are find of criticizing computer models, and cite their inadequacy as grounds for dismissing the threat of climate change. Well, it works both ways. Climate change models can be off in the wrong direction--as we also saw with the Antarctic ozone hole, which was completely missed by the models. These new results imply that if Greenland warms significantly (at least 3° degrees C), Greenland's ice could melt in a few centuries, not 1000 years. With 20 feet of sea level rise locked up in its ice, sea level rises well beyond the capability of humans to handle could occur later this century. The real test of the stability of the Greenland Ice Sheet will come when we reach temperatures not seen since before the last ice age, 125,000 years ago. Warm temperatures then caused the Greenland Ice Sheet to mostly disintegrate, leading to perhaps 14-17 feet (4.5-5 meters) of sea level rise (Cuffey and Marshall, 2000). The likelihood of this scenario is highly uncertain, though, given our lack of understanding of the system, the high amount of natural variability, and the limited amount of historical data we have to look at.

One interesting political note
Rignot works for NASA, which has recently been embroiled in controversy over whether political appointees there had tried to silence NASA climate scientist Jim Hansen from voicing his opinions. According to Time Magazine, when Rignot was asked if anyone at NASA had tried to shut him up, he said he had not been subjected to any such pressure.

The University of Colorado has a nice image showing where Greenland melted in 2005, and which areas melted for the first time.

Jeff Masters

References
Box, J.E., D.H. Bromwich, and L-S Bai, 2004. Greenland ice sheet surface mass balance 1991-2000: Application of Polar MM5 mesoscale model and in situ data. J. Geophys. Res., 109, D16105, doi:10.1029/2003JD004451.

Chylek, P, J.E. Box, and G. Lesins, "Global Warming and the Greenland Ice Sheet", Climatic Change 63:, 201-204, 2004.

Gregory, J.M., Huybrechtsm, P., and Sarah C. B. Raper, "Threatened loss of the Greenland ice-sheet", Nature 428, 616 (8 April 2004) | doi:10.1038/428616.

Johannessen, O.M., et. al, "Recent Ice-Sheet Growth in the Interior of Greenland", Science, 310: 1013-1016, 11 November 2005; published online 20 October 2005 [DOI: 10.1126/science.1115356]

Cuffey, K.M., and S.J. Marshall, "Substantial contribution to sea-level rise during the last interglacial from the Greenland ice sheet," Nature, 404, 591-594 (2000).

Mitrovica, J.X., Tamislea, M.E., Davis, J.L., and G.A. Milne, "Recent Mass Balance of Polar Ice Sheets Inferred from Patterns of Global Seas-Level Change", Nature 409, 1026-1029, 2001.

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69. dcw
6:50 PM GMT on February 23, 2006
*ODD TC FORMATION ALERT*

A Tropical Storm seems to have just formed in the Atlantic. The South Atlantic.



Whoo-hoo! Fun fun fun!
Member Since: August 2, 2001 Posts: 2 Comments: 3
66. oriondarkwood
5:22 PM GMT on February 23, 2006
Hey snap Cregnebaa (and email me)

Webster, NY
Mostly Cloudy
Temp 38
Winds 8-14 MPH from the N/NW
UV Index 2
Humidity: 75%
Barometer: 29.83 in.
Member Since: July 5, 2004 Posts: 51 Comments: 42
65. Cregnebaa
5:09 PM GMT on February 23, 2006
Hey snap Gamma

Current Conditions
George Town, Cayman Islands

Partly Cloudy and Windy

84F
Feels Like
88F

UV Index: 9 Very High
Wind: From the East Southeast at 21 mph

Humidity: 62%


Barometer: 30.06 in.


Member Since: October 19, 2005 Posts: 6 Comments: 323
64. seflagamma
5:03 PM GMT on February 23, 2006
Broward County Florida (SE Florida)

sorry, don't mean to rub this in for those still in the cold!! beautiful day outside.

Updated: 10:53 AM EST on February 23, 2006
Observed At: Fort Lauderdale, Florida
Elevation: 13 ft / 4 m

81 F / 27 C
Clear
Heat Index: 82 F / 28 C
Humidity: 58%
Dew Point: 64 F / 18 C
Wind: 7 mph / 11 km/h Variable
Pressure: 30.10 in / 1019 hPa

Gams
Member Since: August 29, 2005 Posts: 298 Comments: 40891
61. hiseasdrifter
4:57 PM GMT on February 23, 2006
Dear sarahfromfla,kudos on your keen observations.many of my friends on this site tend to get real hung up in the political rhetoric.you know,maybe we are royally screwing up our world.that sucks;but maybe that really is a natural part of the evolutionary process.We make our planet uninhabitable for humans,and in a couple thousand years the slugs shall inherit the earth.and the process starts all over again.lol
60. snowboy
4:43 PM GMT on February 23, 2006
hey seflagamma, good to hear from you - how's things in Fla?
Member Since: September 21, 2005 Posts: 10 Comments: 2547
59. seflagamma
4:35 PM GMT on February 23, 2006
This is so much better. Keeping this blog on topic at all times!!! This should strickly stay a weather or climate related blog. If anyone wants to just chat about lunch or other subjects, there are lots of other blogs you can use, including mine. There are also a lot of other blogs out there for specific topics for debat and discussion.

Thanks to all for keeping this blog for pure information.
Member Since: August 29, 2005 Posts: 298 Comments: 40891
58. theboldman
4:32 PM GMT on February 23, 2006
its not that it cant be proven its that we dont know how to prove it lol
Member Since: September 8, 2005 Posts: 25 Comments: 2
57. theboldman
4:32 PM GMT on February 23, 2006
ya never know snowboy
Member Since: September 8, 2005 Posts: 25 Comments: 2
56. snowboy
4:31 PM GMT on February 23, 2006
Colby, it can never be proven. That is not the point.

Our models predict the warming, and the warming is occurring. Why is it Americans have such a hard time admitting that THE MODELS COULD ACTUALLY BE RIGHT?

There's a neat little story on Accuweather:
http://wwwa.accuweather.com/promotion.asp?dir=aw&page=dustbowl

More a historical piece about the Dust Bowl conditions of the 1930s, but also reflecting the concern which has been voiced elsewhere that the US could be well on the way experiencing similar conditions in the immediate future.
Member Since: September 21, 2005 Posts: 10 Comments: 2547
55. ForecasterColby
3:56 PM GMT on February 23, 2006
Okay, let's assume the whole planet is 10C hotter in a decade. What proof is there that we caused it?
54. snowboy
2:27 PM GMT on February 23, 2006
F5, you say we have no way of measuring man's influence on the environment. What we do have is the scientific method which is being applied. Climate model predictions are made of the degree of warming which could be expected given current atmospheric greenhouse gas levels plus the rate at which they continue to be emitted. These predictions are then compared to what is being observed. And what we've been seeing throughout this century (except for the 1950s through 1970s temperature drop caused by above ground nuclear testing) is precisely what the models predict - significant global warming. Don't believe it? Wait another decade - the rate of change in temperatures is accelerating as various positive feedback loops come into play.
Member Since: September 21, 2005 Posts: 10 Comments: 2547
53. snowboy
2:08 PM GMT on February 23, 2006
hey DenverMark, the current estimate is that the year-round Arctic polar pack ice (ie. ice on the ocean) will be gone within 15 years, after that you will have ice forming annually in the winter and melting in the summer.

This will be the first time in a million years that the Arctic Ocean is ice free in summer, and is leading to strong positive feedback loops which will exacerbate the global warming which is causing the melting.
Member Since: September 21, 2005 Posts: 10 Comments: 2547
52. F5
2:01 PM GMT on February 23, 2006
DenverMark,

That's exactly the problem. We have no way of measuring man's influence on the environment. However, it can be noted that Greenland has suffered wild swings in temperatur of over 2deg C and it seems related to the NAO.
51. KShurricane
1:33 PM GMT on February 23, 2006
NASA scientist Eric Rignot and University of Kansas researcher Pannir Kanagaratnam used ten years of satellite radar interferometry data to arrive at their conclusions.

University of Kansas; that's my school!! GO JAYHAWKS!!!!
50. Inyo
8:36 AM GMT on February 23, 2006
Posted By: SarahFromFLA at 5:39 AM GMT on February 23, 2006.
Umm, if NASA is trying to silence Jim Hansen, how come we all know what hes saying?


maybe they tried and failed?

but anyway, as someone who works for another government agency, i find the claim to be totally believable. i don't know anything about this one case but in both government and especially private firms relating to environmental issues (i think those firms may be part of my dislike of corporations), there is often pressure for findings to go one way or another despite findings.
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49. DenverMark
6:26 AM GMT on February 23, 2006
F5 - Thanks for the links you posted earlier. I'm curious about what more warming would do to the Arctic, but at the same time wonder how much of this involves natural variation rather than human influence. I do think some reports are too alarmist.
Member Since: February 11, 2006 Posts: 125 Comments: 6988
48. DenverMark
5:36 AM GMT on February 23, 2006
I went through some data for a few other stations in the Arctic (Eureka and Resolute in Canada, and Barrow,AK) for the period from 1950 through 2004. I averaged annual mean temperatures by decade and for 2000-2004. At Eureka and Resolute, there was a cooling from the '50s through the '70s of 1.2C for Eureka and 0.7C for Resolute. Comparing the 2000-04 averages with the 1970s, there has been a warming of 2.0C at Eureka and 1.3C at Resolute. At Barrow,the cooling from the '50s through the '70s was only 0.2C, then a warming of 1.7C by the first half of the 2000s.
My sources were Environment Canada and the Western Regional Climate Center. At Barrow there were a few months with some missing data that I had to estimate based on data from Prudhoe Bay or Umiat,AK.

These trends could account for the smaller/thinner summer sea ice pack in the Arctic in recent years. The warming farther west in the Arctic began 15 to 20 years sooner than in Greenland. I'm curious about a couple of things - first, how far back do records go for summer sea ice coverage in the Arctic? Do we know what it was back in the 1930s, for example, and how that compares with recent years? Also, how much additional warming would have to occur for Arctic sea ice to disappear completely during the summer? How might this affect ocean currents, especially if combined with greater melting of the Greenland ice cap?

Dr.Masters - Thanks for your answers to some of our questions tonight! I'm certainly learning a lot.
Member Since: February 11, 2006 Posts: 125 Comments: 6988
47. SarahFromFLA
5:39 AM GMT on February 23, 2006
You would think some smart entrepreneur would bottle the melting glacier water and sell it at outrageous prices.
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46. F5
5:43 AM GMT on February 23, 2006
SarahFromFLA,

It's hard to know what Dr. Hansen's motivations are. I think he sincerely believes what he says, to the point it's become dogma for him, and he's closed his mind to any possibility that he could be wrong. However, that's just my personal opinion and is in no way based on any facts. I find it strange that other scientists at NASA have not felt the same way, so that Dr. Hansen is somehow being "Singled out". Just my .015 cents, adjusted downward for inflation.
45. SarahFromFLA
5:33 AM GMT on February 23, 2006
Umm, if NASA is trying to silence Jim Hansen, how come we all know what hes saying?
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44. Skyepony (Mod)
5:23 AM GMT on February 23, 2006
correction there~ been gathering data since March 2002. Iwatch the launches & was excited about this one, remembered the when wrong though.

To make up for it~ it's not quite the weather ball but~ This is an animation of the GRACE Gravity Model 01 which was released in July of 2003. This model is based upon preliminary data provided by the GRACE mission. The release of this preliminary model is a major advancement for oceanographers and a taste of scientific advancements yet to come from GRACE. Improved weather and climate change predictions now result from this model of Earth's gravity field 10 to 50 times more accurate than previous models.
Member Since: August 10, 2005 Posts: 162 Comments: 37800
43. Skyepony (Mod)
4:50 AM GMT on February 23, 2006
Regardless of the rising interior ice sheet of Greenland the total mass is going down according to 2 satillites in the GRACE NASA prodject that has been gathering data since mid 1999.
Credit NASA~


He's a link to an article about the overall reduction in the ice mass of Greenland. It also highlights other finds by GRACE, including measurements of seasonal changes in the Antarctic Circumpolar Current, Earth's strongest ocean current system and a very significant force in global climate change. This could be a big help in unraveling el Nino & la Nina. GRACE was also able to to measure the change of the Earth's crust caused by the December 2004 earthquake, that caused the huge tsunami.

For the satilite images on the Antarctic Circumpolar Current or the earthquake go here.
Member Since: August 10, 2005 Posts: 162 Comments: 37800
42. F5
4:49 AM GMT on February 23, 2006
California,

If the hurricanes of the past 20 - 30 years don't scare people off living on the coast, I'm not sure potential flooding from rising sea levels will either. Each state that has coastal area needs to develop a comprehensive land-use plan for those areas.

You know, insanity is doing the same thing over and over and expecting a different result. We continue to build and build in harm's way, and then gaze in awe and wonderment at the destruction nature hath wrought. Then we open our hearts, homes, and wallets to those displaced by storms who never should have been allowed to build there in the first place, or at least required much stricter building codes than what are in place. And when the disaster is over, we help rebuild what was lost, only so at some future date, it can be destroyed again and again. I realize that the chance of a direct hit by a major hurricane is minimal, but that does little to help those who were hit by one, or those who will be in the future. We need to stop building in coastal areas, flood-prone areas, etc. Stop the insanity.
41. F5
4:43 AM GMT on February 23, 2006
Snowfire, please refer to the link I posted about the 5th comment in this blog. The Greenland ice sheet is thickening in the interior. This may or may not preclude an eventual thinning of the interior. As you can tell from Dr. Master's post, the NAO seems to play a significant role in the temperate over Greenland, and doesn't seem to correspond to "global" warming.
40. Califonia
2:25 AM GMT on February 23, 2006
Posted By: JeffMasters (Admin) at 2:21 AM GMT on February 23, 2006.

If Greenland's temperatures continue to warm, melting is expected to accelerate and contribute to sea level rise by several millimeters per, due to feedback effects.


Thanks for posting - I wasn't expecting a personal response.

I agree about the feedback effects. In fact, one MAJOR one that I usually don't hear mentioned, is that the ice on the planet is a HEAT BUFFER, ie. as the planet heats, the heat energy is going into MELTING THE ICE rather than raising the temperature.

So whenever ice is melting, there is more GLOBAL HEATING occurring than the rate of GLOBAL WARMING would indicate.

As the ice melts down to nothing, the GLOBAL WARMING rate will increase even though the amount of heating remains constant. (this assumes heating exists, because otherwise ice would not be melting)

That being said, if you have a link to an online source where there is a projection of the anticipated melt rates of Greenland ice, I would like to take a look before responding further.

In general, I am not convinced that we will experience sea level increases that will produce catastrophic results. Not that we won't have to do some planning and relocation, but that we are easily capable of handling that over the time periods invloved.

If melt rates begin to increase, it will show up in sea levels, and communities in coastal areas will be able to make projections and make changes years in advance.

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37. Snowfire
3:31 AM GMT on February 23, 2006
There is another wrinkle to this. When big ice sheets with a lot of water around them are subject to warming, the precipitation rates go up due to the greater moisture capacity of warmer air and to the greater tendency of warmer oceans to give up moisture. Those parts of the ice sheet not yet seeing significant losses due to melting (the interior) will actually thicken, so at first the net effect will be for the ice sheet to draw itself inward and upward. During this phase, there may not be much net ice loss, as the greater outflow at the edges is mostly balanced by greater snow deposition farther inland.
You might not see much of a sea-level signature during this stage. Later, as warming continues, the inland portions will start to experience thinning as well, and then it will be a different story. I am no expert, but my gut hunch is that Greenland's ice sheet is still in the first stage of the process.
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35. ForecasterColby
3:19 AM GMT on February 23, 2006
Michael, if you're a numbers person, the curve would be logistic. If you've got a graphing utility:

y=(1/(a+be^(-cx)))

a,b,c are constants, e is the base of natural logs.
34. Inyo
3:15 AM GMT on February 23, 2006
i imagine if the sea level rose significantly (1 meter or more) it would actively serve to break up the glaciers near the ocean and increase the rate of melting. this is very far in the future. i wonder how much of a raise it would take to stress the coastal ice sheets
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33. KatrinaRitaWilmaZeta
6:55 PM PST on February 22, 2006
JeffMasters nic too see you on the blog maill for you
31. JeffMasters (Admin)
2:43 AM GMT on February 23, 2006
StSimonsIslandGAGuy wrote:

Dr Masters--if the ice sheet melts by thousands of feet how much would preciptation decrease as orographic enhancement fades?


Interesting thought! I don't know very well, but I imagine you'd lose at least 10% of your precipitaion for each 1000 feet of elevation you lose.

Jeff Masters
30. ForecasterColby
2:47 AM GMT on February 23, 2006
I'm not, or I'd have said something :)
29. KatrinaRitaWilmaZeta
6:37 PM PST on February 22, 2006
ForecasterColby i like to say i am vary sorry i did not no that was you i hop youare not mad at me
28. ForecasterColby
2:34 AM GMT on February 23, 2006
It would be a very shallow exponential curve, but we're still talking centuries or milennia.
27. JeffMasters (Admin)
2:12 AM GMT on February 23, 2006
California wrote:
Ok - at the new, much faster rate of apx. 1/2 of one millimeter per year, it would be 13,000 years to create a 6.5 meter sea level rise.

That's by Jeff's own numbers. So what's the big deal?


Unfortunately, the atmosphere does not behave in a linear fashion. If Greenland's temperatures continue to warm, melting is expected to accelerate and contribute to sea level rise by several millimeters per, due to feedback effects. One feedback, for instance, is that melting snow is darker, which absorbs more sunlight, which melts more snow, etc.

Jeff Masters
26. Inyo
2:12 AM GMT on February 23, 2006
I think a major sea level rise would be very bad for most people since a ton of agricultural land is on lowlands and delta type areas. This includes California's central valley, and huge areas of Bangladesh, etc. However, I also think that the sea level rise in the next few hundred years will be minor (and i hope i am not wrong!)
It is possible some will beneifit from climate change in general, but as a rule we are pretty set up for how things are now and if arable areas shift, people can't necessarily shift with them.. they may be poor, or the shifts may occur across country lines. I would say climate change, either antropomorphic and natural, causes more negative than positive effects as a whole.

I haven't seen any real evidence for the earth being in a period of higher solar output. the distance from the sun fluxuates, the output of the sun fluxuates slightly, and the tilt of the earth's axis changes over time. Yes, these things certainly happen and affect the climate, but i havent seen more than a couple claims that this was the reason for the warming, or any real data on increasing solar input. If anyone has this data, by all means post it! In fact, i don't think anyone is really sure about what causes the fluxuations between ice ages, including the natural warming trend we have been in the last few thousand years.. the allignment of continents and mountain ranges, solar output, volcanoes, and naturally fluxuating CO2 levels all seem to play a part. Obviously, any human caused effects are quite recent.

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25. Califonia
1:04 AM GMT on February 23, 2006
Posted by: JeffMasters, 3:11 PM EST on February 22, 2006

...Greenland's contribution to average annual sea rise increased from .23 mm/year in 1996 to .57 mm/year in 2005...

...Greenland holds enough ice to raise global sea level by over 20 feet (6.5 meters), should the ice cap disintegrate.


Ok - at the new, much faster rate of apx. 1/2 of one millimeter per year, it would be 13,000 years to create a 6.5 meter sea level rise.

That's by Jeff's own numbers. So what's the big deal?

Even if it starts melting a LOT faster, we're still talking thousands of years - such a gradual rise that it won't even be noticeable on a decade to decade time frame.

THIRTEEN THOUSAND YEARS!

Geez. Guess we should all go out and buy life jackets before the stores run out of them...
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24. KatrinaRitaWilmaZeta
5:58 PM PST on February 22, 2006
ForecasterColby i like to say i am vary sorry i did not no that was you i hop youare not mad at me
23. ForecasterColby
1:50 AM GMT on February 23, 2006
Here's a slightly different angle: what's so bad about global warming? If the sea levels rise by 200 feet, so what? Have we considered the possibility that it may be a good thing?

By the way, for those who are playing, there's a chance to score big forecasting points on Fantasy Hurricanes Adrian and Bob
22. miken62
1:39 AM GMT on February 23, 2006
Trees come and go....we didn't always have trees in the Eastern US most trees were cut down back in the early settlers days and used for everything from firewood to building ....so O2 levels go up and down....there are so many other reasons ....just can't type that many....

Member Since: January 14, 2003 Posts: 0 Comments: 213
21. miken62
1:36 AM GMT on February 23, 2006
and a few hundred years ago we didn't have autos and factories among other things pumping pollution into the air.....so I don't believe we are the problem....
Member Since: January 14, 2003 Posts: 0 Comments: 213
20. theboldman
5:36 PM PST on February 22, 2006
i totally agree mike this might just be a cycle of the earth if this orbit closer to the sun thing is true in another second (earths time) it will be another ice age
Member Since: September 8, 2005 Posts: 25 Comments: 2
19. theboldman
5:34 PM PST on February 22, 2006
well i do have some imput for this global warming thing i had someone tell me today that the earth has a pattern some years it closer to the sun some years it farther away is this true?

if it is this might be whats causing this meldown and more hurricanes i mean if the earth is even a foot closer to the sun it gets hotter dont you think we are in a pattern closer to the sun?

but i do believe that humans have some effect on it as well but who knows this has happened in the past maby in the next couple years it will cool down again.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.