Global Warming

[Admiral_Bobski]

The 'Jurrasic' started about 190my and was a transition away from the god awful world of the late Permian/Triassic. As we move deeper into the Jurrasic we encounter the evolution of the 'big' dino's (outside the time frame you are in) as the massive continental breakup begins changing deep desert to coastal margins.

In your time frame true dinosaurs were indeed becoming recognisably distinct from the reptiles/mammalian type reptiles but were 'clinging on' in a very harsh environment (in the main) as our own Triassic red sandstones will show you.

The time frame I am using is the Mesozoic era (around 250-65 million years ago), which covers the Triassic, Jurassic and Cretaceous periods. While there was an extinction event at the Triassic/Jurassic boundary (responsible for the extinction of approximately 35% of all life on Earth), the oxygen levels were only gradually increasing all through the Mesozoic.

The amount of oxygen in the atmosphere was at a low point in the early Triassic period, about 245 million years ago, increasing to approximately 18 percent by the end of the Mesozoic 65 million years ago.

(taken from: http://news.nationalgeographic.com/news/20...al_oxygen.html)

Meanwhile, here's a graph of temperatures and CO₂ levels, covering the Mesozoic era:

The Jurassic was far from a "Golden Era" in climatological terms (at least as far as human life goes).

CB

[HighPressure]

Well I have had a look at wobble and solar flux now off to do some research on Ozone depletion so any links either pro or against would be much appreciated. Maybe just maybe this has left a legacy that may be having a knock on effect of GW, I don't know but think its worth a look into?

(sorry if its old ground but its new to me!)

[jethro]

Well I have had a look at wobble and solar flux now off to do some research on Ozone depletion so any links either pro or against would be much appreciated. Maybe just maybe this has left a legacy that may be having a knock on effect of GW, I don't know but think its worth a look into?

(sorry if its old ground but its new to me!)

Hi HP,

Have a look in the thread about GW and declining magnetic field of Earth; I think I posted some relevant links in there, probably in one of the Nuclear links as the two are connected.

Good luck

[Hiya]

Well I have had a look at wobble and solar flux now off to do some research on Ozone depletion so any links either pro or against would be much appreciated. Maybe just maybe this has left a legacy that may be having a knock on effect of GW, I don't know but think its worth a look into?

(sorry if its old ground but its new to me!)

post up your findings in a new topic, its one of my areas of interest.

[parmenides3]

Well I have had a look at wobble and solar flux now off to do some research on Ozone depletion so any links either pro or against would be much appreciated. Maybe just maybe this has left a legacy that may be having a knock on effect of GW, I don't know but think its worth a look into?

(sorry if its old ground but its new to me!)

There's a bucketful of stuff on ozone and ozone depletion available; you are going to have your work cut out. Might be worth focussing on research findings in the last two or three years. You'll need to look at stratospheric and ground-level ozone as distinct but related influences. It is already used as one of the forcings in GCMs.

Have fun.

:)P

[Mondy]

Mmmm: http://news.bbc.co.uk/1/hi/sci/tech/6561527.stm

[BrickFielder]

OZone Links

European Ozone Research

Toms Total Ozone Mapping

NDACC

European Publications

SPARC (Stratospheric Processes and their role in Climate)

Decadal Variability in the stratosphere

Radiative Aerosol forcing

Chemistry Climate Modelling

[Mondy]

Scientist: Warming not caused by humans

Roy Spencer says we don't know yet how changes are happening

MADISON - Roy Spencer is speaking up about his belief that Earth is not headed toward a global warming disaster.

Spencer, a principal research scientist at the University of Alabama in Huntsville and former NASA scientist, said he knows he's in the minority with his opinions, but he doesn't believe manmade influences are causing catastrophic climate changes.

[Gray-Wolf]

Scientist: Warming not caused by humans

So whilst the majority of world climate scientists have been briefing world leaders as to the challenges we face in the warming world you bring us excerpts from an after dinner speech to the Republican Women of Madison? ..........

And then he's off to preach to the converted (Whitehouse) and attempt to convert the Preachers (evangelical leaders)???? All very high fa-looting this naysayer stuff, maybe he has time in his packed schedule to visit Disneyland and advise Mickey Mouse on his 'beleifs'......

Edited April 21, 2007 by Gray-Wolf

[Mondy]

It's just another opinion GW from a former NASA scientist, who if you beg my pardon, has a damn sight more scientific background than you or I. So, without you twisting the story, take out the people he's talking to, he may well have a point. He obviously feels he has, or else he wouldn't be speaking out...how careless of him

Of course, what chance does the guy have when The Alarmists are only too keen to diss.

[Gray-Wolf]

It's just another opinion GW from a former NASA scientist, who if you beg my pardon, has a damn sight more scientific background than you or I. So, without you twisting the story, take out the people he's talking to, he may well have a point. He obviously feels he has, or else he wouldn't be speaking out...how careless of him

Of course, what chance does the guy have when The Alarmists are only too keen to diss.

I think you understand the nature of an 'alarmist'.

If a runaway bus was bearing down on someone the alarmist would be 'alarmed' and try to raise awareness of those in danger of being 'squished', the naysayer would be busy trying to calm everyone down and re-assure them there was no such danger.

The rest are stuck in the middle being dragged one way or another.

Needless to say one 'NASA' Scientist has just gunned down his colleagues at one of thier bases, content and not credentials should be our guide as being part of one body or another doesn't guarantee permanent sanity!!!

Edited April 21, 2007 by Gray-Wolf

[Gray-Wolf]

The researchers at CU-Boulder's Colorado Center for Astrodynamics Research also say there is a 57 percent chance the 2007 sea-ice minimum will be lower than the 2006 minimum of 2.27 million square miles, now the second lowest on record. There is a 70 percent chance the 2007 sea-ice minimum will rank within the lowest five years on record, according to Research Associate Sheldon Drobot of CCAR's Arctic Regional Ice Forecasting System group in CU-Boulder's aerospace engineering sciences department.

Sea-ice extent is the area of an ocean covered by at least 15 percent ice. Declining sea ice in the Arctic is believed by researchers to be caused by higher winter temperatures due to greenhouse warming, said Drobot. Arctic sea ice has been declining since the late 1970s.

Researchers pay particular attention to September and March because they generally mark the annual minimum and maximum sea-ice extents respectively, said Drobot. On April 4, researchers from CU-Boulder's National Snow and Ice Data Center reported the maximum extent of this year's March Arctic sea ice, 5.7 million square miles, was the second-lowest maximum on satellite record.

(From 'Science Daily')

More scaremongering in our 20yr 'cool phase'.

[Admiral_Bobski]

I don't suppose anyone could direct me towards sea ice extent data from prior to 1978, could they?

We know the average global temperature has increased since around 1974-5, and we know sea ice extent has diminished since 1978.

We also know that average global temperature increased between around 1910-1940, and that temperatures decreased slightly between 1940-1970.

What did sea ice extent do between 1910 and 1978? Is there anywhere these data could be found?

Cheers!

CB

[Gray-Wolf]

I don't suppose anyone could direct me towards sea ice extent data from prior to 1978, could they?

We know the average global temperature has increased since around 1974-5, and we know sea ice extent has diminished since 1978.

We also know that average global temperature increased between around 1910-1940, and that temperatures decreased slightly between 1940-1970.

What did sea ice extent do between 1910 and 1978? Is there anywhere these data could be found?

Cheers!

CB

If you look at the correlation between Alpine glacial retreat in terms of the last few years (since 79') you should be able to approximate the polar ice cover.

Alpine glaciers have a pretty long history of observation (which is why I chose them) so I imagine ,over time and not 'one off' hot summers, you'd be able to get some idea of the global state of play (ice wise).

Seeing as we are constantly feted with tales of mountain glacier retreat/dissappearence I don't think you'll find much evidence of 'been here before' and the same should be true of Arctic sea ice extent.

You may argue the point but the indications given by past glacial responses to global climate must give us at least a 'flavour' of what was occurring back then (before sat images).

[parmenides3]

I don't suppose anyone could direct me towards sea ice extent data from prior to 1978, could they?

We know the average global temperature has increased since around 1974-5, and we know sea ice extent has diminished since 1978.

We also know that average global temperature increased between around 1910-1940, and that temperatures decreased slightly between 1940-1970.

What did sea ice extent do between 1910 and 1978? Is there anywhere these data could be found?

Cheers!

CB

I think you'll find the datasets for extent either in the NSIDC or the NCDC sites, somewhere... I'll look it up later when I'm feeling less lazy.

Small note: prior to the satellite era, extent was estimated from in situ reports from ships' officers (mostly military or whalers) and Arctic Circle ground stations, when these were around. They worked out where the ice pack ended & calculated from that. Since 1978, they also measure extent, to maintain the long-term dataset, but use cover (extent minus 'pools') as the more accurate measure of how much ice there actually is.

Try http://nsidc.org/

:)P

Edit: there you go. The Walsh dataset (1901-97) : http://www.nsidc.org/data/g00799.html

Though I read on that the popular datset of choice for the discerning climatologist is the HADISST1, available via: http://dss.ucar.edu/datasets/ds277.3/

:)P

Edited April 23, 2007 by parmenides3

[Devonian]

I think you'll find the datasets for extent either in the NSIDC or the NCDC sites, somewhere... I'll look it up later when I'm feeling less lazy.

Small note: prior to the satellite era, extent was estimated from in situ reports from ships' officers (mostly military or whalers) and Arctic Circle ground stations, when these were around. They worked out where the ice pack ended & calculated from that. Since 1978, they also measure extent, to maintain the long-term dataset, but use cover (extent minus 'pools') as the more accurate measure of how much ice there actually is.

Try http://nsidc.org/

:)P

Edit: there you go. The Walsh dataset (1901-97) : http://www.nsidc.org/data/g00799.html

:)P

The Met Offfice archive at Exeter has sea ice charts (hand drawn) back to 1968. It's well worth a visit for anyone interested.

In spring 1968 right into May (yes, May) ice was 'fast' against much of the N coast of Iceland and thick around Jan Mayen - a recent map with my, from memory, recollection of the charts in '68 is here. Today there is simply just old Arctic sea ice drifting SW in the east Greenland current. The change is stark, obvious and, from a ice watchers pov, rather sad to see.

Edited April 23, 2007 by Devonian

[Admiral_Bobski]

If you look at the correlation between Alpine glacial retreat in terms of the last few years (since 79') you should be able to approximate the polar ice cover.

Alpine glaciers have a pretty long history of observation (which is why I chose them) so I imagine ,over time and not 'one off' hot summers, you'd be able to get some idea of the global state of play (ice wise).

Seeing as we are constantly feted with tales of mountain glacier retreat/dissappearence I don't think you'll find much evidence of 'been here before' and the same should be true of Arctic sea ice extent.

You may argue the point but the indications given by past glacial responses to global climate must give us at least a 'flavour' of what was occurring back then (before sat images).

I'm not looking for a "been here before" situation, Gray-Wolf. but I am interested in seeing how sea ice has varied over the last hundred years. As I say, there's no doubt that sea ice has diminished since '78, and there's no doubt that global average temperatures have increased since the same time, which makes for a pretty straightforward correlation.

What I am interested in is to see how sea ice extent varied during the "cooling years" of 1940-1975(ish), and how much it diminished (or didn't as the case may be) during the "warming years" of 1910-1940(ish). At this stage I am not trying to prove any particular point - I just want the data!

CB

PS - Many thanks, P3. I had a look yesterday but could only find hand-drawn maps which, while potentially very good, are not that easy for a layman such as myself to draw inferences from. I was hoping for data in a tabular (numerical) format. Hopefully you've got me pointed in the right direction - I'm rooting around right now

[Admiral_Bobski]

Still looking at the moment - it seems that sea ice started to decline noticeably around 1953, then more drastically after the mid-1970s (ironically around the time satellite measurements became standard - and they say there's no such thing as coincidence!).

More later...

CB

[Gray-Wolf]

Still looking at the moment - it seems that sea ice started to decline noticeably around 1953, then more drastically after the mid-1970s (ironically around the time satellite measurements became standard - and they say there's no such thing as coincidence!).

CB

?

I thought sat measurement records only went back to 79'? (before that things were being 'tested/calibrated' only)

For one so keen on language you have a very 'conspiritorial lilt' when I can find no obviouse reason for such.

I would think it quite natural that our capacity to gauge sea ice extent by sight alone could not in any way compare to the sat coverage we enjoy today (and not expect it to throw up some surprises when it became oporational could appear niaeve to some).

I would say again that mountain glaciers, which have a much longer period of observation, would be as good a way as any to approximate the polar ice levels (probably as good as sporadic 'sight' records of yesteryear) over time.

Allowing for the initial 'inertia' as multi-year ice decayed you would expect sea ice extent to follow global temps over the long term. the 'end game' for sea ice will of course occur much faster as wind/wave erosion fragments the remaining pack exposing more surface area to ablate (are we becoming perolously close to this 'end game' point with the loss of 'multi-year ice?).

[parmenides3]

Note; The Russian SIGRID programme goes back to the late 1950's, I believe...

You may find references at AARI

:)P

[Admiral_Bobski]

?

I thought sat measurement records only went back to 79'? (before that things were being 'tested/calibrated' only)

For one so keen on language you have a very 'conspiritorial lilt' when I can find no obviouse reason for such.

I've found satellite data going back to 1978, but that first year's results may be open to some interpretation as they iron out the wrinkles in their calibrations I suppose.

The "conspiratorial lilt" of which you speak I assume refers to my comment "...and they say there's no such thing as coincidences..."? I apologise if you inferred it that way, but it was intended as a joke with just a hint of irony. I should have used a winky-face - I have become aware, though, that I do tend to overuse them See?

Various sources suggest caution when using data from pre-1953 (or thereabouts) due to the degree of uncertainty in the data, which makes it a tad harder to make conclusions with regards sea-ice extent during the first half of the twentieth century. Hence my unwillingness to make any comments or pose any questions at present - as always, more study required!

CB

PS - Thanks once again, P3. I'll check that out tomorrow if I get a chance.

[jethro]

Could this have anything to do with the disparity between North and South hemisphere temps rise? At the bottom of the article it notes:

"Another mystery: noctilucent clouds in the Southern Hemisphere are about half a mile higher than in the north."

http://www.nytimes.com/2007/04/24/science/...tml?ref=science

[Gray-Wolf]

Could this have anything to do with the disparity between North and South hemisphere temps rise? At the bottom of the article it notes:

"Another mystery: noctilucent clouds in the Southern Hemisphere are about half a mile higher than in the north."

http://www.nytimes.com/2007/04/24/science/...tml?ref=science

I'd imagine that the huge, great, high Antarctic continent (and it's wind field) coupled with the huge amount of ocean down there has more to do with things. Maybe the recent strengthening of the circumpolar winds will limit the antarctic 'input' (by blocking the continental 'outflow') and will have an effect over the coming years (and not just by battering the ice embayments).

Edited April 24, 2007 by Gray-Wolf

[johnholmes]

Could this have anything to do with the disparity between North and South hemisphere temps rise? At the bottom of the article it notes:

"Another mystery: noctilucent clouds in the Southern Hemisphere are about half a mile higher than in the north."

http://www.nytimes.com/2007/04/24/science/...tml?ref=science

yes an interesting read and yet another part of the atmospheric jigsaw we know little about.

As the scientist suggests, if his suggestion is correct, then we really are in deep poo in what we are doing to our atmosphere.

But yet another arguing point for one and all, scientific based or not.

[parmenides3]

jethro: the cooling of the central part of the Antarctic is consistent with a strengthening of the AAO; the Antarctic Oscillation. Because the continent is surrounded by ocean, there are no continental influence, as there are in the North. When it is 'strong' the AAO effectively creates a 'wall' of wind circulation which blocks incoming air (and thus warming). Another contributing factor is the ozone hole, which serves to suppress temperatures due to atmospheric heat loss during the relevant season; effectively, there is nothing to 'block' rising warmer air or reflect back what little heat there is.

This is consistent with what the climate models suggest should happen at this time, given the observed changes in the climate. Some people seem to believe that the 'cool' Antarctic is eveidence that the global climate isn't really changing, but this is not correct.

This is only a basic explanation, and ignores a lot of the complexities, but I hope it tells you what you need to know.

:)P