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Digital Photography Equipment => Lighting, Flashes, Strobes and Studio Gear => Topic started by: Clive on December 06, 2005, 04:18:35 PM

Title: 2500D not working on 7D
Post by: Clive on December 06, 2005, 04:18:35 PM
Posted at photo.net ... No offense gaz :)

Anyone else have problems using a 2500D flash on their 7D??

Purchased 7D in August..taken 9,600 images since. GREAT camera. Great images. I am a happy guy.

However, it came with a 2500D flash and I've not used the flash much. It did not seem to be working properly (erratic) so my dealer gave me a new one a few weeks back. Seemed okay at first, but again, I only used it once or twice.

Yesterday, I got it out and took a lot of pictures to test it. It simply does not work properly. With exactly the same setup and settings, the images are overexposed and underexposed..all over the map. (If they were all one way or the other, I could take corrective action ... but the exposures are all over the place.) Batteries are fresh. I am NOT using D lenses, but the flash should still work with Maxxum lenses. Had flash set on TTL and camera is defaulted to pre-TTL. I've tried all combinations (even without D lenses) including ADI settings. Nothing works including the recommended settings.

I am taking it back to my dealer and going to ask for a discount on a 3600HS(D) or a 5600HS(D). (KM pulled out of Canad so getting service is going to be tricky. My dealer is real good tho.)

Anyone else have these problems?

(http://members.shaw.ca/ocl4/flash3.jpg)
Title: 2500D not working on 7D
Post by: AScot on December 07, 2005, 02:38:29 AM
Clive, I have the 5600HS(D) and have had no problems using it with my 7D. However I have read many reports, exactly like yours, with the 7D and the three Minolta flashes, 5600, 3600 and 2500. It appears that the 7D is not calibrated correctly and usually has to be returned, with the flash, to KM, who will fix it for free. Why you would need to send the flash also is not clear.
Title: 2500D not working on 7D
Post by: Clive on December 07, 2005, 02:53:47 AM
AScot,

Thanks. I have written to Zoomtron and KM international. Shall see. I do not want to return the camera for (what??) three or four weeks though! Ho boy. I'd die.... (If they'd guarantee turnaround in say 8 days...maybe...)

I am taking pix at a wedding anniv in 2 weeks. The lady wants pix of every guest and the couple as they come in. IN THEORY we will organize it so the couple and the guests will stand in one spot--we have to be careful with backgrounds anyway. In which case, I can use my powerful 5200i. It fires in manual only, but with two quick test shots and I'll have it perfect. It will be 1/60 at f5.6 or f8 and then I can adjust the power level if need be. Obviously this is not good for fast changing situations and distances. For the casual shots I can use the on board flash.

Funny .. took pix a a social function last month and flash images generally were good...

I'd like the 5600 but right now I've spent too much $$ in the past while PLUS the old desktop needs replacing and we are going on a volunteer trip to Mexico in January. Heck .. I'll have to go back to work at this rate! :)

Thanks again. They will contact me soon.

Cheers!

Clive
Title: 2500D not working on 7D
Post by: ISO3200 on December 07, 2005, 05:50:07 AM
Quote from: Clive
 I do not want to return the camera for (what??) three or four weeks though! Ho boy. I'd die....  


*laughter*

My 3600 flash works fine. My 7D has been good and faithful. It;s fun using 1/4000 shutter speeds!

I think the 7D (though still amazing) is a somewhat glitchy camera. It's like KM hadn't quite perfected it's innards but were rushed into releasing it and only cleaned up their act come the 5D (which is also amazing)

In saying that Nikon has had trouble with the D70 locking up and the batteries exploding. So far, it seems, this hasn't affected me either!
Title: 2500D not working on 7D
Post by: Clive on December 07, 2005, 06:10:38 AM
ISO3200...

You ever sleep? :)

Thanks for the insight. Based on AScot and your take it is some sort of chip gremlin. Shall see what the KM agent in the frozen North tells me and take it from there.

"Exploding batteries" conjures up all sorts of evil thoughts  :twisted:  ...

 (http://members.shaw.ca/ocl4/bomb.jpg)
Title: 2500D not working on 7D
Post by: ISO3200 on December 07, 2005, 07:27:48 AM
Quote from: Clive

ISO3200... You ever sleep? :)

 


No, like digital slrs and good mp3 players everywhere, I run off li-ion batteries. Nor do I eat. I just might explode inexplicably, is all.

Actually I'm on 'night work'. I work much better at night. Got lots of work done, in-between emails and forum posts and sorting out ebay. So, while you sleep, Clive, I sleep too, just during our daylight hours. I haven't seen the sun for 3 days. Then again, that happens a lot in England. That's why we have christmas lights up.


Nuclear batteries are the next logical step.
Title: 2500D not working on 7D
Post by: Clive on December 07, 2005, 05:24:42 PM
The official and ENTIRE response from KM Int'l ....

Answer is : In Canada call Zoomtron at 514.333.0004

Will do later today ...
Title: 2500D not working on 7D
Post by: AScot on December 07, 2005, 09:39:35 PM
Clive, where is Zoomtron? Montreal? or Toronto? Either way for you it's a bit of a hassle, to say the least.

If it's in Toronto, I could drive up there and deliver my camera in person, if I had to. I would feel safer doing that. I don't trust courier services. DHL is a nightmare, FedEx and UPS are much better, but still a problem at times. Canada post can be very unreliable at Christmas!
Title: 2500D not working on 7D
Post by: Clive on December 07, 2005, 10:01:09 PM
I just got off the phone with "Meo" at Zoomtron at 514.333.0004 in PQ. I have to ship it to the ON service center, but we both agreed doing so two weeks before Christmas would not be too 'mart. :)

I will call Meo again in the New Year--possibly February now--as I am leaving for Mexico on Jan 28--and he will give me the new address for Zoomtron in the GTA as they are moving the service center early in 2006.

I will pass this along to the camera manager at London Drugs (my dealer) and I am guessing they will cover the shipping. I don't mind doing this BUT I will need some assurance of a fast turnaround before it leaves my hand. When KM Canada still existed (poof   :shock: ) I ordered the 7D on Monday and it arrived at the dealer--remembering we are in a smaller center, 3 hours from the Calgary airport--the next morning! So now..if we can get one or two day courier and two days on site..I bet it is a 6 minute job--I'd be happy. However, if it goes to ON and is placed in a  "holding pattern" on some techy's work bench for Lord knows how long....well, I'd be unimpressed.

If they gave me a guarantee it would turnaround in a few days, I'd ship it Jan 4 or so.

Or maybe I will crank up the ISO to 3200 and never use a flash again. :) Kidding.

I did some test shots with the 5200i in low-ish light conditions last night and after getting the manual settings adjusted (takes 30 seconds) it works spot on. (Such a good old flash--wonderful on the Maxxum 7!) I can also use the pop-up flash for close shots and it exposes accurately.

Cheers!

Clive
Title: 2500D not working on 7D
Post by: Clive on December 07, 2005, 10:08:54 PM
ISO3200

"That's why we have christmas lights up. "

So YOU are the main source of Global Warming then!!  8)
Title: 2500D not working on 7D
Post by: ISO3200 on December 07, 2005, 10:54:17 PM
No, that'd be the USA, with millions of mum's picking up their kids in armoured personel vehicles that average one mile to the gallon, spreading the word that global warming is a lie, that Darwinian evolution is wrong and that dinosaurs shook the hand of Adam and Eve. :roll:

In many respects America is so positive and forward, but in so many others it is laughably backward. What's Canada like in that regard? We don't hear much about it's values across the 'pond'. Seems a quiet place.

I have American relatives, by the way, and used to live there. So I'm really not a prejudiced pig, if anything I'm informed.
Title: 2500D not working on 7D
Post by: Clive on December 07, 2005, 11:20:08 PM
We are a pretty quiet lot and internationally overshadowed by our southern neighbor. We are larger in area than the USA, yet there are a mere 30M of us. We basically stay quiet and TRY to mind our business while trying to stay warm with fossil fuels. :)

If anyone pushed us around we'd send over the navy--both boats--but one is usually in dry dock.  

Overall we are a left-of-centre society that runs around saying, "Eh?" and worshiping eco-cultists who try to blame every single ailment of mankind on "those muck-raking industrialists and oil and gas $%^&£*@s" who clearly are responsible for pretty much anything bad--real or imagined.

Although I am a left-wing environmental type, I do not believe there is any good in trying to stop natural climate change and believe that the sun and oceans dictate millennial shifts in climate. There is more CO2 transferred between oceans and air than we could ever emit--the transfer rates a function of water temps which are driven by the sun. As much as we all don't like "Dubya,"  (and I, for one, think reducing carbon will do nothing), at least the USA increased carbon emissions less than Canada (a Kyoto signatory) ... Most Kyoto signatories have increased emissions.  

We need to conserve fossil fuels because they are finite. There are much larger environmental issues than carbon emissions and we run the risk of failing to address real environmental issues (like clean air and water) because we are addressing an expensive issue and we simply won't change one thing.

Sorry .. what was the question? :)

My wife says I talk way too much ...

Cheers!

Clive
From yesterday's Telegraph...London..Dec 6/05

But the point is, as Steven Guilbeault of Greenpeace puts it: "Global warming can mean colder, it can mean drier, it can mean wetter, that's what we're dealing with." Got that? If it's hot, that's a sign of global warming, and, if it's cold, that's a sign of global warming.

And if it's just kind of average - say, 48F and partially cloudy, as it will be in Llandudno today - that's a sign that global warming is accelerating out of control and you need to flee immediately because time is running out ! "Time is running out to deal with climate change," says Mr Guilbeault. "Ten years ago, we thought we had a lot of time, five years ago we thought we had a lot of time, but now science is telling us that we don't have a lot of time."

Really? Ten years ago, we had a lot of time? That's not the way I recall it: "Time is running out for the climate" - Chris Rose of Greenpeace, 1997; "Time running out for action on global warming Greenpeace claims" - Irish Times, 1994; "Time is running out" - scientist Henry Kendall, speaking on behalf of Greenpeace, 1992. Admirably, Mr Guilbeault's commitment to the environment extends to recycling last decade's scare-mongering press releases.
 
Title: 2500D not working on 7D
Post by: ISO3200 on December 08, 2005, 01:12:48 AM
Quote from: Clive

Although I am a left-wing environmental type, I do not believe there is any good in trying to stop natural climate change and believe that the sun and oceans dictate millennial shifts in climate.  


Clive... Clive... Clive... I am so surprised!

I know there's lots of different world opinions on climate change, but in Europe we now take it as FACT that global warming is happening, that CO2 has increased, and that we are each to blame. I also think this is the right view, judging by the mounting evidence, though it doesn't mean we can now magically fix things either. I'm quite a realisitic person, and also a very-well educated person, even if I say so myself, and can look at things objectively and with piles of scientific and geographic knowledge, just as you can. There's a lot left for humans to discover about the world and how we might affect it, but it's all very easy to write off global warming as 'natural' and say we can't curb it someday.

It's not as if organisms can't affect the environment, in fact organisms make the environment; life is responisble for oxygen even existing on earth, it exists nowhere else in the solar system in any quantity. Humans, in fact, are adept at changing the environment, usually ruining it, and have already induced the fastest extinction rate seen on earth. That's a fact geologist lecturers love to tell you.

We were perfectly capable of pumping out so many CFC's as to damage the ozone layer, and we are equally capable of doing a very different damage to the atmosphere with CO2 emissions, i.e so as to cause climate change. It's on graphs everywhere, each one drawn up by great scientists, not greenpeace potheads. We already have changed the atmosphere. It cannot be 'coincidence' that CO2 started going up as soon as the industrial revolution occured and so continued until the present day. I'm also perfectly aware of things like the carbon-cycle and the waxing and waning of CO2 in the atmosphere due to leafless winters, summers and ocean rocks locking CO2 away. Even with those factored into the graphs, CO2 is going up and up and up in a tight zig-zag line. Carl Sagan and co. spelt all that out ten years ago. He'd be ashamed of the USA today.

If CO2 goes up, so will global temperature, which in turn means more water vapour, which then raises global temperature more; Venus-style, though that's very extreme.

And we're not talking milleniums here, or even lifetimes. The UK used to be cold when october came, but now it hasn't had a bad winter in 15-20 years; there's green leaves on the trees in my garden and it is December - that never ever used to happen, never. Ecologists all over the UK have recorded changes in weather and species not seen since records began. Which might not be long on a geological scale, but I'm still worried.

Scientists recently, and to their surprise, found that the Gulf Stream has slowed by 20% which is a sure sign that fresh water from glaciers is 'polluting' the salty sea around the UK and preventing sinkage of water. So, then we limeys would be in for a cold snap alright!

I could go on, but I know I won't change your opinion.

I don't have time for the argument of global warming being a myth, or not our fault. It's as much our fault as deforestation and pollution. I do not know the answer either, but deforestation is easy to stop compared to global warming and if we can't even stop the former we'll not stop the latter either anytime soon. I agree with you there, at least.
Title: 2500D not working on 7D
Post by: ISO3200 on December 08, 2005, 01:17:49 AM
Of course, no hard feelings - this is what debate is meant to be!

This is also a definate post-hijacking. I'm turning into you! :shock:
Title: 2500D not working on 7D
Post by: Clive on December 08, 2005, 03:46:51 AM
ISO3200 .. "no hard feelings - this is what debate is meant to be!"

Oh heavens, no. I love to debate about technical stuff. Now ... as for taking over my role as The Primo Hijacker , well ... :)

I can't post a specific reply to your comments at this moment, but will try to do so tomorrow. However, I posted on a similar thread recently so copy and pasted most of it below....some of it may not be germane.

BTW .. where I live three of the the past four years have been colder than average, but the patterns vary--we tend to have slightly warmer winters but have abysmal summers.

Climate is changing and if it wasn't then I'd be worried. The earth is always tending to cool or tending to warm.  

Hopefully more tomorrow...

Cheers!

Clive

=============== start of old post ========================
. . .  BTW… the 0.6C°warming of the past century is about what we'd expect from natural trends. And remember further that we are still emerging from the last mini ice age that ended just 200 years ago. The world was in quite a cold spell for a few hundred years around 1400 to 1800 or so. It's a damn good thing it IS getting warmer.

Here's the deal--the correct version of GW according to real climatologists. The driver of climate is the sun and its output varies greatly over time. The effects of this are not on earth directly but in the oceans and over decades and centuries the oceans change and the effects of currents and released energy stored are felt. Now here is the real kicker. The oceans store unimaginable amounts of carbon dioxide. The exchange of CO2 between the oceans and atmosphere vary more than the paltry amount released by man.

Poor Q image ... suns output and temps....
(http://members.shaw.ca/ocl4/temp_sun_radiation.jpg)

Read the last article here from GeoScience Canada:
http://www.esd.mun.ca/~gac/JOURNALS/TOC/GACgcV32No1Web.pdf (http://www.esd.mun.ca/~gac/JOURNALS/TOC/GACgcV32No1Web.pdf)
Or from Harvard …
http://www.news.harvard.edu/gazette/1997/1...teningSuni.html (http://www.news.harvard.edu/gazette/1997/11.06/BrighteningSuni.html)


CO2 may be high now but PRAY TELL why has it gone up and down like this for the past millions of years because it sure as heck was not man. The eco crowd will tell you everything that happened before the past 200 years was a) different or B) natural or c) both. But they will never allow that natural forces are still at play with long term climate. That is simply nonsense, i.e. to deny the existance of natural forces today.

Here’s how carbon dioxide has varied over a LONG time …
(http://www.geocraft.com/WVFossils/PageMill_Images/image277.gif)
Quotes with this chart…
There has historically been much more CO2 in our atmosphere than exists today. For example, during the Jurassic Period (200 mya), average CO2 concentrations were about 1800 ppm or about 4.8 times higher than today. The highest concentrations of CO2 during all of the Paleozoic Era occurred during the Cambrian Period, nearly 7000 ppm -- about 19 times higher than today.
The Carboniferous Period and the Ordovician Period were the only geological periods during the Paleozoic Era when global temperatures were as low as they are today. To the consternation of global warming proponents, the Late Ordovician Period was also an Ice Age while at the same time CO2 concentrations then were nearly 12 times higher than today-- 4400 ppm. According to greenhouse theory, Earth should have been exceedingly hot. Instead, global temperatures were no warmer than today. Clearly, other factors besides atmospheric carbon influence earth temperatures and global warming
.”

So do carbon dioxide and temperatures vary together? Well sort of. As temperatures rise (ever so slightly as we are now seeing) more CO2 is released from the oceans. The proof is that CO2 lags behind temperatures and long-term studies show that temperature rise first and carbon dioxide follows.

Just 1,000 years ago the Vikings farmed in Greenland--now covered with ice. 400 and 500 years ago the rivers in western Europe were often frozen over--it's a damn good thing it has warmed. A short 18,000 years ago Canada (all of it) was covered by the Laurentide and Cordilleran Ice Sheets. These essentially melted in just 90 centuries--between 18K and 9K ybp. The MASSIVE outflows of water created the prairie valleys in Southern Alberta. The melt rates were unimaginably greater that from the current glaciers. What caused those huge melts? It was not man.

The UN's IPCC got everyone hyped up a few years ago with the fallacious "hockey stick" chart that proved that 1998 was the warmest year in 100 year. That chart has been totally debunked yet is the very reason for Kyoto. We are spending billions upon billions on junk science while real climatologists go ignored. Even nay sayers on the IPCC committees are ignored so that the bloody shameful nonsense can continue.

You will find some interesting reading here…
http://www.friendsofscience.org/index.php?ide=4 (http://www.friendsofscience.org/index.php?ide=4)

Cheers!

Clive
Title: 2500D not working on 7D
Post by: ISO3200 on December 08, 2005, 08:56:58 AM
I hope you're right, I really do.

Trust me, you don't have to bother typing out an enormous case, I probably won't read it, I'm already spent on this debate and am too busy trying to figure out christmas and whether or not to try for a D200 in the near future or look into the land of Olympus, about which I'm hearing some rather good things now...

hmmm...
Title: 2500D not working on 7D
Post by: tpe on December 08, 2005, 01:30:11 PM
Ahh so this is the hijak, right, just to poke my oar in whilst not defleasing sheep...

Most of the data made available has to be promoted for the public to receive it, unfortunatly the amount of money spent on diseminating the information and the validity of the information are not necessarily linked. Those that have access to the most non subjective evidence are not those that have the greatest access to the media. Those that have a finacial advantage of promoting the sceptics side also have the financial clout to promote their cause. The primary decenters are also those employed in centers sponsered by those with something to gain by adding subjective research and publicity. Therefore before accepting any information as true it is necessary to identify the source of the information and any associated financial incentives that may bias the results presented.

Here is an editorial from newscientist that is not from departments co finaced by the petrochemical industry...

ON 16 FEBRUARY, the Kyoto protocol comes into force. Whether you see this as a triumph of international cooperation or a case of too little, too late, there is no doubt that it was only made possible by decades of dedicated work by climate scientists. Yet as these same researchers celebrate their most notable achievement, their work is being denigrated as never before.

The hostile criticism is coming from sceptics who question the reality of climate change. Critics have always been around, but in recent months their voices have become increasingly prominent and influential. One British newspaper called climate change a "global fraud" based on "left-wing, anti-American, anti-west ideology". A London-based think tank described the UK's chief scientific adviser, David King, as "an embarrassment" for believing that climate change is a bigger threat than terrorism. And the bestselling author Michael Crichton, in his much publicised new novel State of Fear, portrays global warming as an evil plot perpetrated by environmental extremists.

If the sceptics are to be believed, the evidence for global warming is full of holes and the field is riven with argument and uncertainty. The apparent scientific consensus over global warming only exists, they say, because it is enforced by a scientific establishment riding the gravy train, aided and abetted by governments keen to play the politics of fear. It's easy to dismiss such claims as politically motivated and with no basis in fact - especially as the majority of sceptics are economists, business people or politicians, not scientists (see "Meet the sceptics"). But there are nagging doubts. Could the sceptics be onto something? Are we, after all, being taken for a ride?

This is perhaps the most crucial scientific question of the 21st century. The winning side in the climate debate will shape economic, political and technological developments for years, even centuries, to come. With so much at stake, it is crucial that the right side wins. But which side is right? What is the evidence that human activity is warming the world, and how reliable is it?

First, the basic physics. It is beyond doubt that certain gases in the atmosphere, most importantly water vapour and carbon dioxide, trap infrared radiation emitted by the Earth's surface and so have a greenhouse effect. This in itself is no bad thing. Indeed, without them the planet would freeze. There is also no doubt that human activity is pumping CO2 into the atmosphere, and that this has caused a sustained year-on-year rise in CO2 concentrations. For almost 60 years, measurements at the Mauna Loa observatory in Hawaii have charted this rise, and it is largely uncontested that today's concentrations are about 35 per cent above pre-industrial levels (see Graph).

The effect this has on the planet is also measurable. In 2000, researchers based at Imperial College London examined satellite data covering almost three decades to plot changes in the amount of infrared radiation escaping from the atmosphere into space - an indirect measure of how much heat is being trapped. In the part of the infrared spectrum trapped by CO2 - wavelengths between 13 and 19 micrometres - they found that between 1970 and 1997 less and less radiation was escaping. They concluded that the increasing quantity of atmospheric CO2 was trapping energy that used to escape, and storing it in the atmosphere as heat. The results for the other greenhouse gases were similar.

These uncontested facts are enough to establish that "anthropogenic" greenhouse gas emissions are tending to make the atmosphere warmer. What's more, there is little doubt that the climate is changing right now. Temperature records from around the world going back 150 years suggest that 19 of the 20 warmest years - measured in terms of average global temperature, which takes account of all available thermometer data - have occurred since 1980, and that four of these occurred in the past seven years (see Graph).

The only serious question mark over this record is the possibility that measurements have been biased by the growth of cities near the sites where temperatures are measured, as cities retain more heat than rural areas. But some new research suggests there is no such bias. David Parker of the UK's Met Office divided the historical temperature data into two sets: one taken in calm weather and the other in windy weather. He reasoned that any effect due to nearby cities would be more pronounced in calm conditions, when the wind could not disperse the heat. There was no difference.

It is at this point, however, that uncertainty starts to creep in. Take the grand claim made by some climate researchers that the 1990s were the warmest decade in the warmest century of the past millennium. This claim is embodied in the famous "hockey stick" curve, produced by Michael Mann of the University of Virginia in 1998, based on "proxy" records of past temperature, such as air bubbles in ice cores and growth rings in tree and coral. (see "Hotly contested") Sceptics have attacked the findings over poor methodology used, and their criticism has been confirmed by climate modellers, who have recently recognised that such proxy studies systematically underestimate past variability. As one Met Office scientist put it: "We cannot make claims as to the 1990s being the warmest decade."

There is also room for uncertainty in inferences drawn from the rise in temperature over the past 150 years. The warming itself is real enough, but that doesn't necessarily mean that human activity is to blame. Sceptics say that the warming could be natural, and again they have a point. It is now recognised that up to 40 per cent of the climatic variation since 1890 is probably due to two natural phenomena. The first is solar cycles, which influence the amount of radiation reaching the Earth, and some scientist have argued that increased solar activity can account for most of the warming of the past 150 years. The second is the changing frequency of volcanic eruptions, which produce airborne particles that can shade and hence cool the planet for a year or more. This does not mean, however, that the sceptics can claim victory, as no known natural effects can explain the 0.5 °C warming seen in the past 30 years. In fact, natural changes alone would have caused a marginal global cooling (see Graph).

“Natural changes alone would have caused a marginal global cooling in the past 30 years”How hot will it get?
In the face of such evidence, the vast majority of scientists, even sceptical ones, now agree that our activities are making the planet warmer, and that we can expect more warming as we release more CO2 into the atmosphere. This leaves two critical questions. How much warming can we expect? And how much should we care about it? Here the uncertainties begin in earnest.

The concentration of CO2 in the atmosphere now stands at around 375 parts per million. A doubling of CO2 from pre-industrial levels of 280 parts per million, which could happen as early as 2050, will add only about 1 °C to average global temperatures, other things being equal. But if there's one thing we can count on, it is that other things will not be equal; some important things will change.

All experts agree that the planet is likely to respond in a variety of ways, some of which will dampen down the warming (negative feedback) while others will amplify it (positive feedback). Assessing the impacts of these feedbacks has been a central task of the UN's Intergovernmental Panel on Climate Change, a co-operative agency set up 17 years ago that has harnessed the work of thousands of scientists. Having spent countless hours of supercomputer time creating and refining models to simulate the planet's climate system, the IPCC concludes that the feedbacks will be overwhelmingly positive. The only question, it says, is just how big this positive feedback will be.

The latest IPCC assessment is that doubling CO2 levels will warm the world by anything from 1.4 to 5.8 °C. In other words, this predicts a rise in global temperature from pre-industrial levels of around 14.8 °C to between 16.2 and 20.6 °C. Even at the low end, this is probably the biggest fluctuation in temperature that has occurred in the history of human civilisation. But uncertainties within the IPCC models remain, and the sceptics charge that they are so great that this conclusion is not worth the paper it is written on. So what are the positive feedbacks and how much uncertainty surrounds them?

Melting of polar ice is almost certainly one. Where the ice melts, the new, darker surface absorbs more heat from the sun, and so warms the planet. This is already happening. The second major source of positive feedback is water vapour. As this is responsible for a bigger slice of today's greenhouse effect than any other gas, including CO2, any change in the amount of moisture in the atmosphere is critical. A warmer world will evaporate more water from the oceans, giving an extra push to warming. But there is a complication. Some of the water vapour will turn to cloud, and the net effect of cloudier skies on heat coming in and going out is far from clear. Clouds reflect energy from the sun back into space, but they also trap heat radiated from the surface, especially at night. Whether warming or cooling predominates depends on the type and height of clouds. The IPCC calculates that the combined effect of extra water vapour and clouds will increase warming, but accepts that clouds are the biggest source of uncertainty in the models.

Sceptics who pounce on such uncertainties should remember, however, that they cut both ways. Indeed, new research based on thousands of different climate simulation models run using the spare computing capacity of idling PCs, suggest that doubling CO2 levels could increase temperatures by as much as 11 °C (Nature, vol 434, p 403).

Recent analysis suggests that clouds could have a more powerful warming effect than once thought - possibly much more powerful (New Scientist, 24 July 2004, p 44). And there could be other surprise positive feedbacks that do not yet feature in the climate models. For instance, a release of some of the huge quantities of methane, a potent greenhouse gas, that are frozen into the Siberian permafrost and the ocean floor could have a catastrophic warming effect. And an end to ice formation in the Arctic could upset ocean currents and even shut down the Gulf Stream - the starting point for the blockbuster movie The Day After Tomorrow.

There are counterbalancing negative feedbacks, some of which are already in the models. These include the ability of the oceans to absorb heat from the atmosphere, and of some pollutants - such as the sulphate particles that make acid rain - to shade the planet. But both are double-edged. The models predict that the ocean's ability to absorb heat will decline as the surface warms, as mixing between less dense, warm surface waters and the denser cold depths becomes more difficult. Meanwhile, sulphate and other aerosols could already be masking far stronger underlying warming effects than are apparent from measured temperatures. Aerosols last only a few weeks in the atmosphere, while greenhouse gases last for decades. So efforts to cut pollution by using technologies such as scrubbers to remove sulphur dioxide from power station stacks could trigger a surge in temperatures.

“Efforts to cut aerosol pollution could trigger a surge in temperatures”Sceptics also like to point out that most models do not yet include negative feedback from vegetation, which is already growing faster in a warmer world, and soaking up more CO2. But here they may be onto a loser, as the few climate models so far to include plants show that continued climate change is likely to damage their ability to absorb CO2, potentially turning a negative feedback into a positive one.

Achilles' heel?
More credible is the suggestion that some other important negative feedbacks have been left out. One prominent sceptic, meteorologist Richard Lindzen of the Massachusetts Institute of Technology, has made an interesting case that warming may dry out the upper levels of the innermost atmospheric layer, the troposphere, and less water means a weaker greenhouse effect. Lindzen, who is one of the few sceptics with a research track record that most climate scientists respect, says this drying effect could negate all the positive feedbacks and bring the warming effect of a doubling of CO2 levels back to 1 °C. While there is little data to back up his idea, some studies suggest that these outer reaches are not as warm as IPCC models predict (see "Areas of contention). This could be a mere wrinkle in the models or something more important. But if catastrophists have an Achilles' heel, this could be it.

Where does this leave us? Actually, with a surprising degree of consensus about the basic science of global warming - at least among scientists. As science historian Naomi Oreskes of the University of California, San Diego, wrote in Science late last year (vol 306, p 1686): "Politicians, economists, journalists and others may have the impression of confusion, disagreement or discord among climate scientists, but that impression is incorrect."

Her review of all 928 peer-reviewed papers on climate change published between 1993 and 2003 showed the consensus to be real and near universal. Even sceptical scientists now accept that we can expect some warming. They differ from the rest only in that they believe most climate models overestimate the positive feedback and underestimate the negative, and they predict that warming will be at the bottom end of the IPCC's scale

For the true hard-liners, of course, the scientific consensus must, by definition, be wrong. As far as they are concerned the thousands of scientists behind the IPCC models have either been seduced by their own doom-laden narrative or are engaged in a gigantic conspiracy. They say we are faced with what the philosopher of science Thomas Kuhn called a "paradigm problem".

"Most scientists spend their lives working to shore up the reigning world view - the dominant paradigm - and those who disagree are always much fewer in number," says climatologist Patrick Michaels of the University of Virginia in Charlottesville, a leading proponent of this view. The drive to conformity is accentuated by peer review, which ensures that only papers in support of the paradigm appear in the literature, Michaels says, and by public funding that gives money to research into the prevailing "paradigm of doom". Rebels who challenge prevailing orthodoxies are often proved right, he adds.

But even if you accept this sceptical view of how science is done, it doesn't mean the orthodoxy is always wrong. We know for sure that human activity is influencing the global environment, even if we don't know by how much. We might still get away with it: the sceptics could be right, and the majority of the world's climate scientists wrong. It would be a lucky break. But how lucky do you feel?



Specifically debunking of the sun temp...

CLAIMS that increased solar activity could explain the world's warming climate are challenged by a study of Irish bogs. The research, which is a fresh blow to climate sceptics, shows that while there are cyclical changes in both climate and the sun's activity, there is no obvious link between the two.

"The data shows that there is no simple one-to-one relationship, as some researchers have touted," says Chris Turney of the University of Wollongong in New South Wales, Australia, who led the work.

Other studies have claimed to find a link, but what sets this one apart is that the figures for the sun's heat output and those for climate are from the same source - trees growing in the bogs. This avoids any problems of accurately matching the dates of climate data from one source to solar activity from another, Turney says.

Firstly, the Irish trees already form part of the basis for the international radiocarbon calibration curve, the gold standard for inferring solar activity over the last 9000 years. Radioactive carbon-14 is created when cosmic rays from deep space hit the Earth's upper atmosphere, and trees absorb this carbon, laying down a record of historical levels. When the sun is very active, the increased solar wind of charged particles deflects cosmic rays and reduces carbon-14 production. So a low level of carbon-14 in trees reveals increased solar activity.

To deduce climate variations over the same period, the team used an archive of more than 750 excavated trees from the bogs, dating back 7648 years, to gauge tree cover. Periods of more abundant cover indicate relatively warm and dry spells, while sparser cover suggests the climate was wetter and cooler, since a higher water table makes it difficult for saplings to flourish.

"We find a clear cycle in wetting and drying phases, with shifts about every 800 years," says Turney. But the peaks in solar activity do not coincide with peaks in warmer conditions (Journal of Quaternary Science, vol 20, p 511).

Previous studies have used data from separate sources. In 2003, for instance, Feng Sheng Hu of the University of Illinois at Urbana-Champaign and colleagues reported a study of biological productivity in lakes in the Alaskan tundra, to use as an indicator of changing climate conditions. The team compared this with known changes in sea ice and the international radiocarbon calibration curve, and concluded that variations in climate do seem to tie in with changes in solar activity.

Hu is impressed with the new data though. "The quality of the chronology is extraordinary and the documented dry/wet cycles seem striking." But, he says, there are significant discrepancies between different measures of climate variation. Hu thinks that understanding these will be vital to understanding any link between solar activity and climate.

The question of exactly what is causing the roughly 800-year periodic shifts in North Atlantic climate seen by Turney's team is still open. We are currently a few hundred years into a warm, dry phase that followed the so-called little ice age, which ended around 1850. It is theoretically possible that solar activity might have some role in climate shifts, but if it does it is indirect, Turney says.


O.K back to the sheep :)

tim

another choice snippit

AS NAILS in the coffin go, they don't get much bigger: three independent studies have shown that climate sceptics who claim that Earth is not warming have been using faulty data to make their point.

The debate on climate change has often centred on the temperature of the lower troposphere. Common sense and computer models suggest that as the Earth's surface warms, so should this layer of the atmosphere. But measurements from satellites and balloons did not always support this.

In 1992, John Christy of the University of Alabama in Huntsville analysed the satellite measurements and concluded that the lower troposphere had cooled over the decades, relative to Earth's surface over the tropics. For those arguing against global warming, this analysis was pure gold. "The data from the satellites have taken on almost iconic status," says Ben Santer of the Lawrence Livermore National Laboratory in California.

But the findings remained puzzling. "It is very difficult to understand physically how the lower troposphere could be cooling while the Earth's surface and the middle and upper troposphere were warming, as this study found," Santer says.

Now Carl Mears and Frank Wentz of Remote Sensing Systems in Santa Rosa, California, have an answer. They reanalysed Christy's data and corrected for errors caused by satellite drift. "The satellite is supposed to go over the equator and take measurements at the same time every day," says Mears. Initially this was at around 2 pm local time, but after a few years it was crossing the equator at 5 pm, he says. "Common sense tells you that it's cooler at 5 pm than at 2 pm, and that was biasing the results." Once they factored this in, the data showed that the troposphere is warming (Science, DOI: 10.1126/science.1114772).

Mears and Wentz have strong support from Santer and his colleagues, who used 19 climate models to simulate the changes that would have occurred during the course of the 20th century. "Despite the fact that these models are all different in their physics, they all yield similar results in the tropics," he says. They all predict that warming at the Earth's surface should be amplified in the troposphere. "This makes sense physically," Santer says (Science, DOI: 10.1126/science.1114867).

“As researchers improved on ways to shield the balloon sensors from the sun, they recorded a trend of declining temperatures”Mears agrees. "The only thing left for sceptics to point at would be the weather balloon data that also showed discrepancy with the models." And now Steven Sherwood of Yale University in New Haven, Connecticut, and his colleagues have shown that the balloon measurements are unreliable too.

The problem has to do with protecting temperature sensors from direct sunlight. "It is just a little thing dangling from the balloon and there's no way to shield it consistently," Sherwood says. Over the years, researchers found new ways to shield the instruments from the sun, but rarely bothered to make a note of this shielding or calculate its effect on the raw data. Improved shielding led to a drop in the temperatures recorded by the sensors, and this can explain the trend of declining temperature in the troposphere as recorded by weather balloons, Sherwood says (Science, DOI: 10.1126/science.1115640).

Christy welcomes Mears and Wentz's analysis of the flaws in the satellite data he used. "Their suggestions helped me fix my error pretty quickly," he says. His reanalysis now shows the Earth is warming by about 1.23 °C per century. Mears and Wentz calculate the trend to be about 1.9 °C per century.

The world is not warming as fast as the 1.5 °C to 6 °C per century that models suggest, Christy says. "We all agree that warming is related to human effects, but it's not as dramatic as models say."

Sherwood agrees that the debate will linger. "I don't think we have resolved the controversy over global warming," he says. "But there is no longer any data contradicting the predictions of global warming models."
Title: 2500D not working on 7D
Post by: ISO3200 on December 08, 2005, 02:12:12 PM
My god, tpe, no one is going to read that! I skimmed it, at least.

In short:

The theory is that we are causing Global Warming.

The fact is that Global Warming is happening.


Like:

Darwin's theory as to exactly how evolution occurs, through natural selection, might concievably be wrong, though that is increasingly unlikely.

But the fact is creatures do evolve and change and are 'selected' right before our eyes - like the pepper moth or bird flu, which could, maybe, evolve into a pandemic disease...


...and like anyone who actually believes in created antiquity is completely bonkers, fact.
Title: 2500D not working on 7D
Post by: tpe on December 08, 2005, 02:25:58 PM
LOL, yeah you are right.

However it is undeniable that the environment is dynamic and everything we do has an effect on the environment. The question is how are whatever changes going to affect whatever is living on the planet, and what sort of environment do we want to live in.

If we dont know (I think the case is more clear cut each day though and could go on for years just citing more and more research) how we will change it perhaps we should be cautious untill we do know. If we ever find out hopefully we can chage it to our liking, what would be better than going out for a stroll on the beach in the arctic christmas? Untill we do know for sure we can only use our best bet, and i don't want my idea of how the climit is changing to be determined by any profit orientated organization, i would much rather be able to take a walk in the park in my undies than wear acid resistant hydrocarbon polymers to protect my skin from acid rain and scatered sun cancer.

If shell and bp didnt have so much cash i am sure that they would be lumped in with the intelegent design protaganists by now... Blah blah blah baaa baaa baa, sorry going off into one again.

tim
Title: 2500D not working on 7D
Post by: Clive on December 08, 2005, 03:27:11 PM
Holy cow ... thanks...

tpe .. will read later today. Debate is good which is more than the subjects gets at the UN.

AScot will know Rex Murphy .. a brilliant (and humorous) writer and Rhodes Scholar ..
Perhaps Kyoto is Japanese for hypocrisy
http://www.cbc.ca/national/rex/rex_051206.html

In Montreal yesterday, our prime minister had the audacity to berate the USA while their track record on carbon is better than ours. Mind I think the whole carbon issue is nonsense .. but still.

Later ...

IT IS FINALLY WARMER HERE!!!