A fascinating animation - based on model simulations performed at the National Center for Atmospheric Research (NCAR) in Boulder, CO - illustrates the retreat of Arctic ice to near vanishing by 2040 that could occur with continued global warming. See: http://www.ucar.edu/news/releases/2006/arcticvisuals.shtml

Generic comment about how this is a weather blog, not climate.

;)

Mr. Freedman, you wrote, "Scientists blame human emissions of greenhouse gases for much of the Arctic sea ice decline, but natural factors are also at work in the region, such as variations in ocean currents and atmospheric cycles including the Arctic Oscillation."

First let me applaud you for pointing out that "natural factors are also at work in the region". Well done.

My question would be a simple one, and I think it is one that many Americans have - What percentage would you attribute to man and what percentage would you attribute to nature? Is it 3% man? 5%? What is it?

I find it interesting that the U.K. Met Office and the satellite data both show that 1998 was the warmest year on record, but the Arctic melt has been getting larger with each passing year. Couldn't that lead some reasonable people to conclude that it may be ALL "natural factors" at work in the region?

I found this quote, "At least part of the explanation for this fairly rapid decline lies in the warm conditions that characterized April over the Arctic Ocean and peripheral seas. Anomalies over some regions exceed 5 degrees Celsius (9 degrees Fahrenheit). For the most part, this unusual warmth is consistent with shifts in atmospheric circulation that bring warm air into the region." at one of the sites you linked to in your article ( http://nsidc.org/arcticseaicenews/ ).

I find it disturbing that nearly everyone tries to link man to every little change in the weather, but NOBODY ever assigns a percentage to man's contribution. People try to link man and then leave it at that. Then, once they feel that man MAY be contributing, even if our contribution may be something as insignificant at 3%, they tell everyone how they must change their lives. I don't think so.

One very simple question - What percentage of any recent Arctic melt is directly attributable to man?

Mr. Q.

If, God forbid, man was completely wiped off the Earth tomorrow, what would happen to the Arctic sea ice?

I want to know the answer to that question before I even consider adopting some of the policies being suggested by some scientists and politicians.

Mr. Q.

There were roughly 12000 polar bears in the 1960s. That number has doubled. Why don't policy makers go by the actual number rahter than computer models?

How DARE anyone question Al Gore!!!!!!!!! Shame on you all!! He is the smartest human to ever live!! If he says humans have the ability to control nature, than it is the TRUTH!! You are not allowed to question it anymore. The debate is over......right?

(I hope the sarcasm is obvious enough...)

"Stroeve et al. (2007) suggested that 33-38% of the observed September trend from 1953 to 2006 is externally forced by greenhouse gas emissions. If only the past 27 years are considered, changes induced by greenhouse gas emissions increase to 47-57% of the observed September trend. Given that as a group, the models still underestimate observed ice loss, the authors expect that the externally forced component of Artic sea ice decline may be larger."

I may be mistaken, but unless they have changed the definition of "externally forced", you didn't answer my question.

According to this IPCC paper, externally forced is defined as,
--begin quote--
Externally forced climate variations may be due to changes in natural forcing factors, such as solar radiation or volcanic aerosols, or to changes in anthropogenic forcing factors, such as increasing concentrations of greenhouse gases or sulphate aerosols.
--end quote--

source of the quote -
http://www.grida.no/climate/ipcc_tar/wg1/443.htm

Has the definition of externally forced changed?

If it hasn't, this is part of the problem? Your side of the debate is being very misleading, and one can't help but wonder if it is intentional.

My as of yet unanswered question is, "What percentage of any recent Arctic melt is directly attributable to man?"

Mr. Q.

Alternatively, what percentage of greenhouse gas emissions is directly attributable to man?

And if, God forbid, we all dropped dead tomorrow, what would happen to the Arctic sea ice?

Mr. Q.

The polar bear numbers increase primarily from the Olso Agreement of 1973 which restricted hunting of the bears. Since hunting was restricted their populations recovered. Something not mentioned here before.

As to the impact of losing habitat according to http://www.polarbearsinternational.org/bear-facts/

In areas where long-term studies are available, populations are showing signs of stress due to shrinking sea ice. Canada's Western Hudson Bay population has dropped 22% since the early 1980s. The declines have been directly linked to an earlier ice break-up on Hudson Bay.

Jake in Reston: Our generic response

And likewise to Mr. Quibble.

Mr. Q: Steve did answer your question with his reference to that particular study, which attempted to quantify the proportion of Arctic sea ice decline due to greenhouse gas emissions. I'm not clear on the meaning of your reply to his response, as it seems like you answered your own question.

John, if you have a source on the effects of the 1973 Oslo Agreement, can you please provide it? The increase in the population of polar bears from the levels seen several decades ago is often seen as evidence that bears are doing better now than they ever have before (see the comment by "Skywatcher" for example), when in fact the picture is far more complicated than that. It would be interesting to explore further the effects of anti-hunting efforts on polar bear population numbers.

Re polar bear population:
NOAA's arctic web site has a discussion of environmental impacts on polar bears, although there are no specific population figures.
One point that I haven't seen mentioned in this discussion is that population dynamics was one of the several diverse fields which helped to give rise to chaos theory. James Gleick's classic book on the history of chaos describes how the equations for population growth can diverge to very different solutions from arbitrarily small differences. Clearly, this subject is not fully understood.

Andrew, besides the link above, I looked at
http://www.arctic.noaa.gov/essay_schliebe.html

and

http://www.ens-newswire.com/ens/dec2006/2006-12-15-04.asp

and

http://en.wikipedia.org/?title=Polar_Bear#Contemporary_regulations

Thanks John for the links!

Mr. Freedman, Steve did not answer my question at all.

I asked, "What percentage of any recent Arctic melt is directly attributable to man?"

He answered, "If only the past 27 years are considered, changes induced by greenhouse gas emissions increase to 47-57% of the observed September trend".

Where in his answer is man's contribution? It isn't there. I get the impression, and I pray I am wrong, that he wants people to believe that he answered my question, when in fact he did not. His answer referenced ALL greenhouse gas emissions. I asked about man's contribution. If you can't see the difference, then I don't know what to say.

Let me try this approach -

I have read somewhere, that man's contribution to greenhouse gas emissions is approximately 5%. If, quoting Steve's response, the maximum percentage of Arctic sea ice melt attributable to greenhouse gas emissions is 47-57%, then man's maximum percentage of contribution to Arctic sea ice melt would be 5% of 47-57%.

Man's contribution to Arctic sea ice melt is roughly 2.5%!

Conversely, man is 97.5% not responsible!

And whatever we do (or don't do) will have little or no impact on the Arctic.

Now do you see the difference between what I asked and the answer I received?

Mr. Q.

That is why no one has answered my follow up question - if, God forbid, we all dropped dead tomorrow, what would happen to the Arctic sea ice?

The answer is very little or nothing at all would change.

But no one wants to talk about that.

Mr. Q.

"I have read somewhere, that man's contribution to greenhouse gas emissions is approximately 5%":
Everyone is entitled to their own opinion, but not their own facts:
How Do We Know that the Atmospheric Build-up of Greenhouse Gases Is Due to Human Activity?

Link?

Mr. Q.

Greenhouse gas levels in the atmosphere have risen steadily since the beginning of the industrial revolution. I suppose you can call it a "mere happenstance" so you will feel better when you're behind the wheel of your H2.

We have two cars. A mini-van for when we all need to travel together, and a Mazda Miata for errands and back and forth to work. We do not have a H2.

But I wouldn't mind having one. :)

Correlation does not equal causation.

Mr. Q.

If you guys have the proof, you should present it and pick up a cool half million dollars. The prize has gone unclaimed so far. Why is that?

http://ultimateglobalwarmingchallenge.com/

Mr. Q.

Mr. Q: The "forced change by greenhouse gas (GHG) loading" referred to in the Stroeve et al. paper is all anthropogenic (caused by humans). That the observed increase in GHGs in the atmosphere is human caused is fact and not disputed by anyone in the scientific community, including climate skeptics.

That is simply not true.

Without any effort at all, I found this scientist who disagrees.
http://www.newton.dep.anl.gov/askasci/gen01/gen01824.htm

--begin quote--
Everyone (almost) agrees that the level of
CO2 in the atmosphere has been increasing over the last century. However,
not everyone agrees that this is due to human activity, that it is
necessarily bad, or that it is significant.
--end quote--

Even the IPCC paper I quoted earlier included volcanic aerosols as an external forcing. See my previous comment for the full quote and the link.

I have a lot of work today, but I would be more than happy to post more names of scientists later this evening or tomorrow, if you like.

Mr. Q.

Link in my previous comment should have been this.

It looks to me as if man is responsible for somewhere between 3.4 and 6.5% of the CO2 in the atmosphere, according to this IPCC diagram -
http://www.grida.no/climate/ipcc_tar/wg1/fig3-1.htm
and this Woods Hole Research diagram -
http://www.whrc.org/carbon/images/GlobalCarbonCycleLG.gif

I will look for some more references and names later this evening. But seeing as how the one reference is the IPCC, that should count for something.

If you split the difference, you get approximately 5%. Which is the number I previously used. Which brings us right back to man being responsible for 2.5% of the Artic sea ice melt.

Personally, I think the number is much lower than that, but I don't feel like debating it and am willing to concede the 2.5%. Maybe if everyone in the U.S. stopped breathing, we could get the 2.5% down to about 1.8%. That will really make a difference.

I owe you an apology Steve. I was beginning to believe that you were deliberately providing answers that were misleading. I see now that I wrong. You genuinely believed that man was responsible for all of the GHG. I apologize for having thought otherwise.

Sincerely,
Mr. Q.

Mr. Q is bringing up some EXCELLENT points. You guys on the Capital Weather Gang need some more people like him.....he is presenting not only a fair and unbiased opinion, but facts as well.

If I were in your shoes, I'd start listening to him.

No, he isn't. He is trolling.

Personal attacks will not be responded to and are subject to deletion at the sole discretion of Capital Weather Gang.

I'm sorry folks, but Mr. Q. has not been providing "fair and unbiased" information as Mike suggests. It's blatantly obvious that he's been doing the opposite: clearly arguing, oftentimes rudely, with the blinders on, framing everything as evidence that there is an insignificant human role in global climate change. That's not unbiased, Mike. That's biased. Plain and simple. And it makes for a lousy discussion to what I think are thought-provoking writings on this web site.

And furthermore, I resent the implication that the work that I do in this column, and the work of my colleagues on this site, is somehow devoid of facts and is itself biased. Perhaps my suspicions are correct, and no amount of information will convince Mr. Q and others that anthropogenic climate change is a reality.

How much of the recent CO2 increase is due to human activities?

Excerpt: "This question keeps coming back, although we know the answer very well: all of the recent CO2 increase in the atmosphere is due to human activities, in spite of the fact that both the oceans and the land biosphere respond to global warming."

The Liberal Doomsdayers are the greatest hypocrites of all time. They scream for energy reform yet stop dead in its tracks every avenue of alternative energy resource proposed and then live a lifestyle of glutony. Screaming about the Global Warming farce as they fly in jets and drive their massive SUV's.

If the polar bears die out SO BE IT. Thousand upon thousands of species have died out over the ages and the world still survives. No one can or needs to save the bears. Who is going to save us? NO ONE. We are bound to die out also.

Unless the whole world agrees to go back to the bicycle then there is absolutely NO POINT for the US to do anything to curb energy consumption, period. And even if the whole world does go back to the bicycle, cyclic weather patterns will continue just as they have all through the ages and ice caps will melt and ice ages will follow. This whole debate is a joke and sickening. Start drilling for freaking oil in ANWR & off shore. Start building nuclear power plants and let every liberal US hating energy hypocrite start riding their bicycles and quit preaching to the rest of us about how we should be living our lives while the rest of the entire world is exempt.

I wasn't attacking your positions or your character, Andrew. I know you believe in what you are doing. But there are many people out there with opposing views that are just as credible....and he seems to be one of them.

Already the long-accepted idiom of global "warming" has had to be adjusted to "climate change" to indicate that it is not the greenhouse warming effect that Gore & Co. have been pushing.

Willfully ignorant denialist blather aside, is anyone else concerned about the shift to below last year's amount of Arctic ice coverage for this date that the long graph at Cryosphere Today seems to be showing now?

I recommend we ignore the problem of man made CO2 until atmospheric level reaches 1000 PPM, then see how the world looks and take action accordingly. My neighbour, a cop, uses a similar method to see if her service pistol is loaded. She inserts its barrel into her child's mouth and pulls the trigger. Then she knows for sure!!!

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