WUWT Arctic Sea Ice News #3

Agree about “8 weeks from the really interesting” bit. July 1-15 is my next significant milestone. Tho to the degree I’m looking at anything between now and then, I’m looking at the concentration levels of the central core. This can be checked vs 2007 and 2008 at Cryosphere, tho alas 2009 is not there because of technical issues they had at the time.

LoL …great line
.
“…Arctic ice extent continues downwards on the trend line started at the end of March, having lost a little over 1,000,000 km2 during April. If that linear rate continues, the Arctic will be ice free around January 1, 2011. …”

The real question is…where can I get a pipe like the one St. Nick is smoking from?

The NSIDC 1979-2000 “average” is perhaps the most insidious of statistical measures akin to only tracking sunspots for half a solar cycle.

Don’t worry about Santa. He moved his base to Lapland during the MWP.

“If that linear rate continues, the Arctic will be ice free around January 1, 2011. ”
Trend without end, Amen.
If this trend continues, summer will not get to my place either.

It is a well known fact that the ice from the Arctic migrates every year to the Antarctic… with just a phase change. As you can see, ice is never lost.

When talking about polar regions, how do you determin what is West and what it East? It seems to be to be like using right and left. The crazy thing about the arctic is that the land masses are centralized in each hemesphere.
Is it West is considered near 0° and East is near 180° (East and West)?

This reminds me of the tobacco juice bullet that NYC miraculously dodged early in the last century.
If the linear trend of sidewalk tobacco juice increase that occurred between Feb. 17, 1870 and July 4, 1905 had continued, New York City’s sidewalks would now be under 3.1415926..etc. feet of that unattractive brown liquid. Wheew!!

I do not belive will gone artic ice in jan 1 2011 I don’t think so.

O M F G! S A N T A!!! Noooo
Grennie lunatics, maybe green piecers, actually use that crap to scare children into believing their garbage, and that’s just cruel.

@davidmhoffer says:
May 3, 2010 at 2:17 pm
“May – plant garden
“June – weed garden
“July – weed garden
“August – swear profusely at the multitudes of deer which jumped an 8 foot fence to harvest my whole garden in just a 12 hour period a week or so before I would have myself.”
Hmmm… this sounds like an excellent way to round up some venison. 😀

jeff brown
During the very high ice years in the early 1980s. the AO stayed negative all the time.
http://www.appinsys.com/GlobalWarming/AO_NAO_files/image005.jpg

I would guess otters on a row boat to Santas next mode of transportation.
Mind you Britain has been naughty this year.

stevengoddard says:
May 3, 2010 at 3:19 pm
Steve. I think there you are referring to the winter AO. And yes, a negative winter AO in the past has been associated with more sea ice because of the stronger Beaufort Gyre which causes ice to recirculate in the basin for several years. However, in summer a negative AO pattern has been associated in a number of studies with more ice melt (and especially warmer ice temperatures in the western Arctic). And as you’ll notice from animations of ice age the ice is no longer surviving the Beaufort Gyre in summer like it used to….so a stronger Beaufort Gyre that brings even more of that old ice into the warmer waters is probably not a good thing…
There is a recent paper by Ohashi and Tanaka (Data analysis of recent warming pattern in the Arctic) that says the positive winter AO trend caused warming before 1989 and the negative summer AO trend since then have caused warming. I’m not convinced their analysis is sound, but it is a paper that says all of it is from the AO (and thus natural variability).

@davidmhoffer: I think mamapajamas has an excellent idea, although deer harvest may not be as free as veggie harvest; beware the game warden! But on the topic of weeds, this is the first in 10 years I’m planting a garden and I engineered a solution–got me a Cub Cadet tiller because it’s the proper balance between capability and cost. I’d love a new BCS but they’re about $2600–three times the Cub Cadet. This cheaper unit is big enough w/ a 5hp Honda motor to till if you make 2 passes each way at 3″ and 2 more passes at 7″, with a plastic bucket (not included) tied to the handle stem for collecting rocks and added weight. Running the tines backwards works the unit against the forward-rotating tires which makes tilling easier.
Plant the rows far enough apart that the tiller can move between them without damaging the plants and later on shift the tines to forward and move the depth up to 3″ for taking out the weeds. I’m also looking at a high-wheel cultivator for closer weeding and soil breakup. This will still require some back-breaking row weeding, but that’s not as bad as trying to weed the whole bloomin’ plot all summer. For bird control, hang a bunch of useless CDs on surrounding trees or your fence posts with shoe strings, but to control deer the only effective deterrent is a taller fence.
If my garden fails, I’ll join the Warmers and pretend it was warm and productive.

“Perhaps all the hot air from Copenhagen in December thinned the ice?”
Nope. It’s those hot Norse girls!

Thanks for that nice update Anthony. I personally would like to not only have Santa’s pipe, but what’s in it that makes him so Jolly.
You are right about it being too early in the season to say anything, except more for historical and statistical reasons. The artic was not exceptionally cold this winter, and the negative AO both kept the ice from moving in large amounts through the Fram strait, but also the high pressure from the neg. AO also made Greenland and N. Canada made those areas very warm as you know. A negative AO in the spring and summer has a whole different set of effects, that would not necessarily mean a slowing of ice melt at all–in fact, the higher pressure could lead to more insolation with clearer skies, and certainly warmer temps in the arctic as the colder air is pushed out of the region. I don’t see the AO going exceptionally negative anyway.
A few things for people to watch in the next week: 2010 arctic sea ice dropping below both 2009 and 2008 levels for this time of year.(it’s already below 2009). Statistical point yes, but of interest as we head toward the real melting months. Look also for continued rapid melt in the Barents Sea (but slowing down from the cliff it’s falling off now) and a pick up in melt in Hudson Bay.
Finally, just because someone else mentioned this a few months back because the ice was slightly above normal there at the time, the ice on the Tanana River in Nenana AK has broke up (on April 29), actually a few days earlier than normal, and earlier than in 2008 or 2009, but not as early as 2007.
http://nenanaakiceclassic.com/
Some lucky person or persons will make a nice bit of money off their bet, and most people probably bet the ice would break up on a later date as it was higher than normal during the same time as that March “bump up” in arctic sea.

PaulH says:
May 3, 2010 at 3:57 pm
From Lawrence Solomon at the National Post:
“Arctic ice sets records in April, could auger global cooling”
——–
Too bad Mr. Solomon’s article is completely missing one thing– the truth. He uses the 8 years of JAXA data, completely ignoring the longer 30+ years available through NOAA. If he used that data, he’d of reported the startling headline:
“April Arctic Sea ice comes close, but never quite reaches the long term average…”
But it didn’t suit his political agenda to report this more truthful headline…and with such a lack of attention to the broader truth, I can think of at least one network he could probably get a job with…

R. Gates says:
May 3, 2010 at 5:28 pm:
“…I can think of at least one network he could probably get a job with…”
MSNBC? Or perhaps he could join RePower America?

The rate of ice loss (and increase) is approximately equivalent for every year in the chart. That means someone somewhere is going to claim we’re having the greatest ice loss by volume in recent record. It will be seen as more evidence of man made warming. Nobody will think ice breakers have a thing to do with it.

Feeling the brunt of that cold North Pacific now, snow in the hills, high winds and
below freezing temps in NE Oregon’s Blue mtns. tonight..
Got a crackling fire going as we speak. Also, three roses, several Delphiniums,
and Lilacs await planting-when and if it stops hailing,snowing,and blowing….

Smokey says:
May 3, 2010 at 7:37 pm
please explain the reason why the Arctic sea ice has been declining during the satellite data record and why it has accelerated the past decade. Name the natural variability affects that explain this decline, the percentages of how much of the decline is due to solar variability, the PDO, the AO, etc. etc. etc. You should be able to do that right?

Anu says:
May 3, 2010 at 7:43 pm
That # (1294171 for 05,03.2010) is provisional.
As for the 3rd lowest in IJIS history:
05,03,2003,12742969
05,03,2004,12358750
05,03,2005,12574063
05,03,2006,12191094
05,03,2007,12550000
05,03,2008,12802969
05,03,2009,13031875
05,03,2010,12941719 *provisional*
Your numbers don’t add up. And you cannot compare to other data sets without calibrating first.
Lot’s of work.

The arctic sea ice extent seems to have a multi-decade correlation with the AMO which seemingly peaked this past decade. It tends to have a shorter term (year to year) correlation with the AO/NAO. If you notice during past years, the lowest fall minimum extents have occurred after heavily +AO winters such as 1988-1989, 1994-1995, and 2006-2007. The higher minimum extents in recent years have been occurring after -AO/NAO winters such as 1995-1996 and 2000-2001.
Both of those factors have generally been hostile to arctic sea ice the past couple decades. The AMO is still in positive mode but its past its peak and declining now. The AO/NAO decadal cycle appears to be going back negative. This would argue that we’ve seen the bottom for sea ice extent minimums for the time being. I’d expect another rebound this year given this past winter’s conditions. But nothing is ever set in stone.

nedhead says:
May 3, 2010 at 7:55 pm
Smokey says:
May 3, 2010 at 7:37 pm
please explain the reason why the Arctic sea ice has been declining during the satellite data record and why it has accelerated the past decade. Name the natural variability affects that explain this decline, the percentages of how much of the decline is due to solar variability, the PDO, the AO, etc. etc. etc. You should be able to do that right?

No, you fail to understand the null hypothesis: 1] the modern Arctic sea ice satellite record is not long enough to establish what average or “normal” is. Therefore, 2] it is up to the CO2AGW hypothesis and science itself to give all the mechanisms and percentages you refer to including soot, wind and currents, then say how CO2 climate physics is actually explanatory for any unexplained residual ice decline during this short period of the Earths’s climate; while also explaining 3] the fact that a “death spiral” in Arctic sea ice did not occur as a result of the 2007 decline as predicted by CO2AGW, and other things such as why Trenberth is now urgently looking for the “lost heat”.
So it is instead the CO2AGW hypothesis and science itself which needs to explain things such as any satellite era Arctic sea ice decline, especially since what we are seeing here is not known to be “abnormal”. And the CO2AGW hypothesis needs to be falsifiable, among the other requirements of the Scientific Method.
Or do you not support the idea that Climate Science should be based upon the Scientific Method?

” stan stendera says:
RockyRoad@1:38pm
Some serious cold weather gardening tips. We all may need them soon.
Buy some cheap black plastic sheeting. Thin guage is fine but you have to weigh it down with rocks. Don’t we all have too many of those in our garden!!”
I have enough rocks to use as a border, weighing down plastic, throwing at the
infernal Eastern Red Squirrels that infest the yard. NE Oregon is cold weather
gardening most of the time…. Good advice….

stevengoddard says:
May 3, 2010 at 8:12 pm
Anu,
You forgot to mention that current extent is well above 2003, which was the highest in the AMSR-E record.
2009 was well above 2003 on this date as well, but finished up well below in the summer minimum. 2008 was above 2003 on this data also, and finished even lower than 2009.
Clearly 2003 is old news – the climate has changed. Current ice extent is dipping below 2009, and almost below 2008.
And just like that, the race is on.
(it’s hard to make 5 month races sound exciting…)

What happens to the rotten ice if it doesn’t melt this year? Does it just lurk in the wings, waiting?

Anu
The climate has changed. Chicago is no longer buried under a mile of ice.

I disagree that the Antarctic is boring at the moment, the past trend has been for much increased ice gain from the minima due to wind patterns associated with the increased southern ocean wind circulation, see
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.recent.antarctic.png
for a snap shot. This has not happened this year.
Andy

Arctic ice extent continues downwards on the trend line started at the end of March, having lost a little over 1,000,000 km2 during April. If that linear rate continues, the Arctic will be ice free around January 1, 2011. That would be a complete disaster for Santa Claus and the billions of people who depend on him.

slightly off topic, but it seems rather funny to me …
from the catlin arctic survey 2010 ( http://www.catlinarcticsurvey.com/news.aspx?newsId=112 )
“1. 03/05/2010 – Explorer Team position at 12:00 BST: 88.36.35 N / 63.00.48 W.
2. The team decided to call it a night and decide what to do the next morning. In the clearer light of day, seeing there was no obvious route around it, they had no option but to try and cross, giving Ann another opportunity to climb into her immersion suit and test her “jelly baby crawling skills” across the thin ice”
I’m no specialist, but … “clearer light of day” ?

addendum
It is certainly true that as these icy waters lose their ice to the Sun’s warmth, the seas are cold. However, these heavy waters normally sink as they melt. Under warm conditions, the cold water drops below the surface layer. The only thing that can keep them at the surface are winds that promote upwelling. Papers I have recently read propose that this contributes to, or is even the cause of, the decadal shift between warm and cool phases of the PDO.
I wonder if the shift in winds in this interesting area could be due to shifts in the AO. Might the AO have a multi-decadal position shift regardless of whether it is positive or negative? So far, pressure changes from positive to negative don’t seem to have a multi-decadal or even decadal oscillation but the PDO does. I wonder if the position of the AO pressure cell changes on such a time scale.

jeff brown
This graph shows AO negative for all months in the early 1980s, not just winter.
http://www.appinsys.com/GlobalWarming/AO_NAO

The cover story about Santa’s workshop being at the North Pole is obviously misdirection, for security purposes. Let’s just say that one pole has land under it, while the other does not. Santa’s been a little sloppy, letting photos like this one leak out:
http://www.istockphoto.com/file_thumbview_approve/5973572/2/istockphoto_5973572-santa-and-the-penguins.jpg

stevengoddard says:
May 4, 2010 at 6:58 am
jeff brown
This graph shows AO negative for all months in the early 1980s, not just winter.
http://www.appinsys.com/GlobalWarming/AO_NAO
Steve, all I’m trying to say is that during summer a negative AO state actually favors ice loss, and since a negative winter AO tends to be followed by a negative summer AO, it is likely we’ll have a negative summer AO state.
Some reasons why this matters more now than it did in the past. If you go back to the 1980s during the thick ice regime, anomalously warm temperatures (ocean or air) could cause a lot of ice melt, but the ice was still rather thick, so that melt was expresses as anomalous volume loss, not as extent loss. Today because the ice is thinner, similar anomalously warm conditions will actually be expressed as ice extent loss as the thinner ice melts out entirely.
The Rigor and Wallace 2004 paper discusses the warming in the Beaufort during a negative AO summer. Also recent papers by Overland et al. also discuss the summer AO and its impacts on the ice cover…

Joe Bastardi – AccuWeather prediction: SUNDAY MAY 2
Ice melt forecast idea for summer.
I have been making a big deal about the arctic sea ice returning to levels that are more comfortable, and yet I see people simply in denial over it. I try to be objective about it. I will tell you this. It should be a big summer for ice melt, and while I dont expect it to reach levels we saw in 007, my forecast is for it to bottom out lower than it did last year. We have had an el nino, and the summers after that are the big ones for ice melt. However we are starting at a higher level than we did in 07.
The increase in the ice cap will be a 1 step back, 2 step forward function in the cold PDO. I fully expect by 2020 the low points we see to be running near the 30 year means, in other words its almost always above, rather than below, as the PDO rules.. When its warm there is a step down, when its cold, a step up, we just have not been able to observe it yet because we did not have a cold PDO develop until after the last warm Nino. But I have given you the sites to look at, so you can watch for yourself. Just understand… the product of the past years el nino should mean this does comes down more than it did last year, but the cold PDO overall will take care of that with bigger rebounds next year and the year after.
So the forecast is for summer ice to be bottom out lower than 09, but not as low as 07, however winter ice next year will be higher than it peaked at this year.

Anu
Would raising taxes 20,000 years ago have stopped the ice sheet from melting?

Awesome! After I posted, I realised I hadn’t updated my data since 26th April, so the 2010 average was likely wrong due to missing data. Groan. So I updated the data, re-ran my averager and got the same result ( to 5 sig fig )! kudos to my extrapolator which automatically estimated the missing data and got the right answer. Bit lucky.

Is it my monitor, or ancient eyes, but the colors in the SST graphic appear to repeat. +6 is about the same as -6.
Or have we uncovered “minusgate” ? (re: Finland or at least something up there)

nedhead says:
May 4, 2010 at 8:17 am
“Maybe someone else out there can explain why when you run climate models with the observed record of GHGs you are able to simulate the observed warming trend and the trend towards reduced Arctic sea ice cover, but when you don’t put the observed GHGs in and instead leave them fixed at pre-industrial warming, none of the models show any decline in Arctic sea ice whatsoever.”
Your main argument is that climate computer models do not work without incorporating estimated effects of GHGs. Are you serious?
And the Arctic sea ice is not declining.

Exam question: If Arctic ice finally disappears by New Year’s Day, calculate how long it will be at the current rate of warming until Arctic Sea comes to the boil. (Show all working)

Smokey says:
May 4, 2010 at 10:43 am
Dang…I must be doing something wrong. I haven’t seen a single scientist getting rich off of this grand scheme you are claiming it to be. Guess it must be the universities getting rich though, except they keep cutting the budgets and not giving out raises.

Roger Clague says:
May 4, 2010 at 10:28 am
Yes Roger, here are a few that may help.
Turner et al., Antarctic sea ice extent increases as a result of anthropogenic activity, Nature
Zhang, 2007, Increasing Antarctic sea ice under warming atmospheric and oceanic conditions
Lefebvre and Goosse, 2008. An analysis of the atmospheric processes driving the large-scale winter sea ice variability in the Southern Ocean.
Lefebvre et al., 2004. Influence of the Southern Annual Mode on the sea ice-ocean system.

Rob Dawg says:
May 3, 2010 at 1:30 pm
The NSIDC 1979-2000 “average” is perhaps the most insidious of statistical measures akin to only tracking sunspots for half a solar cycle.
______________________________________________________________________
Very good analogy, I like it. I have been trying to find a way to get that point across concisely and that does it.

RockyRoad says:
May 3, 2010 at 1:38 pm
I’m spacing my garden rows 3 feet apart this year …. If it isn’t better than last year (which saw only 4 days 90 degrees or above and nothing over 93), there’s no use trying to grow veggies. …
_________________________________________________________________________
Tell me about. In 2004 we had a mean for April of 85F and 6 days above ninety, since then the mean is around 73 to 76 and a total of five days above ninety for the entire half a decade. On top of that when it finally warmed up this year it quit raining for going on three weeks. GRRRrrr. I hate watching the thunderstorms drench the other side of the county but not us.

If you’d like to read more about why humans putting gigatonnes of CO2 into the atmosphere every year is no problem at all, check out Dr. Spencer’s Marshall Institute:
http://www.marshall.org/board.php

More recently, the Institute has focused on disputing mainstream scientific opinion on climate change. Funded by ExxonMobil and chaired by a former official of the American Petroleum Institute, the George C. Marshall Institute has been described by the Union of Concerned Scientists as a “clearinghouse for global warming [anti-alarmists]”, and by Newsweek as a “central cog in the [anti-alarmist] machine.”
http://en.wikipedia.org/wiki/George_C._Marshall_Institute

Of course, opinions vary.

davidmhoffer says:
May 3, 2010 at 2:17 pm
I had no idea this had anything to do with gardening. My gardening cycle being a bit unique,…..
Try TWO eight foot fences (angled at the top) about 20 ft apart. Put a pack of BIG dogs in between the fences. Smile.

The null hypothesis, simply worded, is “This is natural.”
Anu, nedhead, et al are giving Smokey grief by saying “Oh yeah, well you tell me what is natural!”
Before you can blame CO2 for the warming, first you have to show the warming is un-natural. Before you can show it is un-natural, you have to show what is natural.
Thus until Anu, nedhead, et al can show what is natural and thus what is un-natural, they don’t even have the bare groundwork to establish that rising CO2 emissions are a problem.
Why are Anu, nedhead, et al insisting that Smokey does their work for them? Can’t they figure it out for themselves?

Smokey says:
May 3, 2010 at 9:35 pm
Anu says:
May 3, 2010 at 9:13 pm:
“Smokey never ‘explains’ what it is in nature that is causing the varying. …
As we can see, Anu still does not understand the scientific method, or scientific skepticism; a failure that is emblematic of the alarmist contingent.
Anu’s fantastic assertions that the minuscule human fraction of a very minor trace gas, comprising only one molecule out of every 2,600 in the atmosphere, is the principal driver of the climate is not only preposterous, but there is zero empirical evidence backing up that ridiculous conjecture. It is rank speculation, nothing more.
_______________________________________________________________________
What is worse in my book is they ignore the real catastrophe. If CO2 decreases by as little as 1 molecule of CO2 in ten thousand then plants will stop growing and most will die killing most of the life on earth too. Talk of death spirals. The natural sequestering of CO2 in limestone, coal and oil was heading us for the real catastrophe. Luckily humans liberated life giving CO2 saving the planet and the environment.

JPeden says:
May 4, 2010 at 11:39 am
It must be frustrating to you that none of your natural variability ideas (e.g. PDO, AMO, AO, solar variability, etc. etc.) can explain the continuing decline of the Arctic sea ice, but when you include GHGs the trend is explained.
Where are the science papers that explain the decline by natural variability? There are plenty that explain it from GHGs. Time to not be so narrow-minded and open up to the possibility that natural variability is no longer cutting it…

Gail Combs says:
May 4, 2010 at 1:46 pm
The natural sequestering of CO2 in limestone, coal and oil was heading us for the real catastrophe. Luckily humans liberated life giving CO2 saving the planet and the environment.
Are you serious?

Smokey says:
May 4, 2010 at 4:14 pm
I’m glad to see you respect professors from my alma mater, MIT.
Why not listen to Professor Prinn, TEPCO Professor of Atmospheric Chemistry, and Director of the Center for Global Change Science, and the co-Director of the Joint Program on Science & Policy of Global Change? One of Prof. Lindzen’s overachieving faculty colleagues at Atmospheres, Oceans, and Climate:
http://eapsweb.mit.edu/people/topic.asp?Topic=PAOC

Study co-author Ronald Prinn, the co-director of the Joint Program and director of MIT’s Center for Global Change Science, says that, regarding global warming, it is important “to base our opinions and policies on the peer-reviewed science,” he says. And in the peer-reviewed literature, the MIT model, unlike any other, looks in great detail at the effects of economic activity coupled with the effects of atmospheric, oceanic and biological systems. “In that sense, our work is unique,” he says.
The new projections, published this month in the American Meteorological Society’s Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees. The difference is caused by several factors rather than any single big change. Among these are improved economic modeling and newer economic data showing less chance of low emissions than had been projected in the earlier scenarios. Other changes include accounting for the past masking of underlying warming by the cooling induced by 20th century volcanoes, and for emissions of soot, which can add to the warming effect. In addition, measurements of deep ocean temperature rises, which enable estimates of how fast heat and carbon dioxide are removed from the atmosphere and transferred to the ocean depths, imply lower transfer rates than previously estimated.
http://web.mit.edu/newsoffice/2009/roulette-0519.html

Do you think Lindzen is the only one at MIT that knows how to do science ?
Care to hear about the work of a dozen more colleagues of Dr. Lindzen ? Why do you think Lindzen is the only one ever quoted by people like you ?

Anu
So the MIT study clams 7C warming in the next 90 years, after 0C warming during the last 15 years and 0.6C warming during the last 120 years. Hopefully you are a little embarrassed by your alma mater?

Robert E. Phelan says:
May 4, 2010 at 3:41 pm
What does 200 ppm have to do with anything? Do you think we’re going to get to 200ppm anytime soon? Do you know what the ppms were 150 years ago when there were only 1 billion people on the planet compared to nearly 7 billion today?
Are you up to speed on the latest CO2 research regarding plants? Do you know that too much CO2 also kills plants?
But more importantly, where do you get the idea that CO2 levels are going to drop to 200 ppm where plants will be negatively affected?

From jeff brown on May 4, 2010 at 9:55 pm:

Are you up to speed on the latest CO2 research regarding plants? Do you know that too much CO2 also kills plants?

From the Wikipedia(!) Carbon Dioxide article, “Agricultural and biological applications” section:

Plants require carbon dioxide to conduct photosynthesis. Greenhouses may (and of large size – must) enrich their atmospheres with additional CO2 to sustain plant life and growth. A photosynthesis-related drop (by a factor less than two) in carbon dioxide concentration in a greenhouse compartment would kill green plants, or, at least, completely stop their growth. At very high concentrations (a factor of 100 or more higher than its atmospheric concentration), carbon dioxide can be toxic to animal life, so raising the concentration to 10,000 ppm (1%) or higher for several hours will eliminate pests such as whiteflies and spider mites in a greenhouse.

First part, a drop by a factor less than two can kill green plants. March 2010 atmospheric CO2 concentration was 389.44 ppm (according to the World Climate Widget), half of that is 194.72 ppm, and the mentioned amount was “a factor less than two”. So 200 ppm sounds about right.
BTW, that was just confirmation of the “plant death” number.
Second and main part, in greenhouses they are running up the concentrations very high to kill animal life without harming plants, over that duration of exposure. Here 1% was mentioned for killing certain bugs in greenhouses. Now let’s check out the “Toxicity” section:

Due to the health risks associated with carbon dioxide exposure, the U.S. Occupational Safety and Health Administration says that average exposure for healthy adults during an eight-hour work day should not exceed 5,000 ppm (0.5%). The maximum safe level for infants, children, the elderly and individuals with cardio-pulmonary health issues is significantly less. For short-term (under ten minutes) exposure, the U.S. National Institute for Occupational Safety and Health (NIOSH) and American Conference of Government Industrial Hygienists (ACGIH) limit is 30,000 ppm (3%). NIOSH also states that carbon dioxide concentrations exceeding 4% are immediately dangerous to life and health[48] although physiological experiments show that such levels can be tolerated for some time [49].

Healthy adults are “rated” for only 5000 ppm over 8 hours, while plants can handle twice that much for “several” hours. Interesting. Let’s look at the next piece of that section:

Adaptation to increased levels of CO2 occurs in humans. Continuous inhalation of CO2 can be tolerated at three percent inspired concentrations for at least one month and four percent inspired concentrations for over a week. It was suggested that 2.0 percent inspired concentrations could be used for closed air spaces (e.g. a submarine) since the adaptation is physiological and reversible. Decrement in performance or in normal physical activity does not happen at this level.[49][50] However, it should be noted that submarines have carbon dioxide scrubbers which reduce a significant amount of the CO2 present.[51]

For some reason, you’re talking about how too much CO2 can kill plants. Yet green plants can tolerate about 25 times the current atmospheric concentration, for at least several hours. Humans can adapt to higher CO2 levels, with 50 times the current atmospheric concentration suggested for closed air spaces.
I think it’s a given that we won’t be seeing atmospheric CO2 levels high enough that plant death from too much CO2 will ever be an issue, barring sudden planetary catastrophes that wipe out all biological conversion of CO2 to something else thus levels from natural sources like volcanoes would be allowed to rise practically unchecked, and in that case we and all the plants will be dead anyway.
So why mention it?

kadaka (KD Knoebel) says:
May 5, 2010 at 1:47 am
Some recent tree mortality numbers:
in the southwestern US, more than 12,000 square km have seen increased mortality rates, killing 40-97% of trees in some sights in less than 3 years [Breshears et al., 2005; McDowell et al., 2008]. This die-off was more severe than mortality events of the 1950s.
in western Canada, millions of trees across 130,000 sq-km of pine forest died in 6 years [Kurz et al., 2008]. Reports of extensive tree mortality have been reported in Africa, Asia, Australi, Europe and South America [Allen et al., 2010].
Most of the above are insect-driven mortality that is related to increased drought conditions and warmer temperatures. Note that models under increased GHGs predict large changes in temperatures and precipitation across the globe (with the largest uncertainties in the precipitation).
Besides the insect-driven mortality, over the past few decades old forests of the western US have shown doubled tree mortality rates (probably related to temperature increases, see van Mantgem et al., 2009). Long-term data from pan-Amazonian forest surveys recently documents effects from a severe drought in 2005, with reduced growth and increased tree mortality driving a marked shift in forest carbon balance [Phillips et al., 2009].
Studies are currently focusing on the mechanisms causing these large tree die-outs. It is unclear if starvation occurs from reduced photosynthesis or a water-stress-induced inability to use stored carbon. Increased temperatures enhance the proliferation of tree-pests which also kill the trees.
With large forest die-outs, the impact of forests as a carbon sink can change. Right now, terrestrial ecosystems absorb 33% of anthropogenic carbon emissions during the 1990s [Bonan, 2008]. It could be that this sink is going to change. For example, in British Columbia, beetle outbreaks reduced the carbon sink by 270 megatons over 20 years. This even reversed the carbon sequestration gains of the previous 20 years across millions of hectares of forest [Kurz et al., 2008]. Chapin et al., 2008 suggest that CO2 released following forest die-out could easily exceed carbon sequestration enhancements from elevated CO2 promoting forest growth.
It is way more complicated than what you found in Wikepedia…

Looks like the Arctic sea ice is taking a sharp turn downwards. The idea of a recovery that has been floating around this blog site might not hold up for much longer…

Smokey says:
May 4, 2010 at 9:18 pm
It seems that way, doesn’t it? Considering the “warming of 5.2 degrees Celsius by 2100″ horse manure being shoveled by his ankle-biters.
You’re getting into dangerous territory there Smokey – actually making a prediction.
Until now, you’ve been saying whatever happens, it’s all “natural variability”. Which, of course, you are under no obligation to explain or understand. Now you’re implying that even “natural variability” wouldn’t be so mischievous as to make the planet warm 5.2 degrees Celsius by 2100. If it does start down that path when you are still alive, your prediction will be on its way to being falsified.
Can you live with that ? Or will “natural variability” still be your dying words, when the planet has only warmed 2 or 3 more degrees C ?
What about the summer arctic ice gone in a decade or two ? Still going to go with “natural variability”, or are you going to go out on a limb and declare “horse manure” right now, that such a thing will never happen ?