By Steven Goddard
No matter what happens with the summer Arctic ice minimum, NSIDC will report that the long-term trend is downwards.
Why? Because of mathematics. In order to reverse the 30 year downwards linear trend, this summer’s minimum would have to be nearly 20,000,000 km². More ice than has ever been directly measured.
In other words, we could have a “Day After Tomorrow” scenario, and the mathematical trend would still be downwards.
Conclusion: You can count on NSIDC to continue reporting a downwards trend, regardless of what happens over the next few years. For now, it will be fun seeing what happens over the next eight weeks.
Well… that’s because the trend for that period is downwards. Whether the period chosen is suitable for indicating trends (rather than just what we have available, say) is another matter.
Interesting – I hadn’t seen that plot before. Evidently the downtrend didn’t start 30 years ago, rather it started in about 1997! Wasn’t that when global warming stopped?!
And don’t forget, that when the trend starts to bend it can still be dismissed as a “blip”
against long term behaviour for quite a while. After all the fate of mankind is at stake…..:-)
That’s because it’s true. Three years does not a trend make. The system fluctuates. Just eyballing the graph you posted, the current “recovery” could be just like the one from 1990 to 1992.
I was thinking along the same lines just recently. Even if all ice indicators returned to average this year, there would still be a downward Arctic trend. The CAGW argument relies on the idea of knock on effects towards a one way tipping point where the system’s not able to return to the former average. A return to average should atleast call into question this idea.
It would be strange to argue that in a situation of total averageness that things are still on the way down, but I’m sure we’ll be hearing a lot of that if indeed it does come to pass.
Trend without the error in the slope is meaningless…
Trends in the Arctic last 30-60 years, the current one has been going on for about 40 years.
http://www.vukcevic.talktalk.net/NFC1.htm
Amount of thermal energy being delivered by the North Atlantic Current is enormous, time is required to be dissipated.
I’m sure I’ve seen a graph like that somewhere before. Both as closely linked to reality as each other 😉
I wonder what the trend would look like if the data went back to 1940.
Hypnos says:
June 25, 2010 at 2:36 am
That’s because it’s true. Three years does not a trend make. The system fluctuates. Just eyballing the graph you posted, the current “recovery” could be just like the one from 1990 to 1992.
More importantly – 30 years does not a baseline make.
Many reports of similar fluctuations in recent human history – but no just look at this small snippet and project and interpolate from that. This is unscientific to a degree that makes it look deliberate.
“For now, it will be fun seeing what happens over the next eight weeks.”
It is ‘fun’ to see what is already happening right now.
tallbloke says:
June 25, 2010 at 3:45 am
I wonder what the trend would look like if the data went back to 1940.
No trend until about 1990. After that a falling trend, with increasing steepness.
Well done, Steven. But how would the trend look like if 2010 got below 2008 and 2009 and close to 2007? And no matter what happens with the summer Arctic ice minimum, some people will always say the volume has gone up (until CryoSat 2 gets operative, of course).
It appears to me from the satellite record there was no downward trend in arctic sea ice from 1979 to 1996 then in 1997 something happened that started a downward trend that lasted for about 10 years then leveled off.
CO2 emissions didn’t skyrocket in 1997 did they?
Hmm… what else can melt some ice? Anyone? Anything? Bueller?
Oh wait! Could this thing described in National Geographic Magazine do that?
How come rocket scientists can’t connect the dots here. No one else seems to have any problem with it.
The $64,000 question isn’t what caused the decline. The big question is what drives these gigantic cyclic ocean surface warming a cooling events. It sure isn’t CO2 as that has been on a very steady upward trend. It sure isn’t the global average atmospheric temperature inching up or down a tenth of a degree or two per decade as the 1997 El Nino made the ocean surface temperature in a huge swath of the Pacific shoot up 5 whole degrees above normal in a matter of months – more extra energy than “a million Hiroshima bombs”!
The answer, my friends, is NOT blowing in the wind. The answer lies deep down in the ocean. This makes abundant sense if and when a person comes to realize that the oceans hold 1000 times more heat than the atmosphere. The tail does not wag the dog.
In any modern “scientific” paper, report or theory relating to human-nature interactions (as if they are separate entities) it appears mandatory to conclude that man is the sole cause of any and all ills. Phrases like “the single greatest health threat”, “I don’t see any future, except extinction”, “the findings spell danger”, and of course, “more research is necessary” and “the long term trend” are seemingly preset on many scientists MS Word applications. (Perhaps there is a special “grant” edition provided by MS?) It is also humorous to note that while many scoff at the “creationists” and the idea of an external divine entity, the similarity to the Catholic dogma of all man born with original “sin” in need of redemption (through the Church) and their redemption (through regulation) is striking. Like many commentators here believe, this is a religious debate, complete with all the usual suspects.
Not to worry. We will be able to use that space to accommodate all of the, errrr penguins(?) that the increasing ice in Antarctica is pushing our way .
I would be much more concerned about Greenland ice melt and the flow of the thermo-haline conveyor (gulf stream) as far a climate and sea level are concerned. Arctic ice is nice but …
Yes, well this is like saying (and I hate it) that “this year, or last, or next, will be in the top ten of warm years”. Aarrgh! Of course it will! For it not to be would mean that the temperature has plummeted – which is highly unlikely.
You can generate any series of random numbers and fit a line to it. There’s about a 50% chance the line will be negative, but it’s meaningless. First, you have to prove what function is appropriate for your system (linear isn’t almost never the “correct” function), then you have to show the error on the function’s coefficients to determine if there’s enough “signal to noise” or statistical evidence that the coefficients are reliable estimates of the true relationship. Being a scientist I doubt the credibility of randomly fitting lines to snipets of data. For example, loss of sea ice cannot be a linear decrease. It has to be at least exponential…the asymptotic limit is zero amounts of sea ice. There can’t be negative amounts of sea ice (which a line is going to drive towards). If you are measuring the loss of sea ice, that function has to be nonlinear as is approaches the limit of zero sea ice. If it’s an exponential decay then you can approximate the initial drop with a line, the slope being the initial rate of decay, but to fully describe the physical event, the line is not sufficient. And if sea ice follows a cyclic time period as well (which is more than likely) then a sinusoidal function is appropriate as well. Using a simple line tells me the science is far from understood and the scientists are at the infancy stage of understanding.
Mr. Goddard, what is the correlation coefficient of their linear regression?
Steve,
Well, I dunno. Maybe they’re using the last Ice Age ice extent as a reference?
I wouldn’t put it past them …
Not bad enough you were misrepresenting data, now you are making it up completely?
Where is the laughing dog smiley when you need it?
RR Kampen says:
June 25, 2010 at 4:02 am
[–snip–]
No trend until about 1990. After that a falling trend, with increasing steepness.
Oh? And according to whom?
Will you next propose to say that the Earth has gotten so very much warmer too?
Will you?
Bob Tisdale says, that heat of 1998 El Nino had been dissipated poleward and takes its time to disappear.
“The trend is your friend. Until it starts to bend.”
What I do not get is the existence of Royal Navy records that show low ice extent at roughly the beginning of the Dalton. This has happened before. look at the location
of Viking Farms in Greenland. I think we hold ourselves in too high esteem for planetary
destruction…
I note that this post makes Tamino mad. Look for a Romm Bomb next. When you spend most of your time reacting you’ve lost the battle.