It's all about where you start.

Peter Cresswell's picture
Submitted by Peter Cresswell on Tue, 2007-05-22 22:29

When you're looking at and presenting global surface temperatures, it really is all about where you start .

  • Start at 1998, and you'll see global surface temperatures stable. (Yes, that's right Josephine, "According to official temperature records of the Climate Research Unit at the University of East Anglia in the UK, the global average temperature did not increase between 1998-2005...")
  • Start at 1860 and you'll see that temperatures have been rising.
  • Start one thousand years ago, and depending on which graph you look at, and how the data has been compiled and used, you'll see a temperature record that has been rising and falling.
  • And now, start back 425,000 years (using results from the Vostok Ice Core, complied by NOAA), and what do you see?
    We see that temperatures have been falling and rising and falling and rising and falling and rising and falling and rising and falling and rising ... In fact, notes the site that hosts this last graph, "there’s quite a bit of fluctuation":
    First of all, There are long periods of time when the average global temperature was as much as 9°C colder than now. These were Ice Ages. Much of the northern part of the world was covered with thick sheets of ice, much like we see today in Greenland and Antarctica. The most recent Ice Age ended about 12,000 years ago. There were also times when it was warmer than today. On the whole, we are in a relatively warm period. What causes these changes in climate?

Well, that's the sixty-four billion dollar question isn't it, and it's sure as hell got Al Bore, Leonardo de Caprio and the IPCC confused. Do you think that we were responsible for those peaks 425,000, 325,000, 225,000 or 125,00 years ago? After all, there were an awful lot of factories and power plants around then, huh?


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Word confusion

Brendan Hutching's picture

Peter: “Brendan, you really think Twentieth Century warming was in the order of 2 degrees C?”

I was referring to your figure: “20C warming when viewed in the complete historical context is far from "historically significant" warming.”

That appears to be 20 deg C, and “historical context” presumably means within recorded history. I charitably interpreted it as 2 deg C. The actual figure over around 100 years is more like 0.8 deg C.

I realise now that by "20C" you probably meant "20th century".

“Temperatures have gone through nearly two complete cycles of warming and cooling over the last 100 years…”

These “cycles” can be explained as the effect of various contributing factors other than CO2, such as changes in irradiance, volcanic activity and aerosol emissions. Nevertheless, the long-term trend is upwards, and your final so-called cycle, from 1998 to now, is not a cooling and still part of the upward trend, since 1998 was a record high and therefore an anomalous measure.

“In fact,temperatures are now about where they were in the 1930's.”

Far from it. The global average is now a good 0.5 deg C above 1930’s temperatures, which in the time-scale is a significant rise.

Brendan

No burden of proof

Brendan Hutching's picture

atlascott: “But we can project based upon past data and make educted guesses about what is happening and why it is happening.”

Of course. Charitably, your claim was that the current warming is consistent with past warming. But we are not currently emerging from an ice age. You are assuming that the current sequence is warming → CO2, when the evidence suggests something more complex. And the mere fact that we are in a warming period does not by itself establish that the sequence is similar to that of the past.

“It seems to me that the burden is on those…prove in a conclusive fashion that there is a crisis…”

The burden is on those who advance a theory to establish its validity. But scientific theories are not “proven”. Successful scientific theories are those that account for the evidence better than rival theories, and that are productive and testable. AGW theory is holding up on all counts.

As a matter of interest, what would you regard as evidence that man-made global warming is occurring?

Brendan

Correlation?

Peter Cresswell's picture

Brendan, you really think Twentieth Century warming was in the order of 2 degrees C? Or that's there's any correlation between CO2 production and temperature? Think again.

Temperatures have gone through nearly two complete cycles of warming and cooling over the last 100 years:

***During the period 1900 to 1940 (before the huge increase in CO2 production) temperatures were increasing.
***Then from 1940 to 1975 (when CO2 production shot up) temperatures were decreasing.
***Then, from 1979 to 1998 they were increasing again.
***Currently, from 1998 to now, they're decreasing slightly.

In fact,temperatures are now about where they were in the 1930's.

Overall, the total average annual temperature increase in the last century is so slight as to be almost unnoticeable, about 0.3-0.6°C, IFF we can rely on the unreliable surface temperature record.

Cheers, Peter Cresswell

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That's how science works

atlascott's picture

"Global temperature data from the geological past shows us what was happening then."

Sure.  But we can project based upon past data and make educted guesses about what is happening and why it is happening.  That's how science works.

How science DOESN'T work is picking certain data, disregarding other data, and special interest groups discrediting any scientist who does not toe the compny line on global warming crisis.  And whipping the public into a frenzy over a natural phenomenon.

It seems to me that the burden is on those who want more tax money, and want private business to be compelled to take all sorts of 'earth-friendly' to prove in a conclusive fashion that there is a crisis, that the crisis is not man-made, and that the proposed actions requested will have a direct, immediate, and curative effect to justify a further adbrigment of individual liberty

The Great Global Warming Swindle fails on all 3 counts.

When the Global Warming groups must defend their data, they say that they are educated guesses.

When they answer data contra to theirs, it is pure conjecture.

Quidquid latine dictum sit, altum viditur!

Integrating the data

Brendan Hutching's picture

atlasscott: “How does the fact that CO2 has 'infrared absorbing properties" mean that it has anything to do with ACTUAL warming when CO2 levelsl increase occurs AFTER temperature increase?”

Because we are not currently emerging from an ice age. The graph in question charts the relationship between CO2 and global warming, but it doesn’t establish causation.

However, we can usefully speculate that the sequence of the planet emerging from an ice age might be: increased absorption of solar radiation, atmospheric and ocean warming, flushing out of CO2 from oceans, greenhouse gases act as feedback, warmth increases, greenhouse gas feedback continues.

This scenario is based on the well-founded supposition that the initial solar warming was insufficient to warm the planet to the end-point temperature 5,000 years later. Is this conjecture? Of course it is. But that’s how science works. Send up a balloon and try to shoot it down.

“When you look closely, the fact that the science of thermodynamics exists really has nothing to do with proving or disproving the theory.”

Sure, the mere existence of a science of thermodynamics – or any science for that matter – has “nothing to do” with the theory of global warming. But if the behaviour of the phenomena covered by the science of thermodynamics can be shown to support AGW theory, then thermodynamics has a lot to do with the theory. That’s how science works.

“The fact that global temperature data shows that it is a natural cycle consistent with the current alleged warming…”

Except that it shows no such thing. Global temperature data from the geological past shows us what was happening then. All things being equal, one might assume that the current warming is consistent with the past natural cycle. But not all things are equal, hence AGW theory.

Brendan

Um...

atlascott's picture

How does the fact that CO2 has 'infrared absorbing properties" mean that it has anything to do with ACTUAL warming when CO2 levelsl increase occurs AFTER temperature increase?

Virtually every crackpot theorist can cite vague, overarching and well accepted scientific theories which 'underpin' their theory.  When you look closely, the fact that the science of thermodynamics exists really has nothing to do with proving or disproving the theory.  It is a scientist's way of saying "Don't worry, there are these other theories that prove mine."  I never trust anyone who in effect says "Trust us, we're SCIENTISTS!"

"the melt-back of northern hemisphere sea ice, the nearly worldwide melting of mountain glaciers, and the simultaneous cooling of the stratosphere and warming of the earth’s surface."

Depends on where you measure, and what you measure.  Michael Crichton does a nice job of explaining this in his book, State of Fear.

I am much more worried about heavy metals in our water and fish, and much more concerned about getting our economy off of oil for political reasons, than I will ever be of global warming.  The fact that global temperature data shows that it is a natural cycle consistent with the current alleged warming utterly defangs the hysteria vested interests and ecoterrorists want to foment.

Quidquid latine dictum sit, altum viditur!

A positive connection

Brendan Hutching's picture

Peter: “20C warming when viewed in the complete historical context is far from "historically significant" warming.”

If you mean 2 deg C warming, that would certainly be significant in the context of the past 1,000 years, not only in terms of the raw figure, but also in terms of the speed of warming.

“Historically, CO2 levels lag BEHIND temperature.”

We’re talking geological time now, and as I have pointed out elsewhere, the measurements in question refer to warming periods lasting around 5,000 years that occur as the planet emerges from an ice age. CO2 is regarded as part of a feedback system, amplifying the warming that is already underway. Sure, this is conjecture, but informed conjecture, not just wild guesswork.

And the lag itself is irrelevant for today’s warming, since we are not emerging from an ice age.

“When the only positive evidence for their being a causal connection betwen CO2 and "historically significant" warming is that the warming is "historically significant…”

The connection between CO2 and warming is more than a correlation. Experiments have demonstrated the infrared absorbing properties of CO2, so the conjecture that CO2 is an important factor in warming is grounded in genuine science, not statistical coincidence.

As I have also mentioned elsewhere, AGW theory fulfils two essential features of a viable scientific theory: it is testable (or falsifiable) and it is productive. Like evolution, AGW theory is based on a sub-set of other substantiated theories, for example thermodynamics and the behaviour of CO2. Some recent vindications of the theory include: the melt-back of northern hemisphere sea ice, the nearly worldwide melting of mountain glaciers, and the simultaneous cooling of the stratosphere and warming of the earth’s surface.

These phenomena are all consistent with the theory. That doesn’t mean AGW is established beyond doubt, but it does mean it satisfies important criteria of a genuine scientific theory.

Brendan

The long view

Peter Cresswell's picture

Brendan: "What counts as warming is the long-term trend, not one anomalous year, and the long-term trend is upwards."

You appear to have missed both the REAL long term trend shown in the bottom graph, and also the point of the post.

In fact, what the graphs show is:
1) 20C warming when viewed in the complete historical context is far from "historically significant" warming.
2) The Vostok measurements do indeed show that there is a "strong relationship" between temperature and CO2 levels; that relationship however is THE REVERSE of that promoted by warmists. Historically, CO2 levels lag BEHIND temperature.
3) When the only positive evidence for their being a causal connection betwen CO2 and "historically significant" warming is that the warming is "historically significant," and it isn't, then it makes those claims look rather weak. And that's being polite.

Cheers, Peter Cresswell

* * * *

'NOT PC.'
**Setting Brushfires In People's Minds**

ORGANON ARCHITECTURE
**Integrating Architecture With Your Site**

Start with the science

Brendan Hutching's picture

Peter: “Start at 1998, and you'll see global surface temperatures stable.”

That’s because 1998 temperatures were a record high. What counts as warming is the long-term trend, not one anomalous year, and the long-term trend is upwards.

“We see that temperatures have been falling and rising and falling and rising and falling and rising and falling and rising and falling and rising ...”

Merely counting the number of warm periods over the past 425,000 years (the Vostok measurements) does not by itself establish that the current warming period is a natural variation.

Cherry-picking data and appealing to logically invalid arguments do not count as sound criticisms of AGW theory. What these graphs do show is that:

1. The record of the past 1,000 years shows historically significant warming during the 20th century;
2. The Vostok measurements show a strong relationship between temperature and CO2 levels.

Brendan

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