Man Based Global Warming....

[TimBikes]

Originally Posted by Alric

Would you also have said the same for the three previous and longer plateaus? There is no cooling. The trend overall continues upward.

Alric - we've already covered this...

Once again, please explain how CO2 caused a sudden temperature step post-1998 but temperatures prior and after remain flat (i.e., unresponsive to CO2). While you're at it, explain how temps rose sharply until 1940 without any significant increase in CO2, then dropped from 1940 to about 1980 with massive increases in CO2.

Until you can satisfactorily answer those questions, your AGW argument and supposed CO2 / temperature correlations look highly suspect.

[Alric]

Yes we've covered this. It is an upward trend that is subject to natural variability.

[MegansPrius]

Originally Posted by TimBikes

You trumpeted the study as showing the east Antarctic was warming, but when challenged now say it is cooling. Which is it?

If you have access to the original journal article, please provide an image of "Figure 2" so we can all look at the data and judge for ourselves.

I also find it mildly amusing that you (RealClimate) have to reach back 50 years (instead of 30) in order to produce a rising temperature trend:

"Our results do not contradict earlier studies suggesting that some regions of Antarctica have cooled. Why? Because those studies were based on shorter records (20-30 years, not 50 years) ..."

This suggests that any increases in temperature in east Antarctic are not recent.

My post from yesterday made this clear
Man Based Global Warming....

The antarctic, as a whole, has warmed over the past 50 years. Even East Antarctica has warmed over that time, although it has cooled during the period 1969-2000, it has warmed for the period 1957-2006. There is nothing "contradictory" in this.

Figure three is attached, as is Figure 2, which shows the trends separated for East and West Antarctica. In both cases, the trend is upward.

[TimBikes]

Originally Posted by Alric

Yes we've covered this. It is an upward trend that is subject to natural variability.

An upward trend of 0.6 - 0.7 C / century, much of which is likely from natural factors.

The temperature rise in the 50 years from 1890 - 1940 was 0.5 C (or 1.0 C per Century), without massive contributions of anthropogenic CO2.

So how much room does that leave for catastrophic warming from CO2? Not much.

[TimBikes]

Originally Posted by MegansPrius

Even East Antarctica has warmed over that time, although it has cooled during the period 1969-2000, it has warmed for the period 1957-2006. There is nothing "contradictory" in this.

As I suspected and as Fig. 2a shows, it has COOLED from 1969-2000. Thank you for clarifying.

On a related note, here is what other climatologist had to say about the study:

"This looks like a pretty good analysis, but I have to say I remain somewhat skeptical," Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research, said in an e-mail. "It is hard to make data where none exist."

"It overstates what they have obtained from their analysis," said Roger Pielke Sr., a senior research scientist at the University of Colorado."

Even the author acknowledges:

And east Antarctica from the late 1970s through the 1990s, cooled slightly, Steig said.

[MegansPrius]

Tim,

There was nothing to clarify. I pretty much said all this yesterday:

Originally Posted by MegansPrius

This research was conducted, as science often is, in order to try to improve upon past research. It does not contradict the East Antarctic cooling shown during the 30 year period of 1969-2000.

RealClimate:

Our results do not contradict earlier studies suggesting that some regions of Antarctica have cooled. Why? Because those studies were based on shorter records (20-30 years, not 50 years) and because the cooling is limited to the East Antarctic. Our results show this too, as is readily apparent by comparing our results for the full 50 years (1957-2006) with those for 1969-2000 (the dates used in various previous studies), below.
2) Our results do not necessarily contradict the generally-accepted interpretation of recent East Antarctic cooling put forth by David Thompson (Colorado State) and Susan Solomon (NOAA Aeronomy Lab). In an important paper in Science, they presented evidence that this cooling trend is linked to an increasing trend in the strength of the circumpolar westerlies, and that this can be traced to changes in the stratosphere, mostly due to photochemical ozone losses. Substantial ozone losses did not occur until the late 1970s, and it is only after this period that significant cooling begins in East Antarctica.
3) Our paper — by itself — does not address whether Antarctica's recent warming is part of a longer term trend. There is separate evidence from ice cores that Antarctica has been warming for most of the 20th century, but this is complicated by the strong influence of El Niño events in West Antarctica. In our own published work to date (Schneider and Steig, PNAS), we find that the 1940s [edit for clarity: the 1935-1945 decade] were the warmest decade of the 20th century in West Antarctica, due to an exceptionally large warming of the tropical Pacific at that time.
So what do our results show? Essentially, that the big picture of Antarctic climate change in the latter part of the 20th century has been largely overlooked. It is well known that it has been warming on the Antarctic Peninsula, probably for the last 100 years (measurements begin at the sub-Antarctic Island of Orcadas in 1901 and show a nearly monotonic warming trend). And yes, East Antarctica cooled over the 1980s and 1990s (though not, in our results, at a statistically significant rate). But West Antarctica, which no one really has paid much attention to (as far as temperature changes are concerned), has been warming rapidly for at least the last 50 years.

Source paper in Nature:

Recent changes in Antarctic ice-sheet surface temperatures appear enigmatic when compared with global average temperature trends. Although the Antarctic Peninsula is one of the most rapidly warming locations on Earth, weather stations on the Antarctic continent generally show insignificant trends in recent decades1. However, all but two of the continuous records from weather stations are near the coast, providing little direct information on conditions in the continental interior. The widely used weather forecast reanalysis data are known to have errors owing to inconsistent assimilation skill in the satellite and pre-satellite eras3.
...

Previous reconstructions of Antarctic near-surface temperatures have yielded inconsistent results, particularly over West Antarctica, where records are few and discontinuous5, 6, 7. We improve upon this earlier work in several ways. We use two independent estimates of the spatial covariance of temperature across the Antarctic ice sheet: surface temperature measurements from satellite thermal infrared (TIR) observations8, and up-to-date automatic weather station (AWS) measurements of near-surface air temperature

[richard schumacher]

The real question is, where is the heat going? It's a fair question; the fair answer is, someplace not well-instrumented, so we don't know where it's going. But unless CO2 gas magically loses its greenhouse properties when no one is looking at it, it is a physical certainty that the Earth is retaining more heat. It is going somewhere.

[TimBikes]

Originally Posted by richard schumacher

But unless CO2 gas magically loses its greenhouse properties when no one is looking at it, it is a physical certainty that the Earth is retaining more heat. It is going somewhere.

Not necessarily true.

There arguably may be many other countervailing factors (natural or anthropogenic) offsetting much of the GHG warming you might expect.

Or, it may be that CO2 is not netting out to much of a warming influence due to negative feedbacks. For instance, former Senior Scientist for Climate Studies at NASA-MSFC, Roy Spencer suggests "Net feedbacks in the real climate system — on both short and long time scales — are probably negative. A misinterpretation of cloud behavior has led climate modelers to build models in which cloud feedbacks are instead positive, which has led the models to predict too much global warming in response to anthropogenic greenhouse gas emissions."

[Shawn Clark]

Originally Posted by TimBikes

Not necessarily true.

There arguably may be many other countervailing factors (natural or anthropogenic) offsetting much of the GHG warming you might expect.

Or, it may be that CO2 is not netting out to much of a warming influence due to negative feedbacks. For instance, former Senior Scientist for Climate Studies at NASA-MSFC, Roy Spencer suggests "Net feedbacks in the real climate system — on both short and long time scales — are probably negative. A misinterpretation of cloud behavior has led climate modelers to build models in which cloud feedbacks are instead positive, which has led the models to predict too much global warming in response to anthropogenic greenhouse gas emissions."

On the contrary it is certainly true. Increased CO2 will result in warming. Hoping for increased cloud cover is a bit of fantasy (see Venus for how wrong that can be.) As it is, you can prove that the assumption of the negative feedback is refuted by comparing temp vs. ice core results.

And what is even more humorous is that you and Spencer are pointing at FEEDBACKS. Feedbacks require that the basic assumption is correct...or they wouldn't occur.

If denialists would quit relying on the Tooth Fairy, Tinkerbell, and Santa Claus in divergent scenarios they would have some credibility. Instead their own theories are almost entirely mutually exclusive and often as not accept the human influence of CO2 to make their basis work.

The only common thread I've found for the denialist theories is that they start with an answer, then try to find any and all theories that support that answer no matter how self-contradictory. That's not science, it is faith.

[darelldd]

Hey. I have a novel idea. Let's forget Climate Change. Instead, how about if we stop throwing crap into the air for one (or more) of the hundreds of uncontested logical/practical/health/security reasons?

Oh wait. Not novel... just ignored.

(I like to toss this in every few pages just for grins).