Place your bets: Make your call on 2010 global average temperature

C02 is estimated to have been maybe 20x current levels, when the sun was about 5% dimmer than now, yielding about the same average global temperature as now. The phrase in italics seems somehow to get deleted on all the denialist websites.

So, if you only get your information from denialists, you might think that climate scientists have never been able to resolve that huge apparent paradox. Instead of the correct story, which is that modern climate models, when tuned for conditions of that ancient era, give roughly the right surface temperature, in so far as we can know the surface temperature some hundreds of millions of years ago. In fact, the estimated tradeoff between solar intensity and C02 concentration at constant temperature is a pretty good validation of the greenhouse effect of C02.


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Recent ice ages were caused by periodic changes in earth's orbit -- the Milankovitch cycle. There is absolutely no disagreement about that. They occurred regularly, exactly when Milankovitch said they would occur.

The reason scientists disbelieved Milankovitch for so long is that orbital changes alone were not sufficient to cause a deep ice age. Only when they figured out the C02 feedback did that fully reconcile all the evidence.

So, C02 didn't cause those changes, it amplified them. Warming released C02 into the atmosphere, largely from the ocean (just like warming up a Coke), and that additional C02 provided the feedback.

Once again, the paleo data roughly validate the estimated greenhouse effect of C02 concentration. Without the C02 feedback, the temperature change over the ice age cycle would have been less than half as deep as observed.

At this point, all you need to do to see the light here is to realize that different things may cause C02 concentration to rise. Once you grasp that, then, bingo, it's not some huge paradox that the best-and-brightest have somehow ignored, it's another piece of evidence that fits into a logically consistent picture of the world.

If, contrary to fact, it were true that the only way C02 could increase was by driving it out of the ocean via increased water temperature (as during the ice ages), then your comment about 800 years (over the >100K year ice age span) would be on point. If, contrary to fact, the only way C02 could rise was as a feedback to temperature increase, then your point is well-taken.

But that's not true. That little C02 feedback from temperature to C02 concentration is only the smallest contributor to the current rise in C02. Instead, the overwhelming source of C02 increase is the burning of fossil fuel. There is zero uncertainty about that -- all you need to prove that is some basic arithmetic. We know the quantities of fuel being burned, so we know the carbon we release every year, and we know that the annual increase in atmospheric carbon is much less than that, meaning that we know that Nature as a whole remains a carbon sink.

How different is that ice-age feedback from the present situation? Compare the time scales. Typical recent ice age warming period, increase of 100 PPM C02 over ~100,000 years. At present, increase of 100 PPM C02 in 100 years. The modern C02 buildup is 1000 times faster than the buildup during the ice ages. It's a completely different animal.

And that should give a hint as to why it's not irrational to think this may be a problem. Atmospheric C02 appears to be a key determinant of climate, any way you look at it, particularly if you look at the paleological data. We've increased atmospheric C02, in the last 100 years, as much as Mother Nature did, over the entire course of the last ~100,000 year ice age warming period. It's important, and we we've perturbed it a lot compared to historical norms. Knowing nothing more than that, I'd expect to see some kind of fallout.


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So, the straight scoop here is that both pieces of paleological evidence demonstrate the warming power of atmospheric C02. But you can't look at them in isolation. Twenty-times-higher C02 with same temperature is no paradox, as long as you realize the sun was about 5% dimmer. A lag from temperature to C02 in the ice age is no paradox as long as you realize that driving C02 out of the ocean is not the only way C02 can increase.

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But all of this is off-topic. In fact, I kind of wish you'd take the argument somewhere else.

As of March, I say there's about an 85% chance of a new record this year. That's what the thread is about.

 

Yes, if this is another Pinatubo, then there will be no record set this year. I see a smattering of reports that say it's not big enough yet to have any significant impact. Interesting to see people mention that immediately.

I vaguely recall that its hard for a high-latitude volcano to have a large effect, but could not recall why. That's explained in the link below. The patterns of stratospheric air circulation tend to limit the spread in the stratosphere:

Wunder Blog : Weather Underground

That site also notes the exceptions. More-or-less, you need a large sustained eruption in the high latitudes to get a large effect.

 

April 2010 Update:

The April temperature anomaly in the GISS series remains well above the annual record. The two satellite series fell to slightly below their respective annual records.

Based on the historical data, there would be about a 96% chance that a new record would be set this year in the GISS series. (That is, only twice since 1950 can we observe cooling in the last eight months of the year that would be large enough to prevent this year from making a record.).

Balancing that, the El Nino has ended. NOAA expects "ENSO-neutral" conditions starting in June and carrying through the rest of the summer. That definitely argues for cooler measured surface temperatures.

The impact of the Icelandic volcano appears small, at least based on what I read among people who have a direct financial stake in understanding the impact: commodities speculators and reinsurers. So far, the only apparent impact on food production is on shipping.

 

May 2010 update.

Satellite data showed a modest increase in temperatures, NASA GISS showed a decline. Based on the first five months of 2010, there's now an 89% probability of a new record for the calendar year (same methods as prior posts).

The most recent El Nino is finished, and NOAA's summary of expert predictions says that the Pacific is likely to move into La Nina mode over the next three months.

 

June update: 93% chance that this calendar year will set a record in the GISS series.

 

Laughable. Aside from the clear bias in the opening segment:

"Most scientists believe that the greenhouse effect causes ... no rise in ... temperature and carbon dioxide .... has only a minor greenhouse effect."


They conveniently managed to forget that:

a) 70% of the earth's surface is oceans, not land-based temperature data at issue. If there had been zero measured increase on land, the data would still show a significant global temperature increase over the last century.
b) Multiple countries do their own temperature analyses, so if we'd fudged it (the allegation), that would be clear.
c) Composites of borehole studies show the same rise as the thermometer data, so that on a timescale of centuries, you don't have to rely on historical thermometer data to know there's been a rise in temperature of roughly this magnitude. That was one of the pieces of evidence used in the National Academies of Science report to demonstrate that the "hockey stick" graph is essentially correct.
d) a "cold thermometer" is not the same as a thermometer showing little warming (trend, not level, is what matters)
e) For the US, if you only take the thermometers that Watts approves of, you get the same trend as shown with the entire historical climate network dataset with edits.
f) Multiple independent competent analyses have shown the same temperature trends despite variation in methods, the most recent of which was the Muir Russel report (the one that exonerated the research produced at CRU), where it took them all of two days to reproduce the temperature timeseries from scratch. Well, even if people ignore that, maybe at least it'll quiet the people who keep whining that the data aren't available.
f) In the US, the new climate reference network shows the same trend, this decade, as the analysis of the historical climate data. So ... the presumed downward bias in temperature trend somehow ceases to matter in the modern era?
g) Since 1980 or so, we've got satellite-based data that's in reasonable accord with the land-based thermometer data. So ... the presumed bias somehow ceases to matter in the modern era?

EDIT: Some background on Coleman, the guy in the video:

http://www.voiceofsandiego.org/environment/article_45f39d86-5be3-11df-9bf5-001cc4c002e0.html

"His college major was journalism; his meteorology training came from a Penn State University correspondence course. He's no longer accredited by the American Meteorological Society. Too much politics, he says."

And his take on global warming, in what appears to be his own words:

http://icecap.us/index.php/go/joes-blog/comments_about_global_warming/

"It is the greatest scam in history. I am amazed, appalled and highly offended by it. Global Warming; It is a SCAM. Some dastardly scientists with environmental and political motives manipulated long term scientific data to create an illusion of rapid global warming. Other scientists of the same environmental whacko type jumped into the circle to support and broaden the “research” to further enhance the totally slanted, bogus global warming claims. Their friends in government steered huge research grants their way to keep the movement going. Soon they claimed to be a consensus."

It gets worse from there.

We all have to make our own choices, but I don't think that's who I'd turn to for level-headed information on this topic.

 

When the short-term trend in air temperatures was flat, your posts here talked about how that showed that global warming didn't exist.

Now that air temperatures appear to be ready to set a new record (since the last record, all the way back in 2005, per the GISS data), its now hey presto, air temperature doesn't matter, you need to focus your attention on a short-term flat spot in a different (noisy, fluctuating) dataset.

And, as ever, we must ignore the fact that if you'd moved your graph back a decade, you'd get a picture that is completely the opposite of what you've shown.

Same old, same old.

Since the point of this thread was prediction, I'll offer a new one: When the heat content data turn up again, you'll find some other short-term trend to look at.

 

From easiest to hardest:

Select?

They wish they could select. That ain't the issue. In the historical climate network, you've got what you've got. You've got 1200 or so currently reporting sites.


The United States Historical Climatology Network (USHCN) Main Page


Thats-f@#$ing-it. NASA GISS didn't drop them, NOAA didn't drop them. The-great-international-climate-conspiracy didn't drop them. They dropped themselves. There-ain't-no-f@#$ing data from the other sites.

Get it? You've got about 1200 sites currently reporting. You have to deal with that.

Why not 60,000: Because there ain't no data.

Why not 6,000: Because there ain't no data.

Why 1200: Because, that's what you've got.

The important thing is that there are relatively few "degrees of freedom" in the temperature trend. To estimate the trend accurately for the US, I've been told you need fewer than 50 thermometers. For example, the trend in Washington, DC is going to pretty much like the trend in Baltimore, MD, and both are going to be similar to Richmond VA and Philadelphia PA.

So if you have temp trend data from those four cities, you don't actually have 4x as much info as you'd have from (e.g.) DC alone.

Or, for a thought experiment, consider adding 5,999 thermometers at Reagan National Airport, separated by 1' from each other. Yeah, you've got 6000 readings, but not 6000x as much new information.

So here's how it actually works. You take all the temp readings from those areas, and when one of them jumps up or down relative to the rest, you bring it back into line with the rest, under the assumption that something (location, instruments used, whatever) changed. For example, it's not possible that the temp trend at Reagan National airport jumped 0.5 degree while the temp trend at Dulles airport didn't.

That's called a homegeneity adjustment. If you're NASA GISS, you only take readings from outside the urban area, to avoid bias from increasing urban heat island effects. Whereas if you're NOAA, you keep all the data, and so a regression-based adjustment for urban heat island effects. The Brits, by contrast, just take them all, under the assumption that the (change in) the heat island effect is small.

And you end up with the same temperature trend estimate.

None of this, by the way, applies to the 70% of the earth's surface that is ocean.