Why did atmospheric CO2 concentrations go negative for the 2008 seasonal cyle?

Question

For the first time the January to July atmospheric CO2 concentration from Mauna Loa shows a reversal, is this from natural sequestration, the world using less hydrocarbons or global cooling?

http://wattsupwiththat.wordpress.com/2008/08/04/mauna-loa-co2-january-to-july-trend-goes-negative-first-time-in-history/

Answer 1

It is called noisy data.  Nothing more to see here.

Answer 2

What are you looking at?  Your link doesn't show anything of the sort.  There is the normal leaf on - leaf off cycle and a steady increase in CO2 over time.  You can't pick January or  July out easily and say anything about carbon sequestration, hydrocarbon use of future "global cooling" from this data.  Grasping at straws!

Answer 3

OMG maybe that's the reason for the cooling!!!!

They'll vote thumbs down, call me unscientific, call me a denier, and all the rest, but if 2009 is still cool and the Mauna Loa station records a flat or declining CO2 concentration, they'll admit the cooling and they will credit the declining CO2 level.

My prediction - the CO2 level starts to increase again but temperatures stay flat.

OMG here we go with "noise" again - - - data that does not fit the thesis is "just noise."

Imagine if that logic were applied to, say, FDA drug trials.     50% of users, the drug worked, 25%, the drug was ineffective, 15%, there were mild negative side effects...... 10% went nuts and committed suicide - but those are just OUTIERS, that's just NOISE.     The TREND LINE is positive, so approve the drug!!!!

Answer 4

If you download the latest NOAA plot of Manua Loa CO2 and zoom in, it just looks like fairly normal noise. You can see similar bumps at previous times.

http://www.esrl.noaa.gov/gmd/webdata/ccg...

But the more important point is to recognize that it's too early to speculate on such data (it was actually changed shortly after Mr. Watts speculation).  The NOAA web-site says:

http://www.esrl.noaa.gov/gmd/ccgg/trends...

"The last year of data are still preliminary, pending recalibrations of reference gases and other quality control checks."

Sadly good science often moves slow.  But the under-informed bloggers of the world are free to speculate and confuse without any fact-checking, peer review, or waiting for data quality checks.

Answer 5

The DOE, seems to agree with your statement, just add in high gas prices. The next data set is due Nov 08.

http://www.eia.doe.gov/oiaf/1605/ggrpt/

Answer 6

Cute, but the observation seems to depend heavily on that last, single, datapoint.  

Answer 7

Hopefully, this will help to settle the debate over cause and effect. Though past data already suggests it, AGW advocates have been ignoring the evidence that temperate change induces changes in CO2 concentration, not the other way around.

Answer 8

Just a short-term variation.  As others said, noise in the data.  It's already spiked back up to the normal trend line.

Coincidentally, Tamino took Watts to task for the entry you link in which he makes a huge deal out of a two month event.  I'm sure he'll neglect to mention that CO2 levels have returned to normal.

Answer 9

Because the data has just a little noise in it.  There are similar downward fluctuations before that in the blue line.

This is a completely incompetent misread of the data by a committed denier.  It simply exposes him for lack of scientific knowledge and objectivity.

Answer 10

Maybe the volcano the Mauna Loa Lab sits on is taking a break from venting all of that CO2...

...and I love how they say it's the "first time in history" when what they mean is it's the first time in RECORDED history, or less than 50 years for that particular lab, and not much more for the rest of the world.

Answer 11

That's extremely interesting. It was one of the scenario possibilities I mentioned in another reply that would help refute the claim that CO2 is the culbrit behind this Global Warming trend. Of course we'd need more years of decreasing CO2 levels and continued warming for my scenario, so will have to see. But I think this is due to the fact the oceans are cooling off, so are now absorbing more CO2 than they are releasing it.

Answer 12

It didn't.

This anonymous poster apparently got bad data. Check out the Mauna Loa data here:

ftp://ftp.cmdl.noaa.gov/ccg/co2/trends/c...

... and you will find that the January '08 value was 385.37, while in July it was 385.6, an increase, not a decrease.

So far this year the actual record shows only normal seasonal variation. The "trend" values in the graph are computed values, not data measurements. They are computed in an attempt to remove seasonal variation, using an unknown algorithm.

Instead of doing that, it's easier and simpler to take a moving 12-month average of the actual datapoints. When you do that, you find that -- no surprise -- in every month since September 1974, the 12-month moving average has increased.