Atmospheric CO2 and climate from 65 to 30 ka B.P.

Using new and existing ice core CO2 data from 65 ~ 30 ka a new chronology for CO2 is established and synchronized with Greenland ice core records to study how high latitude climate change and the carbon cycle were linked during the last glacial period. Atmospheric CO2 rose several thousand years before abrupt warming in Greenland associated with Dansgaard-Oeschger events, 8, 12, 14, 17, four large warm events that follow Heinrich events. The CO2 rise terminated at the onset of Greenland warming for each of these events. Atmospheric CO2 is strongly correlated with the Antarctic isotopic temperature proxy with an average time lag of 720 ± 370 yr (mean ± 1σ) during the time interval studied. The new data and chronology should provide a better target for models attempting to explain CO2 variability and abrupt climate change.

See also: What does the lag of CO2 behind temperature in ice cores tell us about global warming?

Yesterday I posted a graph of average daily temperature in Tucson, Arizona for the last 60 years. The post for today will be similar. I’ve taken the same data, and smoothed it so that the long-term trends are more visible. In the following 2 graphs the temperature (below) is in degrees Fahrenheit, and the precipitation (bottom) is in inches.

I filtered frequencies that occured at 2 years or less. This allows us to see some interesting patterns. As I pointed out yesterday, since a temperature minimum at around 1965, the Tucson area has been heating up. What I didn’t show you yesterday is the precipitation data taken from the same NCDC site. (Note: the 2-year filter will tend to accentuate the patterns that have a period slightly greater than 2 years. Hence, the apparent di-yearly cycle.) The apparent cutoff of temperature data at 2006 is an artifact of the axis. Data goes through May 1, 2007.

The precipitation data unfortunately shows the opposite trend; Tucson has been receiving less rain since the mid-70s. The precipitation data only goes back to 1975 because that’s all I could find on the NCDC site. It is clear that since the temperatures have risen, precipitation has decreased. What is not clear is if this is a natural process or not. The IPCC 2007, and several papers since, have stated that the Southwest United States will experience less annual rainfall because of global warming; others disagree.

In other news, I came across this the other day - The Temperature is Rising in Tucson (subscription required). It frequently cites The skeptical environmentalist by Bjørn Lomborg, so I’d take it as a humorous piece.

A while back, I saw a comment on a blog that doubted the existance of global warming (not surprising, there are lots of those). This person did claimed that the temperature trends around the world had been nil, and wanted to see temperature trends in one location that showed that the temperature had risen in the last century.

Using data from the National Climate Data Center, I’ve plotted the average daily temperature in Tucson for the last 60 years. The dark magenta points are the daily values, and the light magenta line is the best linear fit to the data. It’s a little hard to tell from the image, but the average temperature in Tucson is increasing. Over the last 60 years, it has increased by about 0.5 F/decade (0.28 C/decade).

Is this proof of global warming? Of course not. But it does show a couple of things. The temperature change from winter to summer is large. The graph doesn’t show it, but the temperature change from day to night is large as well, although obviously not as large as summer to winter. If you just look at the summer temperatures (those at the top), you can see an obvious decadal signal. Even with these diurnal, seasonal, and decadal signals, there is still an increasing linear trend in the average daily temperature.

This comes from this webpage, which spouts the typical right-wing anti-science position. Here are some selected quotes.

Funny how you don’t hear the phrase “global warming so much any more. There is a new phrase, you know. Perhaps you didn’t get the memo .. but what was once continually referred to as “global warming” is now just becoming “climate change.” Why? Well, I suppose a few record cold winters around the world have made it a bit harder for the left and the eco-cultists to push the “warming” bit. Besides, as more and more is written more people come to understand that we’re in a period of increased solar activity, and even those educated in government schools understand that increased solar activity might somehow cause a bit of warming here on Earth.

First, I hadn’t noticed the change from “global warming” to “climate change”. I’ve previously discussed this in the difference between climate change and global warming. Climate change and global warming are two seperate and distinct things - both of which are different than anthropogenic climate change. To summarize, global warming is a rising of the mean temperature of the earth; climate change is, obviously, a change in the large-scale climate of the earth (climate includes, but is not limited, to temperature, precipitation, and wind); anthropogenic climate change is simply climate change caused by human actions.

This is interesting. The solar activity is increasing. I’ve heard this argument before from the anti-science crowd, and you’d think that it would only take one figure (perhaps the one below) to show that total solar irradiance has decreased since 2000! And has remained relatively unchanged since satellite measurements started in 1980. Surely this is the cause of global warming - I mean climate change. See also the trouble with sunspots, and the lure of solar forcing.

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