A recent thread at Climate Audit has this gem. They are discussing the rate of increase of CO2 in the atmosphere. Leif Svalgard in the first comment provides the data, which I haven’t verified as accurate, but I’ll assume they are. When plotted they appear as below:

To summarize the data, Leif Svalgard writes:

In 2006 less CO2 was added to the atmosphere than in 1983. In 1980 more CO2 was added to the atmosphere than in 2004.

Geez. How can anyone look at the data and conclude that? Is it ignorance or just blatent misrepresentation of the data? Thankfully, a commenter, John V., later points out that this is cherry picking the data, and that the rate of change of atmospheric CO2 concentration is increasing.

If one blindly plots a time series of noisy data, it is difficult to understand what is going on by visual inspection. The two plots below are fake data (soon to be submitted to The Journal of Geoclimatic Studies); one is of system that is increasing linearly with time and the other is one that has four discrete steps. In both of the fake data, random noise was added. Can you tell which is which? No guessing and no looking at the alternate text - that’s cheating.

The trend in each case is exactly the same, and it is plotted as the dark blue dashed line. The cyan line is the step function without the noise. Astute readers (aka alive) will actually notice that it is a series of 4 steps. This is explained below, so keep reading. They will also notice that the vertical scale is different in the two plots. This is because the author was stupid attempting to show how different random noise would manifest in the two plots.

The top plot is the linearly trended data and the bottom plot is the stepped data. Did you get it right?

The stepped plot is attempting to show how changing the location of surface stations preferentially from native surroundings to more urban locations will have a similar signature when looking at the time series plots. This is the argument that the folks at surfacestations.org are making; that the average surface temperature is not increasing, and it only appears to be increasing due to the fact that the stations are being moved from cooler locations to warmer locations. (Or that the hotter locations, aka cities, are getting larger and thus necessarily getting closer to the stations and warming them.)

However, as can be seen above, it is not possible to know if the trend is due to the heat island effect (steps) or because of global climate change (trend). In practice it is not this simple. The steps from changes in location are easy to find, especially if the meta data is properly maintained. The problem is due to urban sprawl. Stations at the edge of a city in 1950 are likely to be totally urbanized by now. And this urbanization does not happen in steps, it’s a gradual process. Therefore, the steps in the above plots would instead be trends that gradually transition from the initial background temperature to the current higher background temperature.

Via Michael Tobis

The panel, co-winner of this year’s Nobel Peace Prize, said the world would have to reverse the growth of greenhouse gas emissions by 2015 to avert major problems. “If there’s no action before 2012, that’s too late, there is not time,” said Rajendra Pachauri, a scientist and economist who heads the Intergovernmental Panel on Climate Change. “What we do in the next 2-3 years will determine our future. This is the defining moment.”

I must agree with MTs diagnosis. I have seen nothing published that justifies a 2-3 year time after which there will be a “tipping point”. While Michael sees this as food for the defeatest, I see it as food for the denialist. (Note: I use the term denialist for those who strictly believe their own ideology and deny the scientific method.) Denialists have long been touting the IPCC as a international group of environmentalists trying to overthrow the evil capitalists in America. By throwing around numbers that have not been reported in the literature, Pauchari has given denailists the opportunity to again attack the IPCC.

The IPCC cannot be in the advocacy business. It must represent the science completely and without bias. By fabricating numbers to create a false sense of urgency, I believe Pauchari is guilty of what denialists have been accusing the IPCC of all along - being alarmist.

Pauchari, for the sake of scientists everywhere (not just climate scientists), remember that it is important that the general public trust the scientific community. Comments such as you’ve made above need to be cited in the literature. I would urge you to either provide references for your comment or to retract them. Thank you.

[As if Pauchari or anyone he knows (or anyone that knows someone he knows) actually reads this blog.]

There’s an interesting paper recently published in GRL about the future water supply in the Southwest United States.

The high demand for water, the recent multiyear drought (1999–2007), and projections of global warming have raised questions about the long-term sustainability of water supply in the southwestern United States. In this study, the potential effects of specific levels of atmospheric warming on water-year streamflow in the Colorado River basin are evaluated using a water-balance model, and the results are analyzed within the context of a multi-century tree-ring reconstruction (1490–1998) of streamflow for the basin. The results indicate that if future warming occurs in the basin and is not accompanied by increased precipitation, then the basin is likely to experience periods of water supply shortages more severe than those inferred from the longterm historical tree-ring reconstruction. Furthermore, the modeling results suggest that future warming would increase the likelihood of failure to meet the water allocation requirements of the Colorado River Compact.

Citation: McCabe, G. J., and D. M. Wolock (2007), Warming may create substantial water supply shortages in the Colorado River basin, Geophys. Res. Lett., 34, L22708, doi:10.1029/2007GL031764.