11 July 2011

Global mean land temperature chart



This is my version of the well-known chart of NASA's temperature data from land instruments showing global warming since 1880. Yes, the temperature series researched and prepared by James Hansen. I got the data from the Carbon Dioxide Information Analysis Centre. Its just as easy to download the data from NASA as well.

The chart does not show absolute temperature on the vertical axis it shows the difference (or 'anomaly') from the mean temperature recorded for the period 1951 to 1980. In other words, Wellington's actual temperature on any day will be very different from that of a place near the equator. However, the use of the anomaly or difference from the average temperature for 1951-1980, standardises the data to a common scale. Also, absolute temperature varies a lot over short distances, but annual temperature anomalies are strongly correlated out to distances of a 1000 km.

I made the chart with the R programme.

Here's the code, assuming you have downloaded the data file "gl_land.txt" to your R working directory.

glt<-read.table("gl_land.txt",skip=23,header=TRUE,sep="",dec=".",strip.white=TRUE)

str(glt)

'data.frame': 131 obs. of 3 variables:
$ Year : int 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 ...
$ Anomaly: num -0.24 -0.19 -0.14 -0.19 -0.45 -0.32 -0.42 -0.54 -0.24 -0.05 ...
$ mean : num -99.99 -99.99 -0.24 -0.26 -0.31 ...

png("gisstempland.png", bg="white", width=650, height=550,pointsize = 16)
with(glt,plot(Year,Anomaly,type="n", cex.lab=1.2, main="NASA GISS Global Land Temperature Anomalies",xlab="", ylab="Degrees Celsius"))

abline(h=0,col=1,lwd=1)

mtext(side=3,line=0.3,"Difference from mean temperature 1951-1980")

legend(1880, 0.8,bg="white",bty="n", c(paste("Mean", c("annual anomaly", "Lowess anomaly f =0.05"))), lty = c(1,1),lwd=c(2,2), pch=c(16,NA),col = c(4,2))

box(lwd=2)

with(glt,points(Year,Anomaly,pch=16,type="o", col=4))

with(glt,points(lowess(Year,Anomaly,f = 0.05),type="l",col=2,lty=1,lwd=3))

mtext(side=1,line=3,cex=0.8,"Data: Hansen Ruedy Sato Lo 2011 NASA GISTEMP/CDIAC \nhttp://cdiac.ornl.gov/ftp/trends/temp/hansen/gl_land.txt")

dev.off()

2 comments:

  1. Any thoughts on events in Australia re the recently announced carbon tax given your experience and thoughts on ht NZ experience?

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  2. My initial thoughts based on a quick skim of headlines and blog posts, is that the Australian policy has a number of features that make it superior to the NZ ETS. It appears to be a real tax on the 500 participants with real revenue going to the Crown. And that revenue as well as additional funds are being recycled to reduce income taxes. Thats almost a Jim Hansen "Fee and dividend" approach. Whereas, the NZ ETS earns no crown revenue as all tradable permits will be given away.

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