Short term air temperature snapshots aren’t helpful. There are too many other factors that create variation in temperature. It’s thought that ocean temperatures are a better measure of the impact of CO2 increases. I’m trying to get my head around all the temperature data. There appears to be a lot of data manipulation by both sides of the argument to support their point of view. This makes things hard!
There’s certainly some necessary data manipulation. Temperature readings have become more accurate over time, as people realise various flaws in collecting data. Some of these flaws can be corrected, so the data are still useful even though the raw results need fixing.
My friend Loki at work mentioned some factors: temperature readings near roads skew warmer under some circumstances due to the roads releasing heat. Height of nearby vegetation matters, due (I think) to retained moisture. Nowadays, temperature gathering takes all that into account, but it is a bit of a specialist area. I think this is one area where looking at the raw data without context can be misleading.
Yes, there has been cooling, since 1998 due to increased pollution from China, the El Niño system in the Pacific, and a slight drop in the energy Earth gets from the sun.
In fact, we may see cooling for the next few decades.
On you point Andrew, the Urban Heat Island effect as been discussed at length in regards to microclimate influencing land based measurements http://en.wikipedia.org/wiki/Urban_heat_island
I think this highlights a major problem. The time period we are working with for man made CO2 is very short when compiling data on a complex system that has many variables. We know CO2 is increasing but temperature variation through other factors does not allow a ‘clean’ view of the impact of this. The only way to do so is to model it. A model is based on assumptions which can be called into question.
I’m happy to close this point off as largely irrelevant to the debate if we can look at the argument around CO2 impact for the last 100 years or so.
I think a bigger problem than the urban heat island effects are changes in the number and distribution of weather stations – a lot of more remote ones have been removed just when their data would have been useful, I believe especially in the former Soviet Union. Congratulations on establishing such a sane and reasonable site, Admin!
It was ignoble of me to lose contact with you for so long.
Richard Adamson Says:
July 6th, 2011 at 9:56 am
Short term air temperature snapshots aren’t helpful. There are too many other factors that create variation in temperature. It’s thought that ocean temperatures are a better measure of the impact of CO2 increases. I’m trying to get my head around all the temperature data. There appears to be a lot of data manipulation by both sides of the argument to support their point of view. This makes things hard!
admin Says:
July 6th, 2011 at 10:18 am
There’s certainly some necessary data manipulation. Temperature readings have become more accurate over time, as people realise various flaws in collecting data. Some of these flaws can be corrected, so the data are still useful even though the raw results need fixing.
My friend Loki at work mentioned some factors: temperature readings near roads skew warmer under some circumstances due to the roads releasing heat. Height of nearby vegetation matters, due (I think) to retained moisture. Nowadays, temperature gathering takes all that into account, but it is a bit of a specialist area. I think this is one area where looking at the raw data without context can be misleading.
Note to self: find references for this!
Richard Says:
July 6th, 2011 at 2:25 pm
Discussion yesterday in New Scientist.
http://www.newscientist.com/blogs/shortsharpscience/2011/07/why-global-temperatures-held-s.html?DCMP=OTC-rss&nsref=online-news
Yes, there has been cooling, since 1998 due to increased pollution from China, the El Niño system in the Pacific, and a slight drop in the energy Earth gets from the sun.
In fact, we may see cooling for the next few decades.
On you point Andrew, the Urban Heat Island effect as been discussed at length in regards to microclimate influencing land based measurements http://en.wikipedia.org/wiki/Urban_heat_island
Richard Says:
July 6th, 2011 at 2:47 pm
I think this highlights a major problem. The time period we are working with for man made CO2 is very short when compiling data on a complex system that has many variables. We know CO2 is increasing but temperature variation through other factors does not allow a ‘clean’ view of the impact of this. The only way to do so is to model it. A model is based on assumptions which can be called into question.
I’m happy to close this point off as largely irrelevant to the debate if we can look at the argument around CO2 impact for the last 100 years or so.
As an aside, here’s a good reference for temperature data – http://data.giss.nasa.gov/gistemp/graphs/
Chris Says:
August 5th, 2011 at 10:43 am
I think a bigger problem than the urban heat island effects are changes in the number and distribution of weather stations – a lot of more remote ones have been removed just when their data would have been useful, I believe especially in the former Soviet Union. Congratulations on establishing such a sane and reasonable site, Admin!
It was ignoble of me to lose contact with you for so long.