Arguments
Why we can trust the surface temperature record
Posted on 28 August 2010 by John Russell
Surveys of weather stations in the USA have indicated that some of them are not sited as well as they could be. This calls into question the quality of their readings.
However, when processing their data, the organisations which collect the readings take into account any local heating or cooling effects, such as might be caused by a weather station being located near buildings or large areas of tarmac. This is done, for instance, by weighting (adjusting) readings after comparing them against those from more rural weather stations nearby.
More importantly, for the purpose of establishing a temperature trend, the relative level of single readings is less important than whether the pattern of all readings from all stations taken together is increasing, decreasing or staying the same from year to year. Furthermore, since this question was first raised, research has established that any error that can be attributed to poor siting of weather stations is not enough to produce a significant variation in the overall warming trend being observed.
It's also vital to realise that warnings of a warming trend -- and hence Climate Change -- are not based simply on ground level temperature records. Other completely independent temperature data compiled from weather balloons, satellite measurements, and from sea and ocean temperature records, also tell a remarkably similar warming story.
Confidence in climate science depends on the correlation of many sets of these data from many different sources in order to produce conclusive evidence of a global trend.
This post is the Basic version (written by John Russell) of the skeptic argument "Surface temperature record is unreliable". We're currently writing plain English versions of all the skeptic rebuttals. If you're interested in helping with this effort, please contact me.
Virtually every 'adjustment' is made upwards. This is impossible unless sytematic bias is occurring.
'Remarkably similar' is also incorrect. Eg Unadjusted satellite data doesn't fit/isnt similar with other data.
The only consistency is the 'remarkable' number of times adjustments are made upwards, to make them 'remarkably' consistent with each other.
Re: upwards vs downwards adjustments --- there are many cases where the processing of surface data results in a downward adjustment; you just never see them highlighted at WUWT for some reason. When "skeptic" bloggers Jeff Id and RomanM created their own global temperature reconstruction using surface station data, they found a warmer trend than that from Phil Jones's HADCRUT record.
See this post for a more detailed discussion that illustrates how robust the surface temperature trend is. You get very, very similar results to the NASA/CRU temperature records even if you use completely different methods with completely different input data (e.g., daily GSOD data instead of monthly GHCN).
Re: satellites --- The RSS satellite record shows a trend of +0.16C/decade. Over the same time period, GISS, HADCRUT, and NCDC also show trends of +0.16C/decade. The four trends are identical to within 0.01C/decade ... and RSS data are not adjusted in any way to match the surface data.
Conspiracy theories and speculation about fraud or tampering with the data may be popular in certain other quarters of the blogosphere, but let's avoid them here, please.
:-)
I maintain a csv file of monthly temperature anomalies for the 5 major global temperature series that you can download and analyze in Excel, R or other software.
The 3 surface station data (GISS, Hadley, NOAA) run from 1880, the satellite data series (RSS, UAH) run from 1979.
Here's the link to my do-it-yourself post.
Presumably thingadonta will acknowledge Ned's correction?
Or better yet, the fact that his basic claim about the "systematic bias" of the temperature record has been debunked here more times than anyone can count?
For those who haven't visited Kelly's website, there are all kinds of useful and informative tools and graphics there.
Anyway, bookplug!
- changing timing of seasons
- receding glaciers
- rising sea levels
- migration patterns of all sorts of creatures
- declining sea ice
- upward migration of mountain flora and fauna
- increased range of tropical diseases
- increased range of certain insects
- timing of the icing over and thawing of rivers and lakes
- blossoming of plants
- and many, many more indicators, of which there are literally thousands of studies
One does not need thermometers to ascertain increasing temperatures.
The reasons for these can be found in the earth's axis precession of one cycle in 25800 years which equates to one complete day every 70 years.
During the complete cycle the seasons will move completely through the calender in that time.
I suppose it depends which cloud cover dataset you use. The longer term surface observation dataset (SOBS) also shows a gradual increase in global mean cloud cover over a longer period than shown below.
From the 2009 NOAA State of the Climate BAMS supplement.
I hear "I doubt it." Is that all?
Have you ever heard of leap years? Provide evidence of your extraordinary claim that the seasons are precessing as you claim. I note that summer solstice has not shifted, as it would with your claim. Please explain how the seasons could change but the solstice would not. Remember that these types of claim affect your reputation for reliability.
Flowers blooming earlier now than any time in the last 250 years
The paper Climate Change and Cherry Tree Blossom Festivals in Japan shows how the date of flowering for some is now two or three weeks earlier than it was in their youth. From checking records going back to the 11th Century it states that "while temperatures have varied over this period, recent decades have been warmer on average than any time during the past 1000 years"
You appear to be claiming that it doesn't exist as I believe is commonly accepted, or else has stalled. What research is there to support such a claim?
You might add snow line elevation in mountains, ski resort seasonal duration, or even locations chosen for mounting on ski lifts.
Your argument is false on its face. Why should I look up more data when you have not cited a single source for your extraordinary claim? You claim that spring is coming ealier AND fall is coming later due to seasons shifting. This is obviously impossible. It must be one or the other. Is spring coming earlier due to the supposed season shifting or fall later? What accounts for the shift in the other season, since both have been observed to change? In addition, the shift of spring and fall is 7-21 days in the last 30 years. You claim one day shift in 70 years. I suggest the scientists are right in saying there is not a shift in the seasons. Think about what you claim before you write it. The Milankovich cycles change where energy strikes Earth, not the season when it arrives. This is a completely unrelated topic from seasons shifting, you need to learn about the significance of the Milankovich cycles if you want to discuss them. Try Wikipedia for a start.
I guess that's why anomalies are used instead of actual temperatures.
The easiest exposure of the nonsense is solstice and equinox celebrations - they'd be shifted by over a month from ancient times. They haven't done that.
In fact, the northern hemisphere planting season moved later by over a week between 1940 and 1975, and has retreated by over two weeks since then. Like the skit said - "The Milankovich cycle don't enter into it. That theory is dead."
I had overlooked the leap years, and mans ability to change the calender and thus the climate, in a manner of speaking.
However the precession continues it's cycle irrespective of mans adjusting the calender, but adjusting the calender so that defined seasons don't shift on the calender disguises the fact that oils ain't oils, in this case, the orientation of the planet is not the same each repeating solstice or equinox as perhaps more easily shown on this chart.
Effects of axial precession on the seasons
This figure illustrates the effects of axial precession on the seasons, relative to perihelion and aphelion. The precession of the equinoxes can cause periodic climate change because the hemisphere that experiences summer at perihelion and winter at aphelion (as the southern hemisphere does presently) is in principle prone to more severe seasons than the opposite hemisphere.
Given that clouds cover about 2/3 of the earths surface, a small change in coverage makes a significant difference, a change of about 5 percent roughly corresponds to a significant radiative net change of about 0.9 W/m2.
The Milankovich cycles affect very long term climate, beyond one human life. It is known that these currently are a net cooling forcing, not a warming forcing. AGW has overwhelmed this effect and converted the trend into warming.
This does not affect the timing of seasons and the response of animals and plants to those changes referred to by Steve in post 11. The timing of the seasons is a clear mark of AGW in the empirical evidence.
As we have discussed before, there are more factors that determine the timing of the seasons than just temperature or the calender. Seasons can begin and end early or close late for a variety of reasons. This year for instance in south eastern Australia people could be forgiven for think that spring came 6 months early and we went from spring to summer and then straight back to spring again such was the response of the plants and the animals that depend on them, all due to the amount of water vapour that cycled through the hydrological cycle.
If people noticed that you had no winter that is a predicted sign of global warming. You claimed that the seasons were not shifting in post 12. Now we agree that the seasons have shifted so much that people are noticing it. Thats what scientists call "Climate Change". There is more water in the hydrological cycle because of increased temperature of the atmosphere and ocean. Increased temperature is caused by increased CO2. This was forcast decades ago. Water responds to temperature change. Water does not force temperature to change. Yes, it is complicated, but the base of the pyramid of climate change is CO2 forcing in the atmosphere.
(1) fretslider alleges NOAA "ain't so sure" with reference to a project undertaken to "better understand the thermal impacts of buildings with parking lots on air temperature measurements". [first quoted phrase from freslider's comment, second from NOAA report.]
To which it must be said fretslider has failed to demonstrate that there is any reason to doubt that the US temperature record is, for the purposes of global climate science, satisfactorily accurate on the basis of an experiment designed to better understand a phenomenon.
In addition, I find fretslider's insinuation of dishonesty on the part of NOAA, given the lack (as far as I can see) of any evidence to support such insinuation, concerning.
Finally, I question whether NOAA's project viz. its thermal impacts experiment has anything to do with the "questions" raised (or more accurately, allegations made) by Watts.