Summary: Laypeople discussing global warming often describe warming trends as if measured like the temperature in my backyard. This is false on several levels. Collecting the data on global temperatures is a large task, and maintaining a consistent data series over time is even more difficult. Despite the extreme importance of this data, today we do neither task well. Other posts have discussed the lack of quality control and ad hoc adjustments to the data. This post looks at the first step: collecting the data. But the problem is the same throughout the process: underfunding.
This graph has rattled around the Internet: National Temperature 1895-2008, usually by those pointing to the warming trend. They seldom mention its source:
“2008 Temperature for U.S. Near Average, was Coldest Since 1997; Below Average for December“, NOAA, 8 January 2009 — “The 2008 annual temperature for the contiguous United States was near average, while the temperature for December was below the long-term average, based on records dating back to 1895, according to a preliminary analysis by scientists at NOAA’s National Climatic Data Center in Asheville, N.C.”
The US surface temperature record is an important issue. Unfortunately the data is in terrible shape, esp considering what’s at stake (the global data is in far worse shape, of course). Since the issues are technical, here a brief introduction understandable by laypeople (the best I can do in 1000 words) — with links to more detailed information.
Two posts discussing this graph
(1) “The NOAA/NCDC 2008 temperature map shows near normal USA in 2008“, Anthony Watts, posted at Watts Up with That, 15 January 2009 — He shows a valuable NOAA map not included in the press release, illustrating which parts of the US were warmer/colder than usual in 2008. Despire the press release being about 2008, it only shows this map for December 2008. Why is that? Look at the maps to see the an obvious reason.
(2) “NOAA versus NASA: US Data“, Steven McIntyre, Climate Audit, 16 January 2009 — Excerpt:
Readers need to keep in mind that there is a substantial “divergence” between NOAA US and NASA {GISS} US temperatures as shown in the graphic below. Since 1940, NOAA’s US has increased relative to NASA’s US at a rate of 0.39 deg C/century, thus 0.27 deg C since 1940.
At present, we don’t know very much about the NOAA calculation. To my knowledge, they make no effort to make a UHI adjustment along the lines of NASA GISS.
As I’ve mentioned before, in my opinion, the moral of the surfacestations.org project in the US is mainly that it gives a relatively objective means of deciding between these two discrepant series. As others have observed, the drift in the GISS results looks like it’s going to be relatively small compared to results from CRN1-2 stations – a result that has caused some cackling in the blogosphere. IMO, such cackling is misplaced. The surfacestations results give an objective reason to view the the NOAA result as biased.
It also confirms that adjustments for UHI {urban heat island} are required.
Outside the US, the GISS meta-data on population and rural-ness is so screwed up and obsolete that their UHI “adjustment” is essentially random and its effectiveness in the ROW {rest-of-world} is very doubtful. Neither NOAA nor CRU {Climate Research Unit, University of East Anglia} even bother with such adjustments as they rely on various hokey “proofs” that UHI changes over the 20th century do not “matter”.
What are the source of surface temperature data?
There are two major global indices of temperatures that incorporate station data: CRU and GISS. Both rely to different extents on the data from NOAA’s GHCN. A large proportion of the GHCN network is composed of the USHCN.
- CRU: Climate Research Unit, University of East Anglia
- GISS: Goddard Institute for Space Studies, NASA
- GCHN: Global Historical Climatology Network, NOAA — Meteorological data from a global network of land stations.
- USHCN: US Historical Climatology Network, data collected by the National Climate Data Center of NOAA — “A high quality, moderate-sized data set of daily and monthly records of basic meteorological variables for the 48 States.”
This just scratches the surface. For a detailed (if poorly written) tour though the various data sources I recommend this article. Esp note the links directly to the various datasets, and the section about graph scaling at the bottom.
Some of the limitations of the global temperature data
(a) The deveopmed nations have larger and higher quality networks than the emerging nations. The oceans and poles have far less coverage.
(b) Problems in the CRU and NOAA data: many stations disappear over time, and there is no adjustment for the urban heat effect.
- “Realclimate and Disinformation on UHI“, Steve McIntyre, Climate Audit, 20 January 2009
(c) There is a large divergence between surface temperature data and satellite data (UAS and GIS).
The satellite data can be matched with the various surface temperature records only with adjustments roughly as large as the warming “signal”.
- “Divergence Between GISS and UAH since 1980“, Steve Goddard, posted at Watts Up with That, 17 January 2009
- “GISS Divergence with satellite temperatures since the start of 2003“, Steve Goddard and Anthony Watts, posted at Watts Up with That, 18 January 2009
Some sites with more information
The Climate Audit archives:
- about NASA’s GISS data
- about surface temperature data, esp long-term sea surface data
- Descriptions and analysis of the various surface temperature datasets
Afterword
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To read other articles about these things, see the FM reference page on the right side menu bar. Of esp relevance to this topic:
- About Science & Nature – my articles
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Posts on the FM site about climate science
- A look at the science and politics of global warming, 12 June 2008
- An article giving strong evidence of global warming, 30 June 2008
- More forecasts of a global cooling cycle, 15 July 2008
- Two valuable perspectives on global warming, 4 August 2008
- President Kennedy speaks to us about global warming and Climate Science, 7 August 2008
- Good news about global warming!, 21 October 2008 – More evidence of cooling.
- One of the most interesting sources of news about science and nature!, 27 October 2008
- “Aliens cause global warming”: wise words from the late Michael Crichton, 15 November 2008
- Watching the world change before our eyes, 29 November 2008
- This week’s report on the news in climate science, 7 December 2008
- The Senate Minority report is out: “More Than 650 International Scientists Dissent Over Man-Made Global Warming Claims”, 12 December 2008
- Weekend reading recommenations about climate change, 13 December 2008
- An important new article about climate change, 29 December 2008
- My “wish list” for the climate sciences in 2009, 2 January 2009
- Important new climate science articles, 11 January 2009
- Peer review of scientific work – another example of a flawed basis for public policy, 22 January 2009
