WMO Statement On The Status Of The Global Climate in 2006 – A Comment By Climate Science

The World Meteorological Organization (WMO) released a statement on the global climate in 2006 on December 14 2006.

Unfortunately, with respect to reporting on surface temperature trends, the Statement perpetuates the use of surface temperature trends as the metric to assess global warming (or cooling) [i.e. why not, at least, also include ocean heat content anomalies for 2006?]. Moreover, the Statement does not question the accuracy and spatial representativeness of the land surface temperature data.

The WMO Statement on the Status of the Global Climate in 2006 includes the information that,

“The global mean surface temperature in 2006 is currently estimated to be + 0.42°C above the 1961-1990 annual average (14°C/57.2°F), according to the records maintained by Members of the World Meteorological Organization (WMO). The year 2006 is currently estimated to be the sixth warmest year on record. Final figures will not be released until March 2007.

Averaged separately for both hemispheres, 2006 surface temperatures for the northern hemisphere (0.58°C above 30-year mean of 14.6°C/58.28°F) are likely to be the fourth warmest and for the southern hemisphere (0.26°C above 30-year mean of 13.4°C/56.12°F), the seventh warmest in the instrumental record from 1861 to the present.

Since the start of the 20th century, the global average surface temperature has risen approximately 0.7°C. But this rise has not been continuous. Since 1976, the global average temperature has risen sharply, at 0.18°C per decade. In the northern and southern hemispheres, the period 1997-2006 averaged 0.53°C and 0.27°C above the 1961-1990 mean, respectively.

Regional temperature anomalies

The beginning of 2006 was unusually mild in large parts of North America and the western European Arctic islands, though there were harsh winter conditions in Asia, the Russian Federation and parts of eastern Europe. Canada experienced its mildest winter and spring on record, the USA its warmest January-September on record and the monthly temperatures in the Arctic island of Spitsbergen (Svalbard Lufthavn) for January and April included new highs with anomalies of +12.6°C and +12.2°C, respectively.

Persistent extreme heat affected much of eastern Australia from late December 2005 until early March with many records being set (e.g. second hottest day on record in Sydney with 44.2°C/111.6°F on 1 January). Spring 2006 (September-November) was Australia’s warmest since seasonal records were first compiled in 1950. Heat waves were also registered in Brazil from January until March (e.g. 44.6°C/112.3°F in Bom Jesus on 31 January – one of the highest temperatures ever recorded in Brazil).

Several parts of Europe and the USA experienced heat waves with record temperatures in July and August. Air temperatures in many parts of the USA reached 40°C/104°F or more. The July European-average land-surface air temperature was the warmest on record at 2.7°C above the climatological normal.

Autumn 2006 (September-November) was exceptional in large parts of Europe at more than 3°C warmer than the climatological normal from the north side of the Alps to southern Norway. In many countries it was the warmest autumn since official measurements began: records in central England go back to 1659 (1706 in The Netherlands and 1768 in Denmark).”

Climate Science has three comments in this presentation of the temperature anomolies.

1. The summary of regional extremes included only one brief extreme cold period in 2006. If there were just this one, this would be remarkable, and would bolster those who have concluded the global climate system is on a rapid upswing of warming. However, if there were other extreme cold periods, the neglect of including these cold events is a clear example of cherry picking to promote a particular perspective on climate change.

The figure below presents the NCEP/NCAR Reanalysis of the surface temperature anomalies for January to November 2006 (thanks to Phil Klotzbach for this). As clear in this figure, it was significantly warmer than average in the polar latitudes, but there was regions of cooler than average temperatures (such over and near northern Australia and large parts of Siberia). Such regional spatial structure illustrates why a focus of regional trends and anomalies, rather than a global average linear trend should be the emphasis in multi-decadal climate assessments.

surface_temp_anomaly.gif

[Obtained from
http://www.cdc.noaa.gov/cgi-bin/Composites/printpage.pl
].

To provide examples of the regionally large anomalies on shorter time scales, the four figures below illustrate both significant cold and warm anomalies for the January-February and October-November 2006 time periods (for both the surface air and 700 hPa temperatures). The large winter cold anomaly is quite clear in the January-February figure, for example.

jan_feb_2006_sfc_t.png
janfeb_2006_700mb.png
oct_nov_2006_sfc_t.png
oct_nov_2006.png

Other figures which document regionally large warm and cool anomalies are available from the excellent NOAA Climate Diagnostic website.

2. As we have documented most recently in

Pielke Sr., R.A., C. Davey, D. Niyogi, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, J. Angel, R. Mahmood, S. Foster, J. Steinweg-Woods, R. Boyles , S. Fall, R.T. McNider, and P. Blanken, 2006: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Research, submitted,

there are significant biases in the land surface component of the temperature trend record. This includes a warm bias in the nighttime minimum temperatures (if the intent is to monitor climate system heat content changes). The WMO is either ignoring or is unaware that any warming (or cooling) in the nighttime boundary layer results in near surface temperature anomalies that overstate the actual warming or cooling in the boundary layer; see

Pielke Sr., R.A., and T. Matsui, 2005: Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same? Geophys. Res. Letts., 32, No. 21, L21813, 10.1029/2005GL024407.

3. The WMO Statement reports on where the surface temperature data used to prepare the Statement comes from; i.e.

“Information sources

This preliminary information for 2006 is based on observations up to the end of November from networks of land-based weather stations, ships and buoys. The data are collected and disseminated on a continuing basis by the National Meteorological and Hydrological Services of WMO Members. However, the declining state of some observational platforms in some parts of the world is of concern.

It should be noted that, following established practice, WMO’s global temperature analyses are based on two different datasets. One is the combined dataset maintained by the Hadley Centre of the UK Met Office, and the Climatic Research Unit, University of East Anglia, UK. The other is maintained by the US Department of Commerce’s National Oceanic and Atmospheric Administration (NOAA). Results from these two datasets are comparable: both indicate that 2006 is likely to be the sixth warmest year globally.”

The two data sets that are referred to, however, are NOT different and are NOT independent assessments of temperature anomalies. As we report in the Pielke et al. paper,

“The raw surface temperature data from which all of the different global surface temperature trend analyses are derived are essentially the same. The best estimate that has been reported is that 90-95% of the raw data in each of the analyses is the same [Phil Jones, personal communication]. That the analyses produce similar trends should, therefore, come as no surprise.”

Thus the WMO Statement that there are two data sets is misleading, and provides a reader of the Statement with an inaccurate assumption on the robustness of the assessment of the surface temperature trends.

The preparation of the WMO Statement, therefore, is not a balanced presentation of climate system heat content changes (e.g. “global warming”), or climate, in general, in 2006. What should be of concern to everyone is that peer-reviewed issues that have been reported in the scientific literature concerning the robustness of the land surface temperature data to assess multi-decadal trends and anomalies to tenths of a degree are being ignored. Moreover, there is a clear emphasis on warm events rather than also including the colder than average episodes that occurred during the year. It is encouraging, however, that the WMO Statement had a regional focus in part of their Statement, as has been urged by Climate Science.

For their Final Statement for 2006, all of us should encourage the WMO to prepare a summary of the climate which includes each of the major regional temperature anomaly events, even if they conflict with the multi-decadal global climate models predictions.

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