Instrumental Surface Temperature Record Snow/Ice Report Finish Climates of the Past Data Sources Land vs. Ocean Patterns Instrument Siting Concerns For Next Class: Read Climate Studies Ch. 11-12

Figure SPM.1a Observed globally averaged combined land and ocean surface temperature anomaly 1850-2012 All Figures © IPCC 2013 Figure SPM.1, Panel a Complete caption of Figure SPM.1: Figure SPM.1 | (a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. Top panel: annual mean values. Bottom panel: decadal mean values including the estimate of uncertainty for one dataset (black). Anomalies are relative to the mean of 1961−1990. (b) Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends determined by linear regression from one dataset (orange line in panel a). Trends have been calculated where data availability permits a robust estimate (i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Grid boxes where the trend is significant at the 10% level are indicated by a + sign. For a listing of the datasets and further technical details see the Technical Summary Supplementary Material. {Figures 2.19–2.21; Figure TS.2}

Figure SPM.1b Observed change in surface temperature 1901-2012 All Figures © IPCC 2013 Figure SPM.1, Panel b Complete caption of Figure SPM.1: Figure SPM.1 | (a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. Top panel: annual mean values. Bottom panel: decadal mean values including the estimate of uncertainty for one dataset (black). Anomalies are relative to the mean of 1961−1990. (b) Map of the observed surface temperature change from 1901 to 2012 derived from temperature trends determined by linear regression from one dataset (orange line in panel a). Trends have been calculated where data availability permits a robust estimate (i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Grid boxes where the trend is significant at the 10% level are indicated by a + sign. For a listing of the datasets and further technical details see the Technical Summary Supplementary Material. {Figures 2.19–2.21; Figure TS.2}

Trends in Mean Annual Temperature Enormous amounts of observational data from over the land and sea go into computing the global mean surface temperature The trend in global mean temperature was generally upward from 1880 until about 1940, downward or steady from 1940 to about 1970, and upward again through the 1990s and early 2000s © AMS

Trends in Mean Annual Temperature © AMS

Weather Coder http://wxcoder.org/wxcoder/home/

Surface Temperature Summary Surface temperature records indicate significant warming has occurred nearly everywhere on Earth since 1900. Warming has been most pronounced since the late 1970s and at high latitudes in the Northern Hemisphere.

Surface Temperature Concerns? Do you have any concerns about the surface temperature record? If so, what are they?

Trends in Mean Annual Temperature Integrity of Instrument Data Potential sources of error in hemispheric or global mean temperature records: At sea, huge gaps in monitoring networks Improved reliability of weather instruments through the period of record Changes in location & exposure of instruments Warming effect of urbanization © AMS

Urban Bias on Temperature? Have urban-affected temperature records significantly biased large-scale temporal trends? “Some individual stations may be affected . . . but all global-scale studies indicate the urban heat island affect is a very small component of large-scale averages” (Trenberth et al. 2007, p. 244).

The Urban Environment Figure 4.21 11

Urban Heat Island Figure 4.22 12

Recent Research Suggests that station siting quality (e.g., 1 vs. 5) is more important influence on temperature bias than geographical location. http://www.agu.org/journals/jd/jd1114/2010JD015146/2010JD015146.pdf http://pielkeclimatesci.files.wordpress.com/2011/07/r-367.pdf