Instrumental Surface Temperature Record Current Weather Data Sources Land vs. Ocean Patterns Instrument Siting Concerns Return Exam II For Next Class: Read Ch. 10 (pp )

Figure SPM.1a Observed globally averaged combined land and ocean surface temperature anomaly All Figures © IPCC 2013

Figure SPM.1b Observed change in surface temperature All Figures © IPCC 2013

Surface Temperature Anomalies,

Temperature Datasets CRUTEM – UK Hadley Center GHCN – Global Historical Climate Network (NCDC) GISS – NASA Goddard Institute for Space Studies Berkeley – California Berkeley

© AMS6 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

© AMS7 Trends in Mean Annual Temperature

Thermometer and Instrument Shelter Figure 5.2Figure 5.3

Weather Coder

Annual Anomalies of Maximum and Minimum Temperatures and Daily Temperature Range

Surface Temperature Summary Surface temperature records indicate significant warming has occurred nearly everywhere on Earth since 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?

© AMS14 Trends in Mean Annual Temperature  Integrity of Instrument Data Potential sources of error in hemispheric or global mean temperature records: Potential sources of error in hemispheric or global mean temperature records: At sea, huge gaps in monitoring networksAt sea, huge gaps in monitoring networks Improved reliability of weather instruments through the period of recordImproved reliability of weather instruments through the period of record Changes in location & exposure of instrumentsChanges in location & exposure of instruments Warming effect of urbanizationWarming effect of urbanization

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

Urban Heat Island Figure 4.22

USHCN (Red) vs. USHCN Urban (Blue & Green) No Significant Difference According to IPCC

Recent Research Suggests that station siting quality (e.g., 1 vs. 5) is more important influence on temperature bias than geographical location /2010JD pdf /07/r-367.pdf