Instrumental Surface Temperature Record

Current WeatherData SourcesLand vs. Ocean PatternsInstrument Siting ConcernsReturn Exam II

For Next Class: Read Ch. 10 (pp. 319-320)

Figure SPM.1aObserved globally averaged combined land and ocean surface temperature anomaly 1850-2012

All Figures © IPCC 2013

Figure SPM.1bObserved change in surface temperature 1901-2012

All Figures © IPCC 2013

Surface Temperature Anomalies, 1850-2012

Temperature DatasetsCRUTEM – UK Hadley CenterGHCN – Global Historical Climate Network (NCDC)GISS – NASA Goddard Institute for Space StudiesBerkeley – California Berkeley

© AMS 6

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 7

Trends in Mean Annual Temperature

Thermometer and Instrument Shelter

Figure 5.2 Figure 5.3

Weather Coderhttp://wxcoder.org/wxcoder/home/

Annual Anomalies of Maximum and

Minimum Temperatures and Daily Temperature

Range

Surface Temperature SummarySurface 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?

© AMS 14

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

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 ResearchSuggests 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.pdfhttp://pielkeclimatesci.files.wordpress.com/2011/07/r-367.pdf