In our papers
Pielke Sr., R.A., C. Davey, and J. Morgan, 2004: Assessing “global warming” with surface heat content. Eos, 85, No. 21, 210-211
and
Davey, C.A., R.A. Pielke Sr., and K.P. Gallo, 2006: Differences between near-surface equivalent temperature and temperature trends for the eastern United States - Equivalent temperature as an alternative measure of heat content. Global and Planetary Change, 54, 19–32
we urged the adoption of a more complete measure of heat content trends in the near-surface atmosphere (i.e. moist enthalpy).
Thanks to Souleymane Fall of Purdue for alerting us to a new paper which has built on this idea with important new insight into this climate metric.
The paper is
Rogers, J.C., S.H. Wang, and J.S.M. Coleman, 2007: Evaluation of a Long-Term (1882–2005) Equivalent Temperature Time Series. J. Climate, 20, 4476–4485.
The abstract reads
“A 124 (1882-2005) summer record of total surface energy content consisting of time series of surface equivalent temperature (TE) and its components T (mean air temperature) and Lq/cp(moist enthalpy, denoted Lq) is developed, quality controlled, and analyzed for Columbus, Ohio, where long records of monthly dewpoint temperature are available. The analysis shows that the highest TEoccurs during the summer of 1995 when both T and Lq were very high, associated with a severe midwestern heat wave. That year contrasts with the hot summers of 1930-36, when Lq and TEhad relatively low or negative anomalies (low humidity) compared to those of T. Following the 1930-36 summers, T and Lq departures are much more typically the same sign in individual summers, and the two parameters develop a statistically significant high positive correlation into the twenty-first century. Mean T and Lq departures from the long-term normal have opposite signs, however, when summers are stratified either by seasonal total rainfall amounts or by the Palmer drought severity soil moisture index. Normalized trends of T, Lq, and TE are downward from 1940 to 1964 with those of TE exceeding T. Since 1965, however, significant positive T trends slightly exceed TEin magnitude and those of dewpoint temperature and Lq are comparatively lower. A highly significant upward trend in minimum temperatures especially dominates the T variability, creating a significant downward trend in the temperature range that dominates recent summer climate variability more than moisture trends. Regional moisture flux variations are largest away from Columbus, over the upper Midwest and western Atlantic Ocean, during its seasonal extremes in total surface energy.”
In the assessment of global warming (and global cooling), this research further shows that unless the role of near surface vapor trends are included, a quantitatively erroneous assessment will necessarily result. Thus, when a media report or scientific paper claims that a certain increase (or decrease) in temperatures have occurred over a period of years, this cannot by itself, be used to say this is warming or cooling (in terms of heat), unless the changes in water vapor concentrations are simultaneously assessed so that moist enthalpy changes are computed.