Dr. Roger Pielke Sr. highlighted this major new paper in JGR yesterday, I consider it important as it relates to the works I’m doing on station siting. The key points of the paper are supportive of what I’ve been saying for years, and show a significant effect on temperature trends, just as we’ve noted in the discussion paper Watts et al 2012.
- Temperature trends are correlated to the intensity of human activity
- Local warming is highly dependent on energy consumption pattern in urban areas
- The local effects on temperature trends is 0.14 to 0.25°C/decade
Yan Li, Key Laboratory for Earth Surface Processes, Peking University, Ministry of Education, Beijing, China, College of Urban and Environmental Sciences, Peking University, Beijing, China
Xinyi Zhao, Key Laboratory for Earth Surface Processes, Peking University, Ministry of Education, Beijing, China, College of Urban and Environmental Sciences, Peking University, Beijing, China
Abstract: (bold and paragraph formatting mine)
Human activity is an important contributor to local temperature change, especially in urban areas. Energy consumption is treated here as an index of the intensity of human induced local thermal forcing. The relationship between energy consumption and temperature change is analyzed in China by Observation Minus Reanalysis (OMR) method. Temperature trends for observation, reanalysis and OMR are estimated from meteorological records and 2 m-temperature from NCEP/NCAR Reanalysis 1 for the period 1979–2007.
A spatial mapping scheme based on the spatial and temporal relationship between energy consumption and Gross Domestic Production (GDP) is developed to derive the spatial distribution of energy consumption of China in 2003. A positive relationship between energy consumption and OMR trends is found in high and mid energy consumption region. OMR trends decline with the decreasing intensity of human activity from 0.20°C/decade in high energy consumption region to 0.13°C/decade in mid energy consumption region.
Forty-four stations in high energy consumption region that are exposed to the largest human impact are selected to investigate the impact of energy consumption spatial pattern on temperature change. Results show human impact on temperature trends is highly dependent on spatial pattern of energy consumption. OMR trends decline from energy consumption center to surrounding areas (0.26 to 0.04°C/decade) and get strengthened as the spatial extent of high energy consumption area expands (0.14 to 0.25°C/decade).
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, D17117, 12 PP., 2012
One of the key passages of the paper Dr. Pielke highlighted was this:
Besides the impact of land use change on climate, the thermal impact induced by human activity within city plays significant role and should not be ignored. One of them is the anthropogenic heat released from energy consumption. Several studies have shown that anthropogenic heat is important to the development of UHI. Simulation results from a case study in Philadelphia suggested that anthropogenic heat contributes about 2~3C to the nighttime heat island in winter [Fan and Sailor, 2005].
Here’s one of the maps from the paper, showing the areas of highest energy consumption with meteorological station locations plotted on the map:
Here’s a plot of Nanjing’s (in the red zone on the coast) temperature from NASA GISS, note how the trend is basically flat until 1990. Obviously the station data didn’t make it to GISS for awhile after 1990, but when it resumed, what a difference there was:
Now look at Fuzhou, also in the coast, but not in the red zone of energy consumption:
In the conclusion:
Our results show significant warming has occurred for most stations in China and the magnitude of warming is closely related to energy consumption, which represents the intensity of human activity. For high and mid energy consumption group, OMR trends decline with the decrease of energy consumption. OMR trends for high and mid energy consumption group is 0.20 and 0.13C/decade respectively. Stronger warming is observed for station with high energy consumption, which usually locates in or near cities. Therefore, the strong warming is more likely a consequence of the local thermal forcing induced by human activity.
It seems that stations belong to high and mid energy consumption group in this study are affected
by human impact to a discernible extent. Just as De Laat demonstrated, anthropogenic heat released from energy consumption may very well have contributed to the observed temperature change patterns.Thus, it may raise more attention to consider the influence of human activity on surface temperature records in the past and next decades.
The bottom line – energy consumption matters, UHI matters, siting matters. Stations that are free of those issues should be the ones we base our land surface temperature record on. NCDC has already proven this point by commissioning the Climate Reference Network, guaranteed from its inception to be free of these issues.