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.
Key Points
- 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[2008] 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.
Simon says:
October 2, 2012 at 11:58 pm
This is very picky subject to be sure! Could I take a very idealistic example to show you what I think is correct and how any adjustments should be made?
Take 10,000 equally spaced points on this globe, 1000 of those coincide with population centers. the thermometers recorded to represent an average global temperature are all at the 1000 cities. If all cities have a population of one a century ago and if all 1000 said 25C the average would be 25C and correct. Now fast forward to today. Each city has one million and even though the 9000 say 25C the cities are now 27C.
Ok, are the readings in the cities correct. Yes. Should they be adjusted? I say no. They are scientifically correct. Do these small warmer areas really affect the global average? YES! The average global temperature now says 27C with a 2C per century slope, all readings are in the cities. Is that the REAL average global temperature. NO! The real unrealized average is nine tenths 25C plus one tenth of 27C or 25.2C with a slope of 0.2C per century.
That is the real situation. It is the calculation of the mean that is in error, not the individual station readings. Do you ever see this type of adjustments to the calculation being performed? NO! That is the problem.
Also Simon, I didn’t play in the area weighting for the small area occupied by just the cities and this magnifies that error even more.
@Philip Bradley
>Waste heat will have minimal spatial extent (try detecting the waste heat from your house 500 meters away). Whereas aerosols have well documented effects tens to even hundreds of kilometers from their source.
Someone with knowledge about aerosols (condensed particles) and other (agglomerated or accumulated) particles is Dr Tami Bond (U of Illinois) who is quite an expert on the subject of black carbon and heating potential downwind. Without offending most people (unlike the majority of bloggers 🙂 she has brought this carefully to the fore including testimony to Congress. Another contributor to the science is Prof Philip Hopke (Clarkson) who develops aethelometers for measuring BC nanoparticles, heretofore missing from the measurements because they do not interact with visible light. It may interest researchers to consider that as the UV radiation level increases during solar max (faculae and all that) these BC nanoparticles, collectively called ultrafine particulate matter (UFP), come into play. As the wave length descreases, the UFP’s play a more important direct atmospheric heating role. There are masses of UFP’s in the atmosphere resulting from burning any and everything. Bursts of EUV light up these particles, literally (if you could see them) and they happily float around the entire atmosphere.
For those not following the above, the maximum size of particle can will react with visible light is about 0.1 microns and the efficiency of doing so is low (1-5%?). Thus black carbon (BC) is considered an important heating influence on the atmosphere but discussion to date has not recognized what were ‘invisible particles’. Organic Carbon (OC) is whitish and has a cooling effect. Both are created by burning biomass (badly), as in forest fires. Diesel engines, even ‘very clean ones’ produce large numbers of BC UFP’s and are rated ‘clean’ because the compliance equipment used does not detect nanoparticles. It borders on humorous.
Crispin in Singapore’s perpetual summer says:
October 3, 2012 at 6:59 pm
that’s interesting, but I’m not sure of the implications.
so, in a nutshell, there seems some indication that BC and UFP’s are potentially ‘very warming’? Is it being suggested they are the ‘equivalent’ of a GHG as they are widespread in the atmosphere and are absorbing UV energy? If so, are these particles not doing something that would happen to the UV anyway (i.e. absorbing it) when it reaches the surface? It strikes me this could well account for atmospheric warming to some degree, whilst preventing energy reaching the surface and thereby causing ‘surface’ cooling?
I’m a bit curious, as this also harks back to the ‘absorbing’ atmosphere issue again – whereby our amazing atmosphere has this ability to trap heat and never release it back to space (/sarc?).
Human patterns of energy consumption have a large effect on surface temperature trends — as misrepresented by urbanized stations. The actual amount of energy introduced into the troposphere by said consumption is too trivial to create any real general effect.
@Kev-in-Uk
>that’s interesting, but I’m not sure of the implications.
>so, in a nutshell, there seems some indication that BC and UFP’s are potentially ‘very warming’?
It has been known for a long time that BC particles are very warming, but it was always played down (see early IPCC references to them falling to the ground early (within 10 days of source) and only having a ‘local effect’. Per kg (which is not a fair comparison) BC has about 640 times the heating effect of CO2 but recall my contribution above that it only picks up a wavelength that is related to its physical size.
Consider: if there are no UFP’s there is no heating in the atmosphere at that point. If there are UFP’s and there is a high energy, short-enough-wavelength photon incoming it is going to capture it (because it is black). The interesting thing that happens is that the ozone which would have been created instead, is not.
There are hints that the altitude at which ozone is created varies with solar activity, right? Could BC/OC be affecting this? It would not be for the first time that an element of misdirection was involved in our analyses. The total solar energy output doesn’t vary much, leading to thoughts that it ‘can’t matter’ yet the upper spectrum of that energy changes a lot. So it might matter, or matter a lot.
>Is it being suggested they are the ‘equivalent’ of a GHG as they are widespread in the atmosphere and are absorbing UV energy?
The effect per kg is far greater than a GHG or ice but the total mass is such that there is a reduced overall effect. It is presently assumed (hard to test etc) that is it about 20% of the GHG effect but I am not up to date. I believe that privately it is thought to be much higher but the ears cannot bear to hear the message. Suppose it was 40%. What are the implications? The main one is that CO2’s 0.8 per doubliing is perhaps 0.5 deg. To me, that is significant and worth investigating.
>If so, are these particles not doing something that would happen to the UV anyway (i.e. absorbing it) when it reaches the surface?
They are certainly interacting with suitably sized particles (anything above a certain size depending on their wavelength). The only thing I have seen referenced is ozone and UV, but BC and OC in the same ‘sphere of influence’ will be in the mix. OC will reflect it, for sure. Remember when conceptualising this that you cannot see these particles at all. They are transparent as far as our eyes are concerned.
>It strikes me this could well account for atmospheric warming to some degree, whilst preventing energy reaching the surface and thereby causing ‘surface’ cooling?
Good thoughts and worth considering as part of the whole. It is probably worth honing in on the UV because it is so variable and it is already known to affect ozone altitude of formation. It is now clear that BC and OC are floating around at nearly all altitudes (you can collect them at 40,000 ft sitting in your ‘steerage’ seat watching bad re-runs). They do not ‘fall to earth’ in the vicinity of where they are created.
Consider: when they do eventually fall or grow in size and fall, they and maybe end up on ice somewhere enhancing the dirty snow effect. But the measurement of dirty snow is limited to large-ish particles so the effect of present/absent UFP is not perhaps considered. But there is less effect on the ground anyway. It is probably going to be the most interesting to find out what happens in the regions where ‘we want’ ozone to form.
Crispin in Singapore’s perpetual summer says:
October 5, 2012 at 3:36 pm
just seen your post….
you say ”Consider: if there are no UFP’s there is no heating in the atmosphere at that point. If there are UFP’s and there is a high energy, short-enough-wavelength photon incoming it is going to capture it (because it is black). The interesting thing that happens is that the ozone which would have been created instead, is not.”
so you are suggesting that UFP’s may prevent ozone formation by ‘capturing’ uv that would have otherwise formed said ozone? as for the UFP’s actually capturing UV, you’ve already hinted it will be wavelength dependent? Is ozone forming UV the same wavelength as that potentially captured by UFP’s?
As a slight aside, surely most atmospheric molecules can technically capture UV? I’m not sure I buy the ‘it has to be black’ suggestion! My physics is old and rusty, but I would have thought the capturing issue is more due to the particle size and molecular constituents rather than its colour! IIRC correctly, the photon capture (whether UV or whatever) is essentially due to the wavelength and receptiveness or ‘need’ to a photon of the molecule itself – for example, is it +ve or -ve charged, etc, etc…..but I have no intention of rereading my old physics stuff as I’ve no doubt its out of date (like me!).
I think the dirty snow thing is completely different – being that this is mostly absorbing IR – or have I got that wrong?
I could also query whether these UFP’s are actually persistent in the atmosphere – meaning that, unless they are essentially nonvalent, inert type molecules, they could presumably react with something else? (even if it was simply being absorbed into/onto water droplets!) That’s enough brain/memory thoughts for a saturday night….ouch……
regards
Kev