Are
urban heat islands correctly defined and what is the big deal for climate
warming. By
Dr Chris Barnes, Manager at Bangor
Scientific and Educational Consultants http://bsec_wales.co.uk First Published online 10th
February 2025
Abstract
Urban heat islands (UHI) cause and
effect are briefly described and reviewed.
The paper enquires if we are correct about the
causes of and components of UHI.
Calculations are made which show that waste heat has a far more major
part to play in modern day UHI than previously acknowledged and the work of
Bian (2020) in this respect is supported.
In a large city the waste heat contribution to UHI is shown to be
some 1.6K to 2,7 K. Averaged over the world this represents
about 50 milli-Kelvin of warming which is greater than the figure for CO2 alone
as supplied by Smirnov and some 25% of the all cause warming figure quoted by Smirnov. Electricity distribution networks are also
briefly considered as a special case of waste heat and other energetic radiations capable of causing environmental change. for example,
interactions between HVAC power
lines and space weather and has shown
there to be a very significant climatic effect, http://www.drchrisbarnes.co.uk/eep.htm
The upshot of that work is that we
need either to switch entirely to HVDC
transmission or generate all power locally I order to remove the
climatic effects of power generation.
Given that it has now been shown that the planet has a relatively fixed adiabatic lapse rate substantially independent of gaseous atmospheric composition, means that we can
never, ever get rid of waste heat effects and no amount of decarbonisation will do so. The big deal
for climate is that Net Zero will have just that. Zero effect, absolutely zilch!! The counter suggestion made here is that we would be better employed simply re-cycling
as much heat as we can and using
local all local power
generation. Failing that use HVDC
transmission or undergrounded HVAC transmission. Likewise, we can redesign our cities and
our houses to have less UHI.
Introduction
Typically an urban heat island is
defined thus : "The relative warmth of a city compared with surrounding
rural areas." This relative warmth is caused by "heat trapping due to land
use, the configuration and design of the built environment, including street layout and
building size, the heat-absorbing properties of urban building materials,
reduced ventilation, reduced greenery and water features, and domestic and
industrial heat emissions generated directly from human activities".
Figure
1
Generally speaking, the difference in temperature
between the urban and surrounding rural area is more pronounced at night than
in daytime. For example, in the
United States, the temperature in urban areas tends to be warmer than the
surrounding area by about 1–7 °F (0.6–4 °C) during the daytime, and
about 2–5 °F (1–3 °C) warmer at night. However, the difference
is more pronounced during the day in arid climates such as those in
southeastern China and Taiwan. Studies have shown that diurnal variability is
impacted by several factors including local climate and weather, seasonality,
humidity, vegetation, surfaces, and materials in the built environment.
Are we
correct about UHI?
Traditionally,
the idea is that the combination of concrete, bricks and tarmac acts in
conjunction with the underlying soil as a sort of ‘storage heater’. Heat is trapped and slowly released exactly
as in a real storage heater.
Moreover,
where there are skyscrapers, these can act as to further funnel the sun’s rays
to the ground by way of multiple downward reflections but also to confine
access to updrafts for later and subsequent heat removal by convection.
The
difficulty with the definition comes in two parts. First is assessing the relationship with Global Heating. Are we looking at a driver or an
amplifier? Second, is assessing the
dominant component, i.e. physical heat trapping or anthropogenic
emission.
The fact
that temperature records in rural areas show completely different trends and
significantly lower trends of increase from those in built up and city
areas tends to suggest that UHI is a driver of change
rather than an amplifier. Yet many
texts insist otherwise. One interesting
piece of work describes that UHI has contributed a spurious +.1C to overall
temperature records in the Northern Hemisphere ( NH) in the first 8 decades of
the 20th Century. The Effect of Urban Warming on the Northern Hemisphere
Temperature Average in: Journal of Climate Volume 2 Issue 3 (1989)[1]
In China for the period 1961-2023 it is estimated that UHI has given rise to almost 0.5 C of warming or over a third of all warming.
Lui et al
(2022) [2] found through
statistical analyses of satellite land surface temperatures (2002 to 2021), they
found that the mean surface warming trend is
0.50 ± 0.20 K·decade−1 (mean ± one S.D.) in the urban
core of 2000-plus city clusters worldwide, and was 29%
greater than the trend for the rural background.
I would
suggest inspection of figure 1 above to be instructive. The data indicates total UHI in cities is
approximately twice that in suburbs.
This suggests that a maximum of circa 2C is the ‘city’ effect. That is about 50% of the total observed
warming.
Waste
Heat: the real culprit
It is
very instructive to make a waste heat calculation here. Under
clearest sky conditions a maximum of
1140 W/m^2 has been recorded at the earth’s surface. Averaged over the whole earth surface,
however, this falls to some 200 W/m^2. Assume this, long term, gives rise to an
average earth temperature of some 387K. An average house between both gas and
electricity will be using an instantaneous
power of circa 1.5 KW.
Ultimately, about half of this energy finishes up as waste heat. Let the
house have an area of 250m^2 and be
losing 750 watts. This translates to
about 3 watts/m^2. 3 W/m^2 is 1.5% of the incoming solar
energy. This increase 387K by 1.5% yields
5.3K. In a high
density city about 30-50% of the area is houses and buildings. This yields a
figure of between 1.6K and 2,7 K.
Indeed Bian 2020
Environ Syst Res [3] https://doi.org/10.1186/s40068-020-00169-
Also concur the present author’s findings.
This is
suggestive of the fact that waste heat alone can more than account for the
‘city effect’ and has even a far greater part to play in actual or perceived
warming then previously acknowledged. Moreover, as technology has advanced far
more homes have both summer air conditioning and winter central heating.
The next
question to answer is the degree to which UHI informs or causes modern warming.
One
possible problem is that the majority of
temperature stations tend to be in urban and built up
areas. Urban
areas are heavily overrepresented in the siting of temperature stations: less
than 1% of the globe is urban but 27% of the Global Historical Climatology
Network Monthly (GHCN-M). This can only cause
an over exaggeration of both warming and
be problematic for figures being fed into present climate models.
In reality thus averaged over the globe the
waste heat component of UHI is probably responsible for about
50 milli- Kelvins of warming.
But likewise anthropogenic
warming usually ascribed to CO2 has also been vastly overestimated as a result of the above.
In this respect Smirnov 2019 is extremely instructive and shows all the warming due to
CO2 alone to amount to a mere 20 milli Kelvin since 1850 and all cause warming to be only 0.4 C or 400 milli Kelvin., see
Smirnov (2019) [4]
Waste heat and power radiated from world Electricity distribution networks.
There is
one other element of energy production worthy of mention and this has been raised by the present
author elsewhere, http://www.drchrisbarnes.co.uk/eep.htm [5]
This is in connection with electrical energy
transmission. It is known that in HVAC
transmission systems losses amount to about 6% and about half of that figure
for HVDC.
By
extension we can conclude since most
transmission in the world is HVAC that some 3% of losses are I^2R and will add a few millikelvins to the above
figure. However where do the other 3% of losses go? The subtle difference is that AC lines
radiate EM energy whereas DC do not significantly. The author has previously dealt with the interaction between HVAC power lines and space
weather and has shown there to be a very
significant climatic effect, [5]. Indeed prior to the
author’s work, the World's HVAC power grids were a hitherto unconsidered cause
of climate and wx. changes. Yet the leaked power harmonics they radiate
into space could be many hundreds or even thousands of times the power of
HAARP!!
The upshot of that work is that we need either to switch entirely to
HVDC transmission or generate all power
locally I order to remove the climatic effects of power generation.
Future thoughts on UHI/Waste Heat: A massive deal for climate
and the farce of Net Zero.
Given a
fixed adiabatic lapse rate independent of atmospheric composition, as
explained in the work of Nikolov and
Zeller, (2017) [6] and very importantly also Ned Nikolov & Karl Zeller: Exact Calculations of Climate
Sensitivities Reveal the True Cause of Recent Warming – Iowa Climate Science
Education May 2022 [7] means that we
can never, ever get rid of waste heat
effects and no amount of decarbonisation will do so. The big deal for climate is that Net Zero will have just
that. Zero effect, absolutely zilch!! The counter suggestion I would make here is that we would be better employed simply re-cycling
as much heat as we can and using
local all local power
generation. Failing that use HVDC
transmission or undergrounded HVAC transmission. Likewise, we can redesign our cities and
our houses to have less UHI.
Inevitable warming and factors which we could control.
Even with the above precautions, some anthropogenic warming
may continue. Moreover, natural
warming due to as yet
poorly understood natural solar cycles and/or earth tilt/ and or earth
hydrology/ and/or earth cloud cover could also happen or be happening.
In any
event, the author is not in favour of dangerous chemical means of climate
control such as Stratospheric Injection. However, in his opinion, it may be possible
using simple aviation cloud, adjusted
for seasons and times of day and OTHER innocuous types of seeding for cloud production or removal to produce
virtually any type of weather or climate we seek. Moreover, given the effects of EEP,
electromagnetic methods of climate control should also not be overlooked.
References
1.
. The
Effect of Urban Warming on the Northern Hemisphere Temperature Average in:
Journal of Climate Volume 2 Issue 3 (1989)
2.
https://www.nature.com/articles/s43247-022-00539-x
3.
https://doi.org/10.1186/s40068-020-00169-
4.
https://link.springer.com/article/10.1134/S0018151X19040199
5.
http://www.drchrisbarnes.co.uk/eep.htm