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There is an article on the BBC talking about an alarming increase of heatwaves in India. It also says that:

Average temperatures in India have risen by around 0.7% between 1901 and 2018,

partly due to climate change.

The second part is vague and it is also getting close to a stereotype. In this case it is obvious that the growth of the cities and the expansion of the urban heat islands has a role. But it won't stop there because vast tract of forests have been cut down to make space for roads, railroads and other infrastructure. I guess that also the expansion of the arable land has a role. Once the surface is flattened the winds carry quickly away the moist and the air that was refreshed by water evaporation.

Is there any study that tries to quantify these factors and estimate the impact on the temperatures rise?

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    $\begingroup$ @gansub Thanks. It's behind a paywall, but at least I cna see that some serious research is going on, $\endgroup$
    – FluidCode
    Commented Apr 24, 2023 at 11:25
  • $\begingroup$ Note that the BBC article misquotes the PIB press release: it's 0.7°C, not 0.7%. $\endgroup$
    – Jean-Marie Prival
    Commented Apr 24, 2023 at 12:01
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    $\begingroup$ @Jean-MariePrival Thanks. I didn't even notice that I copied a percentage symbol. My brain automatically translated it into a Celsius symbol. $\endgroup$
    – FluidCode
    Commented Apr 24, 2023 at 12:17
  • $\begingroup$ Are you asking about the impacts of these factors to the local measuring stations or to the global average? Are you sure that less moist air translates into reduced cooling? if the air is drier, there is a stronger evaporation to take into account (see basic fisiology engineering.mit.edu/engage/ask-an-engineer/…. ) $\endgroup$
    – EarlGrey
    Commented Apr 25, 2023 at 9:45
  • $\begingroup$ Are you assuming a link between climate change and overpopulation? if this is the case, as you stated in the now rolled back edit, please clearly state it. It is relevant to the question (but please define overpopulation). $\endgroup$
    – EarlGrey
    Commented Apr 26, 2023 at 9:23

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Regarding population growth, a quick and dirty computation is as follows:

  • a human body emits about 80W in form of heat.

  • global warming arises from an increase in radiative forcing of about 2.43W/m2 (IPCC report, chpater 6);

radiative forcing due to the increases in the well-mixed greenhouse gases from the pre-industrial (1750) to present time (1998) is now estimated to be +2.43 Wm−2

The population density increased in the time span you provided of almost a factor 6, from ~100 inhabitants/km2 to ~600 inhabitants/km2. However, at the beginning the radiative heat from human bodies alone was about 0,004 W/m2, today is a factor 6 --> 0,024 W/m2, even in absolute terms still 100 times less than the increased radiative forcing from greenhouse gases.

So no, the increase in number of living heat sources has no tangible direct effect on the temperature increase.

Answering to your Update: of course there is a link between (over)population and climate change. If the added (over)population will emit as much CO2eq as the average (please note: average, not median) western or the chinese o russian or or or citizen, then there is a linear relation ... between average temperatures anywhere in the world and the local increase in population.

Additionally, reg. your Update: please define overpopulation: do you mean that an increase of the population in India of a factor 6 between 1901 and 2018 is overpopulation, while an increase of population in California of a factor 40 between 1901 and 2018 is ... population increase?

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  • $\begingroup$ On the other hand, the densiest city in the world, Manila in the Philippines, with its >43'000 inhabitants/km2 should have some slight effect on the order of 1.72 W/m2 due to the human heat sources. $\endgroup$
    – EarlGrey
    Commented Apr 24, 2023 at 10:23
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    $\begingroup$ The issue of population growth isn't so much about the heat more bodies produce, it's more about the activities people do that contribute to warming & how much this increases because of more people engaging in those activities. If you want to find the effect produced by warm human bodies it must also be compensated for by the loss of animals that have been displaced by humans, that once lived in areas now being colonized/invaded by humans. $\endgroup$
    – Fred
    Commented Apr 24, 2023 at 18:58
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    $\begingroup$ Population growth results in larger cities with more buildings, more streets, and more parking lots. Population growth also results in more land being converted to agricultural purposes. While body heat is irrelevant, all of these and more do measurably contribute to climate change. $\endgroup$
    – David Hammen
    Commented Apr 25, 2023 at 1:03
  • $\begingroup$ @DavidHammen absolutely. That is way I state the increase in number of living heat sources has no tangible direct effect. There are all sort of indirect effects, the ones you describe and the one OP briefly and axiomatic introduced, such as "the winds carry quickly away the moist and the air that was refreshed by water evaporation." which I think it is wrong, as it is currently formulated (less moisture => more evaporation and therefore more cooling). $\endgroup$
    – EarlGrey
    Commented Apr 25, 2023 at 9:32
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    $\begingroup$ @EarlGrey "There are all sort of indirect effects, the ones you describe and the one OP briefly and axiomatic introduced ..." If the question is not well written the addition of word plays and fussy lawyers does not help. $\endgroup$
    – FluidCode
    Commented Apr 25, 2023 at 10:22

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