1. Introduction
So far, the predictions of climate changes are those reported in
successive
Intergovernmental
Panel on Climate Change (IPCC) reports (IPCC, 2014; IPCC, 2022) issued
from an international consensual exploitation of the available
literature to predict climate changes in distant future. The trends are
still small but nevertheless detectable today. The consensus is adopted
almost universally although controversies exist, the dispatching of
which is limited to articles in open access archives, blogs and magazine
outlets [Dunlap & Jacques, 2013].
Until recently, global climate changes were assigned to imbalanced
inputs and outputs of electromagnetic infrared radiations and to
anthropogenic greenhouse gas, especially CO2, considered
as sources of radiative anthropogenic heat release at the top of the
troposphere (rAHR) (IPCC, 2014; NASA, 2009; Mackenzie & Lerman, 2006)
without consideration to heat in the low atmosphere, notably
anthropogenic heat release (eAHR), also known as waste heat energy,
generated by the sources of energy produced and exploited by humanity
for works. In the past, only rAHR related to greenhouse gas was taken
into account and considered as absorbed predominantly by oceans (Hansen,
et al., 2011; Trenberth et al., 2014; IPCC, 2014). rAHR is said
resulting from electromagnetic radiative flux that amounted annually
from 0.5 to 1 W/m2 in the early 2000s (Trenberth et
al., 2014; IPCC, 2014), i.e. between about 8 and 16 x
1021 Joules (8 and 16 Zeta Joules (ZJ)). The AR6 IPCC
reports an observed annual average rate of heating of the climate system
at 0.79 [0.52 to 1.06] W m–2 (12.7 ZJ) for the
period 2006–2018 (IPCC, 2022). Regardless of its origin, heat energy
released or generated in the atmosphere has to be evacuated to space
otherwise it is absorbed and causes warming as it is proposed in the
case of residual radiative forcing assigned to greenhouse gas. According
to (IPCC, 2022), “ocean warming accounted for 91% of the heating
in the climate system, with land warming, ice loss and atmospheric
warming accounting for about 5%, 3% and 1%, respectively (high
confidence) ”.
In general, global ice was considered a negligible heat absorber
relative to oceans (Hansen et al., 2011; IPCC 2022). Based on
outstanding facilities including satellites, NASA is the reference body
to quantify ice imbalance and its role on the polar environment (Scott
& Hansen, 2016). The occurrence of dramatic global ice loss is now
certain, especially over the recent years, and concerns different ices,
namely ice caps, sea ice, glaciers and permafrost (Rignot et all, 2019;
Slater et all, 2021). Ices melting is generally considered as a source
of ocean rise (Allan & Liepert; 2010) on top of temperature-dependent
dilatation. Long considered negligible, eAHR is now more and more
regarded as a contributing factor to climate changes. The context and
the history are well introduced in a recent publication (Yang et al,
2017) in which the authors proposed an algorithm to evaluate global
eAHR. This approach consisted in calculations based on heat energy
estimates derived from urban zones. Although there were limitations, the
algorithm provided multi-scale anthropogenic heat information said
reliable and useable for further research on regional or global climate
changes and on urban ecosystems despite difficulties to establish ratios
for converting energy consumption to anthropogenic heat.
Earth, as living systems, is too complex to be represented
experimentally so that exploitations using climate models is necessarily
based on local measurements or on global averaged data like radiative
forcing in term of flux in W/m2. We recently attempted
a different approach (Vert, 2021) based on ice loss, fundamentals of
chemistry and physics and annual global energy consumptions derived from
various sources (fossil ones, biomass, nuclear electricity, etc.) found
converted in oil-equivalents (Martin-Amouroux, 2015; BP, 2019).
According to (Manowska, & Nowrot (2019), eAHR corresponds to c.a. 60 %
of the global energy consumption, the rest being consumed to provide
work. On the basis of this estimate, it was deduced that eAHR released
from all the energy sources in the low atmosphere between 1994 and 2017
provided enough thermal energy (7.2 ZJ) to melt 77% (Vert, 2021) of the
28 trillion tonnes of disappeared ice reported recently for the same
long period (Slater et all, 2021). The corresponding 0.31 ZJ annual
average eAHR estimate was effectively negligible when compared with the
12.7 ZJ estimate of annual average rAHR deduced from the 0.79
W/m2 annual average rate of heating of the climate
system applied to the surface of the planet (IPCC AR6, 2022). As ices
imbalance is a partial signature of heat energy supply regardless of its
origin, the large dominance of rAHr, a source of energy assigned to
CO2-based radiative forcing, raises a question: why rAHR
that is said warming the environment does not cause much greater ices
imbalance than presently observed since, in physics, any source of heat
tend to transfer part of it to its environment up to equilibrium?
In attempt to answer this question, , let us consider that solar
radiations have been heating the global environment over billions of
years without dramatic heat accumulation despite occurrence of short and
long and more or less important local ups (high temperature) and downs
(glaciation) periods. The relative stability included natural greenhouse
effect assumed the origin of a 15°C excess of average temperature
relative to an atmosphere-free Earth. eAHR, rAHR and any other sources
of heat on Earth have to be managed similarly and simultaneously to
solar heat to keep Earth’s environment and climate under relative
control and compatible with Life. Indeed, the Earth can be schematically
considered as a huge globe with land, solid matters, surface water and
atmosphere heated locally since no matter or molecule can escape in
intersidereal space. Only the energy stored in molecules can escape to
space through radiation phenomena.
A few thousand years ago, humans began to use biomass as sources of heat
and light. The generated eAHR remained very small compared with solar
inputs until about 150 years ago when humans began to exploit fossil
sources and, more recently, nuclear energy and renewable resources for
the production of electricity in order to satisfy work, heat and comfort
needs. The side effect was the appearance of increasing eAHR in the low
atmosphere in addition to rAHR in the high troposphere (Yang et al.;
2017). Therefore, Earth can be compared to a mammalian body which has
its metabolism generating heat in a closed space, the body. This body
which burns foods has to be cooled to keep its temperature constant.
Cooling is provided by the evaporation of sweat. If water cycle has been
recognized for years as an important factor in climate control (Allan &
Liepert; 2010), water evaporation and condensation have not been
considered as important to limit the storage of radiative forcing in
oceans.
The present article aims to compare Earth’s water with the refrigerant
that controls the temperature inside a refrigerator, a simpler example
than human body, where inner heat has to be eliminated. Results are
discussed relative to global warming and climate changes.