- 4288 - VENUS AND EARTH - The Earth is a wonderful blue and green dot covered with oceans and life, while Venus is a yellowish sterile sphere that is not only inhospitable but also sterile. The runaway greenhouse effect can transform a temperate habitable planet with surface liquid water ocean into a hot steam dominated planet hostile to any life.
------------------------- 4288 - VENUS AND EARTH
- However, the
difference between the Earth and Venus is only a few degrees in temperature. A
team of astronomers has achieved a world's first by managing to simulate the
entirety of the runaway greenhouse process that can transform the climate of a
planet from idyllic and perfect for life, to a place more than harsh and
hostile.
-
- The scientists
have also demonstrated that from initial stages of the process, the atmospheric
structure and cloud coverage undergo significant changes, leading to an
almost-unstoppable and very complicated to reverse runaway greenhouse effect.
-
- On Earth, a
global average temperature rise of just a few tens of degrees, subsequent to a
slight rise of the sun's luminosity, would be sufficient to initiate this
phenomenon and to make our planet inhabitable.
-
- The idea of a
runaway of the greenhouse effect is not new. In this scenario, a planet can
evolve from a temperate state like on Earth to a true hell, with surface
temperatures above 1,000°C.
-
- The cause? Water
vapor, a natural greenhouse gas. Water vapor prevents the solar irradiation
absorbed by Earth to be reemitted towards the void of space, as thermal
radiation. It traps heat a bit like a rescue blanket. A dash of greenhouse
effect is useful, without it, Earth would have an average temperature below the
freezing point of water, looking like a ball covered with ice and hostile to
life.
-
- On the opposite
side, too much greenhouse effect increases the evaporation of oceans, and thus
the amount of water vapor in the atmosphere.
There is a critical threshold for this amount of water vapor, beyond
which the planet cannot cool down anymore. From there, everything gets carried
away until the oceans end up getting fully evaporated and the temperature
reaches several hundred degrees.
-
- One of the key
points of the study describes the appearance of a very peculiar cloud pattern,
increasing the runaway effect, and making the process irreversible. From the start of the transition, we can
observe some very dense clouds developing in the high atmosphere.
-
- This discovery is a
key feature for the study of climate on other planets, and in particular on
exoplanets, planets orbiting other stars than the sun. How could this cloud pattern create a
specific signature, or 'fingerprint,' detectable when observing exoplanet
atmospheres.
-
- A planet Earth in
a fragile equilibrium. With their new
climate models, the scientists have calculated that a very small increase of
the solar irradiation leading to an increase of the global Earth temperature,
of only a few tens of degrees. This
would be enough to trigger this irreversible runaway process on Earth and make
our planet as inhospitable as Venus.
-
- One of the current
climate goals is to limit global warming on Earth, induced by greenhouse gases,
to only 1.5° by 2050. The Earth is thus
not so far from this apocalyptical scenario.
Assuming this runaway process would be started on Earth, an evaporation
of only 10 meters of the oceans' surface would lead to a 1 bar increase of the
atmospheric pressure at ground level.
-
- In just a few
hundred years, we would reach a ground temperature of over 500°C. Later, we
would even reach 273 bars of surface pressure and over 1,500°C, when all of the
oceans would end up totally evaporated.
-
- Well, I can not wait for this to happen!
-
-
December 27, 2023
VENUS AND
EARTH 4288
------------------------------------------------------------------------------------------
-------- Comments
appreciated and Pass it on to whomever is interested. ---
--- Some reviews are
at: -------------- http://jdetrick.blogspot.com -----
-- email feedback,
corrections, request for copies or Index of all reviews
--- to: ------
jamesdetrick@comcast.net
------ “Jim Detrick” -----------
--------------------- ---
Wednesday, December 27, 2023 ---------------------------------
No comments:
Post a Comment