- 4107 - ATLANTIC
OCEAN - is heating up, why? The ocean system, known as the “Atlantic
Meridional Overturning Circulation” (AMOC) had previously been measured to be
dramatically weakening in conjunction with rising ocean temperatures.
-
-------------- 4107 - ATLANTIC OCEAN - is heating up, why?
- Shutting down the Atlantic
Meridional Overturning Circulation can have very serious consequences
for Earth’s climate by changing how heat and precipitation are distributed
globally. Finding that direct
measurements of the AMOC's strength have only been made for the past 15 years.
-
- Scientists applied sophisticated
statistical tools to ocean temperature data going all the way back to the
1870s. This detailed analysis ultimately suggested significant warning signs of
the AMOC shutting down between 2025 and 2095, with a staggering certainty of
95%. The most likely time for this
collapse would be around 2057.
-
- The AMOC, which includes the Gulf Stream as
part of its system, is our planet's main mode of transporting heat away from
the tropics. Without it, the tropics would rapidly increase in temperature
while vital tropical rains get disrupted. Such rains are essential for the
environments of South America, western Africa as well as in India and other
regions of south Asia.
-
- Meanwhile, northern and western Europe would
lose their source of warm water from the tropics, leading to more storms and
severely cold winters in these areas. The loss of the Gulf Stream in particular
would also result in rising sea levels on the US’ eastern seaboard.
-
- We have already seen the dangers of
human-induced climate warming play out as heatwaves grip much of the northern
hemisphere. And although the loss of the AMOC may see northern and western
Europe cool, this shutdown will contribute to an increased warming of the
tropics where rising temperatures have already given rise to challenging living
conditions.
-
- It’s easy to think of Earth as a water
world, with its vast oceans and beautiful lakes, but compared to many worlds,
Earth is particularly wet. Even the icy moons of Jupiter and Saturn have far
more liquid water than Earth. Earth is unusual not because it has liquid water,
but because it has liquid water in the warm habitable zone of the Sun.
-
- Water is one of the more common molecules
in the universe. Hydrogen is the most abundant element, and oxygen is easily
produced as part of the stellar CNO fusion cycle. So we would expect water-rich
planets to be plentiful in stellar systems.
-
- In our solar system, two kinds of worlds
have liquid water. Earth and gas giant moons.
Like other warm terrestrial planets such as Venus and Mars, Earth had
liquid water in its youth. Mars was too small to retain its water. Much of it
evaporated into space, while some froze into its surface crust.
-
- Venus was large enough to retain water, but
its extreme heat boiled much of it off into its thick atmosphere. We still
aren’t entirely sure how Earth managed to retain its oceans, but it was likely
a combination of a strong magnetic field and an extra helping of water from
asteroids and comets during the heavy bombardment period.
-
- The icy moons of Jupiter and Saturn were
far enough from the Sun that they retained the water of their formation. They
quickly formed a thick layer of ice to prevent water from evaporating into
space. But these moons are small worlds and would have very quickly frozen
solid were it not for the tidal forces exerted by their gas giant.
-
- Since cold gas planets are likely to have
icy moons, the general thought we would be far more likely to find life on a
Europa-like world than an Earth-like one. But this new study begs to differ. It
argues that liquid water is much more likely to be found on super-Earths.
-
- Super-Earths span a mass range from a
couple of Earth masses to Neptune mass. On the large end, they are likely to be
gassy worlds with thick atmospheres. On the small end, they are likely to be
more Earth-like. Based on the exoplanets we’ve found so far, super-Earths are
by far the most common. And a majority of them are likely to be outside their
star’s habitable zone in the cold regions of the star system. So they are
likely water-rich.
-
- The reason has to do with the various
freezing and melting points of ice. The kind of ice we have on Earth melts at
around 0 °C. But this is only true at around Earth’s atmospheric pressure. At
higher pressures, there are several varieties of ice with differing melting
points. Although it’s a bit complicated, generally at higher pressures ice can
have a much higher melting point. So even if a super-Earth is geologically
active, it might not be warm enough to melt ice.
-
- This new study shows that super-Earths don’t
have to be hot enough to create a deep ocean. Through geothermal and nuclear
heating it can melt a thin layer of water at its surface, and thanks to
fissures and various water phase transitions water can creep up to the layer
just below the frozen surface. This process would be enough to create a rich
ocean layer of liquid water. Since the heat of a super-Earth lasts billions of
years, it could maintain a liquid ocean long enough for life to evolve.
-
- Based on what we know about exoplanets,
super-Earth oceans could be 100x more common than those of Earth-like worlds or
icy moons. And that means life has even more possible homes than we thought.
-
- No worries.
We can just move to another planet that has oceans of water. It’s easy to think of Earth as a water world,
with its vast oceans and beautiful lakes, but compared to many worlds, Earth is
not particularly wet.
-
- Even the icy moons of Jupiter and Saturn
have far more liquid water than Earth. Earth is unusual not because it has
liquid water, but because it has liquid water in the warm habitable zone of the
Sun.
-
- Water is one of the more common molecules in
the universe. Hydrogen is the most abundant element in the cosmos, and oxygen
is easily produced as part of the stellar CNO fusion cycle. So we would expect
water-rich planets to be plentiful in stellar systems. But that isn’t to say
liquid water will be plentiful. In our solar system, two kinds of worlds have
liquid water. Earth and gas giant moons.
-
- Like other warm terrestrial planets such as
Venus and Mars, Earth had liquid water in its youth. Mars was too small to
retain its water. Much of it evaporated into space, while some froze into its
surface crust. Venus was large enough to retain water, but its extreme heat
boiled much of it off into its thick atmosphere.
-
- We still aren’t entirely sure how Earth
managed to retain its oceans, but it was likely a combination of a strong
magnetic field and an extra helping of water from asteroids and comets during
the heavy bombardment period.
-
- The icy moons of Jupiter and Saturn are
another story. They were far enough from the Sun that they retained the water
of their formation. They quickly formed a thick layer of ice to prevent water
from evaporating into space. But these moons are small worlds and would have
very quickly frozen solid were it not for the tidal forces exerted by their gas
giant.
-
- Since cold gas planets are likely to have
icy moons, the general thought we would be far more likely to find life on a
Europa-like world than an Earth-like one.
Liquid water is much more likely to be found on super-Earths.
-
- Super-Earths span a mass range from a
couple of Earth masses to Neptune mass. On the large end, they are likely to be
gassy worlds with thick atmospheres. On the small end, they are likely to be
more Earth-like. Based on the exoplanets we’ve found so far, super-Earths are
by far the most common.
-
- And a majority of them are likely to be
outside their star’s habitable zone in the cold regions of the star system. So
they are likely water-rich. But they also aren’t likely to be found orbiting a
gas giant, so it’s generally been assumed that their ice layer would be mostly
frozen solid over time.
-
- The reason has to do with the various
freezing and melting points of ice. The kind of ice we have on Earth melts at
around 0 °C. But this is only true at around Earth’s atmospheric pressure. At
higher pressures, there are several varieties of ice with differing melting points.
Although it’s a bit complicated, generally at higher pressures ice can have a
much higher melting point. So even if a super-Earth is geologically active, it
might not be warm enough to melt ice.
- This new study shows that super-Earths
don’t have to be hot enough to create a deep ocean. Through geothermal and
nuclear heating it can melt a thin layer of water at its surface, and thanks to
fissures and various water phase transitions water can creep up to the layer
just below the frozen surface. This process would be enough to create a rich
ocean layer of liquid water. Since the heat of a super-Earth lasts billions of
years, it could maintain a liquid ocean long enough for life to evolve.
-
- Based on what we know about exoplanets,
super-Earth oceans could be 100x more common than those of Earth-like worlds or
icy moons. And that means life has even more possible homes than we thought.
-
-
July 28, 2023 ATLANTIC
OCEAN - is heating up, why? 4107
------------------------------------------------------------------------------------------
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Sunday, July 30, 2023
---------------------------------
