
© ESA/Herschel/NASA/JPL-Caltech, CC BY-SA 3.0 IGO; Acknowledgement: R. Hurt (JPL-Caltech)
This mosaic combines several observations of the Taurus Molecular Cloud performed by ESA's Herschel Space Observatory. Located about 450 light-years from us, in the constellation Taurus, the Bull, this vast complex of interstellar clouds is where a myriad of stars are being born, and is the closest large region of star formation.
During almost four years of observing the cosmos, the Herschel Space Observatory traced out the presence of water. With its unprecedented sensitivity and spectral resolution at key wavelengths, Herschel revealed this crucial molecule in star-forming molecular clouds, detected it for the first time in the seeds of future stars and planets, and identified the delivery of water from interplanetary debris to planets in our solar system.
Water is essential to life as we know it on Earth. It covers over 70 percent of our planet's surface and is present in trace amounts in the atmosphere. While it may seem abundant, especially if we're looking at the blue-hued stretch of a lake, sea or ocean, water is only a minor component of the total mass of Earth.
In fact, it is not at all clear whether the water that is currently present on our blue planet was there around the time of its formation, 4.6 billion years ago, or it is was delivered by later impacts of smaller celestial objects.
According to one of the leading theories to explain how the solar system came into being, Earth and the inner
planets were extremely hot and dry for the first several hundred million years after their formation. In this scenario, water was delivered to these planets only later by violent impacts of small bodies such as meteorites, asteroids, and/or comets - the remaining debris of the protoplanetary disc out of which the planets and their moons took shape.
Comment: The real story is more nuanced. It is possible to have both Arctic ice gain and melting permafrost, if you don't try to ascribe them to the same mechanisms.
Melting permafrost is associated with methane pockets bubbling up to the surface. This implies heating from within, such as undetected movements of magma
- Melting permafrost methane emissions: The other threat to climate change
- Methane outgassing from Arctic lakes faster than ever
- Greenland ice sheet is melting but much of the heating is coming from inside the earth
and, there can still be a general cooling trend if one looks to solar activity as a driver, instead of man's puny effect on the atmosphere.