Climate change is not just earth bound

By measuring the temperature of the gas present between galaxies, using quasar light that was more than ten billion years old by the time it reached Earth, astronomers have found evidence of a climate change  in our Universe. In the beginning the Universe went through a warming trend which was  caused by the huge amount of energy output from young, active galaxies. The vast majority of matter was not in stars or galaxies University of Cambridge astronomer George Becker explains but was spread out in a very thin gas that filled up all of space. Just as Earth's climate can be studied from ice cores and tree rings, the quasar light contains a record of the climate history of the cosmos. There is a connection between temperature, time and expansion of the Universe. As the cosmos expands, the gas should get colder and the Universe is expected to cool down over time. "The likely culprits in this intergalactic warming are the quasars themselves", explains fellow team member Martin Haehnelt, who is also at Cambridge University's newly-established Kavli Institute for Cosmology.  "Over the period of cosmic history studied by the team, quasars were becoming much more common.  These objects, which are thought to be giant black holes swallowing up material in the centres of galaxies, emit huge amounts of energetic ultraviolet light.  These UV rays would have interacted with the intergalactic gas, creating the rise in temperature we observed." "One of the lightest and most abundant elements in these intergalactic clouds, helium, played a vital role in the heating process.  Ultraviolet light stripped the electrons from a helium atom, freeing the electrons to collide with other atoms and heat up the gas.  Once the supply of fresh helium was exhausted, the universe started to cool down again. Astronomers believe this probably occurred after the cosmos was one quarter of its present age."