By studying data from orbiting satellites, ocean buoys, land-based stations, and computer models, scientists from the NASA, Earth Institute at Columbia University, and Lawrence Berkeley National Laboratory have concluded that more energy is being absorbed from the Sun than is emitted back to space, throwing the Earth's energy "out of balance" and warming the planet.
The study appears in this week's Science Express. It concludes that this imbalance is (historically) quite large, and will cause an additional warming of 0.6°C by the end of this (21st) century. Although it looks small, even such rise can result in further melting of the ice-caps, thus disrupting some ecosystems, and also flooding some low-lying areas.

Reflected and Emitted radiations (Courtesy: PhysOrg)In the above picture, the lightest areas represent thick clouds, which both reflect radiation from the Sun and block heat rising from the Earth’s surface. This will cause a greenhouse-style warming of the atmosphere, which will then warm the oceans. As the oceans get warmer, more evaporation takes place, which increases the cloud cover, thus causing further warming.
This imbalance, according to the scientists, is an expected consequence of increasing atmospheric pollution, especially carbon dioxide, methane, ozone, and black carbon particles (soot). These pollutants block the Earth's radiant heat from escaping into space, increasing absorption of sunlight and trapping heat within the atmosphere.
However, the process is quite slow, and thus it might represent an oppurtunity for us to do something to reverse it. Steps need to be taken to reduce the amount of the above chemicals, and then it might still be possible to turn this around.