According to this article:it’s probably cooling!
Here it is in a nutshell: energy from the sun enters the Earth’s atmosphere as infra-red radiation. This long wave radiation is reflected from the earth’s surface back out into space. Some of that radiation is absorbed by “greenhouse” gases in the atmosphere and converted to heat.
Thus the earth is a cozy warm place for life, rather than a frigid ice box.
The idea behind global warming is that humans are producing CO2 that increases the level of greenhouse gases in the atmosphere, thus heating the atmosphere and the planet. This implies that less long wave radiation should be escaping the Earth into space.
Hey, why don’t we test this hypothesis? Let’s measure it and see what’s really happening!
As it turns out, measurements comparing 1970, 1997 and 2006 have been made, and guess what?
There is more outbound longwave radiation leaving the earth’s atmosphere now than there was in 1970. More radiation leaving the earth means … oh dear … the earth is cooling.
So what about the global average surface temperature?
Urban heat island effect.
The cat’s out of the bag. Don’t throw those woolies out just yet.