If CO2 lets heat in and not out and that were it, How has the world ever cooled. Surley it should get hotter than the piddling 0.8C?

Barry,

CO2 is one of the greenhouse gases, they’re so-called because they have the ability to trap heat in Earth’s atmosphere thus causing it to warm or cool.

When heat energy reaches us from the Sun it comes from an extremely hot and highly energetic source, this ensures the energy has a very short wavelength and can pass through our atmosphere almost unimpeded.

The heat from the Sun warms the surface of the Earth and everything on it, as ambient temperatures drop this absorbed heat is re-radiated back out. This time it’s coming from a much cooler source and so the wavelength of the radiated heat is a lot longer. This new wavelength corresponds with the vibrational frequency of greenhouse gas molecules allowing it to become trapped within the atmosphere.

Once the greenhouse gases have captures the photons of energy they are once again reradiated back outwards, the direction is random and some heat comes back down to Earth (the greenhouse effect), some is lost into space and some gets absorbed by other greenhouse gas molecules.

This in essence is how and why the greenhouse effect works, but there’s more to it than that.

Each greenhouse gas has a set of characteristics, one of these is the atmospheric residence period – how long it stays in the atmosphere. Some greenhouse gases only exist in the atmosphere for a few years, methane for example remains there for 12 years. Others, including many of the synthetic gases, remain there indefinitely. Carbon dioxide has a residence period of about 114 years.

If emissions of greenhouse gases fall below this rate of decay than the amount of greenhouse gas in the atmosphere falls and cooling ensues.

As for how the world has cooled in the past, this is because Earth progresses through a series of complex cycles that affect it’s relationship with the Sun. In simple terms, Earth wobbles like a spinning top, it bounces up and down like a yoyo, it tilts back and forth on it’s axis and it follows a constantly changing orbit around the Sun. Each of these cycles lasts for tens of thousands of years and during a full cycle there is a cooling and a warming phase.

On much longer time-scales, the entire solar system orbits around the galactic centre, this cycle lasts 220 million years and causes huge temperature swings, the change is only 1°C every 2 million years but over time it’s enough to melt all the ice on the planet, whilst at the other extreme all but the Equatorial regions freeze.

It lets heat in, and lets heat out. The warmer it gets, the more it radiates out. When the temperature has gone up enough, the increased radiation balances the heat trapped by the excess CO2. By How much? Some simple equations give a simple answer, but the system is complex and not completely understood.

Yes, and CO2 is not that important in this, as it is in feeding plants that make our oxygen.

It will get hotter, its just it doesn't happen overnight.

Just like when you turn the oven on, it doesn't instantly heat up.

That's because climate deniers only look at surface temps because they are too stupid to look at oceans as well. Normal people look at both surface and oceans. :)

Clearly an increase of 0.012% in co2 is far too small to make any impact on the planet. The Sun is the source for all warmth we have, and its output is never constant.

Negative feedbacks.

.8c averaged over a big planet. that is a lot of energy.

meltic ice caps, changing weather patterns.