Human role in warming 'more certain' - UN climate chief

[Old Hack]

actually you didn't my apologies.

Ooooh, got that wrong too.

Fook him

[pjclarke]

Drivel.

When I see some conclusive facts then I will be convinced,

The scientific facts can be summed up in a paragraph. We know there is a greenhouse effect, we know that human emissions and deforestation have increased the amount of greenhouse gases, mainly but not exclusively CO2 (CO2 is up more than 30%, CH4 has more than doubled, N2O is up 15%, tropospheric O3 also up) in the atmosphere. We know how long they will remain and we know how these cause a radiative imbalance ( a difference in the incoming and outgoing radiation) or 'forcing' and we have a good estimate (around +-10% uncertainty) of the size of this imbalance. It amounts to about an 'extra' 2.5 Watts per square metre, offset to some extent by manmade aerosols and natural negative forcings, giving a net change of around 1.6 Watts/m2. May not sound like much but multiply it by the surface area of the globe and that is a lot of extra energy in the system. None of the above 'drivel' is remotely controversial.

Thermodynamics tells us that an object in radiative imbalance will increase in temperature until the imbalance is removed. The question is what other effects will be triggered by the warming and whether these will have a positive or negative feedback - how 'sensitive' the planet is to the increased energy. This is less certain, however the paleoclimatic evidence indicates that feedbacks are overwhelmingly positive, leading to a best estimate of around 3C for the equivalent of a doubling in CO2.

Increasing the planetary temperature by 2-3C will have significant humanitarian and economic consequences for billions of people. And the best science tells us that we have already whooshed past the point at which we could have avoided it.

HTH.