The World Is Getting Cooler*

*  Not!

This is something of a pre-emptive strike against the quote miners of this world.  I predict that they will use a new study of cloud seeding to sell ice damage insurance or something.

If you sprinkle a cup of water on a bonfire it will have a tiny cooling effect.  It will not put out the fire or wishomagically reverse the heating effect.  Scientists know exactly what they mean by a cooling effect, and so does everyone who ever used a cooling fan in summer.  But there are some snake oil salesmen who want to convince you that a simple cooling fan can lower the air temperature.

A new study on clouds demonstrates a cooling effect.  Most of us know what that means.  For those who don't, let me explain as subtly as I can:


“We suggest that the co-condensation of semi-volatile organic compounds with water vapour has a substantial impact on the radiative properties of clouds.”

From the abstract - see below.

A cooling effect is mentioned by the World Meteorological Organisation in its announcement of a new  Statement on the Status of the Global Climate :
“We need to understand how much of the extra heat captured by greenhouse gases is being stored in the oceans and the consequences this brings in terms of ocean acidification and other impacts. We need to know more about the temporary cooling effects of pollution and other aerosols emitted into the atmosphere. We also need a better understanding of the changing behaviour of extreme weather and climate events as a consequence of global warming, as well as the need to assist countries in the most affected areas to better manage climate-related risks with improved climate early warning and climate watch systems,” said Mr Jarraud.

Got that?  It's not "Wow! The planet is cooling down, stop climate research worrying."  It's a cooling effect and it's temporary.

The new study on clouds, from Nature Geoscience

Clouds profoundly influence weather and climate. The brightness and lifetime, of clouds is determined by cloud droplet number concentration, in turn dictated by the number of available seed particles. The formation of cloud droplets on non-volatile atmospheric particles is well understood. However, fine particulate matter in the atmosphere ranges widely in volatility. Co-condensation of semi-volatile compounds with water increases a particle’s propensity for cloud droplet formation, with potential consequences for feedbacks between the terrestrial biosphere and climate. Here we systematically study cloud droplet formation, using a cloud parcel model extended to include co-condensation of semi-volatile organic compounds under a broad variety of realistic conditions. As an air parcel rises and cools, the concentration of organic vapour that it can hold declines. Thus, the simulated organic vapours become increasingly saturated as they ascend, and so condense on growing particles as they swell into cloud droplets. We show that condensation of increasingly volatile material adds to the soluble mass of these droplets and facilitates the uptake of additional water, which leads, in turn, to a substantial increase in the number of viable cloud droplets. We suggest that the co-condensation of semi-volatile organic compounds with water vapour has a substantial impact on the radiative properties of clouds.

Cloud droplet number enhanced by co-condensation of organic vapours
David Topping,   Paul Connolly  and Gordon McFiggans
Nature Geoscience (2013)  doi:10.1038/ngeo1809
Note to editors:
A copy of the Nature Geoscience paper, ‘Cloud droplet number enhanced by co-condensation of organic papers,’ by Gordon McFiggans et al, is available on request.  Follow link below for contact details:
Faculty of Engineering and Physical Sciences
The University of Manchester