James Lovelock, the scientist responsible for the Gaia theory, today (Wednesday, August 26) describes environmentalists who campaign on climate change but ignore population growth as irrational, ignorant or “hiding from the truth”.

I rather subscribe to both the Gaia theory and to the idea that humanity will have to control it’s population at some point. The Gaia theory is that the Earth will tend to keep our atmosphere and biosphere constant within narrow limits until a certain point when, if the pressures on it continue, it will change rapidly to a new status which could involve dramatically different conditions across the globe. This would be cataclysmic for today’s life forms and only the most hardy would survive to rebuild.

The amount of carbon dioxide in our atmosphere is a pressure on the global system that could push it towards a ‘Gaia shift’, and it’s increase since the industrial revolution has been alarming and is still gathering pace. If you compare it to a chart of population growth, the two are very similar.

The effects of the increase in CO2 include storing more of the sun’s heat in the atmosphere, thus ‘Global Warming’, but we are also seeing an increase in the acidity of our oceans, which means that it is more difficult for organisms to use CO2 to make their shells, and can result in shell materials being dissolved. To put this in context, calcium carbonate shells and reefs built by tiny marine organisms account for all the chalk and limestone on the planet, and there is a great deal more spread through the oceans as living or recently dead organisms. If this material dissolves, it realeases yet more CO2 into the atmosphere and prevents more shells being made. If you think this through, it is a vicious cycle and not the only one we face.

The point is, the more CO2 we release by buring fossil fuels, the more is released from other sources around the planet. And even if humans were not responsible for global warming, even if it were true that we are going through a very rapid ‘natural’ cycle as some believe, then surely it would make sense for us to reduce our global warming gas output so as not to exacerbate a dangerous trend?

We cannot escape the logic that the more people there are, the more CO2 we will release by burning fossil fuels, an effect that will be magnified many fold as they all aspire to be richer and consume more.

There is much that we can, and must, do to mitigate our environmental impact, and this starts with each of us as individuals. According to Jonathan Porritt, the UK Government is very comitted to action on climate change and to helping individuals and communities play their parts whilst the government handles things at a national and international level: let’s hope so!

Internationally, the Copenhagen conference in December will be key in moving things forward; in fact in instigating a step change in the way governments behave.

We must make a start on working out how to control population growth, which does not mean that we put on hold reducing our energy use and environmental footprint: in fact that has to be where we start because it will take effect much more quickly than any population measures.

This all comes back to my “Death to The Environmentalist” blog: we can no longer be ‘greens’ and the rest but must pull together to stabilise the situation now as far as we can. People who believe that there is a problem need to work in concert, bringing their different expertises and energies to bear on its many facets, including global warming, biodiversity, habitat protection, equalisation of resources and population control.

Dr Lovelock is in good companyas Sir David Attenborough, Jane Goodall and Jonathon Porritt have all said that we must address the population issue.

To take a one-sided view and work as if the other stake-holders didn’t have a case is a recipe for disaster in the form of a Gaia shift.