Our numbers have a huge effect on our natural environment. The more of us there are, the bigger the impact on nature. Human population growth is a key driver of biodiversity loss, resource depletion, deforestation, climate emissions and pollution.

In the 1970s, Population Matters Patron Paul Ehrlich and his colleague John Holdren developed an equation to describe our impact on the environment:

I = P x A x T

Where "I" is impact, "P" is population, "A" is affluence and "T" is technology. The "IPAT" equation shows that our numbers, how we live, and the technology we use all have an effect on our finite environment.

See our latest news stories and blog posts about the environment below.

14 July 2016

Our 25th anniversary

The Optimum Population Trust (OPT) was founded by David Willey and others on 24 July 1991. Its goals were: “to collect, analyze and disseminate information about the sizes of global and national populations and to link this to a study of carrying capacities and inhabitants’ quality of life in order to support policy decisions.”

Read more

Sir David Attenborough speech to the RSA, 2011

Download
3 July 2014

Porritt on British e-NGOs and population

It doesn’t take too long to open up incredibly divisive discussions about population, development and the environment. For instance, how would you respond to the following facts?

Read more

Journal April 2013 Vol. 13, No 1

Download