14 June 2012 Last updated at 12:36 ET

Rio+20: What is there to talk about?

A new environmental summit has taken place in Brazil, 20 years after 172 nations gathered in Rio, for the Earth summit. To find out more about the issues facing the United Nations Conference on Sustainable Development, or Rio+20, see below.

What is the Rio summit about?

The Rio summit will focus on efforts to reduce poverty, while protecting the environment. This task is made harder as the world's population is expected to rise steeply in the years ahead.
The planet's population could be 15 billion people by 2100. Wealth is also expected to rise but its effect on the environment is unclear.

In the past, more people, with more wealth has meant increased consumption.
Since the last Rio summit in 1992, the
number of people on Earth has gone up by
22%
Seafood consumption has gone up by
32%
Meat by
26%
The average person eats 43 kg of meat a year. In 1992 it was 34 kg.
Source: UNEP, 2011. Figures relate to 2007

While food consumption is rising, there are still large numbers of people who are undernourished.
It is one of the UN's many development goals to halve the number of people who suffer from hunger by 2015.

How able is the planet to meet increasing demand?
In 1960, a little over half the planet's land, forests and
fisheries were needed to meet human consumption.
By the late 1970s, consumption was equal to one planet.
By the first years of this century, one-and-a-half planets
were needed to meet consumption.

This deficit can only be met by the depletion of renewable
resources and increased pollution.

Consumption isn't equal. North Americans and Europeans consume far more resources than are available solely within their borders.

As human populations increase, the number and diversity of birds
and animals is falling.
Decreasing biodiversity undermines the planet's ability to sustain humanity. Its reductions typically affect the poorest the most. These issues are right at the heart of the Rio talks.

Some argue that the planet has limits to the stress its different systems can undergo, beyond which a stable future cannot be guaranteed.
This graphic from the scientist and sustainability expert Johan Rockström suggests those limits have already been broken for climate change, biodiversity and the nitrogen cycle.

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