The Minister for the Environment, Martin Cullen, has said the big challenge for Ireland and the world is to ensure that policies on sustainable development are implemented rather than discussed.

He was speaking at the publication of the Government's policy document for the upcoming World Summit which takes place in South Africa next month.

The melting of ice caps is just one indicator that the earth's temperature is rising and that greenhouse gases are contributing to a dramatic change.

The Earth Summit in Rio ten years ago was supposed to herald a new dawn in which protection of the environment was of equal importance to economic development.

With a follow-up to Rio taking place in Johannesburg, South Africa next month, the Government published its policy paper claiming significant progress in 10 years but arguing we now need to implement.

Many environmentalists attended today's event. They point to the fact that Ireland's record on reducing greenhouse gasses has been terrible. We are currently 100% over the intended target.

The environmentalists' policy platform will be published on 22 August.

Meanwhile, Mr Cullen has dismissed reports that money raised by the plastic bag levy will go into the road building programme.

Martin Cullen said the levy would raise about €2 million this year, but said legislation prevented it going anywhere other than the environment fund.

He said suggestions that it would be spent on roads were laughable.

The bag tax was introduced earlier this year and has been highly successful. Environmental groups claimed it was a late but welcome move.