World leaders last week reiterated their commitment to tackling biodiversity loss after a major new report warned that the deterioration of the natural world is already costing the global economy billions of pounds a year.

The interim report was released at the UN-backed Convention on Biological Diversity (CBD) Summit in Bonn and warned that there was a "comprehensive and compelling economic case for the conservation of biodiversity".

The Economics of Ecosystems and Biodiversity review was commissioned in 2007 by German environment minister Sigmar Gabriel of Germany and European Environment commissioner Stavros Dimas and aims to assess the economic value society receives from nature through benefits such as food, water, soil, flood protection, medicines and carbon sinks.

Undertaken by Deutsche Bank economist Pavan Sukhdev, the interim report warns that without the adoption of new policy measures, biodiversity will continue to decline at unprecedented rates, predicting that of over a tenth of the natural areas remaining in 2000 could be lost by 2050, "chiefly as a result of conversion for agriculture, the expansion of infrastructure, and climate change ".

The interim report primarily focuses on the economic cost of deforestation and warns that the global economy is currently losing forest ecosystem services with a value of around €28bn a year. It added that these losses are felt in future years as well as in the year of deforestation, and therefore the net present value of services from forests ecosystems that we lose each year is estimated at between $1.35 trillion and $3.1 trillion, for discount rates of four per cent and one per cent respectively.

The interim report does not detail the full economic cost of biodiversity loss, but speaking at the opening of the summit CBD executive secretary Ahmed Djoghlaf said that Sukhdev had put the cost at $3.1 trillion a year or six per cent of global GDP.

Sukhdev called for the adoption of a new economic measure that is more sophisticated than GDP, and includes the benefits that ecosystems and biodiversity provide. By no longer ignoring these benefits, such systems would help policymakers adopt the right measures and to design appropriate financing mechanisms for conservation," the report argued.

The study came as politicians at the summit unveiled a raft of measures designed to help slow rates of biodiversity loss.

Speaking at the opening of the conference, German Chancellor Angela Merkel announced €500m of funding for forest protection measures up to 2012 and €500m a year thereafter under a new global programme called the Life Web initiative. According to the CBD, 60 countries have already pledged their support for the programme with Norway committing to provide hundreds of millions of euros of additional funding.

Meanwhile, delegates agreed to a new roadmap for negotiations up to 2010 designed to deliver new international rules on the sharing of benefits accrued from genetic resources, the establishment of wider network of protected areas, and improved policies for addressing the environmental impact of increased biofuel use.

In addition, environment ministers from 60 countries including the UK pledged to work towards a WWF-proposed target of ensuring zero net deforestation by 2020.