New ways of combating the destruction of the natural world will be sought by delegates from almost every government at a two-week meeting now under way in Nagoya, Japan.
The United Nations Convention on Biological Diversity (CBD) came into being 17 years ago, the BBC reports, and in 2002 governments promised an improvement in the situation by this year - but it hasn't happened.
The latest gathering on the convention has opened with warnings that the ongoing loss of nature is hurting human societies as well as the natural world.
Japanese environment minister Ryo Matsumoto says biodiversity loss will become irreversible unless curbed soon.
The executive secretary of the CBD, Ahmed Djoghlaf, has described the meeting as a "defining moment" in the history of humankind.
"[Buddhist scholar] Daisetsu Teitaro Suzuki said 'the problem of nature is the problem of human life'," he told delegates in his opening speech. "Today, unfortunately, human life is a problem for nature."
'Admit that we have failed'
Referring to the target set at the UN World Summit in 2002, Mr Djoghlaf said:
"Let's have the courage to look in the eyes of our children and admit that we have failed, individually and collectively, to fulfil the Johannesburg promise made by 110 heads of state to substantially reduce the rate of loss of biodiversity by 2010.
The gathering aims to set new targets for conserving life on Earth.
Earlier this year, the UN published a major assessment - the Global Biodiversity Outlook - indicating that virtually all trends spanning the state of the natural world were heading downwards, despite conservation successes in some regions.
It showed that the loss and degradation of forests, coral reefs, rivers and other elements of the natural world were having an impact on living standards in some parts of the world - an obvious example being the extent to which loss of coral affects fish stocks.
