The United Nations is warning the earth's environmental systems "are being pushed towards their limits."

In a 525-page report, it says sudden, irreversible and potentially catastrophic changes are looming. According to the UN's Environment Program, climate change, depletion of the ozone layer, plummeting fish stocks and mass extinction of animals are among the most worrying threats.

In recent years, little or no progress has been made in reducing environmental destruction. The report calls on policymakers from member states to take urgent action.

The United Nations is warning the earth’s environmental systems "are being pushed towards their limits".