Complex sentence: The need for an islands specific conference was highlighted some two years prior at the 1992 United Nations Conference on Environment and Development (Earth Summit), held in Rio de Janeiro where 179 governments voted to adopt Agenda 21.
Split into simpler sentences: The need for an islands specific conference was highlighted some two years prior at the 1992 United Nations Conference on Environment and Development (Earth Summit), held in Rio de Janeiro. It was at the Earth Summit where 179 governments voted to adopt Agenda 21.