She highlighted energy, disease, earthquakes, food and digital connectiveness as priority areas for collaborative research.
Dr Merkel, who grew up and worked as a research scientist in the former East Germany, said that her "whole life changed" with the fall of the Berlin Wall on November 9, 1989, which signalled her entry to politics.
Freedom remained humanity's main driving force, and life in former Communist states had been a "schizophrenic" experience for scientists in particular. They had been encouraged to think freely in their specialist fields but not when they left their institutes and turned their attention to wider society.
Dr Merkel said the fall of the Iron Curtain had opened the way for globalisation.
"Who would have thought the leaders of the leading countries would one day be sitting round a table (in Brisbane this weekend) talking about our common challenges."