Fortunately, by the beginning of the conference the ban had been lifted, and the effects were limited, organisers said. More than 400 delegates were able to take part in the opening plenary session.

Nobel laureate Prof. Rajendra Pachauri, chairman of the UN's Intergovernmental Panel on Climate Change, appeared by video-link to remind the delegates that sea-levels are rising, temperatures and rising, and snow levels are falling. It is expected that global average temperatures will rise over the course of this century by between 1.8 and 4 degrees Celsius. The amount of resources mankind now consumes exceeds the planet's ability to regenerate by 30%.

Prof. Pachauri's message - he shared the Nobel prize with Al Gore in 2007 - is a familiar one: mankind has to change his habits. In particular, developed nations have to lead from the front to cut the link between economic progress and depletion of the world's resources. In other words, economically developed nations need to make more of an effort than developing nations, because they are more of a threat.

Ingrid Lieten, Flemish minister for science and innovation, talked about clean technologies in Flanders, and the enshrinement of the principle in the government's Flanders in Action (ViA) programme. As well as climate change, the programme focuses on traffic mobility, the greying of the population and dependence on fossil fuels for energy. She also spoke about the Flanders Cleantech Association which aims to develop innovative projects in conjunction with the Environmental Innovation Platform (MIP) and with Flanders Investment and Trade and the Flemish Institute for Technological Research (VITO).

"It is important to raise awareness among the general public about the importance of the transformation of our economy into a sustainable one," the minister told the conference.

• A webcast of Professor Pachaudri's address to the conference can be watched online in streaming video, accompanied by a PowerPoint presentation, by clicking this link.