Barely two months from now, the international community will meet in Copenhagen to map out a co-operation framework to deal with climate change after year 2012. The aviation sector clearly has an important role to play in this discussion. I am therefore most happy to see so many of us gathering in Hong Kong and on the move to meet the challenge of climate change.

In the Fourth Assessment Report published by the Intergovernmental Panel on Climate Change in 2007, the world's scientific community told us that "warming of the climate system is unequivocal as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global sea level", and that "most of the observed increase in temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations". We are also told that there is "no choice of inaction now".

We are glad that national leaders across continents are now joining forces to take up this challenge of the century. This December, they will try their best to thrash out a successor framework to the Kyoto Protocol.

To address the issue of climate change, we need action from each of the economies and from every sector. Tomorrow, ministers from member states of the International Civil Aviation Organisation will meet in Montreal to facilitate the dialogue and agreement of countries on a global approach to a sustainable aviation future.

Being the UN body responsible for international aviation, ICAO has long been providing information to countries with a view to assessing current and future aviation emissions as well as different policy options available.

I wish that the upcoming High-level Meeting of ICAO can help chart out the future direction of mitigating aviation emissions to support a successful conclusion in Copenhagen later this year. Here, I should congratulate IATA and its members for your continuous efforts in contributing suggestions and views to ICAO on this very important issue.

While the international community is forming an agreement on our future co-operation framework, I see no reason why our actions should not start now.

Many IATA members are already actively reducing their emissions in the sky. And you are certainly not alone in this fight. Your partners are also moving forward to reduce emissions on the ground.

For example, the integration of public transport systems with our international airport at Chek Lap Kok substantially reduces emissions associated with ground transport to and from the airport.

The Airport Authority is also experimenting with the use of alternative fuel, such as biodiesel and electricity, to power ground equipment. To provide a cleaner alternative to airlines, the airport is providing fixed ground power and pre-conditioned air to aircraft at the parking stands during turnaround.

These simple means reduce both greenhouse gas emissions and air pollutants. I therefore encourage every carrier travelling to and from Hong Kong make better use of these systems.

Your partners in the Government and the community are also in action. This April, two funding schemes worth $450 million (US$58 million) were launched in Hong Kong to provide incentives for building owners to conduct energy and carbon audits and to carry out energy-efficiency improvement projects on their buildings. So far about 800 applications have been received.

More than 120 organisations in Hong Kong are taking voluntary action by joining our "Green Hong Kong * Carbon Audit" campaign. These green partners are from property development and management, professional bodies, banking, hotels, universities, aviation and logistic, and non-government organisations.

They are committed to quantifying their emissions and taking steps to reduce it. Some are even encouraging the public at large to make essential behavioural and lifestyle changes required for a low-carbon society.

Let's take Cathay Pacific Airways here, one of our green partners, as an example: The company is not only making every effort to reduce their emissions arising from its operations, it is also encouraging its customers to offset their emissions.

The message is clear. Climate challenge does not have boundaries. Addressing climate change can only be successful if there is co-operation and partnership. This is not only true among countries. This is also true among the stakeholders in the same business sector, among different sectors in a community, among different individuals in the world.

Secretary for the Environment Edward Yau gave this address at the Third Greener Skies Conference.