Survivor: earth

How many people do you think would attend a day of science talks about climate change in busy Hong Kong? On Wednesday - a working day - 500 people from business, industry, academia, government and the community carved out some precious time to listen to some of the world's top scientists at the Climate Dialogue conference. They went because they felt it was important to better understand a fast-moving area of knowledge that affects their lives and work. The large turnout tallies with the finding from a recent public opinion survey, commissioned by Civic Exchange and conducted by the Hong Kong Transition Project, that nine out of 10 people in Hong Kong see climate change as a serious danger to their children and grandchildren.

What did they hear? That human activities are putting pressure on our planet to such an extent that there could be abrupt global environmental change.

Johan Rockstrom, from the Stockholm Environment Institute, proposed a new approach to global sustainability by identifying and defining 'planetary boundaries' within which humanity can operate safely. Of the nine boundaries he identified, we have probably already transgressed three - climate change, loss of biological diversity and changes to the global nitrogen cycle. David Drewry, a recipient of Britain's Polar Medal for his contribution to knowledge of polar regions, spelled out how fast ice caps and glaciers are melting and how permafrost areas will change, while Will Steffen, from the Australian National University, talked about ocean acidification and species extinction.

Rockstrom hypothesised that transgressing one or more planetary boundaries may tip the earth over to catastrophe, due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change. Moreover, because of the interdependence of these systems, transgressing one may shift the position of, or result in transgressing, other boundaries. He emphasised that changes to the earth's functioning system do not mean the planet won't survive - it will, but humans are the ones who will be affected.

While there are still large gaps in our knowledge, the concept of planetary boundaries lays the groundwork for us to think about a new approach to governance and management of the earth, to ensure human development can continue in a safe environment.

Dr James Hansen, head of Nasa's Goddard Institute for Space Studies, proposed a special tax to deal with coal. He argues that burning fossil fuels would threaten humanity's survival because fossil fuels produce carbon dioxide that stays in the atmosphere, ocean, soils and biosphere for millennia. He worries that burning more fossil fuel will change the earth into a different, desolate planet. For humans, the transition will be painful and out of our control.

So, how can we avoid these climate-tipping points? Through multiple and concurrent action. In other words, many things have to be done, and done quickly.

Rockstrom stressed the need for world governments to get tough on carbon dioxide reduction. Hansen argued that society must phase out coal burning and make fossil-fuel burning prohibitively expensive through a carbon tax. He also thinks nuclear power should be part of the world's energy mix.

Filmmaker turned soil expert John D. Liu showed how the badly eroded Loess Plateau in northern China was restored over a decade through a sensitive rehabilitation project that strengthened ecosystems, provided jobs, and increased agricultural production and incomes on 15,600 square kilometres of land. Such low-cost, high-benefit projects can help the earth stay within planetary boundaries because they revive ecosystems damaged by overcultivation and degradation.

Hong Kong people want to know more - a prelude to preparation for action. Let's not fail ourselves; the government needs to know there is public support for strong action.

Christine Loh Kung-wai is chief executive of the think tank Civic Exchange, which organised Climate Dialogue