Though there are some people who still believe that climate change is a "conspiracy", global warming – once only in scientists' domain – has become an increasingly incontestable ground reality which demands our serious attention.

Island countries in the Pacific and Indian oceans, such as Tuvalu, Kiribati and the Maldives, which are particularly vulnerable to rise in sea levels, face the threat of being submerged. People living on the islands for generations have to seek new settlements in other countries should their bountiful homelands become uninhabitable.

For example, Tuvalu has been implementing an immigration plan with nearby New Zealand as the main destination. Many local Tuvaluans are reluctant to abandon their beautiful islands and culture while New Zealand prefers to receive only those who already have jobs in the country. For many Tuvaluans, it is difficult to migrate to other countries.

We cannot be indifferent to Tuvalu's troubles not only as a matter of humanity, but also because the suffering of Tuvaluans and other islanders would befall us in the near future. According to a United Nations report, only a slight rise in sea level caused by climate change would bring disastrous floods and chaos to the Yangtze River Delta, Red River Delta, the Ganges-Brahmaputra River Delta and other densely populated mega-deltas. Climate change would also intensify the shortage of food and drinking water in Asia and Africa. It is predicted that there would be 120 million to 1.2 billion Asians facing water shortages by 2020.

Climate change also has accelerated the melting of glaciers at the poles. The World Wild Fund for Nature has warned that the speed of glacier melting at the Arctic Pole is "much faster than any previous professional speculation", with the melting acreage equivalent to Turkey's land mass every six months. The Arctic Pole would see no ice in summer within 30 years if the trend is not reversed. Without glaciers, which throw back nearly 90 percent of the sunlight cast on the globe, more sunshine would be received directly by seawater and the Earth's surface, which in turn would accelerate global warming, resulting in a vicious circle between glacier melting and global warming.

Apart from the threat of rising sea levels, China's Qinghai-Tibet Plateau, or "the Roof of the World" where local temperatures have risen by 1.1C over the past 20 years, will also witness glacier melting. As the plateau is the source of seven major Asian rivers affecting more than 2 billion people, and agricultural and industrial production, hydropower generation and water transportation depending on it, the outcome would be disastrous if large-scale glacier melting occurs.

Personal experiences and startling realities have led to more and more people appealing to "save the earth". Lester Brown, a famous US eco-economist, proposed last year that it is time for us to tackle the environment issue like "war mobilization".

Strictly speaking, however, Earth does not need human beings to save it because the history of human existence accounts for only one ten-thousandth of the age of the planet and even if humankind vanished in the future, Earth would still exist.

Obviously, what we must save is not Earth but human beings. Human civilization is a fragile flower, which came into being in the process of billions of years of natural evolution. A delicately balanced natural system, with the average temperature as a key parameter, is a prerequisite for humankind's survival and procreation. If the balance of the natural system is upset, human civilization would lose its footing and vanish in the boundless universe.

In this sense, the prediction of the UN report that "the earth temperature will rise by 2C if greenhouse gas emissions by 2050 are not cut to half of the 2000 level" is a warning that is "better late than never". Imagine how a person would feel if his body temperature is raised from 37C to 39C. Like the human body, Earth is also a highly complicated and delicate being which cannot tolerate imbalance.

However, with people all over the world keen for joint efforts to deal with the environment crisis, some developed countries, which should take major responsibility for climate change since the Industrial Revolution, and at the same time have the economic might and advanced technology, are assuming an ambiguous attitude and are reacting slowly. Even the proclaimed target of reductions by the US, the largest emitter of greenhouse gases, which has disappointed many people, might not be passed by its Congress.

Meanwhile, some influential figures warn climate change might trigger new conflicts, friction and even wars among countries, including the so-called "water resource war" in some areas facing water scarcity. In the US, some southwestern states have been in dispute with states around the Great Lakes over water, and countries around the Arctic Circle have been contesting for undersea resources of the Arctic Ocean. This is akin to passengers on a sinking giant vessel striving for first-class cabins instead of making concerted efforts to save it.

The author is former deputy head of the Institute of Japan Studies at the Chinese Academy of Social Sciences.