Hot on the trail of global warming
Zhang Qian Shanghai Daily 6 Jan 09;
AS glaciers melt and sea levels rise, low-lying Shanghai is on the front lines of global warming and rising waters. Environmental scientist Kang Jiancheng tells Zhang Qian there's no end in sight.
It's chilly these days, but global warming is full speed ahead, and both temperature and sea level are rising in China and around the world. Chinese academics and environmental campaigners are trying to raise awareness.
Shanghai, a low-lying city on the East China Sea, is literally on the front lines of climate change as the sea level rises millimeter by millimeter. We'll all be gone by the time it gets really bad, but that doesn't mean we shouldn't be helping to reduce emissions that lead to global warming and rising waters.
"Though the global temperature did change from time to time over the past 800,000 years, it has been increasing at an unprecedented speed in the past 100 years," says Professor Kang Jiancheng, deputy director of Urban Ecology and Environment Research Center of Shanghai Normal University.
Globally, we have experienced the warmest 100 years in the past 2,000, and the warmest 10 in the past 100, says Kang. "Sadly, there's no sign yet that it is dropping."
The temperature in China, he tells Shanghai Daily, has increased about 0.7 centigrade, compared with the average temperature from 1961 to 1991. And it is likely to increase by another 3.8-5.8 centigrade by 2100.
The average national temperature in 2006 was 9.9 degrees centigrade, while it was 10.6 degrees centigrade in 2007, says Kang. The biggest change was warmer winters in northern China.
Rising sea levels caused by melting ice sheets and warmer waters are one of the most serious challenges, since 65 percent of the world's population live near coasts and more than 80 percent of the world's big cities are coastal, like Shanghai.
The global sea level started to rise in the 19th century, after remaining constant for around 2,000 years, says professor Kang. It increased at 1.7mm per year in the 20th century, and has been rising at a rate of 3mm every year since 1993.
The sea level around China has risen 90mm in the past 30 years; the level in Shanghai has increased 120mm in the same period and is predicted to increase another 37mm in the next 10 years, he says.
"If the sea level keeps rising at an increasing rate, Shanghai - which is only 4.5m above sea level - will be vulnerable to floods, typhoons and high tides," says Kang. All delta regions face the same problem.
Shanghai has a coastline of 172 kilometers.
And the major culprit in 100 years of global warming and rising sea levels, says the professor, is carbon dioxide emissions.
"We now have agreement that human activities, including industry and daily life, are 90-95 percent responsible for the abnormal temperature increase," says Kang. "Greenhouse gas emissions, especially CO2 from burning fossil fuels (coal, oil) are the main causes."
Slowing global warming is a much better idea than simply building a big dam around Shanghai, says Kang, though he recognizes the magnitude of the problem.
CO2 concentration in the atmosphere was between 170-280 parts per million per volume (ppmv) in the past 10,000 years, but in the last 100 years it has risen to 380-384ppmv, he says.
Even if emissions ended right now, Kang says, a high level of CO2 would persist in the atmosphere for 50 to 200 years, "yet doing nothing will definitely make the situation worse."
China is tackling the problem.
The amount of CO2 and other greenhouse gases emitted in China annually may now equal the amount emitted in the United States with fewer people - but the per-capita emission is only about one-fifth that of the US, according to an announcement last October by Xie Zhenhua, vice president of the National Development and Reform Commission.
China decreased its GDP energy consumption by 1.79 percent in 2006 and 3.66 percent in 2007.
