GLACIOLOGIST Sun Bo has made six trips to Antarctica over 16 years, watching the ice sheet melt and braving worsening polar cyclones - at last returning with arguably the holy grail of polar research: the deepest ice core drilled to date.

Sun, deputy head of China's 29th expedition to Antarctica, said the team returned with three precious tubes of ice: a total length of 11.2 meters - all drilled starting from the depth of 3,200 meters in Dome A (Argus), the highest point on the Antarctic continental ice sheet. They drilled near China's Kunlun Station at an altitude of 4,087 meters.

Sun, the head of Kunlun Station, has called it a breakthrough in earth science, saying analysis can unlock secrets of ancient climate change.

"People may think Antarctica is far away from where we live, and has little to do with our life, which is very wrong," he told Shanghai Daily in a recent interview at his office in the Polar Research Institute in Shanghai.

"Antarctica is very sensitive to the global climate change. It tells us what the earth has been through and where it will go. Antarctica has a very close bond with us, although it's invisible," the 48-year-old Shaanxi Province native said.

The 239-member research team returned to Shanghai on April 9, after a 156-day expedition that departed from Guangzhou last November 5 on the ice-breaker Xuelong, or Ice Dragon. The journey covered 29,000 nautical miles and at one point the Xuelong was frozen and shrouded with ice as the sea waves froze at soon as they hit the icebreaker.

"Deep ice core is essential to analyze the world's climate change," Sun said. "The ice core from Dome A is considered the most ancient in the world, thus, its research value is infinite. Scientists from the whole world are dreaming of analyzing the ice core collected from Dome A, and we did it this time."

It was also very significant that researchers could drill so deep beneath the ice sheet. Reaching the land under the ice sheet is fascinating to every scientist studying Antarctica.

After preliminary drilling in January, China's State Oceanic Administration quoted Sun as saying, "China's success at drilling the deep ice core at Kunlun Station represents a breakthrough in the deep ice core drilling, and provides a great opportunity to intensify research on ice sheet."

Now, back in Xuelong's home port, it's time for ice core research and analysis in the lab and Sun will be very busy.

Expedition to harsh land

China launched its first scientific expedition to Antarctica in 1984. It operates three research stations, Kunlun, Changcheng and Zhongshan, and plans to build two more by 2015. It carries out a range of climatic, glacier, environment, geographic, geophysical, oceanic, biological and other research.

Around 30 countries, all members of the 1959 Antarctic Treaty, operate scientific research bases in Antarctica. For now, exploiting Antarctica's vast natural resources is prohibited by the Antarctic Treaty System and its 1991 Madrid Protocol, but the ban is up for review in 2041.

Sun calls Antarctica a land of cruel weather and harsh environment but also a land of pure beauty.

"I believe the ultimate beauty of nature exists in the most dangerous, precipitous areas," he said.

After 25 days at sea, the team landed at Zhongshan Station. Sun and others made their way inland to Kunlun where they constantly battled the cold, high altitude and continuously violent weather. They traveled by snowmobiles, towing sleighs. It exacted physical and psychological toll. Compared with Zhongshan Station, which is well established and even has a hospital, Kunlun is fairly new, a pioneer outpost.

"If you live in this kind of environment, you'll find that even eating is torture," Sun said. "The oxygen was thin; the weather was always cold beyond imagination, the wind-proof protection suit weighed more than 5 kilograms. Just making a small movement required great energy, to say nothing of having to work."

Researchers needed a lot of energy and protein; beef and mutton were staples. They also ate tinned fruit and frozen or dried vegetables. On the way from Zhongshan to Kunlun they ate reheated in-flight meals. At Kunlun, they had a cook, who usually works for an airline company.

"We seldom had entertainment, so the chef tried very hard to cheer us up, once preparing a hotpot party for someone's birthday," Sun said.

"All of researchers at Kunlun are men and we were under great pressure, so as a result, our language became fouler and fouler," Sun said. When they returned to "co-ed" Zhongshan, everyone was very self conscious and had to clean up their language.

"We needed to be well-mannered in front of women," he said.

Sun's father was a surveyor and cartographer, influencing his son's interest in the natural sciences. Sun majored in electrical engineering at Xi'an Jiaotong University in Shaanxi and obtained a PhD in glaciology and global climate change at the Cold and Arid Regions Environmental and Engineering Research Institute of the Chinese Academy of Sciences in Lanzhou, Gansu Province. In 1996 he started to work for the Polar Research Institute in Shanghai.

Science studies

In 1997, Sun went to Antarctica for the first time with the 14th Chinese expedition. Their mission was to explore the interior, but back then, there was no Kunlun Station and they had no practical knowledge of conditions deep in Antarctica. That first trip was traumatic.

"Our lack of experience caused us a lot of trouble," Sun said. "We encountered a polar cyclone, and the snowmobile was stranded in a snow storm. At that time we didn't know the cyclone would end in two or three days and we freaked out. Everything around was vast, white and endless. I completely lost my sense of direction and had vertigo."

Successive missions were somewhat easier because they knew more.

In 2009, Sun and scientists from several countries co-authored a paper about the Gamburtsey Mountains and the origin and early evolution of the Antarctic ice sheet. It was published in the journal Nature.

Nowadays trips to Antarctica seem normal to Sun and his family. This time, his wife didn't pick him up at the port when he returned, just asking later, "How's it going?"

Sun said that although he is nearly 50 years old, he has the energy to go on more expeditions. Age 55 is usually the cut-off for team members who have to be in top physical condition.

After passing a rigorous physical, candidates for Antarctica then go to the Tibet Autonomous Region for 15 days to prepare themselves for high altitude and also do some rock climbing. Tibet is sort of a trial run.

Sun says he has a healthy lifestyle and doesn't drink much or stay out late. "Instead, I'm the table tennis champion of the institute, and I stay close to the nature," he said.

China's Antarctic exploration

China is one of around 30 nations operating scientific research bases in resource-rich Antarctica, where the environment is protected by a 1959 treaty and commercial mining, oil and gas drilling is prohibited - at least until 2041.

China sent its first expedition to Antarctica in 1984 and now operates three research stations. Zhongshan, the main station on the coast opened in 1989. Around 1,280 kilometers inland, Kunlun Station is on the summit of the East Antarctic Ice Sheet; it opened in 2009 and is much smaller and "rougher." Changcheng (Great Wall), the first station, opened in 1985 on King George Island off the Antarctic Peninsula.

During the latest expedition, site inspections were completed for two more stations to be built by 2015. According to the State Oceanic Administration, they include a summer station in Princess Elizabeth Land that can provide replenishment and logistical support and a year-round research station in Victoria Land.

The 1959 Antarctic Treaty was signed by around 30 countries. Exploitation was not envisioned at the time, but it was in the 1980s. The 1991 Madrid Protocol to the Treaty sets out measure to protect the environment and bans exploitation of natural resources for 50 years; that period ends in 1941 when the issue is up for review.

Antarctica is rich in resources, though known sizeable deposits that are easy to reach are rare. Transport and extraction are difficult and dangerous because of treacherous weather, ice floes, glaciers, icebergs that can crush drilling equipment.