The UN climate conference took place in Poland earlier this month, and issues related to climate change once again dominated global headlines. In today's Tech It Out, scientists are looking to a sea creature, for records of the climate's past, and to forecast levels of future global warming.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "Many people ask how warm this planet can be. Has it ever been as warm as it is now? Is it getting warm faster than it did in history? Our job is to study climate of the past, so can we adapt to the future. The materials for our study are very limited. Men invented thermometer only a century ago. Weather stations too. Traces of climate changes are reserved on earth, and in the lives that live on it. The truth of nature is documented in its own archive."

Giant clams are the largest mollusks on the planet. They get only one chance to find a nice home. Once they fasten themselves onto a reef, there they sit for the rest of their lives. Because of that elements in the surrounding water can deposit and become part of their shells through the nearly 100 years of their life span until the shells become a work of art.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "When we cut open a giant clam, we see these layers like tree rings. The time lapse between every two visible layer is approximately a year."

And it's much more than art. Hotter sea temperatures can drive up metabolism in giant clams. Wider increments mean warmer years, and thinner ones mean the opposite. However, the width of layers cannot help scientists calculate the exact sea temperature. Two elements can.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "The shells of giant clams are made of calcium carbonate. Strontium belongs to the same chemical family as calcium. It replaces calcium during the formation of the calcium carbonate shells. And this substitution reaction is affected by temperature. We can use modern technologies to calibrate that process in order to find out what temperature leads to what ratio."

By taking samples from its different layers and measuring the ratio of strontium and calcium involved, scientists can reconstruct the temperature records and have a full picture of what the climate was like in the past.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "Around one thousand years ago, that's about China's Song Dynasty average temperature is higher by 0.7 Celsius degrees. This tells us we are not warmer than we can afford to. But it does tell us that earth is getting warmer faster than it did in that period."

But to unlock the secret of climate change, scientists need giant clams to tell them more.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "If we can get hourly ratios of strontium/calcium we can better study short-term weather events."

The laser confocal microscope that has been designed to observe cells is used on the shells for the first time. One layer has been zoomed in to hundreds of parallel arcs which formed on the daily or even shorter-term base. But when they try to measure the element ratio like before, something abnormal just pops up.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "Apart from temperature sensitive elements like Sr/Ca ratio, we also detected a change in the content of barium and iron which lead to a very interesting fact. A large amount of barium and iron would appear in the layers every once in a while. We were quite confused."

The reason that made them confused is that giant clams habitat in the shallow sea, while barium and iron are usually found on the much deeper seabed. What can carry them from remote water and travel all the way to the offshore moving powerful and quickly is nothing but typhoon.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "Strong winds can stir the sea, and lead to an exchange of substances between different layers of water. So barium and iron can be brought from the seabed up to shallow waters where the giant clams are."

What scientists are doing now is to find giant clams or fossils which lived in the past warmer periods of Earth history. Adding the typhoon records to that calendar may tell us if major storms will increase with global warming.

PROF. YAN HONG INSTITUTE OF EARTH ENVIRONMENT CHINESE ACADEMY OF SCIENCES "We have only studied typhoon for a very short time. It's difficult to link global warming and higher occurrence of typhoon. But with giant clams as samples, we can try to figure out the relation. What we need now is more data Climate data from the past can be a very reliable source of evidence in predicting the future."