Counting 50,000 stripes and 500,000 grains

Professor Takeshi Nakagawa, Newcastle University, believes the key to predicting the future of the world’s climate lies in studying its past.
In a public lecture tomorrow (23 March 2011) at the Great North Museum in Newcastle, the quaternary scientist will tell the audience that ‘one of society’s biggest concerns is identifying what the earth’s climate will be like in the future’.

“We now understand that climate change is not universally equal, which is why it’s important to study climatic events that took place in similar time frames within the last 50,000 years,” he said. “Knowledge about the past provides insights into the type and mechanism of the climate change, as well as providing a basic tool for validating current computer-based climate simulation models.

“We need to look at past climate changes in a comparable time resolution, which poses a huge challenge for scientists because most conventional age-identification methods, such as radio-carbon dating, are not precise enough and only offer indicative time frames,” he explained.

Professor Nakagawa leads an international research group which has been studying annually laminated sediment core from Lake Suigetsu in Japan. This sediment is an exact archive of past climate change due to the annual settlement of pollen fossils over the last 150,000 years.

The composition of the pollen fossil links directly with atmospheric conditions at the time, for example, colder conditions result in higher proportion of pollen from coniferous trees, while warmer conditions are dominated by pollen from broadleaved evergreen trees. This information can then be used to track changes season by season.

The lake’s rare and undisturbed sediments provide a delicate and precise record and Professor Nakagawa’s work is an important part of building a more complete picture of what has been happening to the earth’s climate over its most recent glacial and inter-glacial periods.

The climate record from Lake Suigetsu, which reveals the changes taking place in a monsoon non-glacial region, is being compared with similar ‘archives’ from the ice cores of Greenland and ocean sediments from around the world.

“Our record suggests there are different types of climate change and that the process is very complex,” said Professor Nakagawa. “Some climate change is regional rather than global and when there are similarities across the globe they do not necessarily happen at the same time.

“We need a more sophisticated model and to accept that some climate change is unpredictable. One of our biggest findings is that some climate changes are really abrupt - sometimes a significant change can take place in less than five years.”

Professor Nakagawa’s work is embodied by Newcastle University's current campaign 'Enough, For All, Forever' which aims to showcase what has been, and will be, achieved by the University working in partnership to transform NewcastleGateshead into a living, urban laboratory for sustainability.

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The title of his lecture “Counting 50,000 stripes and 500,000 grains” refers to the team’s painstaking work examining the many layers of sediment and pollen grains within the lake. The lecture takes place on Wednesday 23 March 2011 from 5.30pm until 8pm in the Clore Suite, Great North Museum.

Provided by Newcastle University