Carbon and oxygen isotopes in tree rings may shed new light on past climate events

December 4th, 2009 - 4:58 pm ICT by ANI  

Washington, December 4 (ANI): Scientists have determined that the analysis of carbon and oxygen isotopes embedded in tree rings may shed new light on past climate events.

Scientists have long looked at the width of tree rings to estimate temperature levels of past years.

Larger rings indicate more tree growth in a season, which translates into warmer summer temperatures.

But, according to researchers working in northern Canada, the analysis of carbon and oxygen isotopes in tree rings can also provide accurate data on past climate events in the Mackenzie Delta region.

In a new research, Trevor Porter, a PhD student in Geography and Environmental Science at Carleton University, and three other authors compared temperature data collected in Inuvik, Northwest Territories (NT) since 1957 with their own analysis of isotopes found in white spruce trees in the Mackenzie Delta region of the NT.

They found a strong correlation between the two data sets and temperatures.

“Isotope analysis is a good way to measure past climate change,” said Porter about the results.

Porter’s work was carried out on the northern edge of the boreal forest in the NT where trees are small but surprisingly old.

“A 15 to 20 cm. tree could be a 300 to 400 year old tree,” said Porter.

This slow rate of growth actually helps researchers because smaller trees stay standing longer. Trees that fall begin to decay making data analysis difficult or impossible.

“Once they get too large, it’s difficult for trees to persist. They are susceptible to wind and ice storms. One of the reasons trees (in the North) persist so long is because they don’t grow as much,” said Porter.

Isotope analysis allows researchers to conduct their work using a smaller sample size than needed when trying to re-construct temperature records using tree ring width.

Porter explains that the width of rings can vary considerably between trees even when they are growing in the same stand.

This variation can complicate reconstructions of past climate. (ANI)

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