Japanese Lake Provides More Definitive Record of Carbon-14 Levels

Bill Sweet
Friday, October 19, 2012
IEEE Spectrum: Inside Technology
http://spectrum.ieee.org/energywise/energy/environment/japanese-lake-provides-more-definitive-record-of-carbon14-levels

Summary
Thirteen years ago, an team of scientists created a record of atmospheric greenhouse gas concentrations and temperatures dating back 420,000 years (shown in chart below). This chart has been invaluable in climate science, emphasizing the relationship between greenhouse gases and temperatures. Some have skepticized that the leads and lags in the record suggest that temperature changes cause changes in greenhouse gases, instead of vice versa. The roadblock in finding out whether or not this is true, is that there has not been a developed record of carbon-14 concentrations in the atmosphere dating back beyond 12,000 years ago, which would help to clear up various theories about the last ice age. But this week, an account of yearly changes in C-14 levels in the atmosphere dating back more than 50,000 years was published based on the sediments in a Japanese lake. These concentrations vary throughout time, and this new chart provides a greater solution for the periods that have previously been unclear and could show a more detailed history of solar activity, a factor in climate change. This Japanese lake, Lake Suigetsu, is surrounded by trees whose leaves drop into the water, falling to the bottom of the lake every year, and has been virtually undisturbed for thousands of years. Using carbon dating, the concentrations of C-14 found in the leaf layers help improve carbon dating and unveil a record of radiocarbon levels and local climate changes. These can be compared with other climate records to see how climate changes in different parts of the world relate to each other, and where it leads and lags. According to scientist Paula J. Reimer, this new record "stretches back over the full length of the radiocarbon age scale," helping to improve the accuracy at which radiocarbon dates are converted to calendar time.

Connection
This article is connected to the matter and energy and ecosystems units. It connects to Matter and Energy because carbon-14 is a radioactive isotope which decays over time and helps researchers to determine dates of the organic objects they are dating. Also, this article relates ecology because of carbon cycle impacts. The releasing of carbon dioxide into the atmosphere is what the graph above is based on. The increase in carbon dioxide and other gases have contributed to the greenhouse effect, causing temperature and climate change on Earth.