Doug Keenan’s long essay about the IPCC treatment of surface temperature trends that I discussed earlier had a digression into his work on the calibration of radiocarbon dates that he published in 2012 in the open access EGU journal Nonlinear Processes in Geophysics.
This caught my attention as I have a research interest in radiocarbon dating and constructing age-depth models.
performed the molecular work under supervision by L.
did the main interpretations of the results, with additional statistical analysis from R.
In recent years batteries have changed out of all recognition. Today the cells are components in battery systems, incorporating electronics and software, power management and control systems, monitoring and protection circuits, communications interfaces and thermal management. Mesopotamia, incorporating Sumer, Babylonia and Assyria, known in the West as the Cradle of Civilisation was located between the Tigris and Euphrates rivers (The name means "land between the rivers") in the so called Fertile Crescent stretching from the current Gulf of Iran up to modern day Turkey. the Sumerians of ancient Mesopotamia developed the World's first written language.
(See Map of Mesopotamia) Unfortunately this accolade ignores the contributions of the Chinese people and the Harappans of the Indus Valley, (Modern day Pakistan) who were equally "civilised" during this period practicing metallurgy (copper, bronze, lead, and tin) and urban planning, with civic buildings, baked brick houses, and water supply and drainage systems. Called Cuneiform Writing from the Latin "cuneus", meaning "wedge", it was developed as a vehicle for commercial accounting transactions and record keeping.
There are two reasons uncalibrated dates must be mentioned: 1) this prevents people from making up any number they please, and 2) it is for the sake of posterity, where future scientists can check the results and apply new ideas of calibration. Radiocarbon dates are affected by many outside factors.
The accuracy of the machines is not in question (especially modern ones, which are astoundingly accurate when properly zeroed in). But, any source of old carbon in the ancient environment can affect the amount of C-14 in a sample.
We find evidence of steppe vegetation, bison and mammoth by approximately 12.6 cal.
Radiocarbon dates need calibrating because the relationship between calendar age and radiocarbon age is non-linear.
This is due to fluctuations in the concentration of radiocarbon in the atmosphere caused, for example, by changes in solar activity and hence variability in the flux of cosmic radiations that produces radiocarbon.
There have been several versions of the calibration curve, beginning, I think, in 1986 with Stuiver and Kra (1986).
The current version of the calibration curve is Int Cal13.
scanned cores for X-ray fluorescence and magnetic susceptibility.