FIGURE 3. Comparison of modelled and measured Delta14C, together with 10Be flux and proxy climate data from 15,000 to 9,300 yr bp.

From the following article:

Changes in deep-water formation during the Younger Dryas event inferred from 10Be and 14C records

Raimund Muscheler, Jürg Beer, Gerhard Wagner and Robert C. Finkel

Nature 408, 567-570(30 November 2000)



a, Grey scale versus age for Cariaco basin core PL07-56PC (ref. 24). The Younger Dryas cold climate event is clearly visible as a minimum in the grey scale. In the GRIP ice core the Younger Dryas is dated by annual layer counting to lie between 11,550 plusminus 70 and 12,700 plusminus 100 yr bp (ref. 28). The timescale of core PL07-56PC differs from the GRIP timescale by approx300 yr at the beginning of the Younger Dryas and by approx100 yr at the end. b, Measured Delta14C values from core PL07-56PC (ref. 4) detrended by subtracting a linear fit from 15,000 to 9,300 yr bp and plotted on the same time scale as the grey scale. c, Measured (black line) and 10Be-derived Delta14C including changes in deep-water formation (grey curve). A 30% reduction in the diffusion constant throughout the Younger Dryas was assumed for the model run. This reduction in the oceanic ventilation rate produces a change in Delta14C of approximately 40permil, which is comparable to model calculations with a halved rate of NADW formation6. As there are indications that the start of the Younger Dryas at 12,700 yr bp is well dated in the GRIP ice core3, both measured and 10Be-derived Delta14C are plotted on the GRIP timescale and linearly detrended. d, Modelled and detrended Delta14C based on the 14C production rate derived from the 10Be flux to Summit (e) and assuming no changes in deep-water formation throughout the complete deglaciation. The relative timing between the climate proxies delta18O measured in the GRIP ice core (f) and grey scale as suggested by Hughen et al.24 is indicated by the vertical dashed lines. The correlation between measured and 10Be-based Delta14C from 13,500 to 10,500 yr bp increases from R 2 = 0.47 to R 2 = 0.73 (n = 28) if changes in deep-water formation are included.