How does rising atmospheric CO2 affect marine organisms?

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East-Central China
Tian, H., Stige, L.C., Cazelles, B., Kausrud, K.L., Svarverud, R., Stenseth, N.C. and Zhang, Z. 2011. Reconstruction of a 1.910-y-long locust series reveals consistent associations with climate fluctuations in China. Proceedings of the National Academy of Sciences USA 108: 14,521-14,526.

Tian et al. reconstructed a 1910-year-long time series -- stretching from AD 2 to AD 1911 -- of outbreaks of Oriental migratory locusts in China, based on information they extracted from more than 8000 historical documents, plus relationships they developed between these data and indices of temperature at both annual and decadal time scales. This work revealed that there was, as they describe it, "a negative association between locust abundance and annual temperature," which was most strongly manifest when the temperature index was representative of the whole of China. And as may be seen in the figure below, the interval of lowest locust index during this period (~AD 1030-1250) -- which would thus represent the warmest period of the record -- falls right in the middle of the mean global Medieval Warm Period, as illustrated by the body of data accumulated to date and displayed in the Interactive Map and Time Domain Plot of our Medieval Warm Period Project.

Figure 1. Chinese decadal locust abundance index vs. year. Dashed lines connect data points across periods with no locust reports. Adapted from Tian et al. (2011).

Unfortunately, the locust data of the figure above end in 1911, so we are unable to either quantitatively or qualitatively determine the peak warmth of the MWP relative to that of the CWP. Nevertheless, the reality and timing of the MWP in China are both clearly evident.