From a comparison of C14/C1s and Cla/C1* ratios in wood and in marine material and from a slight decrease of the C14 concentration in terrestrial plants over the past 50 years it can be concluded that the average lifetime of a CO, molecule in the atmosphere before it is dissolved into the sea is of the order of 10 years. This means that most of the CO, released by artificial fuel combustion since the beginning of the industrial revolution must have been absorbed by the oceans. The increase of atmospheric CO, from this cause is at present small but may become significant during future decades if industrial fuel combustion continues to rise exponentially.Present data on the total amount of C 0 2 in the atmosphere, on the rates and mechanisms of exchange, and on possible fluctuations in terrestrial and marine organic carbon, are inadequate for accurate measurement of future changes in atmospheric COP An opportunity exists during the International Geophysical Year to obtain much of the necessary information.

Height and weight at menarche were found for each subject in three longitudinal growth studies. Early and late maturing girls have menarche at the same mean weight, but late maturers are taller at menarche. Two other major events of adolescence, initiation of the weight growth spurt and maximum rate of weight gain, also occur at an invariant mean weight. The hypothesis is proposed that a critical body weight may trigger each of these adolescent events. Such an interaction would explain the secular trend to an earlier menarche.

. (1971). Archives of Disease in Childhood, 46, 695. Height and weight at menarche and a hypothesis of menarche. Height and weight at menarche were estimated by interpolation of longitudinal growth data for 181 girls. Mean weight at menarche, about 48 kg, does not change as menarcheal age increases, whereas mean height increases significantly. Early and late menarcheal girls gain the same amount of height, about 22 cm, and the same amount of weight, about 17 kg, in the interval from the initiation of the adolescent spurt to menarche, though late maturers grow at slower rates during the spurt, including the year of menarche. A hypothesis of a direct relation between a critical weight and menarche is proposed. Such an interaction would explain the delaying effect of malnutrition on menarche and the secular trend to an earlier menarche.Though there are many general observations that girls at menarche are taller and heavier than those of the same age who have not achieved menarche (Tanner, 1962), there are no published data on actual height and weight at menarche, as far as we know. In a preliminary report we gave data for height and weight at menarche obtained for each girl by interpolation of the data of three longitudinal growth studies. At menarche, the mean weight of early and late menarcheal girls did not differ, whereas late menarcheal girls were significantly taller than girls with early menarche (Frisch and Revelle, 1970).Menarche occurs after the initiation of the adolescent growth spurt and the attainment of the maximum rates of growth in height and weight (Frisch and Revelle, 1969b;Simmons and Greulich, 1943). Our analysis of the same longitudinal growth studies for the height and weight of each child at the time of spurt initiation (Frisch and Revelle, 1971), and the maximum rates of growth (Frisch and Revelle, 1969b) also showed that the mean weight of early and late maturing girls did not differ at each of these events, whereas late maturers were significantly taller at each event.These results account for the many observations that early maturers have more weight for height before, and throughout the adolescent spurt, including the year of menarche (Tanner, 1962).Received 16 March 1971. It was unexpected, however, that three of the major events of adolescence were related to an unchanging mean weight. This paper gives additional findings of our analysis of height and weight at menarche as a function of age of menarche. A hypothesis of menarche and an explanation of the secular trend to an earlier menarche (Tanner, 1966;Marshall and Tanner, 1968) are proposed. MethodWe are grateful to Dr.

From a comparison of C14/C12 and C13/C12 ratios in wood and in marine material and from a slight decrease of the C14 concentration in terrestrial plants over the past 50 years it can be concluded that the average lifetime of a CO2 molecule in the atmosphere before it is dissolved into the sea is of the order of 10 years. This means that most of the CO2 released by artificial fuel combustion since the beginning of the industrial revolution must have been absorbed by the oceans. The increase of atmospheric CO2 from this cause is at present small but may become significant during future decades if industrial fuel combustion continues to rise exponentially. Present data on the total amount of CO2 in the atmosphere, on the rates and mechanisms of exchange, and on possible fluctuations in terrestrial and marine organic carbon, are inadequate for accurate measurement of future changes in atmospheric CO2. An opportunity exists during the International Geophysical Year to obtain much of the necessary information.

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