landicesedimentsCaCO3 ocean: O18/O16
方法的优点:地理连续性和时间连续性As an indicator of shifts in the Earths climate, the isotope record3 has two advantages. First, it is a global record: there is remarkably little variation in isotope ratios in sedimentary specimens taken from different continental locations. Second, it is a more continuous record than that taken from rocks on land.Because of these advantages, sedimentary evidence can be dated with sufficient accuracy by radiometric methods to establish a precise chronology of the ice ages. The dated isotope record shows that the fluctuations in global ice volume over the past several hundred thousand years have a pattern: an ice age occurs roughly once every 100,000 years6. These data have established a strong connection between variations in the Earths orbit and the periodicity of the ice ages.
延伸性内容:其他影响气候的因素有哪些However, it is important to note that other factors, such as volcanic particulates or variations in the amount of sunlight received by the Earth, could potentially have affected the climate. The advantage of the Milankovitch theory is that it is testable: changes in the Earths orbit can be calculated and dated by applying Newtons laws of gravity to progressively earlier configurations of the bodies in the solar system. Yet the lack of information about other possible factors affecting global climate does not make them unimportant.
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