School of Geography, Earth & Environmental Sciences, Plymouth University, Drake Circus, Plymouth, UK.
Sci Rep. 2013;3:1438. doi: 10.1038/srep01438.
Atmospheric CO2 concentrations appear to have been considerably higher than modern levels during much of the Phanerozoic and it has hence been proposed that surface temperatures were also higher. Some studies have, however, suggested that Earth's temperature (estimated from the isotopic composition of fossil shells) may have been independent of variations in atmospheric CO2 (e.g. in the Jurassic and Cretaceous). If large changes in atmospheric CO2 did not produce the expected climate responses in the past, predictions of future climate and the case for reducing current fossil-fuel emissions are potentially undermined. Here we evaluate the dataset upon which the Jurassic and Cretaceous assertions are based and present new temperature data, derived from the isotopic composition of fossil brachiopods. Our results are consistent with a warm climate mode for the Jurassic and Cretaceous and hence support the view that changes in atmospheric CO2 concentrations are linked with changes in global temperatures.
大气中的二氧化碳浓度在整个显生宙的大部分时间里似乎都明显高于现代水平，因此有人提出，地表温度也更高。然而，一些研究表明，地球的温度（根据化石贝壳的同位素组成估算得出）可能与大气中二氧化碳的变化无关（例如在侏罗纪和白垩纪）。如果过去大气二氧化碳的大幅变化没有对气候产生预期的响应，那么对未来气候的预测以及减少当前化石燃料排放的理由就有可能受到影响。在这里，我们评估了侏罗纪和白垩纪断言所依据的数据集，并提出了新的温度数据，这些数据来自化石腕足动物的同位素组成。我们的结果与侏罗纪和白垩纪的温暖气候模式一致，因此支持这样一种观点，即大气二氧化碳浓度的变化与全球温度的变化有关。
