Numerous studies over the past 30 years have suggested there is a causal connection between the motion of the Sun through the Galaxy and terrestrial mass extinctions or climate change. Proposed mechanisms include comet impacts (via perturbation of the Oort cloud), cosmic rays and supernovae, the effects of which are modulated by the passage of the Sun through the Galactic midplane or spiral arms. Supposed periodicities in the fossil record, impact cratering dates or climate proxies over the Phanerozoic (past 545 Myr) are frequently cited as evidence in support of these hypotheses. This remains a controversial subject, with many refutations and replies having been published. Here I review both the mechanisms and the evidence for and against the relevance of astronomical phenomena to climate change and evolution. This necessarily includes a critical assessment of time series analysis techniques and hypothesis testing. Some of the studies have suffered from flaws in methodology, in particular drawing incorrect conclusions based on ruling out a null hypothesis. I conclude that there is little evidence for intrinsic periodicities in biodiversity, impact cratering or climate on timescales of tens to hundreds of Myr. Furthermore, Galactic midplane and spiral arm crossings seem to have little or no impact on biological or climate variation above background level. (truncated)
Comment on 'Investigations into the impact of astronomical phenomena on the terrestrial biosphere and climate' (arXiv:1505.07856 [astro-ph.EP]) by Fabo Feng
On the astronomical origin of the Hallstatt oscillation found in radiocarbon and climate records throughout the Holocene
在宇宙源放射性同位素(C-14和Be-10)和整个全新世的古气候记录中发现了一个周期约为2100-2500年的振荡,即哈尔施塔特周期。在这里,我们展示了这个周期的天文起源。也就是说,这种振荡是相干的主要稳定共振涉及四个类木行星-木星,土星,天王星和海王星-其周期为p=2318年。哈尔施塔特周期可能来自于太阳系盘圆度的节律性变化,假设这种动态最终可以调节太阳风,从而调节入射宇宙射线通量和/或地月系统周围的行星际/宇宙尘浓度。行星质量中心(PMC)相对于太阳的轨道被用作代理。我们分析了这个虚拟轨道的瞬时偏心率矢量是如何从13,000 B变化的。C. 17,000 A. D..我们发现,它经历了一种脉动,因为它清楚地呈现出有节奏的收缩和膨胀模式与2318年的周期连同一些已知的更快的振荡与行星轨道稳定共振。我们发现,太阳-PMC轨道的快速膨胀,然后缓慢收缩,似乎可以阻止宇宙射线进入系统内部区域,而缓慢膨胀,然后快速收缩有利于它。同样,同样的动力学可以调节落在地球上的行星际/宇宙尘的数量。然后,这些将通过云/日冕调制引起辐射潮汐的产生和气候变化。其他稳定的轨道共振频率(例如,20年、45年、60年、85年、159-171-185年等周期)在科学文献中确定的辐射潮汐、太阳、极光和气候记录中都有。因此,该结果支持太阳和/或气候变化的行星理论。
Short-Term Orbital Forcing: A Quasi-Review and a Reappraisal of Realistic Boundary Conditions for Climate Modeling
本文的目的是为地球科学家提供最准确的一套地球的天体气候参数和每日日照量,能够描述短期轨道强迫(STOF)所代表的不断变化的入射太阳辐射。我们提供了一个更新的审查和实用的工具/数据库,使用最新的天文模型和轨道星历,为整个全新世和一千年的未来。我们的结果进行了比较,最重要的数据库产生的研究长期的轨道强迫没有系统的差异,在整个一万三千年的研究期间。我们的详细分析,目前在STOF的周期,作为扰动的太阳系机构,产生了非常丰富的动态调制的年度到十年的时间尺度相比,以前的结果。此外,我们首次讨论了将日日照视为轨道半径相对于标称值的连续函数时所犯的错误,即,用{ \it at noon}的轨道坐标计算相应的日射量。我们发现了重要的相对差异$\pm$ 5\%,这对应于2.5 W m $^{-2}$的日平均日射误差,完全相同的日历日和一套天文气候参数。这种以前未被认识到的错误可能会对任何气候模拟实验的初始和边界条件产生重大影响。