Abstract
The periodicity of Vostok ice core climate temperature and gas concentration data indicate inherent long term past regularity of Earth’s climate, with a period of around 100,000 years, warming around 15,000 and cooling of around 85,000 years. At this point we are at the top of one of the warming periods. Vostok data cover around 430,000 years, ie 4 climate cycles (warming-cooling), of similar but not quite the same duration. In this paper we perform a detailed time and frequency analysis of these data for each of the cycles as well as their various combinations, including a full tested period of 430,000 years. Time correlation analysis allows for more accurate time lag estimate in each cycle already noted between temperature change and carbon dioxide content. We estimate these lags to lie between 1000-2500 years, longer than previously concluded. On the frequency side we perform Fast Fourier Analysis and identify full spectrum of harmonics for various cycles, and then perform energy analysis to identify which of the harmonics contributes the most. The idea is to reduce the computational load for further modeling and analysis using Kalman Filter based prediction method. Once the prediction model is defined (a follow up paper) data will be split into two segments, Learning and Testing, in preparation of a Machine Learning fine tunning methodology. We can use last three or last two or even just last cycle to learn on, and then the current on going cycle to test on. This will result in real time prediction of relevant climate data. Assuming causal time regularity, more of these cycles are employed in training, more the prediction error for the next cycle should be reduced. Hence it is critical to perform very detailed time and frequency analysis of Vostok data as a solid data base for the prediction model to follow.
Highlights
Extensive climatic data on the past four ice ages and beyond is available from various studies, commencing from mid 1950s until now
In this paper we focus on specific analysis related to only two Vostok data variables, namely relative temperature and CO2 content
Originally thought that the CO2 data might be considered as proof of its causal role in global warming, it is widely considered that CO2 lags temperature change and its lower rate of solution in and release from sea water is more likely the cause of the relationship
Summary
Extensive climatic data on the past four ice ages and beyond is available from various studies, commencing from mid 1950s until now. The Vostok ice core data set includes derivations of relative temperature, carbon dioxide (CO2), PEN Vol 7, No 2, August 2019, pp.907 923 methane (CH4), oxygen and solar variation (insolation), during the last 430,000 years. Reference [10] presented the first record to span and full glacial-interglacial from an ice core drilled in the Russian Vostok station in Antarctica. A 430,000 year record was constructed from the Petit et al study on a 3 km deep core of ice (Fig. 2). Another source of similar ice core data is available from European EPIC drilling project (European Project for Ice Coring in Antarctica) which lasted from 1998 until 2005 (Fig. 3). Originally thought that the CO2 data might be considered as proof of its causal role in global warming, it is widely considered that CO2 lags temperature change and its lower rate of solution in and release from sea water is more likely the cause of the relationship
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