Correlation and Causation: Changing Baltic Sea Climate

The atmospheric concentration of CO2 has been increasing the last centuries, but at an especially fast rate during the last 5-6 decades. Contemporary global air temperatures have been warming at a rather high rate and are well correlated with rising CO2. Coinciding trends and good correlations are found in many other global and regional variables, as increasing sea level, increasing sea surface temperature, decreasing ice cover or increasing alien species entries. However, correlation does not necessarily imply causation, as known from the good correlation between the number of storks and the number of newborn babies. Therefore we apply here a newly developed technique that allows discrimination between correlation and causality by quantifying the information flow between time series. With this method we can demonstrate a clear one-way causality in the sense that the CO2 increase is causing the temperature increase and not the other way around. This result cannot be inferred from traditional time delayed correlation analysis. Many Baltic climate variables and ecosystem variables are well correlated as for example air temperature and alien species entry, but are they causal connected? We use this new method for answering the question for which variables correlation also means causation and for which not. For the first time we can demonstrate the strong causality of rising CO2 levels on the increasing number of alien species entries.

STIPS Adolf;  MACIAS MOY Diego;  GARCIA GORRIZ Elisa; 

2016-01-18

University of Riga

JRC95412

https://publications.jrc.ec.europa.eu/repository/handle/JRC95412,