Climate networks around the globe are significantly affected by El Nino

The temperatures in different zones in the world do not show significant changes due to El Nino except when measured in a restricted area in the Pacific Ocean. We find, in contrast, that the dynamics of a climate network based on the same temperature records in various geographical zones in the world is significantly influenced by El Nino. During El Nino many links of the network are broken, and the number of surviving links comprises a specific and sensitive measure for El Nino events. While during non-El Nino periods these links which represent correlations between temperatures in different sites are more stable, fast fluctuations of the correlations observed during El Nino periods cause the links to break.