Global Climate Variations Over the Past 250 Years: Relationships with the Middle East

We analyze recent global temperature reconstructions over several centuries in time based on calibrations of temperature patterns against global networks of long instrumental and “proxy” data (natural archives such as ice cores, corals, and tree rings), focusing on long-term climatic variations in the Middle East. The pattern of global warming of the past century does not show a strong influence in this region. Instead, patterns of natural low-frequency variability appear to dominate the region. One of these patterns is associated with the well-known “North Atlantic Oscillation” and leads to changes on interannual and decadal timescales. Another distinct pattern appears to relate to influences of low-frequency variability in the North Atlantic ocean circulation and overlying atmosphere circulation, and describes changes that are predominantly multidecadal in timescale. This latter pattern is especially important in predicting possible climate change scenarios in future decades in this region. INTRODUCTION Documenting the patterns of large-scale climate variability during the past several centuries is important to understanding the significance of long-terms trends and low-frequency variations in the global climate. Once such large-scale patterns of variability are established and statistically verified, they can provide a context for understanding the variations present in particular regions of the globe, including those regions of importance in the history of human civilization. Unfortunately, there is no instrumental climate data available on the century and longer timescales of interest in this context. However, widespread networks of high-resolution proxy climate indicators and the few very long instrumental and historical climate indicators available several centuries back can be combined into a global “multiproxy” network that can potentially be used to describe annual global temperature patterns during past centuries. Here we analyze climatic variability back to the mid-18th century based on the multiproxy-reconstructed global surface temperature patterns of Mann et al. (1997a). We focus here on the variations in the Middle East region and its relationship with larger-scale patterns of climate variability. We can thus examine in detail the relationship between Middle Eastern climate and global climatic variations several centuries back in time. DATA The reconstructed surface temperature patterns of Mann et al. (1997) are based on the multivariate calibration of globally distributed annual resolution proxy climate indicator network. The net-