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Droughts have had large impacts on past and present societies. High‐resolution paleoclimate data are essential to place recent droughts in a meaningful historical context and to predict regional future changes with greater accuracy. Such records, however, are very scarce in the Middle East in general, and the Fertile Crescent in particular. Here we present a 2400 year long speleothem‐based multiproxy record from Gejkar Cave in northern Iraq. Oxygen and carbon isotopes and magnesium are faithful recorders of effective moisture. The new Gejkar record not only shows that droughts in 1998–2000 and 2007–2010, which have been argued to be a contributing factor to Syrian civil war, were extreme compared to the current mean climate, but they were also superimposed on a long‐term aridification trend that already started around or before 950 C.E. (Common Era). This long‐term trend is not captured by tree ring records and climate models, emphasizing the importance of using various paleoclimate proxy data to evaluate and improve climate models and to correctly inform policy makers about future hydroclimatic changes in this drought‐prone region. A long‐term drying trend was present in the Fertile Crescent from at least 950 C.E.The recent droughts were extreme compared to the mean climate and superimposed on the long‐term aridificationThe long‐term trend is not captured by tree ring records or climate models

Palaeoclimate variability must be constrained to predict the nature and impacts of future climate change in the Eastern Mediterranean. Here, we present a late Holocene high‐resolution multiproxy data set from Kocain Cave, the first of its kind from SW Turkey. Regional fluctuations in effective‐moisture are recorded by variations in magnesium, strontium, phosphorous and carbon isotopes, with oxygen isotopes reacting to changes in precipitation and effective‐moisture. The new record shows a double‐peak of arid conditions at 1150 and 800 BCE, a wet period 330–460 CE followed by a rapid shift to dry conditions 460–830 CE, and a dry/wet Medieval Climate Anomaly/Little Ice Age pattern. Large discrepancies exist between Turkish records and the Kocain record, which shares more similarities with other Eastern Mediterranean coastal records. Heterogeneity of regional climate and palaeoclimate proxy records are emphasized. Records of past climate are essential in the Eastern Mediterranean to understand regional impacts of modern climate change. In combination with archeology, these allow us to examine climatic impacts on people in the past to help us prepare for the future. Here, we examine a stalagmite (Ko‐1) from Kocain Cave, southwest Turkey, which contains information about past climate change in its chemistry. Measurements of trace‐metals and carbon isotope ratios record the amount of water entering the cave, oxygen isotope ratios record rainfall amount. Measurements of uranium are used to date the climate changes. Earthquakes that damaged nearby cities and caused tsunamis changed the angle of the stalagmite, providing more evidence for dating the sample. The Kocain Cave record shows climatic conditions changed frequently in southwest Turkey. Important are dry conditions 1150 and 800 BCE, wet conditions 330–460 CE followed by a rapid shift to dry conditions 460–830 CE, and a dry/wet Medieval Climate Anomaly/Little Ice Age pattern. These climate changes were different to records from elsewhere in Turkey and matched better with coastal records from Greece and Lebanon/Israel. The complex nature of past climate is emphasized due to varied climatic regions in Turkey and the many impacts on each record. Stalagmite Ko‐1 record of effective‐moisture from SW Turkey stresses spatial and temporal heterogeneity of Turkish climateClimate changes share more similarities with other Eastern Mediterranean coastal regions, than central or northern TurkeyHeterogeneity of modern climate and proxy records highlight the complexity of historical comparisons Stalagmite Ko‐1 record of effective‐moisture from SW Turkey stresses spatial and temporal heterogeneity of Turkish climate Climate changes share more similarities with other Eastern Mediterranean coastal regions, than central or northern Turkey Heterogeneity of modern climate and proxy records highlight the complexity of historical comparisons

The ratio of boron to calcium (B/Ca) in a subset of foraminifera has been shown to covary with seawater carbonate chemistry, making this geochemical signature a promising proxy for carbon cycle science. Some studies suggest complications with the B/Ca proxy in photosymbiont‐bearing planktonic foraminifera, while relatively few studies have investigated B/Ca in species that lack large dinoflagellate symbionts. For the first time, we use a sediment trap time series to evaluate B/Ca of subtropical and subpolar planktonic foraminifera species that are asymbiotic (Globigerina bulloidesand Neogloboquadrina incompta) and a species that hosts small intrashell photosymbionts (Neogloboquadrina dutertrei). We find that B/Ca measurements across size fractions indicate overall little to no size‐dependent uptake of boron that has previously been reported in some symbiont‐bearing foraminifera. Neogloboquadrina incomptaand N. dutertreiB/Ca are strongly correlated with calcite saturation, pH, and carbonate ion concentration, which is in good agreement with the limited number of published core top results. While G. bulloidesB/Ca trends with seasonal fluctuations in carbonate chemistry, during discrete periods considerable B/Ca offsets occur when a cryptic G. bulloidesspecies is known to be seasonally present within the region. We confirm presence and significant B/Ca offset between cryptic species by individual LA‐ICP‐MS analyses. This finding calls into question the use of traditional morphological classification to lump what might be genetically distinct species for geochemical analyses. Our overall results highlight the utility of G. bulloides, N. incompta, and N. dutertreiB/Ca while bringing to light new considerations regarding divergent geochemistry of cryptic species. Analyzed populations of Neogloboquadrinaforaminifera show no size‐dependent offsets in B/Ca and significant correlations with carbonate system variablesB/Ca of individual G. bulloidesanalyzed by LA‐ICP‐MS indicates that local cryptic species have significant B/Ca offsetsDivergent geochemistry of cryptic species calls into question the use of traditional species classification for B/Ca analysis