Marine microcharcoal records provide invaluable information to understand changes in biomass burning and its drivers over multiple glacial and interglacial cycles and to evaluate fire models under warmer climates than today. However, quantitative reconstructions of burnt area, fire intensity and frequency from these records need calibration studies of the current fire-microcharcoal relationship. Here, we present the analysis of microcharcoal concentration and morphology in 102 core-top sediment samples collected in the Iberian margin and the Gulf of Cádiz. We show that microcharcoal concentrations are influenced by the water depth or the distance from the river mouth. At regional scale, the mean microcharcoal concentrations and microcharcoal elongation (length to width ratio) show a marked latitudinal variation in their distribution, primarily controlled by the type of burnt vegetation in the adjacent continent. High microcharcoal concentrations in marine sediments represent rare, large and intense fires in open Mediterranean woodlands. Based on these results, the increasing trend of microcharcoal concentrations recorded since 8 ka in the well-known marine sedimentary core MD95-2042 off the Iberian margin indicates the occurrence of large and infrequent fires of high intensity due to the progressive degradation of the Mediterranean forest and the expansion of shrublands.

海洋微炭记录提供了宝贵的信息，以了解生物量燃烧的变化及其在多个冰期和间冰期循环中的驱动因素，并在比今天更温暖的气候下评估火灾模型。然而，根据这些记录对燃烧面积、火灾强度和频率的定量重建需要对当前火灾-微炭关系进行校准研究。在这里，我们介绍了在伊比利亚边缘和加的斯湾收集的 102 个岩心顶部沉积物样本中的微炭浓度和形态分析。我们表明，微炭浓度受水深或与河口距离的影响。在区域尺度上，平均微炭浓度和微炭伸长率（长宽比）显示出其分布的显着纬度变化，主要受邻近大陆烧毁植被类型的控制。海洋沉积物中高浓度的微炭代表了地中海开阔林地中罕见的、大而强烈的火灾。根据这些结果，自 8 ka 以来在伊比利亚边缘著名的海洋沉积核心 MD95-2042 中记录的微炭浓度增加趋势表明，由于地中海森林的逐渐退化，发生了大而罕见的高强度火灾和灌木地的扩张。