Complex sentence: The spatial distribution and accuracy of global data must be significantly improved before realistic quantitative assessments of the global impacts of coastal hazards can be made, as currently much of the data is collected and analysed in the aftermath of disasters.
Split into simpler sentences: The spatial distribution and accuracy of global data must be significantly improved before realistic quantitative assessments of the global impacts of coastal hazards can be made. As currently much of the data is collected and analysed in the aftermath of disasters.