Karst aquifers are vital water resources for a large part of the global population, yet their functioning and vulnerability to climate variability and change remain difficult to quantify. Their complex subsurface structure leads to highly heterogeneous flow and storage dynamics, making it challenging to assess how water availability will evolve in the future. In this talk, I will present different perspectives on understanding and modeling karst water resources across scales. A central focus will be groundwater recharge as the primary control on water availability. I will highlight large-scale modeling approaches that explicitly represent karst-specific processes and demonstrate how they can be used to estimate recharge across regions and continents. These applications provide new insights into spatial patterns and sensitivities of karst water resources that go beyond what can be learned from individual case studies. In addition, I will introduce data-driven approaches that use soil moisture observations to infer recharge dynamics, offering an alternative and complementary perspective that is more directly constrained by observations. Together, these approaches help to better understand how karst systems respond to climate variability and change, including potential impacts on water supply. I will conclude with an outlook that extends beyond karst, discussing how the concepts and methods developed here can inform the assessment of groundwater resources in other hydrogeological settings.