Deriving from the Greek ‘kryos’, the term ‘cryosphere’ is generally defined as all parts of the Earth’s surface system where water is in solid form, such as mountain glaciers, ice sheets, permafrost and seasonally frozen soil, snow cover, icebergs, sea ice, river ice and lake ice [1–5]. Over the past decade, research on the cryosphere, ranging from changes to impacts and adaptation, has received worldwide attention. As a result, the field of Cryosphere Science has seen rapid development [5].

The cryosphere makes significant contributions to human well-being (HWB) directly or indirectly and materially or spiritually, providing a wide array of benefits. All kinds of benefits that the cryosphere provides for humans can be considered cryosphere services (CSs) [6,7]. In prehistoric periods, early human evolution, migration out of Africa and occupation of the Tibetan Plateau have been closely linked to major environmental changes that the cryosphere has supported [8–10]. Later, important ocean “bridges” formed, for example across the Bering Sea and between southeastern Pacific islands, as the cryosphere fixed oceanic water in continental ice sheets and ocean shelves were exposed in the Ice Age [11]. These bridges (examples of cryospheric “bearing services”) greatly facilitated migrations across continents and the global dispersal of modern Homo sapiens. However, the most important human benefits (HBs) from the cryosphere is probably its ongoing involvement in the creation and regulation of suitable climatic conditions for human habitation [6]. In extensive cold and arid regions of the world, human socio-economic development strongly depends on freshwater resources that the cryosphere provides, which can be widely used for ecosystem integrity, agricultural irrigation, developing hydropower, domestic and industrial activities. It also lends important environmental support for animal and plant habitats, and unique natural resources are generated in cryosphere-dominated regions. In addition, it provides crucial load-bearing services for diverse types of infrastructure required for numerous human activities in cold regions. Moreover, elements of the cryosphere provide aesthetic, cultural, spiritual and recreational benefits for people living around it and far away that cannot be obtained elsewhere [6].

Although there is a wealth of studies on cryospheric processes and mechanisms, the interaction between the cryosphere and other spheres, and the cryospheric disaster risk, the systematic research on CSs is still in its early stage [5,7,12]. Some previous studies have also investigated polar or mountainous ecosystem services (ESs) [13–17], which generally take cryosphere as a component of large ecosystems that functionally supports the formation of ESs [18]. But CSs and their relatively direct contribution to HWB have received less attention [19,20]. Eicken et al. [18] considered the Arctic sea ice, one of the basic elements of the cryosphere, as a relatively independent system and identified its services categorization with a purpose of providing detailed and effective information for stakeholders perceiving and using sea ice. Taking all elements of the cryosphere into account, Xiao et al. [6] presented a preliminary classification and value evaluation method for CSs. Since 2017, the National Natural Science Foundation of the People’s Republic of China has launched a research project series entitled Determination of cryosphere service function and methods for service value evaluation and Formation Process of Chinese Cryosphere Service Functions and Integrated Regionalization, the major objectives of which are to elucidate relationships between cryospheric processes and CSs in detail and promote sustainable regional development. Up to now, the main relevant achievements include but are not limited to [21–30]. Also, recently, based on the CSs concept, Mukherji et al. [7] reviewed the contributions of the cryosphere to mountainous communities across the Hindu Kush Himalaya.

To make the concept of CSs more specific and feasible, there needs to be a more systematic classification to enable conceptualization, assessment, valuation and policymaking; there also needs to be a detailed understanding from the formation processes of various CSs to their linkages with HWB. To address these needs, we first propose a classification system based on descriptions of the processes involved in the formation of CSs and their links with HWB, and discussions of basic principles for an effective typology. Then we review the formation, current status and anticipated changes of the various types of the services and their links to HWB in detail. Finally, the spatio-temporal scales, the linkages between CSs and HWB, and climate-dependence are further discussed.

2. Cryosphere Services Classification System

2.1. The Formation of Cryosphere Services and Their Links to Human Well-Being

Each service the cryosphere provides to human society depends upon cryosphere functions (CFs), which refer variously to the cryosphere’s environmental nature, structures and processes, as illustrated in Figure 1. The distinguishing feature of the cryosphere in relation to other environmental elements is the presence of water in the frozen state. Cryospheric processes cover cryospheric changes and their interaction with other spheres [5]. CFs include energy regulation, material (especially water) storage and migration, load-bearing, natural cooling capacity and release, and surface erosion or consolidation, etc. However, these functions are natural attributes of the cryosphere. Switching attention from CFs to CSs not only changes the research perspective, but also fundamentally extends the objectives, from solely considering the cryosphere’s nature to addressing its relationship with human society. Specifically, CSs are based on CFs, with orientations towards human needs and values. That is, the cryosphere meets human’s material and spiritual needs, thereby contributing to HWB, which focuses on the positive effects of the cryosphere, in contrast with the negative effects (i.e., cryospheric disasters).

HWB has multiple constituents, but its core is quality of life [20,31]. According to the Millennium Ecosystem Assessment (MA), HWB has five constituents: basic material for good life, health, security, good social relations, freedom of choice and action [20]. All types of CSs have a positive impact on human’ social, economic and spiritual needs, by definition, so they all contribute (directly or indirectly) to HWB. However, the linkages between CSs and HWB are also complex processes (Figure 1). Firstly, the links between supplies and consumptions of the services involve a great deal of investments of built and human capital together with appropriate socioeconomic regimes and value orientation [32]. Then there is spatial separation, and hence, complex nonlinear and hysteretic relationships between the services’ supply and HBs from them (Ibid.). In some cases, their contributions to HWB may also be marginal, and dependent on levels of human demand or even mental status [33]. However, the essential issues are the dynamic relationships between CSs and CFs, which determine how, where, when and what benefits from the cryosphere can be used to improve HWB.