Vulnerable Cryosphere Changes around the Tipping Point and their Impacts on Earth’s Future

The current global climate warming is unprecedented and extensively accelerated. This is partly evidenced by the months of June, July, and August (considered meteorological summer in the Northern Hemisphere) combined were 0.23 °C warmer than any other summer since global records began in 1880. Additionally, they were 1.2 °C warmer than the average summer between 1951 and 1980. August alone saw a 1.2 °C increase from the average.  In many places around the world, the near-surface temperature was 1.5 °C above pre-industrial levels.

Given the ongoing global climate warming, the climate and atmospheric environment are experiencing irreversible changes. One prominent manifestation of this is the prevalent change in the cryosphere system. Over the past few decades, the Earth's cryosphere system has undergone dramatic increases of retrogressive thaw slumps, solifluction, thermo-karst landforms, massive retreat and collapse of glaciers, significant reductions in snow cover extent, and rapid permafrost degradation. These changes in the cryosphere have detrimental impacts on water supply safety, damage to engineering projects, lead to an abrupt rise of global sea level, and cause a surge in greenhouse gas emissions, ultimately threatening the sustainable development of Earth’s future.

There are indications that the Earth's cryosphere system is becoming increasingly fragile, and the multi-level cascading effects are pushing it towards a tipping point. The cascading effects related to cryosphere elements around the tipping point can further exacerbate global climate warming.

Although some mechanistic understanding can be gleaned from scattered and relatively short-term field observations, many phenomena remain incompletely understood due to the current relevant research being fragmented or biased. Regarding model simulations, while they can offer insights into past changes and future climate scenarios under various shared socioeconomic pathways (SSPs), they lack sufficient and confidently verified actual observational data. Consequently, they might not be entirely convincing, particularly when projecting future scenarios. This uncertainty limits the suggestions that can be offered to relevant decision-makers and stakeholders.

The scientific community urgently needs to facilitate a comprehensive knowledge exchange and brainstorming involving multiple elements and facets, which fundamentally promotes not only the harmonious symbiosis and development of all components of cryosphere systems, but also sustainable socioeconomic development and ecological preservation.

This Collection aims to enhance understanding of the past development, present status, and future trajectories of cryosphere systems. We invite Original Research and Review articles that delve into the latest advancements concerning glaciers, permafrost, snowpack, sea and lake ice, as well as cryosphere-related hazards and sustainable development. Key areas for conceptual discussion or applications to specific case studies may include, but are not limited to:

• Changes in snow cover, permafrost, glaciers, sea and lake ice, river icings, and periglacial landforms within the cryosphere.
• Repercussions of cryosphere element changes on cold region environments and engineering projects.
• Strategies for sustainable development, social adaptation and mitigation of changes in cryosphere elements in a warming climate.
• Interplay between the cryosphere and the atmosphere, hydrosphere, lithosphere, and pedosphere within geosystems.
• Field observations and numerical simulations of cryosphere elements at various spatiotemporal scales.