Global Tipping Points Report 2023: Ch1.2: Cryosphere tipping points.

Drastic changes in our planet’s frozen landscapes have occurred over recent decades, from Arctic sea ice decline and thawing of permafrost soils to polar amplification, the retreat of glaciers and ice loss from the ice sheets. In this chapter, we assess multiple lines of evidence for tipping points in the cryosphere – encompassing the ice sheets on Greenland and Antarctica, sea ice, mountain glaciers and permafrost – based on recent observations, palaeorecords, numerical modelling and theoretical understanding. With about 1.2°C of global warming compared to pre-industrial levels, we are getting dangerously close to the temperature thresholds of some major tipping points for the ice sheets of Greenland and West Antarctica. Crossing these would lock in unavoidable long-term global sea level rise of up to 10 metres. There is evidence for localised and regional tipping points for glaciers and permafrost and, while evidence for global-scale tipping dynamics in sea ice, glaciers and permafrost is limited, their decline will continue with unabated global warming. Because of the long response times of these systems, some impacts of crossing potential tipping points will unfold over centuries to millennia. However, with the current trajectory of greenhouse gas (GHG) emissions and subsequent anthropogenic climate change, such largely irreversible changes might already have been triggered. These will cause far-reaching impacts for ecosystems and humans alike, threatening the livelihoods of millions of people, and will become more severe the further global warming progresses

Antarctic ice sheet modelling – the needs, challenges, and opportunities for Norwegian Antarctic research

Academic presentation at "Antarktisseminaret 2024", 07.05.24 08.05.24 Tromsø, Norway.Antarctic Ice Sheet mass loss accounts for the largest uncertainties in global sea level projections. Antarctic meltwater and iceberg calving, together with changes in sea ice, also impact global ocean circulation, carbon uptake, and ecosystems. To understand, quantify and predict these changes and impacts, we employ climate and ice sheet models. Over the past 5+ years the Norwegian polar research community has been building up expertise in Antarctic ice sheet modelling. In this presentation I aim to highlight our recent progress, and to identify our future needs, challenges, and opportunities. An example of recent progress is our work on simulating ocean – ice sheet interactions (recently finished EU project TiPACCs). This work revealed that abrupt changes in the ice sheet can occur, but that we have likely not crossed these tipping points – yet. Our latest science focusses on (1) the impact of Antarctic meltwater on ocean circulation (e.g. EU project OCEAN:ICE), (2) linkages between ice sheets and the global heat budget and carbon cycle (e.g. SFF iC3), and (3) Antarctic Ice Sheet projections (e.g. ISMIP). I will make suggestions for the tools we need to (continue) to be a world player in Antarctic ice sheet modelling. On a national level, there is a strong will to collaborate on Antarctic modelling, especially linking Bergen and Tromsø researchers (e.g. SFF iC3, RCN CLIM2ANT). This brings great opportunities, especially if we acknowledge and overcome the (potential) challenges that collaboration brings. Making Antarctic research ideas and outcomes easily accessible to a wide Norwegian audience is important. Not only for informing, but also for building a sustainable and solid Antarctic research basis in Norway. If time permits, I am happy to share some examples of outreach projects where art and comic books made our, sometimes heavy, Antarctic research interesting for a general audience