Increasing riverine heat influx triggers Arctic sea ice decline and oceanic and atmospheric warming

Abstract

Arctic river discharge increased over the last several decades, conveying heat and freshwater into the Arctic Ocean and likely affecting regional sea ice and the ocean heat budget. However, until now, there have been only limited assessments of riverine heat impacts. Here, we adopted a synthesis of a pan-Arctic sea ice–ocean model and a land surface model to quantify impacts of river heat on the Arctic sea ice and ocean heat budget. We show that river heat contributed up to 10% of the regional sea ice reduction over the Arctic shelves from 1980 to 2015. Particularly notable, this effect occurs as earlier sea ice breakup in late spring and early summer. The increasing ice-free area in the shelf seas results in a warmer ocean in summer, enhancing ocean–atmosphere energy exchange and atmospheric warming. Our findings suggest that a positive river heat–sea ice feedback nearly doubles the river heat effect.

Serpentine (Floating) Ice Channels and their Interaction with Riverbed Permafrost in the Lena River Delta, Russia

“…In addition to the complex interactions between hydrological, sedimentological, and biological processes that occur in most river deltas, Arctic deltas are characterized over a long period by the cryosphere, which is strongly affected by amplified Arctic climate warming and subject to profound changes. The observed increase of solid precipitation (Prowse et al, 2011), earlier river ice break up and later freeze up (Cooley and Pavelsky, 2016;Park et al, 2016;Brown et al, 2018), thinning of the river ice (Prowse et al, 2011;Shiklomanov and Lammers, 2014;Arp et al, 2020;Yang et al, 2021), degradation of the permafrost within the river catchments (Biskaborn et al, 2019), as well as the increase of water and heat energy discharge (Ahmed et al, 2020;Park et al, 2020) in most of the Arctic rivers induce a multitude of interacting processes controlling the physical and ecological state of these regions and the adjacent coastal and offshore waters of the Arctic Ocean. Understanding Arctic delta systems and their response to climate warming requires more detailed knowledge of the interactions between deltaic processes and the three components of the cryosphere: snow, river ice and permafrost.…”

The Winter Heat Budget of Sea Ice in Kotzebue Sound: Residual Ocean Heat and the Seasonal Roles of River Outflow

“…Coastal areas have seen the most warming, with SST anomalies of up to +4°C during recent summers in marginal seas such as the Chukchi, Beaufort, and Laptev (Timmermans & Ladd, 2019). This is in part due to riverine heat flux to the Arctic shelves, which has been increasing at a rate of 2.5 EJ/decade (Park et al., 2020), causing a ∼10% reduction in basin‐wide September sea ice extent from 1979 to 2012 (Whitefield et al., 2015). Over 10% of freshwater input to the world's oceans occurs via river outflow into the Arctic (Aagaard & Carmack, 1989), carrying with it an average heat input of 3 TW, equivalent to 7% of the total oceanic heat inputs from the Atlantic and Pacific oceans (and 44% of the heat flux associated specifically with the Bering Strait throughflow; Park et al., 2020; Whitefield et al., 2015).…”

“…This is in part due to riverine heat flux to the Arctic shelves, which has been increasing at a rate of 2.5 EJ/decade (Park et al., 2020), causing a ∼10% reduction in basin‐wide September sea ice extent from 1979 to 2012 (Whitefield et al., 2015). Over 10% of freshwater input to the world's oceans occurs via river outflow into the Arctic (Aagaard & Carmack, 1989), carrying with it an average heat input of 3 TW, equivalent to 7% of the total oceanic heat inputs from the Atlantic and Pacific oceans (and 44% of the heat flux associated specifically with the Bering Strait throughflow; Park et al., 2020; Whitefield et al., 2015). A majority of the riverine heat flux occurs during spring and early summer, when river freshets driven by terrestrial warming deliver as much as 12 TW of heat to the largely ice‐covered coastal shelves (Park et al., 2020; Whitefield et al., 2015).…”

“…Over 10% of freshwater input to the world's oceans occurs via river outflow into the Arctic (Aagaard & Carmack, 1989), carrying with it an average heat input of 3 TW, equivalent to 7% of the total oceanic heat inputs from the Atlantic and Pacific oceans (and 44% of the heat flux associated specifically with the Bering Strait throughflow; Park et al., 2020; Whitefield et al., 2015). A majority of the riverine heat flux occurs during spring and early summer, when river freshets driven by terrestrial warming deliver as much as 12 TW of heat to the largely ice‐covered coastal shelves (Park et al., 2020; Whitefield et al., 2015). While the importance of Arctic rivers is only recently becoming understood, it is clear that they have the potential to significantly impact the heat budget of coastal sea ice on which many Arctic communities depend.…”

Integrating intensity and context for improved supervised river ice classification from dual-pol Sentinel-1 SAR data 

“…Apart from the importance to monitor breakup occurrence, location and timing for local socio-economic effects, the timing is also an important factor in the context of global warming. For example, earlier breakup due to climate change has a positive feedback on Arctic sea ice melt (Park et al, 2020) and the intensifying hydrological cycle in polar regions (Déry et al, 2009, Peterson et al, 2002.…”