Transition énergétique ?

Het zeewater rond Antarctica werd het afgelopen decennium steeds zouter, blijkt uit een nieuwe studie. Hoe dat kan, kunnen de onderzoekers nog niet verklaren. Wat betekent dit voor het klimaatprobleem?

For decades, the surface of the polar Southern Ocean (south of 50°S) has been freshening—an expected response to a warming climate. This freshening enhanced upper-ocean stratification, reducing the upward transport of subsurface heat and possibly contributing to sea ice expansion. It also limited the formation of open-ocean polynyas. Using satellite observations, we reveal a marked increase in surface salinity across the circumpolar Southern Ocean since 2015. This shift has weakened upper-ocean stratification, coinciding with a dramatic decline in Antarctic sea ice coverage. Additionally, rising salinity facilitated the reemergence of the Maud Rise polynya in the Weddell Sea, a phenomenon last observed in the mid-1970s.

Despite working on polar science for the British Antarctic Survey for 20 years, Louise Sime finds the magnitude of potential sea-level rise hard to comprehend

Le ministre de l’intérieur américain a notamment annoncé le rétablissement d’un programme permettant d’exploiter le pétrole et le gaz dans l’ensemble de l’Arctic National Wildlife Refuge, une aire protégée qui s’étend sur plus de 630 000 hectares.

Antarctica's remote and mysterious current has a profound influence on the climate, food systems and Antarctic ecosystems. Can we stop it weakening by 2050?

The Antarctic Circumpolar Current (ACC) is the world's strongest ocean current and plays a disproportionate role in the climate system due to its role as a conduit for major ocean basins. This current system is linked to the ocean's vertical overturning circulation, and is thus pivotal to the uptake of heat and CO2 in the ocean. The strength of the ACC has varied substantially across warm and cold climates in Earth's past, but the exact dynamical drivers of this change remain elusive. This is in part because ocean models have historically been unable to adequately resolve the small-scale processes that control current strength. Here, we assess a global ocean model simulation which resolves such processes to diagnose the impact of changing thermal, haline and wind conditions on the strength of the ACC. Our results show that, by 2050, the strength of the ACC declines by ∼20% for a high-emissions scenario. This decline is driven by meltwater from ice shelves around Antarctica, which is exported to lower latit

Mechanisms behind a steep rise in temperature

Sea ice extent for the Arctic overall as of mid-December is at the lowest for this point in the season in the entire satellite era record (since autumn 1978) Whether this is a transient low extent or not, expanded open water now, with the winter solstice upon us, means that there’s less time for ice, once it forms, to thicken up before the spring melt commences in a few months.

In March 2022, a New York City-sized ice shelf collapsed in East Antarctica, long thought to be relatively stable against rapid change. The Conger-Glenzer ice shelf collapsed following decades of ocean-induced thinning, allowing its long-stabilizing features to transform into destabilizing ones.

Global warming has already caused the Arctic to release more climate-warming methane—but exactly how much will depend closely on the actions we take to halt climate change.