This summer’s minimum ice cover was twelfth-lowest ever — and scientists warn that the long-term trend towards shrinking continues.
Arctic sea ice has passed its minimum extent for this year, shrinking to 4.72 million square kilometres on 16 September, the US National Snow and Ice Data Center (NSIDC) has reported.
Owing to a cool and cloudy Arctic summer, this year’s annual minimum was the highest since 2014 — ice covered nearly 1 million square kilometres more than last year’s extent of 3.82 million square kilometres, which was the second-lowest ever observed (see ‘Ice cover’). But it is still the twelfth-lowest sea-ice extent in nearly 43 years of satellite recordings, and scientists say that the long-term trend is towards lower ice cover.
Satellite monitoring shows that the overall rate of ice loss from West Antarctica has increased five-fold over a 25-year period. This one glacier – Thwaite’s glacier – alone now accounts for 4% of global sea level rise.
Needless to say, this acceleration is a result of us humans polluting the air with greenhouse gases. That fact explodes any impression that the ice is overwhelming. The opposite is true, we are overwhelming the ice.
Ecosystem transformation is emerging as a global threat under climate change (1–3). Conversion of conifer forest to shrubland, steppe, and other ecosystems is underway from Mexico to Alaska (1, 3). Shrub steppe and chaparral are giving way to non-native annual grassland in the western United States. Floodplain forests are yielding to savanna in Amazonia, shrubs and trees are invading Arctic tundra, reef corals are being replaced by macroalgae, and geographic shifts in pelagic marine species are creating unprecedented combinations. Climate change is a primary driver of these transformations. Rapid ecological change is receiving increased scientific attention (4), much of which is focused on identifying tipping points between alternative stable states, tying into powerful theoretical and conceptual frameworks. However, ecological transformation can occur gradually, as incremental changes in dominant species populations accumulate and species ranges shift under changing climate. Developing a science of transformational ecology is timely in view of ongoing and imminent changes.
MARIO MOLINA CENTER FOR STRATEGIC STUDIES ON ENERGY AND THE ENVIRONMENT CDMX