Just an additional half degree of temperature rise and we lose the Antarctic Peninsula.
The Paris Climate Accord goal of limiting temperature rise to 1.5 Celsius was to prevent runaway climate change (the world is currently at a 1C increase above preindustrial temperatures ).
The study authors did note that humanity can avoid the loss of the Antarctic Peninsula by keeping temperature rise to the Paris goal but, unfortunately for us, a 1.5C rise is already locked in and, we are well on our way to blowing past the 2.0C warming that scientists say will be catastrophic.
The Antarctic Penninsula is one of the areas on the planet that is warming faster than the rest of the earth. In the past 50 years, the peninsula has warmed almost 2.5 degrees Celsius (three times faster than the rest of the planet), the only area warming faster is the Arctic. The peninsula juts North toward South America (and, is the krill nursey of the southern hemisphere), making the region more susceptible to warming than the rest of the continent.
The Antarctic peninsula is the canary in the coal mine for the rest of the continent, and it is in trouble. Scientists have warned that under a global temperature rise of 1.5 Celsius, radical changes to the ecosystem will become observable and irreversible.
Frontiers provide a summary of the peer-reviewed study.
Warming of the Antarctic Peninsula in the latter half of the twentieth century was greater than any other terrestrial environment in the Southern Hemisphere, and clear cryospheric and biological consequences have been observed. Under a global 1.5°C scenario, warming in the Antarctic Peninsula is likely to increase the number of days above 0°C, with up to 130 of such days each year in the northern Peninsula. Ocean turbulence will increase, making the circumpolar deep water (CDW) both warmer and shallower, delivering heat to the sea surface and to coastal margins. Thinning and recession of marine margins of glaciers and ice caps is expected to accelerate to terrestrial limits, increasing iceberg production, after which glacier retreat may slow on land. Ice shelves will experience continued increase in meltwater production and consequent structural change, but not imminent regional collapses. Marine biota can respond in multiple ways to climatic changes, with effects complicated by past resource extraction activities. Southward distribution shifts have been observed in multiple taxa during the last century and these are likely to continue. Exposed (ice free) terrestrial areas will expand, providing new habitats for native and non-native organisms, but with a potential loss of genetic diversity. While native terrestrial biota are likely to benefit from modest warming, the greatest threat to native biodiversity is from non-native terrestrial species.
— Bethan Davies (@AntarcticGlacie) July 3, 2019
From the study: (pdf)
How will the Antarctic Peninsula respond in a 1.5°C scenario?
Climate and weather. Antarctic Peninsula temperatures will increase by more than the global average in a 1.5°C scenario2. This level of warming has already been exceeded in the northern Peninsula10, despite the recent pause in rising temperatures in the region11. Regional temperatures could increase by 1-2°C in winter and 0.5-1.0°C in summer beyond current levels12. Warming of 1°C from today will result in a 50 to 150 percent increase in days per year above 0°C, from a range of 25 to 80 days in the northern Antarctic Peninsula to between 35 and 130 days.
While there has been a 10 to 20 per cent increase in precipitation, and an increase in extreme precipitation events13, there is unlikely to be much further increase beyond current levels12. The greatest change in atmospheric circulation affecting the Peninsula is a weakening of the circumpolar summer westerly winds in response to stratospheric ozone recovery. Increased levels of surface water run-off (from rain and snow/glacial melt) and/or melting of any thin layers of frozen sediment may alter the strength of the ground considerably, albeit for limited periods of the year. Such change may have an impact on station buildings and, potentially, airstrips.
Ocean conditions. The west of the Peninsula is influenced by warm Circumpolar Deep Water (CDW), in contrast to the east of the Peninsula where waters are much colder14. The Southern Ocean is warming15, but we have no clear evidence that the Polar Front is moving as a result of this change16. However, the CDW is both warming and becoming shallower17, and the amount of turbulence in the Southern Ocean is increasing18. We expect these trends to continue.
— The Antarctic Report (@AntarcticReport) July 24, 2017
Sea ice. The two sides of the Antarctic Peninsula have very different sea ice conditions. The ice edge is generally at a higher latitude on the Peninsula’s west compared with the east. In summer, virtually the whole Bellingshausen Sea is free of sea ice, but on the east in the Weddell Sea, the sea ice typically extends to the northern end of the Antarctic Peninsula and is thicker so, even in the summertime, the highest classification ice-breaking ships can have great navigational difficulty. Since satellite records began around 30 years ago, there has been a modest increase in total annual Antarctic sea ice extent, though the variability from year to year is large19, and regional and seasonal changes are mixed. To the west, annual sea ice extent has decreased by around six to ten per cent per decade with the greatest changes in autumn and summer20. The length of the sea ice season on the west of the Peninsula has also reduced by around four days21. We expect increased sea ice variability on the west of the Peninsula, compared with the east, as the climate warms. These changes will increasingly need to be accounted for by shipping.
— Antarctic Survey (@BAS_News) May 13, 2019
Land ice. Antarctic Peninsula glaciers are steep and fast flowing, and respond rapidly to climate change6. Ocean warming is likely to cause accelerated recession of glaciers that are in contact with the sea, with slower recession driven by atmospheric changes for glaciers that end inland. Thinning and recession of glaciers that extend from the land into the ocean, known as marine-terminating glaciers, are therefore expected to accelerate, driven largely by increased upwelling of warm CDW. Once the marine-terminating glaciers retreat to their land margins they will experience slower thinning and recession. In southern Palmer Land, glaciers are grounded deeply below sea level which could lead to significant glacier retreat16. Under a 1.5°C scenario, glaciers on land will experience more melting than at present16, 22, causing increased surface run-off.
Ice Shelves. It is likely that Antarctic Peninsula ice shelves will continue to thin, primarily due to increased surface melting23,24. If meltwater collects in ponds, it could cause ice-shelf bending and fracture; a process implicated in the collapse of Larsen B25. However, surface rivers may help prevent some of this ice-shelf instability by transporting meltwater into the ocean26. Ice shelves will also thin in response to melting of their undersides by warm ocean water27. While ice-shelf thinning increases the likelihood of icebergs breaking off, the largest ice shelves (e.g., Larsen C and George VI) have sufficient surface area to avoid catastrophic failure.
— Climate Guardians (@ClimateGuardia) November 2, 2018
Marine Ecosystems. The response of marine living systems to climate change is complicated by the extraction of marine resources. Sequential over-exploitation of seals, whales and some species of fish over the last two centuries has severely perturbed the food web, making it hard to unravel its consequences from those of climate change28. Responses of marine life to the 1.5°C scenario will be diverse with likely changes in behavior, physiology, geographic or depth distribution, plus evolutionary adaptation. An observed southward shift in the distribution of living things down the peninsula is likely to continue29.
— WWF Ã°ÂÂÂ¼ (@WWF) October 19, 2018
Terrestrial Ecosystems. Terrestrial biology is limited to ice-free areas, of which only a fraction is currently visibly colonized. The seasonally-exposed terrestrial area of the Peninsula is expected to expand29. This will provide new habitats for colonization by native and, likely, non-native organisms. It will also lead to the coalescing of some areas that are currently isolated, and a loss of genetic diversity. Native plants and invertebrates are well adapted to the variable conditions of the Antarctic Peninsula30,31 and are likely to benefit from modest warming32. However, a wide range of non-native species could survive in parts of the Antarctic Peninsula. Thus, the threat of non-native species to native biodiversity far outweighs the impacts of climate change under a 1.5°C scenario. In light of these pressures, environmental protection of the Antarctic Peninsula must remain resolute.