The IPCC report on oceans and cryosphere is frightening, but the Truth might be worse

The IPCC Special Report on Ice and Oceans was released this week. It describes proven and indisputable changes occuring in the oceans and in the cryosphere.

The IPCC first notes that global warming has melted glaciers and ice over the Arctic Ocean in recent decades and is warming the permafrost (A1 SROCC_SPM).

1. Less life in the oceans

Ocean temperatures have increased and aquatic ecosystems are already hindered by global warming.

Currently, corals experience severe damage, more than half of the Great Barrier Reef died due to heatwaves in recent years. It was the richest ecosystem of the oceans. Corals face serious risk even at 1.5 ° C.

Kelp korests, seagrass meadows and epipelagic ecosystems (top 200 m) are already hurt by warming.

Epipelagic ecosystems are less productive. All species combined, there are fewer fishes.

 It is most obvious in the North Atlantic, but also everywhere else, in the South Atlantic, in the North and in South Pacific, and the tropical parts of these oceans, in the EBUS currents (Canaries, California, Humbolt...), and in a lesser extent in the Indian Ocean. Fishing yields are already lower in these waters.

Several critical thresholds for life in the ocean will be exceeded before 2100: oxygen, acidification, nitrogen, ocean stratification, etc. So we'll lose part of oceans living creatures.

Marine heatwaves will multiply 20 -50 times, and their severity will increase several times. They recently devastated the Great Barrier Reef and millennial kelp forests. Years of extreme El Nino, probably hotter than 2016 will occur more often. Ocean circulation will most likely slow down.

2. Ice and permafrost melt

Glaciers melt and permafrost thaws. The IPCC notes that it releases greenhouse gases.These gases accelerate global warming.

The melt of permafrost and the retreat of glaciers reduce the stability of high mountain slopes. New floods, avalanches, landslides and other land destabilization will increase the risks for infrastructure and for people.

The area covered by Arctic ice is decreasing by 12.8% per decade. In addition, this ice is thinner, ice more than 5 years old has lost 90% of its surface (A1.4 SROCC_SPM).

Old ice, about a meter thick, wouldn't melt in the summer. It has almost disappeared and the ice on the Arctic Sea is now thin and fragile. Its melt will speed up the warming of the Planet.

3. Sea level rise

The ocean has absorbed over 90% of the warming energy (A2). The Southern Ocean has absorbed half of this energy since the year 2000. It is warming up fast, to depths greater than 2000 m, and the stratification of the ocean is increasing.

The melting of Greenland and Antarctica has increased and is now the main factor for sea level rise. The IPCC estimates that the sea could rise by 1m20 if carbon emissions remain high. Yet warming could have different consequences for Antarctica ice and sea-level rise.

Some scientists point that the Antarctic-West platform has already collapsed in the past. At this time, the sea level rose very quickly, several meters per century. This platform blocks the huge Antarctic glaciers and its collapse could lead to several meters of sea-level rise.

The glaciers of Greenland and Antarctica are studied by many scientists through polar expeditions, satellites, or by sophisticated models. These scientists, such as James E. Hansen, Eric Rignot, and Jason Box are not part of the IPCC, so it does not seem to include their knowledge nor expertise.

The phenomenon that could lead to the collapse of West Antarctica, called "marine icesheet instability" is presented by the IPCC and described as needing further studies. If this gigantic 'accident' occurs, it will totally change the forecasts of sea level rise and the correct adaptation measures. James Hansen's model, which already includes a strong stratification of the oceans now described by the IPCC, predicts that sea level rise will double regularly, for example every 20 years. The current centimeters would thus become meters towards the end of the century, and the oceans would flood half of the cultivated lands of the Earth.

 The IPCC models might correctly predict the stability of West Antarctica. The IPCC seems to communicate only indubitable changes of the Biosphere, and remains a global reference on climate change. Yet perhaps they were too sensible and they did not include in the models latest governments actions, nor the sudden heatwaves that currently precipitate the melt of polar ice. They should expand their team of experts and include specialists of Antarctic ice melting. Their estimate of sea-level rise, which was revised upwards for the second time as rapid icemelt occured in recent years, could evolve a lot. The collapse of Antarctic huge glaciers will most likely be predictable a few years or even decades before it happens.

Based on https://blogs.letemps.ch/dorota-retelska/2019/09/27/rapport-du-giec-sur-les-oceans-ca-va-mal-mais-ca-peut-encore-etre-pire/ and on: https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/