Reliefs No. 17: Ice floes.
Reliefs| N° d'inventaire | 28302 |
| Format | 19 x 27 |
| Détails | 184 p., illustrated, paperback. |
| Publication | Paris, 2023 |
| Etat | Nine |
| ISBN | 9782380361001 |
It was through my involvement in the study of past variations in our climate based on the analysis of core samples taken in Antarctica and Greenland that I became interested in the polar regions. Since the 1970s, I have been familiar with these glacial archives and the information they provide us on the functioning of the climate system; deep drilling in East Antarctica has highlighted a close relationship between climate and the greenhouse effect in the past, and drilling in Greenland has documented the existence of rapid and significant climate variations on the scale of a few decades, or even a few years. I am much less familiar with the sea ice that extends – with areas and thicknesses varying with the seasons and the evolution of our climate – in the Arctic regions to the north and in the Southern Ocean to the south. And I very much appreciated this dossier constructed from different perspectives on the ice pack and excerpts from texts devoted to it.
Jérôme Weiss's diagnosis of the decline of sea ice, as global warming linked to our activities takes hold, is unequivocal. This decline, which began in the 1970s in the Arctic Basin, where its minimum extent and average thickness have been at least halved, is much more recent in the Southern Ocean. Sea ice cover actually increased slightly until the mid-2010s. This observation was widely used by climate skeptics to deny the reality of global warming at a time when it was already well documented on a global scale, particularly in the ocean, where it is reflected in an acceleration of sea level rise. Now, the argument no longer holds, since this cover has begun to decrease, with a record minimum extent in December 2022. This decrease is expected to continue over the coming decades, and in the Arctic, models predict summers with a virtually ice-free ocean as early as 2050.
This near-disappearance of the ice pack in summer is rightly presented as a threat with numerous impacts on the climate, but also on a unique ecosystem that Christophe Barbraud shows us to be on borrowed time. The list of endangered species at the end of the report clearly demonstrates this. While the disappearance of the ice pack offers the possibility of new maritime routes for a few months of the year, this advantage is very small compared to the risks associated with the announced exploitation of gas, oil, and other resources. This disappearance will also have consequences for indigenous populations and for the vision—very well conveyed in the texts of this report—of the polar regions as lands of adventure.
All of this argues in favor of measures to ensure that the sea ice does not disappear completely during the Arctic summer. The projections presented in the IPCC's 6th report , adopted last March, give us some hope. Since the pre-industrial period, our planet has warmed by a little more than 1 degree Celsius on average. If this warming were limited to 1.5°C, or at least well below 2°C, the minimum extent of ice in the Arctic basin could stabilize and the sea ice would not completely disappear in summer. This requires that carbon neutrality be achieved by 2050. Certainly, many countries have stated this objective; our country has enshrined it in law. But there is a gap between the stated objectives and reality. We are on a trajectory that takes us towards warming close to 3°C in the second half of this century. Limiting global warming to 1.5°C is therefore an immense challenge for humanity and the nature that surrounds it. Preserving the ice pack provides us with an additional reason to take it on.
It was through my involvement in the study of past variations in our climate based on the analysis of core samples taken in Antarctica and Greenland that I became interested in the polar regions. Since the 1970s, I have been familiar with these glacial archives and the information they provide us on the functioning of the climate system; deep drilling in East Antarctica has highlighted a close relationship between climate and the greenhouse effect in the past, and drilling in Greenland has documented the existence of rapid and significant climate variations on the scale of a few decades, or even a few years. I am much less familiar with the sea ice that extends – with areas and thicknesses varying with the seasons and the evolution of our climate – in the Arctic regions to the north and in the Southern Ocean to the south. And I very much appreciated this dossier constructed from different perspectives on the ice pack and excerpts from texts devoted to it.
Jérôme Weiss's diagnosis of the decline of sea ice, as global warming linked to our activities takes hold, is unequivocal. This decline, which began in the 1970s in the Arctic Basin, where its minimum extent and average thickness have been at least halved, is much more recent in the Southern Ocean. Sea ice cover actually increased slightly until the mid-2010s. This observation was widely used by climate skeptics to deny the reality of global warming at a time when it was already well documented on a global scale, particularly in the ocean, where it is reflected in an acceleration of sea level rise. Now, the argument no longer holds, since this cover has begun to decrease, with a record minimum extent in December 2022. This decrease is expected to continue over the coming decades, and in the Arctic, models predict summers with a virtually ice-free ocean as early as 2050.
This near-disappearance of the ice pack in summer is rightly presented as a threat with numerous impacts on the climate, but also on a unique ecosystem that Christophe Barbraud shows us to be on borrowed time. The list of endangered species at the end of the report clearly demonstrates this. While the disappearance of the ice pack offers the possibility of new maritime routes for a few months of the year, this advantage is very small compared to the risks associated with the announced exploitation of gas, oil, and other resources. This disappearance will also have consequences for indigenous populations and for the vision—very well conveyed in the texts of this report—of the polar regions as lands of adventure.
All of this argues in favor of measures to ensure that the sea ice does not disappear completely during the Arctic summer. The projections presented in the IPCC's 6th report , adopted last March, give us some hope. Since the pre-industrial period, our planet has warmed by a little more than 1 degree Celsius on average. If this warming were limited to 1.5°C, or at least well below 2°C, the minimum extent of ice in the Arctic basin could stabilize and the sea ice would not completely disappear in summer. This requires that carbon neutrality be achieved by 2050. Certainly, many countries have stated this objective; our country has enshrined it in law. But there is a gap between the stated objectives and reality. We are on a trajectory that takes us towards warming close to 3°C in the second half of this century. Limiting global warming to 1.5°C is therefore an immense challenge for humanity and the nature that surrounds it. Preserving the ice pack provides us with an additional reason to take it on.