世界最大の氷山「A23a」が座礁か、南大西洋の島付近で停止 2020年から漂流

World's largest iceberg, A23a, is either stranded or has come to a halt near an island in the South Atlantic. It has been drifting since 2020.

World's largest iceberg, A23a, is either stranded or has come to a halt near an island in the South Atlantic. It has been drifting since 2020.
2020年から南極大陸付近の南極海を漂流していた世界最大の氷山「A23a」が、座礁したとみられることが分かった

The world's largest iceberg, A23a, which has been drifting in the Southern Ocean near Antarctica since 2020, is believed to have run aground.

The world's largest iceberg, A23a, which has been drifting in the Southern Ocean near Antarctica since 2020, is believed to have run aground.
英国南極観測局(BAS)の声明によると、重さ約1兆トンのA23aは、南太平洋に浮かぶ英海外領サウスジョージア島の沖合で停止した

The A23a, weighing about one trillion tonnes, came to rest off the coast of the British overseas territory of South Georgia in the South Pacific, the British Antarctic Survey (BAS) said in a statement.

The A23a, weighing about one trillion tonnes, came to rest off the coast of the British overseas territory of South Georgia in the South Pacific, the British Antarctic Survey (BAS) said in a statement.
24年8月の測定では、A23aの面積は3672平方キロメートル

As of August 2012, the area of A23a was 3,672 square kilometers.

As of August 2012, the area of A23a was 3,672 square kilometers.
これは米ロードアイランド州よりやや小さく、英ロンドンの倍以上の大きさに当たる

That's slightly smaller than the state of Rhode Island and more than twice the size of London.

That's slightly smaller than the state of Rhode Island and more than twice the size of London.
A23aは1986年、南極のフィルヒナー棚氷から分離し、その後30年あまりウェッデル海の海底に沈んでいた

A23a broke off from the Filchner Ice Shelf in Antarctica in 1986 and remained on the bottom of the Weddell Sea for more than 30 years.

A23a broke off from the Filchner Ice Shelf in Antarctica in 1986 and remained on the bottom of the Weddell Sea for more than 30 years.
2020年に海流に乗って漂い始めたが、24年後半、海底の山の周りを回転して身動きが取れなくなり、予想されていた北への移動が遅れた

It began drifting with ocean currents in 2020, but in late 2024 it became stuck after rotating around an underwater mountain, delaying its expected northward movement.

It began drifting with ocean currents in 2020, but in late 2024 it became stuck after rotating around an underwater mountain, delaying its expected northward movement.
最終的に動き出したA23aはサウスジョージア島の方向へ向かい、島に生息するアザラシやペンギンの餌場利用の妨げになるのではないかと懸念されていた

When A23a finally did move, it headed towards South Georgia, raising concerns that it could disrupt feeding grounds for the island's seals and penguins.

When A23a finally did move, it headed towards South Georgia, raising concerns that it could disrupt feeding grounds for the island's seals and penguins.
だが、A23aは海岸から約90キロ離れた大陸棚に座礁したとみられ、こうした懸念は和らいだ

But the A-23a appears to have run aground on the continental shelf about 90km from the coast, easing those concerns.

But the A-23a appears to have run aground on the continental shelf about 90km from the coast, easing those concerns.
BASの海洋学者アンドリュー・マイヤーズ氏は声明で「氷山が座礁したままであれば、サウスジョージア島の野生生物に大きな影響を与える見込みはない」と指摘した

If the iceberg remains stranded it is unlikely to have a significant impact on South Georgia's wildlife, BAS oceanographer Andrew Myers said in a statement.

If the iceberg remains stranded it is unlikely to have a significant impact on South Georgia's wildlife, BAS oceanographer Andrew Myers said in a statement.
むしろA23aの到来が野生生物に恩恵をもたらす可能性もあり、「座礁や氷山の融解によって栄養素がかき混ぜられることで、ペンギンやアザラシなど、この地域の生態系全体にとって食料供給量が増える可能性がある」という
A23aは現時点では氷山の構造を維持しているように見えるが、ここ数十年、このルートをたどった大きな氷山は「すぐに崩壊、分散し、融解している」とマイヤーズ氏
「座礁した現在、圧力が増大したためにA23aが崩壊する可能性は一層高まっているが、予想はほぼ不可能だ」としている
研究者はA23aについて、化石燃料による気候危機ではなく、おそらく棚氷の自然な成長サイクルの一環で分離したとの見方を示す
ただ、地球温暖化は南極大陸に憂慮すべき変化をもたらしており、世界の海面上昇に壊滅的な影響を及ぼす可能性がある