[해류] 대서양해류(AMOC) 붕괴 가능성 가속화

 

 

 

 

 

 

북대서양의 해양 순환이 기후 변화의 영향으로 예상보다 빨리 붕괴될 가능성이 있으며, 이는 전 세계적으로 기상 패턴에 더 큰 격변을 야기할 것이라는 새로운 분석이 나왔다.

 

최근 코펜하겐대 연구진은 열대 지방에서 따뜻한 물을 위쪽으로 운반하는 해류 또는 "컨베이어 벨트"에 대한 최신 연구를 통해 대서양자오선역전해류(AMOC, Atlantic Meridional Overturning Circulation)이 2025년에서 2095년 사이 어느 시점에 종료될 것이며 2050년대가 가장 가능성이 높다고 네이처지에 발표했다.

 

AMOC는 북반구의 대표적인 해류순환으로 지구 온도를 조절하는 역할을 한다.

 

열대 지방과 대서양 최북단 지역 사이에서 더위, 추위, 강수량을 재분배하는 중요한 해류는 현재의 온실 가스 배출이 지속된다면 2060년경에 중단될 것이라는 것이다.

 

 

 

 

 

Amoc의 붕괴는 북반구 전역에 뚜렷한 냉각을 일으켜 유럽과 북미 지역에서는 극한 추위와 더 건조한 여름으로 이어 지는 반면, 열은 더 남쪽으로 더 강해져 적도 인근에는 폭염이 발생할 것으로 예상된다.

 

이번 연구 결과는 최근 유엔 기후위기에 관한 정부간 협의체(IPCC)이 AMOC가 금세기에 멈출 가능성이 낮다고 전망한 것과 상반된 주장이고, 양 연구에 활용된 데이터에 대한 논쟁이 있는 가운데, AMOC 중단 시기를 앞당겨 예고함으로써 온실가스 배출이 변곡점에 이르렀다는 경고로 평가된다.

 

 

 

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Gloomy climate calculation

: Scientists predict a collapse of the Atlantic ocean current to happen mid-century

 

 

 

* Source : the University of Copenhagen 

 

 

 

OCEAN CURRENTS

 

 

Important ocean currents that redistribute heat, cold and precipitation between the tropics and the northernmost parts of the Atlantic region will shut down around the year 2060 if current greenhouse gas emissions persist.

 

This is the conclusion based on new calculations from the University of Copenhagen that contradict the latest report from the IPCC.

 

Contrary to what we may imagine about the impact of climate change in Europe, a colder future may be in store.

 

 

In a new study, researchers from the University of Copenhagen’s Niels Bohr Institute and Department of Mathematical Sciences predict that the system of ocean currents which currently distributes cold and heat between the North Atlantic region and tropics will completely stop if we continue to emit the same levels of greenhouse gases as we do today.

 

Using advanced statistical tools and ocean temperature data from the last 150 years, the researchers calculated that the ocean current, known as the Thermohaline Circulation or the Atlantic Meridional Overturning Circulation (AMOC), will collapse – with 95 percent certainty – between 2025 and 2095.

 

This will most likely occur in 34 years, in 2057, and could result in major challenges, particularly warming in the tropics and increased storminess in the North Atlantic region.

 

"Shutting down the AMOC can have very serious consequences for Earth's climate, for example, by changing how heat and precipitation are distributed globally. While a cooling of Europe may seem less severe as the globe as a whole becomes warmer and heat waves occur more frequently, this shutdown will contribute to an increased warming of the tropics, where rising temperatures have already given rise to challenging living conditions," says Professor Peter Ditlevsen from the Niels Bohr Institute.

 

"Our result underscores the importance of reducing global greenhouse gas emissions as soon as possible," says the researcher.

 

 

 

 

 

 

The calculations, just published in the renowned scientific journal, Nature Communications, contradict the message of the latest IPCC report, which, based on climate model simulations, considers an abrupt change in the thermohaline circulation very unlikely during this century.

 

Early warning signals present

The researchers' prediction is based on observations of early warning signals that ocean currents exhibit as they become unstable. 

 

These Early Warning Signals for the Thermohaline Circulation have been reported previously, but only now has the development of advanced statistical methods made it possible to predict just when a collapse will occur.

 

 

Facts about the ocean current

○ The Atlantic Meridional Overturning Circulation (AMOC) is part of a global system of ocean currents. By far, it accounts for the most significant part of heat redistribution from the tropics to the northernmost regions of the Atlantic region – not least to Western Europe.

○ At the northernmost latitudes, circulation ensures that surface water is converted into deep, 

southbound ocean currents. The transformation creates space for additional surface water to be moved northward from equatorial regions. As such, thermohaline circulation is critical for maintaining the relatively mild climate of the North Atlantic region.

 

 

 

The researchers analysed sea surface temperatures in a specific area of the North Atlantic from 1870 to present days. These sea surface temperatures are "fingerprints” testifying the strength of the AMOC, which has only been measured directly for the past 15 years.

"Using new and improved statistical tools, we’ve made calculations that provide a more robust estimate of when a collapse of the Thermohaline Circulation is most likely to occur, something we had not been able to do before," explains Professor Susanne Ditlevsen of UCPH’s Department of Mathematical Sciences.

The thermohaline circulation has operated in its present mode since the last ice age, where the circulation was indeed collapsed. Abrupt climate jumps between the present state of the AMOC and the collapsed state has been observed to happen 25 times in connection with iceage climate. 

 

These are the famed Dansgaard-Oeschger events first observed in ice cores from the Greenlandic ice sheet. At those events climate changes were extreme with 10-15 degrees changes over a decade, while present days climate change is 1.5 degrees warming over a century.

 

 

 

 

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