Implications of the Weakening or Collapse of a Major Atlantic Current on New Zealand’s Climate

Recent assessments indicate that the Atlantic Meridional Overturning Circulation (AMOC) is slowing down, with a collapse being a real possibility in this century. The AMOC is a crucial current in the Atlantic Ocean, responsible for moving warm water towards the Arctic and impacting global climate.

If the AMOC collapses, it could have devastating effects on Europe’s climate, with temperatures in the UK and Scandinavia potentially dropping by 5–15°C in just a few decades. However, the interconnected nature of Earth’s climate system means that these impacts could have a global reach. Research has shown that past changes in the AMOC have significantly influenced temperatures in New Zealand and the southern hemisphere, implying that a future collapse could accelerate ongoing warming trends.

Between 20,000 and 10,000 years ago, Earth underwent a transition from peak ice-age conditions to a climate more similar to today’s. This period of natural warming was marked by rising global temperatures, melting ice sheets, and rising sea levels, similar to present-day climate change. Evidence from ice cores in Greenland and marine sediments in the North Atlantic suggests that changes in the AMOC played a significant role in these abrupt climate shifts.

By studying the past extent of mountain glaciers in New Zealand and reconstructing sea-surface temperatures in the Tasman Sea, researchers have found that changes in the AMOC have had a direct impact on New Zealand’s climate. Climate model simulations support this evidence, showing that changes in the AMOC can rapidly affect air and sea surface temperatures in New Zealand and the southern mid-latitudes.

The implications of a future collapse of the AMOC are significant, as it could further accelerate warming trends in New Zealand and globally. While current projections estimate a 1°C to 3°C increase in temperatures by the end of the century, the potential impacts of an AMOC collapse are not yet fully accounted for. This research highlights the global reach of the AMOC tipping point and underscores the need to address human-caused climate change to prevent further disruptions in Earth’s climate system.