A recent study has revealed that Greenland is losing 30 million tonnes of ice per hour.
According to a recent study, the Greenland ice cap is experiencing a loss of approximately 30 million tonnes of ice per hour as a result of the climate emergency. This is 20% higher than previous estimates.
Certain scientists are worried that the influx of freshwater in the north Atlantic could potentially lead to the disruption of the Atlantic meridional overturning circulation (Amoc), which could have detrimental effects on human populations.
For many years, there has been significant melting of ice in Greenland due to the effects of global warming. The methods used to track this, such as measuring the height and weight of the ice sheet using gravity data, are effective in calculating the amount of ice that ends up in the ocean and contributes to rising sea levels.
Unfortunately, these findings do not take into consideration the melting of glaciers that are already mostly submerged in the narrow fjords surrounding the island. The research involved analyzing satellite images to track the movements of Greenland’s numerous glaciers on a monthly basis from 1985 to 2022. The results revealed extensive and significant shrinkage, totaling in a loss of one trillion tonnes of ice.
Dr. Chad Greene, from Nasa’s Jet Propulsion Laboratory in the US, who headed the study, stated that the transformations occurring in Greenland are significant and evident in numerous areas. He also mentioned that almost all glaciers have receded in the last few decades. Dr. Greene added that it is logical to assume that introducing freshwater into the north Atlantic Ocean would result in a decrease in the strength of the Amoc, although he is unsure of the extent of this weakening.
In 2021, researchers discovered that the Amoc, which has been weakening for 1,600 years, may be nearing a tipping point. A recent study indicates that the collapse could occur as early as 2025 in the worst-case scenario. Additionally, scientists believe that a significant portion of the Greenland ice sheet is also close to reaching a tipping point, resulting in irreversible melting and potentially causing a rise in sea levels equivalent to 1-2 meters.
The research, printed in the publication Nature, utilized advanced technology to chart over 235,000 endpoints of glaciers during a 38-year span, with a precision of 120 meters. The results revealed that the Greenland ice sheet has diminished by approximately 5,000 square kilometers at the edges since 1985, which is equivalent to a trillion metric tons of ice.
The latest report from a project that combines all measurements of Greenland’s ice concluded that the ice has been decreasing at a rate of 221 billion tonnes per year since 2003. The recent study also includes an additional 43 billion tonnes lost annually, resulting in a total average loss of 30 million tonnes per hour.
The researchers expressed worry that even a small amount of freshwater could potentially cause the Amoc to collapse, leading to disruptions in global weather patterns, ecosystems, and food security. However, current oceanographic models do not take into account freshwater from the melting glaciers in Greenland. The introduction of less dense freshwater into the ocean hinders the normal process of denser saltwater sinking in the polar region and driving the Amoc.
Professor Tim Lenton, from the University of Exeter in the United Kingdom, who was not involved in the research, expressed concern about the increased amount of freshwater entering the North Atlantic. This could potentially impact the formation of deep water in the Labrador and Irminger Seas, which are part of the subpolar gyre. Other evidence suggests that these areas are at a higher risk of transitioning into an “off” or collapsed state.
According to the speaker, this would resemble a partial collapse of Amoc, but would occur at a faster rate and greatly affect the UK, western Europe, parts of North America, and the Sahel region. This could result in severe disruption of the west African monsoon. The impact of this previously unaccounted source of freshwater would depend on the proximity to the tipping point of the subpolar gyre. Recent models indicate that we may be approaching this tipping point due to current levels of global warming.
However, Prof Andrew Shepherd, at the University of Northumbria, UK, said: “Although there was a step-change in glacier retreat at the turn of the century, it’s reassuring to see that the pace of ice loss has been steady since then and is still well below the levels needed to disturb the Amoc.”
According to Greene, the identification of additional ice loss is significant for determining the Earth’s energy imbalance. This involves calculating the amount of solar heat that the Earth is retaining as a result of human-caused emissions of greenhouse gases. Greene explains that a significant amount of energy is required to melt 1 trillion tonnes of ice. Therefore, in order to create accurate models for the Earth’s energy balance, this must be taken into consideration.
The study examined glaciers that were primarily located below sea level. Therefore, the melted ice was replaced by seawater and did not have a direct impact on sea level. However, according to Green, there is likely an indirect effect as it may accelerate glacier movement. This is due to the narrow fjords acting as a bottleneck, and removing ice from the edges is similar to pulling the plug in a drain.
In a study published in 2022, Chad and his team examined the changes in Antarctic ice shelves over time. They discovered that the total amount of ice lost from these shelves has doubled since 1997, when taking into account both their shrinking size and thinning.