Inasmuch as the specular reflectance of water at 75 deg N lat never gets below 20%, and can be as high as 100%, I’m confident that the ’10X’ claim is wrong. I’ll let those getting paid to do such things actually do it. To properly calculate the warming impact, one has to integrate the hourly water-reflectivity over the ~6 months that the area inside the Arctic Circle is illuminated, also taking into account the longer path length, resulting in increased absorption and scattering. That happens only one day out of the year. During the Solstice, when the sun never sets, the specular reflectance varies between about 2X the reflectance at normal incidence, to about 50X (100%!) at the Terminator when the sun is on the horizon. At the Equinox, the specular reflectance of water at 75 deg is about 11X that at the Equator at noon. Unfortunately, the sun is NEVER directly overhead at 66 deg latitude and above the most northerly the sun can be directly overhead is at the Tropic of Cancer (23.4° N lat). The claim of an order of magnitude increase in warming is based on the albedo of ice, and the combined specular reflectance of the water and the diffuse reflectance of suspended particles in the water, for high noon (when the sun is directly overhead). The problem is that the claim is not accurate. Be that as it may, someone took the liberty to add something that wasn’t in the published, peer-reviewed research. Perhaps the press-release writer decided to ‘improve’ upon the actual research. I cannot find this claim in the actual research article. “Where white ice reflects the rays of the sun, a dark sea will absorb more than ten times as much solar energy and thereby increase global warming.” Cronin, Martin Jakobsson and Christof Pearce, 20 March 2023, Communications Earth & Environment.įunding: Aarhus Universitets Forskningsfond, Vetenskapsrådet, Horizon 2020 Framework Programme. Reference: “Seasonal sea-ice in the Arctic’s last ice area during the Early Holocene” by Henrieka Detlef, Matt O’Regan, Christian Stranne, Mads Mørk Jensen, Marianne Glasius, Thomas M. This news is not making the situation more depressing, just more urgent. This is echoed by Christof Pearce: “The study is a wake-up call because we know that it will happen. If we can keep temperatures stable or perhaps even make them fall, the sea ice would return to the area,” says Henrieka Detlef. The good news is that our data shows the trend is reversible and we can do something about it if we reduce greenhouse gas emissions and set ambitious political goals. “The bad news is that we can see this happening very soon. How will the marine ecosystems be affected globally if the sea ice disappears? We don’t know the answer yet,” says Henrieka Detlef, an assistant professor at the Department of Geoscience.Īccording to the researchers from Aarhus University, the study can be interpreted as good and bad news for the climate. The algae we examined are food for fish, fish are food for birds, etc. “The sea ice is a base for many ecosystems. Where white ice reflects the rays of the sun, a dark sea will absorb more than ten times as much solar energy and thereby increase global warming. When the sea ice in the Lincoln Sea begins to melt during the summer months, it can have major consequences for the climate. The researchers can thereby determine when summer sea ice was present in the area. Among other things, they studied molecules from certain algae that are only produced when there is sea ice. In Aarhus, the marine samples have been analyzed in collaboration with Associate Professor Marianne Glasius and academic technical staff Mads Mørk Jensen from the Department of Chemistry. Although this was caused by natural climate variability as opposed to human-induced warming, it still is a natural laboratory for studying the fate of this region in the immediate future. During this time period, summer temperatures in the Arctic were higher than today. The researchers have used data from the Early Holocene period to predict when the sea ice will melt today. This project has demonstrated that we’re very close to this scenario and that temperatures only have to increase a little before the ice will melt,” says Christof Pearce, Assistant Professor at the Department of Geoscience, Aarhus University. “Climate models have suggested that summer sea ice in this region will melt in the coming decades, but it’s uncertain if it will happen in 20, 30, 40 years, or more. The research team concluded that summer sea ice melted at a time when temperatures were at a level that we are rapidly approaching again today. The sediment samples were collected from the seabed in the Lincoln Sea, part of the “Last Ice Area.” They showed that the sea ice in this region melted away during summer months around 10,000 years ago. “If we can keep temperatures stable or perhaps even make them fall, the sea ice would return to the area.” - Henrieka Detlef
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