The Arctic Ocean has had ice on it, in some form, for essentially the entire span of recognisably modern human existence. The most recent interglacial period warm enough to have melted the summer ice cap was the Eemian, approximately 130,000 to 115,000 years ago, during which paleoclimate evidence suggests the Arctic was seasonally ice-free at its summer minimum — most clearly during the warmest phase around 130,000 years ago, with conditions gradually cooling toward the end of the period around 115,000 years ago, when the Arctic returned to continuous year-round ice cover. The Eemian ended before any sustained migration of anatomically modern humans out of Africa, before the development of agriculture, before recognisable language families had differentiated, before the construction of the first permanent settlements, and before essentially every aspect of human society that the present civilisation rests on. For approximately the past 115,000 years — through the entire emergence of modern civilisation — the Arctic has carried summer ice. That period is now ending. By the most recent peer-reviewed projections, the first single year in which the Arctic Ocean drops below the technical threshold for “ice-free” status — defined as less than 1 million square kilometres of sea ice, compared to the historical summer minimum of approximately 5 to 7 million square kilometres — is likely to occur sometime in the 2030s.

According to a 2023 study in Nature Communications by Seung-Ki Min and colleagues at Pohang University and the University of Hamburg, the projected date of the first ice-free Arctic September is now substantially earlier than the IPCC’s 2021 Sixth Assessment Report had concluded. The 2021 IPCC report had projected ice-free conditions “near mid-century” under intermediate and high emissions scenarios, with substantial uncertainty under low-emissions scenarios. Min and colleagues reanalysed the underlying climate models using observational constraints — adjusting the model projections to match the actual rate of Arctic sea ice decline measured by satellites over the past four decades — and concluded that the first ice-free September will likely occur in the 2030s under all emissions scenarios, including the most ambitious low-emissions trajectory. In the words of Dirk Notz, one of the study’s authors and a contributor to the IPCC reports: “We basically are saying that it has become too late to save the Arctic summer sea ice.”

What “ice-free” actually means

The technical definition of “ice-free” in this context is not the literal absence of all sea ice. As reported by a 2024 synthesis review of ice-free Arctic projections in Nature Reviews Earth & Environment, the threshold researchers use is sea ice area below 1 million square kilometres — substantially less than the approximately 4 to 7 million square kilometres that has been the typical late-summer minimum over the past several decades, but not literally zero. Some ice will continue to form along the northern coast of Greenland and within the Canadian Arctic Archipelago even after the central Arctic Ocean has lost its summer cover. The threshold is set at the level below which the central Arctic basin would be effectively open ocean during the September minimum — navigable, exposed to sunlight rather than reflecting it back, and fundamentally different in its physical, ecological, and atmospheric behaviour than the ice-covered Arctic that has characterised the Earth for approximately the last 115,000 years.

The first ice-free year is unlikely to be permanent. Winter ice will continue to form for some additional decades after the first ice-free summer, and there will be year-to-year variability in summer ice extent. But once the threshold has been crossed, it will be crossed with increasing frequency, and the long-term direction of travel is clear: the Arctic is heading toward a configuration in which late summer is reliably open water, with all of the consequences that flow from that change. A more recent 2024 paper in *Nature Communications* by Heuzé and colleagues projects that the first single ice-free day in the Arctic could occur even earlier than the first ice-free month — potentially before 2030, depending on whether an extreme weather year produces a sufficiently sharp summer melt.

Why the loss matters beyond the Arctic itself

The Arctic Ocean is not a self-contained system. The presence of summer ice across its surface is one of the major regulators of the global climate, and its loss will produce consequences across the planet. The most direct mechanism is the albedo effect: sea ice reflects approximately 80 percent of incoming sunlight back to space, while open ocean absorbs approximately 90 percent of it. Replacing ice with water at the top of the planet means substantially more solar energy is being absorbed into the Arctic Ocean, which then transfers that heat to the surrounding atmosphere, accelerates the warming of the broader Arctic region (which is already warming approximately four times faster than the global average), and propagates the change southward through atmospheric and oceanic circulation patterns.

Per a 2023 analysis in The Conversation of the implications of an ice-free Arctic, the downstream effects include disruption of mid-latitude weather patterns through changes to the polar jet stream (which is increasingly destabilised by the diminishing temperature gradient between the Arctic and lower latitudes); accelerated melting of the Greenland ice sheet (which contributes directly to sea-level rise, unlike sea ice itself); progressive thaw of Arctic permafrost (which releases methane and carbon dioxide stored in frozen organic matter, creating a self-reinforcing warming loop); collapse of Arctic ecosystems built around the seasonal sea ice cycle (including polar bears, ringed seals, walruses, ivory gulls, and the entire food web that depends on ice algae); and substantial disruption to the lives of the approximately 4 million people who live in the Arctic regions of the eight Arctic Council countries — including roughly 400,000 Indigenous people from more than 40 distinct ethnic groups, whose traditional food, transport, and cultural systems are particularly closely tied to a reliably frozen sea.

The geopolitical and economic dimensions

An ice-free Arctic will, simultaneously, open commercial shipping routes that have been closed for the entirety of recorded history. The Northern Sea Route along the Russian Arctic coast, the Northwest Passage through Canadian waters, and a potential central Transpolar route across the open polar ocean will all become reliably navigable during summer months. Container ships travelling from Northeast Asia to Northern Europe will be able to save approximately 40 percent of the distance compared to the traditional Suez Canal route. Energy resources currently inaccessible beneath the Arctic seafloor — estimated at approximately 13 percent of the world’s undiscovered oil and 30 percent of its undiscovered natural gas — will become commercially extractable. Russia, the United States, Canada, Norway, Denmark (via Greenland), and increasingly China (which has declared itself a “near-Arctic state”) are now actively positioning themselves for the strategic competition that an open Arctic Ocean will produce.

The threshold itself, when it is crossed sometime in the next 15 years, will not look dramatic from any vantage point available to most people. It will appear as a satellite image showing slightly less ice than the previous year. It will be reported as a single statistical metric falling below a defined value. The lived experience of most humans alive on the planet at the time will be substantially unchanged on the day of the threshold crossing. But the underlying transition is one of the larger physical changes to the planet that any modern human society has lived through — a return, after approximately 115,000 years, to a configuration of the polar regions that predates the entire arc of recognisably modern human civilisation. The species will, within the lifetimes of most people reading this, become the first generation to witness an Arctic Ocean without its summer ice. The change will not be reversible on any timescale relevant to human institutions. The question is no longer whether it happens but precisely when, and how rapidly the societies that depend on the old configuration adapt to the new one.

The post Most people alive today will live to see the Arctic Ocean lose its summer ice — for the first time since before our species left Africa, 115,000 years ago appeared first on Space Daily.

Rising seas could turn mangroves from carbon-storing climate allies into unexpected carbon emitters. Mangroves are among the most effective natural systems for capturing and storing carbon, but new research suggests that rising sea levels could significantly reduce that benefit and may even cause these coastal forests to release carbon in the future. Made up of [...]

It feels like there's no escaping AI right now, whether you’re trying to type a sentence without being interrupted by a digital “assistant” or struggling to find a new refrigerator that doesn’t require a Wi-Fi connection for some reason. You’d be forgiven for wondering if we’re in the midst of a quantum leap in tech or whether people are just hyping up a heap of slop.

So what should we make of the growing use of AI in weather and climate modeling?

The conversation didn't get off to a great start earlier this year when a National Weather Service office posted a forecast map featuring nonexistent cities in Idaho with names like “Whata Bod” and “Orangeotild.” Thankfully, that was just an AI-generated image produced for social media, not the actual forecast model. Meteorologists and climate scientists are not yet being replaced by large language model prompt engineers.

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According to predictions from weather organizations across the planet, a super El Niño weather event is likely to begin over the next few weeks. It’s predicted to drive up temperatures across the globe, bringing increased chances of heatwaves, drought, wildfires, and even famines – plus, this year’s El Niño is likely to be stronger than usual, making those effects worse. Let’s take a look.

Scientists say melting sea ice may have pushed the Arctic Ocean past a tipping point, triggering changes that could reshape marine life for decades. Scientists have identified what appears to be a major and potentially irreversible change in the Arctic Ocean. According to a new study, climate-driven sea ice loss has altered the region’s chemistry [...]

The years 2023 and 2024 were the warmest on record, coinciding with a powerful Pacific climate event known as El Niño. El Niño is the warm phase of a natural climate cycle in which surface waters in the eastern Pacific are unusually warm, bringing record-breaking heatwaves in the Amazon and heavy rainfall in the southern USA. Its counterpart, La Niña, is the cool phase that brings wetter conditions to the Northern USA. 

In a typical El Niño, warm water in the eastern Pacific weakens the winds blowing westward across the tropical Pacific, known as trade winds, allowing more warm water to flow eastward – a self-reinforcing cycle that amplifies the event. However, the 2023 El Niño differed because the ocean warmed intensely, but the trade winds remained strong. Researchers from the Scripps Institution of Oceanography, led by Qihua Peng and Shang-Ping Xie, recently investigated how and why this unusual event occurred.

First, the researchers tracked how air pressures changed across the Pacific during the event using a metric calculated by NOAA, known as the Southern Oscillation Index. When the eastern Pacific warms during an El Niño, the difference in air pressure across the Pacific typically decreases. In 2023, they found that temperatures in the eastern Pacific rose to more than 3°F (2°C) above normal, yet the drop in air pressure was only about 31% as strong as they expected. They also calculated that changes in wind speed and direction could only account for about 30% of the warming. So why was the 2023 El Niño so strong?

To answer this question, the research team then looked beyond the Pacific, analyzing sea surface temperatures from NOAA satellite data. They found that the North Atlantic and Indian Oceans also experienced record-breaking heat in 2023, with temperatures in the North Atlantic exceeding 2°F (1°C) above normal – the warmest in recent history. This suggested that El Niño events can develop in response to ocean conditions worldwide, not just those in the Pacific.

Next, the team used a computer program that simulates how the atmosphere responds to ocean temperatures, called the Community Atmosphere Model, to examine how heat from other oceans affects the Pacific. They found that heat in the North Atlantic and Indian Oceans generated large columns of hot air rising over those regions. This air cooled at high altitudes and then sank over the central Pacific, strengthening a large-scale loop of rising and sinking air that drives trade winds westward. Strengthening this circulation worked against El Niño by keeping trade winds blowing westward about 30% more strongly than Pacific warming alone would have. If the trade winds remained strong, why was the eastern Pacific so warm in 2023?  

To answer this question, the researchers studied 3 consecutive La Niña years between 2020 and 2023, analyzing ocean temperature and sea level data from NOAA’s Global Ocean Data System. During those years, strengthened trade winds transported heat into the western Pacific. As the seawater got warmer, it expanded, a process known as thermal expansion. Over those 3 years, thermal expansion and constant wind created a “pile” of warm water in the western Pacific, which reached its highest level of stored heat since 1982. When the trade winds eventually relaxed as La Niña faded, this piled-up warm water surged eastward, setting the stage for the El Niño event.

To test whether this stored heat alone could drive an El Niño, the team used a computer program that models oceanic and atmospheric interactions, called a coupled general circulation model. They input observed ocean temperatures from April 1, 2023, when La Niña ended, but removed all wind changes after that date. Their model successfully reproduced 87% of the warming observed between June and December 2023, which suggested that trade winds contributed just 13%. Stored heat was carried eastward by massive underwater waves traveling along the equator. As these waves reached the Eastern Pacific, they pushed cold water deeper, allowing surface water to warm. The researchers concluded that this oceanic process drove the 2023 El Niño to develop without the usual wind-driven feedback.

The team suggested that in a warming world, large heat reservoirs in the western Pacific will likely become more common, leading to more frequent strong El Niños. However, because their analysis focused on a single event, it remains unclear how often El Niños develop through oceanic processes alone. Ultimately, their study showed that the ocean can be more than a passive partner in El Niño – it can be the driving force.

The post Why the 2023 El Niño broke records appeared first on Sciworthy.