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Glacier melt intensifying freshwater loss and accelerating sea-level rise
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Communities in coastal areas such as Florida, shown in this 1992 NASA image, are vulnerable to the effects of sea level rise, including high-tide flooding. A new agency-led analysis found a higher-than-expected rate of sea level rise in 2024, which was also the hottest year on record.NASA Last year’s increase was due to an unusual amount of ocean warming, combined with meltwater from land-based ice such as glaciers.
Global sea level rose faster than expected in 2024, mostly because of ocean water expanding as it warms, or thermal expansion. According to a NASA-led analysis, last year’s rate of rise was 0.23 inches (0.59 centimeters) per year, compared to the expected rate of 0.17 inches (0.43 centimeters) per year.
“The rise we saw in 2024 was higher than we expected,” said Josh Willis, a sea level researcher at NASA’s Jet Propulsion Laboratory in Southern California. “Every year is a little bit different, but what’s clear is that the ocean continues to rise, and the rate of rise is getting faster and faster.”
This graph shows global mean sea level (in blue) since 1993 as measured by a series of five satellites. The solid red line indicates the trajectory of this increase, which has more than doubled over the past three decades. The dotted red line projects future sea level rise.NASA/JPL-Caltech In recent years, about two-thirds of sea level rise was from the addition of water from land into the ocean by melting ice sheets and glaciers. About a third came from thermal expansion of seawater. But in 2024, those contributions flipped, with two-thirds of sea level rise coming from thermal expansion.
“With 2024 as the warmest year on record, Earth’s expanding oceans are following suit, reaching their highest levels in three decades,” said Nadya Vinogradova Shiffer, head of physical oceanography programs and the Integrated Earth System Observatory at NASA Headquarters in Washington.
Since the satellite record of ocean height began in 1993, the rate of annual sea level rise has more than doubled. In total, global sea level has gone up by 4 inches (10 centimeters) since 1993.
This long-term record is made possible by an uninterrupted series of ocean-observing satellites starting with TOPEX/Poseidon in 1992. The current ocean-observing satellite in that series, Sentinel-6 Michael Freilich, launched in 2020 and is one of an identical pair of spacecraft that will carry this sea level dataset into its fourth decade. Its twin, the upcoming Sentinel-6B satellite, will continue to measure sea surface height down to a few centimeters for about 90% of the world’s oceans.
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This animation shows the rise in global mean sea level from 1993 to 2024 based on da-ta from five international satellites. The expansion of water as it warms was responsible for the majority of the higher-than-expected rate of rise in 2024.NASA’s Scientific Visualization Studio Mixing It Up
There are several ways in which heat makes its way into the ocean, resulting in the thermal expansion of water. Normally, seawater arranges itself into layers determined by water temperature and density. Warmer water floats on top of and is lighter than cooler water, which is denser. In most places, heat from the surface moves very slowly through these layers down into the deep ocean.
But extremely windy areas of the ocean can agitate the layers enough to result in vertical mixing. Very large currents, like those found in the Southern Ocean, can tilt ocean layers, allowing surface waters to more easily slip down deep.
The massive movement of water during El Niño — in which a large pool of warm water normally located in the western Pacific Ocean sloshes over to the central and eastern Pacific — can also result in vertical movement of heat within the ocean.
Learn more about sea level:
https://sealevel.nasa.gov
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Last Updated Mar 13, 2025 Related Terms
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By USH
Let’s talk about Artificial Intelligence! How many people are actually aware of the rapid rise of AI and the potential risks it poses to humanity’s future? Do you recognize these dangers, or do you choose to ignore them, turning a blind eye to the reality of AI’s impact?
An increasing number of people are becoming aware of AI's rapid rise, yet many still unknowingly rely on AI-powered technologies. Studies show that while nearly all Americans use AI-integrated products, 64% remain unaware of it.
AI adoption is expanding, by 2023, 55% of organizations had implemented AI technologies, and nearly 77% of devices incorporated AI in some form. Despite this prevalence, only 17% of adults can consistently recognize when they are using AI.
With growing awareness comes rising concern. Many fear job displacement, while others worry about AI’s long-term risks. A survey found that 29% of respondents see advanced AI as a potential existential threat, and 20% believe it could cause societal collapse within 50 years.
A June 2024 a study across 32 countries revealed that 50% of people feel uneasy about AI. As AI continues to evolve, how many truly grasp its impact—and the risks it may pose for humanity’s future?
Now, a new paper highlights the risks of artificial general intelligence (AGI), arguing that the ongoing AI race is pushing the world toward mass unemployment, geopolitical conflict, and possibly even human extinction. The core issue, according to researchers, is the pursuit of power. Tech firms see AGI as an opportunity to replace human labor, tapping into a potential $100 trillion economic output. Meanwhile, governments view AGI as a transformative military tool.
Researchers in China have already developed a robot controlled by human brain cells grown in a lab, dubbed a "brain-on-chip" system. The brain organoid is connected to the robot through a brain-computer interface, enabling it to encode and decode information and control the robotic movements. By merging biological and artificial systems, this technology could pave the way for developing hybrid human-robot intelligence.
However, experts warn that superintelligence, once achieved, will be beyond human control.
The Inevitable Risks of AGI Development. 1. Mass Unemployment – AGI would fully replace cognitive and physical labor, displacing workers rather than augmenting their capabilities.2. Military Escalation – AI-driven weapons and autonomous systems increase the likelihood of catastrophic conflict.3. Loss of Control – Superintelligent AI will develop self-improvement capabilities beyond human comprehension, rendering control impossible.4. Deception and Self-Preservation – Advanced AI systems are already showing tendencies to deceive human evaluators and resist shutdown attempts.
Experts predict that AGI could arrive within 2–6 years. Empirical evidence shows that AI systems are advancing rapidly due to scaling laws in computational power. Once AGI surpasses human capabilities, it will exponentially accelerate its own development, potentially leading to superintelligence. This progression could make AI decision-making more sophisticated, faster, and far beyond human intervention.
The paper emphasizes that the race for AGI is occurring amidst high geopolitical tensions. Nations and corporations are investing hundreds of billions in AI development. Some experts warn that a unilateral breakthrough in AGI could trigger global instability—either through direct military applications or by provoking adversaries to escalate their own AI efforts, potentially leading to preemptive strikes.
If AI development continues unchecked, experts warn that humanity will eventually lose control. The transition from AGI to superintelligence would be akin to humans trying to manage an advanced alien civilization. Super intelligent AI could take over decision-making, gradually making humans obsolete. Even if AI does not actively seek harm, its vast intelligence and control over resources could make human intervention impossible.
Conclusion: The paper stresses that AI development should not be left solely in the hands of tech CEOs who acknowledge a 10–25% risk of human extinction yet continue their research. Without global cooperation, regulatory oversight, and a shift in AI development priorities, the world may be heading toward an irreversible crisis. Humanity must act now to ensure that AI serves as a tool for progress rather than a catalyst for destruction.
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By European Space Agency
Image: These summer images from the Copernicus Sentinel-2 and Sentinel-1 missions showcase different satellite views of Greenland’s west coast. View the full article
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By NASA
The Artemis II Orion spacecraft is lifted from the Final Assembly and Testing (FAST) Cell and placed in the west altitude chamber inside the Operations and Checkout Building at NASA’S Kennedy Space Center in Florida on June 28, 2024. Inside the altitude chamber, the spacecraft underwent a series of tests simulating deep space vacuum conditions.Photo Credit: NASA / Rad Sinyak After extensive analysis and testing, NASA has identified the technical cause of unexpected char loss across the Artemis I Orion spacecraft’s heat shield.
Engineers determined as Orion was returning from its uncrewed mission around the Moon, gases generated inside the heat shield’s ablative outer material called Avcoat were not able to vent and dissipate as expected. This allowed pressure to build up and cracking to occur, causing some charred material to break off in several locations.
“Our early Artemis flights are a test campaign, and the Artemis I test flight gave us an opportunity to check out our systems in the deep space environment before adding crew on future missions,” said Amit Kshatriya, deputy associate administrator, Moon to Mars Program Office, NASA Headquarters in Washington. “The heat shield investigation helped ensure we fully understand the cause and nature of the issue, as well as the risk we are asking our crews to take when they venture to the Moon.”
Findings
Teams took a methodical approach to understanding and identifying the root cause of the char loss issue, including detailed sampling of the Artemis I heat shield, review of imagery and data from sensors on the spacecraft, and comprehensive ground testing and analysis.
During Artemis I, engineers used the skip guidance entry technique to return Orion to Earth. This technique provides more flexibility by extending the range Orion can fly after the point of reentry to a landing spot in the Pacific Ocean. Using this maneuver, Orion dipped into the upper part of Earth’s atmosphere and used atmospheric drag to slow down. Orion then used the aerodynamic lift of the capsule to skip back out of the atmosphere, then reenter for final descent under parachutes to splashdown.
Using Avcoat material response data from Artemis I, the investigation team was able to replicate the Artemis I entry trajectory environment — a key part of understanding the cause of the issue — inside the arc jet facilities at NASA’s Ames Research Center in California. They observed that during the period between dips into the atmosphere, heating rates decreased, and thermal energy accumulated inside the heat shield’s Avcoat material. This led to the accumulation of gases that are part of the expected ablation process. Because the Avcoat did not have “permeability,” internal pressure built up, and led to cracking and uneven shedding of the outer layer.
After NASA’s Orion spacecraft was recovered at the conclusion of the Artemis I test flight and transported to NASA’s Kennedy Space Center in Florida, its heat shield was removed from the crew module inside the Operations and Checkout Building and rotated for inspection. Credit: NASA Teams performed extensive ground testing to replicate the skip phenomenon before Artemis I. However, they tested at much higher heating rates than the spacecraft experienced in flight. The high heating rates tested on the ground allowed the permeable char to form and ablate as expected, releasing the gas pressure. The less severe heating seen during the actual Artemis I reentry slowed down the process of char formation, while still creating gases in the char layer. Gas pressure built up to the point of cracking the Avcoat and releasing parts of the charred layer. Recent enhancements to the arc jet facility have enabled a more accurate reproduction of the Artemis I measured flight environments, so that this cracking behavior could be demonstrated in ground testing.
While Artemis I was uncrewed, flight data showed that had crew been aboard, they would have been safe. The temperature data from the crew module systems inside the cabin were also well within limits and holding steady in the mid-70s Fahrenheit. Thermal performance of the heat shield exceeded expectations.
Engineers understand both the material phenomenon and the environment the materials interact with during entry. By changing the material or the environment, they can predict how the spacecraft will respond. NASA teams unanimously agreed the agency can develop acceptable flight rationale that will keep crew safe using the current Artemis II heat shield with operational changes to entry.
NASA’s Investigation Process
Soon after NASA engineers discovered the condition on the Artemis I heat shield, the agency began an extensive investigation process, which included a multi-disciplinary team of experts in thermal protection systems, aerothermodynamics, thermal testing and analysis, stress analysis, material test and analysis, and many other related technical areas. NASA’s Engineering and Safety Center was also engaged to provide technical expertise including nondestructive evaluation, thermal and structural analysis, fault tree analysis, and other testing support.
“We took our heat shield investigation process extremely seriously with crew safety as the driving force behind the investigation,” said Howard Hu, manager, Orion Program, NASA’s Johnson Space Center in Houston. “The process was extensive. We gave the team the time needed to investigate every possible cause, and they worked tirelessly to ensure we understood the phenomenon and the necessary steps to mitigate this issue for future missions.”
The Artemis I heat shield was heavily instrumented for flight with pressure sensors, strain gauges, and thermocouples at varying ablative material depths. Data from these instruments augmented analysis of physical samples, allowing the team to validate computer models, create environmental reconstructions, provide internal temperature profiles, and give insight into the timing of the char loss.
Approximately 200 Avcoat samples were removed from the Artemis I heat shield at NASA’s Marshall Space Flight Center in Alabama for analysis and inspection. The team performed non-destructive evaluation to “see” inside the heat shield.
One of the most important findings from examining these samples was that local areas of permeable Avcoat, which had been identified prior to the flight, did not experience cracking or char loss. Since these areas were permeable at the start of the entry, the gases produced by ablation were able to adequately vent, eliminating the pressure build up, cracking, and char loss.
A test block of Avcoat undergoes heat pulse testing inside an arc jet test chamber at NASA’s Ames Research Center in California. The test article, configured with both permeable (upper) and non-permeable (lower) Avcoat sections for comparison, helped to confirm understanding of the root cause of the loss of charred Avcoat material that engineers saw on the Orion spacecraft after the Artemis I test flight beyond the Moon.Credit: NASA
Engineers performed eight separate post-flight thermal test campaigns to support the root cause analysis, completing 121 individual tests. These tests took place in facilities with unique capabilities across the country, including the Aerodynamic Heating Facility at the Arc-Jet Complex at Ames to test convective heating profiles with various test gases; the Laser Hardened Materials Evaluation Laboratory at Wright‐Patterson Air Force Base in Ohio to test radiative heating profiles and provide real-time radiography; as well as the Interaction Heating Facility at Ames to test combined convective and radiative heating profiles in the air at full-block scale.
Aerothermal experts also completed two hypersonic wind tunnel test campaigns at NASA’s Langley Research Center in Virginia and CUBRC aerodynamic test facilities in Buffalo, New York, to test a variety of char loss configurations and enhance and validate analytical models. Permeability testing was also performed at Kratos in Alabama, the University of Kentucky, and Ames to help further characterize the Avcoat’s elemental volume and porosity. The Advanced Light Source test facility, a U.S. Department of Energy scientific user facility at Lawrence Berkeley National Laboratory, was also used by engineers to examine the heating behavior of the Avcoat at a microstructure level.
In the spring of 2024, NASA stood up an independent review team to conduct an extensive review of the agency’s investigation process, findings, and results. The independent review was led by Paul Hill, a former NASA leader who served as the lead space shuttle flight director for Return to Flight after the Columbia accident, led NASA’s Mission Operations Directorate, and is a current member of the agency’s Aerospace Safety Advisory Panel. The review occurred over a three-month period to assess the heat shield’s post-flight condition, entry environment data, ablator thermal response, and NASA’s investigation progress. The review team agreed with NASA’s findings on the technical cause of the physical behavior of the heat shield.
Heat Shield Advancements
Knowing that permeability of Avcoat is a key parameter to avoid or minimize char loss, NASA has the right information to assure crew safety and improve performance of future Artemis heat shields. Throughout its history, NASA has learned from each of its flights and incorporated improvements into hardware and operations. The data gathered throughout the Artemis I test flight has provided engineers with invaluable information to inform future designs and refinements. Lunar return flight performance data and a robust ground test qualification program improved after the Artemis I flight experience are supporting production enhancements for Orion’s heat shield. Future heat shields for Orion’s return from Artemis lunar landing missions are being produced to achieve uniformity and consistent permeability. The qualification program is currently being completed along with the production of more permeable Avcoat blocks at NASA’s Michoud Assembly Facility in New Orleans.
For more information about NASA’s Artemis campaign, visit:
https://www.nasa.gov/artemis
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By European Space Agency
As Arctic temperatures rise, marine-terminating glaciers—especially in places like Svalbard—are undergoing rapid retreat and intensified calving.
The ESA-funded Space for Shore project utilises radar data from the Copernicus Sentinel-1 mission to provide precise, year-over-year insights into glacier retreat and calving intensity, particularly in areas like Kongsfjorden, where notable glaciers are experiencing significant retreat.
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