GPS denied: time to upgrade

From Pulse by Mark Munsell, former Chief AI Officer of NGA

The Fragile Foundation of Modern Navigation

The Global Positioning System (GPS) is arguably the greatest dual-use technology ever developed.
It saves us trillions of dollars in wasted fuel and inefficient logistics.
However, our modern world is built on a system that is terrifyingly fragile, highly vulnerable to jamming, spoofing, and the existential threat of anti-satellite weapons.

Recent events prove this vulnerability.
On February 28, ships navigating the Strait of Hormuz started appearing on tracking screens in places they couldn't possibly be.
They appeared to be sitting on airport runways, parked on Iranian land, and clustered at nuclear power plants.
More than 1,100 commercial vessels had their navigation systems scrambled in a single day following US-Israeli airstrikes on Iran, bringing a waterway that handles a fifth of the world's oil exports to a halt.

A similar crisis unfolded months earlier in the Caribbean.
During a U.S. standoff with Venezuela, jammed signals caused commercial flights to experience severe GPS problems, resulting in a near-collision for a JetBlue pilot and forcing a cruise ship to navigate by charts and landmarks for three hours.

These are no longer isolated incidents.
Today, anyone can pull up independent tracking sites like gpsjam.org—which aggregates aircraft data to visualize daily GPS disruptions worldwide—and view a heat map of the globe bleeding red with active interference.

But conflict zones aren't the only risk.
In 2013, a truck driver with a $100 jammer accidentally knocked Newark Liberty International Airport's GPS offline just to hide from his employer's vehicle tracker.
This system is used by over 6 billion people, yet it could be blinded by cheap gadgets bought off of eBay (now illegal btw).

The Invisible Metronome

GPS was designed for military position, navigation, and timing in the 1960s and 70s.
Its signals travel 20,000 kilometers from space, arriving 100,000 times weaker than ambient noise.
This makes them easily overwhelmed by low-cost eBay jammers emitting stronger radio noise on the same frequency.

Crucially, GPS isn't just a map; it is the invisible metronome for the modern world.
The atomic clocks on GPS satellites synchronize cellular networks, timestamp billions of financial transactions, and regulate power grids.
Lose the timing signal, and our global digital infrastructure fundamentally breaks down.
We've wired the heartbeat of the global economy to a whispering radio signal from space.

Diverging Strategies: U.S. vs. China

The U.S. government has focused its response almost entirely on advancing military resilience measures like encrypted M-code signals and anti-jam antennas.
This does nothing for commercial pilots or global logistics networks navigating denied environments.
The U.S. defends GPS purely as a military asset.

Meanwhile, China has taken a radically different approach.
It has poured state investment into the BeiDou satellite system, which achieved full global coverage in 2020 and surpasses the U.S. network in size.
In parallel, China has built a deep bench of geospatial experts and backed BeiDou with a layered terrestrial architecture that includes a 20,000-kilometer fiber network and a national eLoran system.
By actively exporting BeiDou through the Belt and Road Initiative and achieving full-stack autonomy in domestic navigation chips, China is building an ecosystem with commercial and strategic leverage that will matter as GPS-denied environments become the norm.

Moving Beyond GPS 2.0

The private sector is beginning to field alternative positioning systems, but competing against “free” will require game-changing innovation, not just incremental improvement.
Inertial navigation systems are expensive and drift over time.
Satellite constellations that simply move GPS-like spacecraft closer to Earth carry many of the same vulnerabilities as the system they’re meant to replace.

Commercial alternatives must go beyond GPS 2.0 to address both resilience and new use cases that justify adoption on their own merits.
Remarkable new startups like EarthTraq aim to fill these gaps by providing new purpose-built constellations paired with low-cost, low-powered devices not dependent on any GPS constellations.
Other companies are actively using computer vision or radar to automatically determine positions with what I call "artificial intelligence dead reckoning." 

Powerhouse companies like Vantor and Niantic Spatial are going big on high fidelity photogrammetric digital models of the world for precision navigation in denied environments.
Other examples, Skyline Nav AI uses computer vision and deep learning to determine a vehicle's location in real time based solely on its surroundings.
Similarly, European startup Vydar uses onboard AI to match live camera feeds of the ground with offline maps, computing highly accurate coordinates even during a complete GPS blackout.
Daedalean AI is taking a complementary approach, building visual positioning systems that integrate seamlessly with radar and inertial sensors to operate in challenging conditions like fog or darkness.
All of these alternatives offer mission performance that GPS cannot and have great promise to supplement or replace it in a denied environment.

We’re all going to have to get used to a world without GPS.
The era of implicit trust in a single vulnerable satellite network is over.
If we want to safely operate autonomous systems and AI in the real world, we must develop higher-fidelity methods of positioning within the eternal reference frame that cannot be defeated by cheap eBay jammers.
It's time to make the system resilient, redundant, and reliable through alternate means to make autonomous AI-driven navigation a reality.

Shift in the Gulf Stream could signal ocean current collapse

The Gulf Stream ocean current carries warm water from the Gulf of Mexico up the US east coast
NASA’s Scientific Visualization Studio/Science Photo Library

From New Scientist by Alec Luhn

 
Models show that as the Atlantic Meridional Overturning Circulation gets weaker, the Gulf Stream will drift northwards.
There are signs that this is already happening, and a more abrupt shift could warn of more severe climate impacts

A gradual northward shift in the Gulf Stream has provided more evidence that the system of currents that keeps Europe warm is weakening.
What’s more, modelling suggests that any abrupt shift in the Gulf Stream could signal an imminent, catastrophic collapse in the ocean current.

The Atlantic Meridional Overturning Circulation (AMOC) is the flow of warm, salty surface water from the tropics to north-western Europe, where it cools and sinks, returning south along the ocean floor.
The part of this circulation running from the Gulf of Mexico up the US east coast to North Carolina, where it veers east into the Atlantic, is called the Gulf Stream.

Horizontal velocities responses. Credit: Communications Earth & Environment (2026)

 

The AMOC is expected to lose strength as the melting of the Greenland ice sheet dumps fresh water into the north Atlantic, diluting the dense, salty AMOC water and slowing the rate at which it sinks and flows southward.
Some research suggests that this is already happening, but scientists don’t have direct proof.
Now, a modelling study by René van Westen and Henk Dijkstra, both at Utrecht University in the Netherlands, has shown that a weakening AMOC would shift the path of the Gulf Stream so it follows the US seaboard further north before it veers into the Atlantic.
Moreover, the study finds the Gulf Stream has already shifted northward by about 50 kilometres in 30 years, according to satellite data.
“This is something we can measure,” says van Westen.
“So it is very likely that this reflects that the AMOC is indeed weakening.”
Reconstructions that estimate the AMOC flow rate based on historic sea temperatures suggest it has weakened 15 per cent since 1950.
But its actual flow has only been monitored by moored instruments since 2004, not long enough to say whether observed changes are natural fluctuations or a trend.
“Therefore, we are trying to come up with some alternative approaches, such as the Gulf Stream path,” says van Westen.
The model in the study represents the world in 10-kilometre pixels rather than the typical 100-kilometre pixels, allowing the researchers to track the bulge where the Gulf Stream is carrying masses of water.
The path of the bulge changes because of the Deep Western Boundary Current, one of the arms of the AMOC carrying cold, salty water southward along the seafloor.
This current normally flows down the coast of North America under the Gulf Stream, tugging it to the south.
As the AMOC weakens, so does the Deep Western Boundary Current, and the curve of the Gulf Stream gradually shifts northward.
However, 392 years into the simulation’s future, the Gulf Stream jumps more than 200 kilometres to the north in just two years.
Twenty-five years after that, the AMOC collapses.
Previous research has shown that such a collapse would drastically cool Europe; London could see cold snaps of -20°C (-4°F) and Oslo, Norway, could reach -48°C (-54°F).

 

Gulf Stream path in observations. Credit: Communications Earth & Environment (2026).

The modelling is an idealised scenario that does not suggest the AMOC will collapse in 400 years.
But it does suggest an abrupt shift in the Gulf Stream could serve as an early warning of an impending AMOC shutdown, the only such prior indicator we know of.
While it may be too late at that point to avoid AMOC collapse, Europe could prepare by insulating houses and finding more southerly places to grow food.
“There is now a very proper early warning indicator that actually goes off,” says van Westen.
“You can measure this very easily.”
But it’s unclear in the real world how long after a Gulf Stream shift the AMOC could collapse.
And projections of when the AMOC might shut down range from decades to centuries.
Dan Seidov, an oceanographer retired from the US National Oceanic and Atmospheric Administration, cautions that fresh water from Greenland could “hose” the AMOC at a different rate and in a different place from what the model assumes.
“How, when and why it may or may not happen is the big question,” he says.
“If it happens as is prescribed in the model, then the Gulf Stream can be a precursor and provide a warning signal.”
While the link between the abrupt shift and AMOC collapse will need to be corroborated by other models, this study provides more evidence the AMOC is already slowing, says Stefan Rahmstorf at the University of Potsdam in Germany.
“This slowing is occurring earlier than in the global warming scenarios,” he says.
“Climate models appear to underestimate the problem and thus potentially how soon an AMOC tipping point will be reached.”

Links :

• Nature Communications Earth & Environment DOI: 10.1038/s43247-026-03309-1 
• US East Coast faces rising seas as crucial Atlantic current slows 
• LiveScience : Early warning indicator hidden within the Gulf Stream could signal the collapse of key Atlantic currents, study finds 
• Phys : How a shift in the Gulf Stream could signal the collapse of a major ocean current system 
• IFLScience : The Gulf Stream Is Moving North – And It Could Be An Early Warning Sign 
• MSN : Gulf Stream shift could warn of collapse
•  GeoGarage blog : Gulf Stream could collapse as early as 2025, study suggests / What is the Gulf Stream? / The Gulf Stream continues to slow down, new data shows ...  / Image of the week : vertical extent of Gulf Stream  / Atlantic Ocean is headed for a tipping point − once melting ... / Climate crisis: scientists spot warning signs of Gulf Stream collapse  / Atlantic Ocean circulation at weakest in a millennium, say ... / This Old Map: Benjamin Franklin's Gulf Stream, 1786 / How soon might the Atlantic Ocean break? Two sibling ... / Gulf Stream diverted more than 100 Miles North in 2011 / Scientists say the global ocean circulation may be more ... / New map of global ocean temperatures is a work of art / Slow-motion ocean: Atlantic's circulation is weakest in ... /

Squid, a new mobile navigation app compatible with the GeoGarage platform

 Squid on the AppleStore

 

The route-planning app used by Vendée Globe skippers.

Advanced weather forecasting, multi-model GRIBs, smart route planning—ultra-low data usage, even at sea.

The trusted weather routing app of the world’s top offshore sailors.

Squid is the mobile version of SquidX—the routing solution used by elite teams in the Vendée Globe, Route du Rhum, Transat Jacques Vabre, The Ocean Race, and many more.

That same level of professional performance now fits in your pocket.

From solo ocean racers to weekend sailors, Squid offers every sailor access to accurate multi-model weather data and smart routing tools—reimagined for speed, simplicity, and offshore use.
 

A brand-new version has just been launched: 

a completely redesigned interface, significant performance improvements, and new features in continuous development.

Key Features

• Intelligent routing engine with roadbook tool
• Cloud-based routing with multi-route comparison
• Multi-model GRIB viewer (GFS, ECMWF, AROME, ARPEGE, GEM, NAM, and more)
• Forecasts up to 10 days, with 1- to 3-hour intervals
• Meteograms for multi-model comparison (wind & pressure)
• Extensive database of polar charts (racing & cruising yachts)
• Lightweight GRIBs optimized for offline use
• Iridium GO!® compatible — designed for low-bandwidth environments
• Custom map visualizations: contour lines, wind vanes, arrows, particles

Weather data : 

Wind, gusts, MSLP, precipitation, cloud cover, CAPE, humidity, temperature, surface currents, swell & wind waves. 

 

Squid is compatible with the nautical charts form the GeoGarage platform via some yearly subscriptions also available for Weather 4D Routing & Navigation on iOS / SailGrib on Android / NavimetriX multiplatform

 

Wind assisted propulsion on cargo ships

Wind assisted propulsion on cargo ships
pic.twitter.com/AWOVqtJbRC

— Science girl (@sciencegirl) February 27, 2026

Master & cartographer : Greenvile Collins

 

From The History Press

 
A Life of Captain Greenv

 
‘Fascinating and elegantly written, Master & Cartographer introduces a largely forgotten naval hero of Stuart England’ – N.A.M. Rodger, author of The Safeguard of the Sea, The Command of the Ocean and The Price of Victory

This is a book about maps and map-making, about power and class, and about war, seamanship and navigation.

It is a study of wealth, patronage and money, in an England riven by religious disorder and toxic politics.

Greenvile Collins (1643–94) was a naval warrant officer who caught the attention of a King.

His seagoing career took him from Patagonia to the Arctic, into battles against Dutch men of war and Barbary corsairs, and to the slave markets and Silk Road ports of the Mediterranean.

A scientific navigator, his professional drive drew him to Shetland, the Scilly Isles and all points in between, as he undertook the most ambitious hydrographic survey of the British coastline yet attempted.

Then, even as he laboured to complete his monumental sea atlas, he was summoned yet again to the service of the Crown.

The Glorious Revolution was a campaign of crisis for a deeply conflicted Royal Navy, and a crucial test of loyalty for Greenvile Collins and his fellow officers.

Nautical chart by Collins (1698) showing the North Sea

from the Thames Estuary (left) to the Wash(right)

Reviews

‘Fascinating and elegantly written, Master & Cartographer introduces a largely-forgotten naval hero of Stuart England’
N.A.M. Rodger, author of The Safeguard of the Sea, The Command of the Ocean and The Price of Victory

‘Greenvile Collins emerges as a sympathetic hero, who served three kings while compiling invaluable charts and navigational data for his fellow sailors. Not since Patrick O’Brian’s Aubrey-Maturin novels have I enjoyed such rollicking armchair adventures at sea’
Dava Sobel, author of Longitude

‘A triumph. Far more than just the man who charted Britain, Greenvile Collins developed faster survey techniques, commanded ships, fought in battle, and ended his career as the leading hydrographer of the Navy. Alan Harper’s major contribution places Collins in a critical series of events, linking charts and navigation with wars and the fast-paced transitions that occurred after 1688, adding a significant new dimension to the naval side of that tumultuous year’
Andrew Lambert, Laughton Professor of Naval History, Kings College, London

‘Very worthwhile – the author has an excellent grasp of his material, writes well, and his seagoing experience adds colour and interest to a compelling narrative’
Dr David Davies, author of Pepys’s Navy and Kings of the Sea, chair of the Society for Nautical Research