← Daily DoseThe Wandering Pole — Daily Dose No. 048
Daily Dose / Sep 1, 2026 / Magnetic North
The Wandering Pole
There are two norths. One is a fixed point on the axis of the Earth. The other is a churning knot of molten iron 3,000 km beneath your feet — and it has spent the last two centuries walking out of Canada.
2,200km
The distance magnetic north has traveled since James Clark Ross first stood on it in 1831. It began on the Boothia Peninsula in Arctic Canada. It is now closer to Siberia than to the country where it was found.
01 / The Track
It is walking across the top of the world
Plotted on a polar map, nearly two centuries of surveys and model estimates form an almost straight line: out of the Canadian Arctic, over the geographic pole, and down toward the Siberian coast.
Positions before 1994 come from field surveys; later positions are model estimates from IGRF-13 and the World Magnetic Model. The dashed segment is the model's forward projection, not an observation.
02 / The Speed
It sped up sixfold — then hit the brakes
For most of the twentieth century the pole ambled along at under 10 km a year. Then, from the mid-1990s, it broke into a run. The 2025 model records the sharpest slowdown yet measured.
The south magnetic pole, by contrast, is barely moving: 9 km per year in the same 2025 assessment. The two poles are not mirror images and never have been.
03 / The Strength
A field that is fading as it drifts
Magnetic field strength at the surface is measured in nanoteslas. It is strongest near the poles and weakest over the South Atlantic — and globally, it is about a tenth weaker than it was two centuries ago.
Global dipole
−9%
Loss of overall field strength in the last 200 years, measured against the earliest systematic observations. ESA, 2020.
Anomaly growth
+8% / yr
Expansion of the South Atlantic Anomaly over the year covered by the 2025 World Magnetic Model annual report.
Westward drift
20km/yr
Speed at which the anomaly itself is sliding west across the Atlantic, having grown steadily since 1970.
04 / The Dent
There is a bruise in the shield over Brazil
The South Atlantic Anomaly is a region where the field sags far enough for the inner radiation belt to dip toward the atmosphere. Spacecraft crossing it take a measurable beating — and since 2014 it has spread by an area close to half of continental Europe.
Within the last few years a second centre of minimum intensity has begun to open inside the anomaly, splitting it into a two-lobed structure. The GFZ Potsdam assessment is that this is probably not the onset of a reversal.
Bar lengths are scaled within each row; the three rows use different units and are not comparable to each other.
05 / The Paperwork
Every compass on Earth needs a software update
A moving pole means the correction between true north and compass north — magnetic declination — is always going stale. The World Magnetic Model is the global fix, rebuilt every five years by NOAA and the British Geological Survey. In 2019 it could not wait.
1831
James Clark Ross records the pole on the Boothia Peninsula. 70.1°N, 96.8°W — Arctic Canada.
1970–2007
Drift accelerates from 9 to 52 km per year. Geological Survey of Canada tracking.
2015
WMM2015 released, intended to hold good until 2020.
Jan 2018
Modellers find Arctic error climbing fast — on track to breach the specification early. NOAA NCEI.
Feb 2019
An out-of-cycle release of the model. The pole had gone from ~15 km/yr in the mid-1990s to about 55.
Dec 2024
WMM2025 published, valid through the end of 2029. NOAA NCEI and British Geological Survey.
2026
Annual report: north pole at 36 km/yr, south pole at 9, anomaly up 8% in a year.
Runways get repainted
18R → 19R
Runway numbers are magnetic headings rounded to ten degrees. As declination shifts, the paint stops matching the compass. Tampa International renumbered 18R/36L to 19R/1L in 2011; London Stansted had done the same in 2009.
Storms logged
18
Strong-to-severe magnetic storms recorded between 1 November 2023 and 31 October 2025 — the tail of an active solar cycle riding on top of a slowly weakening shield.
06 / The Stakes
What a bad day in the magnetosphere costs
The field is not decoration. It is the thing standing between a solar storm and the grid, the satellites, and the navigation everything else depends on. The bill has already come due more than once.
Québec, 13 Mar 1989
6million
People left without power. Ground currents induced by the storm collapsed the entire Hydro-Québec grid 90 seconds after the shock arrived. The blackout lasted about nine hours, in a Canadian March.
Low Earth orbit, Feb 2022
38of 49
Starlink satellites lost days after launch. A merely G1–G2 storm — minor to moderate — puffed up the upper atmosphere and raised drag by up to 50% over previous launches.
Modelled worst case
$41.5bn / day
Modelled, not observed. US GDP lost per day in an extreme space-weather blackout reaching 66% of the population, plus $7bn through international supply chains. Oughton et al., 2017.
In that model, disruption to electricity itself accounts for only 49% of the total macroeconomic damage. More than half the loss lands outside the blackout zone entirely.
Why it matters
The compass is a subscription, not a constant
Do not read this as a reversal. The last full flip was about 780,000 years ago, and over the last 20 million years reversals came roughly every 200,000–300,000 years. GFZ Potsdam's read is that the South Atlantic Anomaly is probably not evidence one is beginning.
Check your declination before you trust a bearing. If you navigate by compass — hiking, sailing, flying, surveying — the correction for your location changes measurably within a decade. NOAA NCEI publishes a free calculator built on the current model.
Space weather is infrastructure risk, not sci-fi. Québec 1989 and the 2022 Starlink losses were both caused by storms far short of a worst case. Grid operators and satellite fleets now plan around forecasts the way ports plan around tides.
The measurement is the achievement. Two centuries of ships, sleds, ground observatories and satellites produced a number precise enough that a 40-kilometre-a-year wobble in the core forces an emergency software release. That is a quietly extraordinary piece of collective bookkeeping.