The South Atlantic Anomaly and Your Skin

Most conversations about sun damage start and end in the same place: sunny days, SPF numbers, and the importance of reapplying at the beach. That framework is useful — but it’s incomplete. Beneath the surface of conventional sun-safety advice lies a much larger story, one that involves the invisible shield surrounding our planet, a growing gap in that shield over the South Atlantic, and what it might mean for the cells in your skin.

Earth’s Magnetic Shield — and the Gap Above the South Atlantic

Earth’s geomagnetic field is one of the planet’s most fundamental defences against harmful radiation. Generated by the movement of molten iron in the outer core, it extends far into space and acts as a buffer, deflecting high-energy solar wind particles and galactic cosmic rays before they can reach us at ground level. Without it, life as we know it would look very different.

But the field is not uniform. There is a region where it is substantially weaker than everywhere else — a vast magnetic depression stretching from the coast of South America, across the South Atlantic, to southern Africa. This is the South Atlantic Anomaly (SAA). Within this region, the protective magnetic canopy dips lower, and high-energy charged particles are able to penetrate closer to Earth’s surface than they can anywhere else on the planet.

The SAA has been known to scientists since the nineteenth century, but its behaviour in recent decades has become markedly more pronounced. According to ESA Swarm satellite data published in February 2026, the anomaly has grown by an area nearly half the size of continental Europe since 2014. Since 2020, a region southwest of Africa has begun weakening even more rapidly, with ESA’s scientists noting that the SAA is no longer behaving as a single uniform structure — it is evolving differently towards Africa than near South America, driven by unusual reverse flux patches at the boundary between Earth’s liquid outer core and solid mantle. The picture the ESA Swarm data paints is of a dynamic, expanding anomaly that is not about to stabilise in the near future.

What This Means for UV Exposure

Here is where the geomagnetic picture intersects directly with skin health. Solar ultraviolet radiation — the UV-A and UV-B that your SPF is designed to address — arrives from the sun on a relatively predictable basis and varies with latitude, season, altitude, and cloud cover. Conventional sunscreen testing and SPF labelling have been built entirely around this solar UV model. That remains the dominant risk factor for most of the world.

But in SAA-affected regions, there is a second variable operating alongside solar UV: elevated particle radiation. Because the weakened magnetic field allows charged particles to descend closer to Earth’s surface, people living or travelling in southern Africa, South America, and the broader South Atlantic zone may be receiving a higher total radiation dose than the ambient UV index alone would suggest. SPF ratings, as currently defined, measure only solar UV protection — they say nothing about the additional particle radiation load that is the signature of the geomagnetic anomaly.

This is not a theoretical concern reserved for astronauts or high-altitude aviators. It is a ground-level reality for hundreds of millions of people, and it is one that conventional sun-safety messaging has not yet addressed.

The Melanoma Connection

In May 2025, the International Agency for Research on Cancer (IARC) and the World Health Organization published findings showing that more than 83% of all new melanoma cases worldwide in 2022 were attributable to ultraviolet radiation exposure — a figure that underscores just how central radiation is to melanoma risk. Meanwhile, a 2025 global assessment published in Nature Scientific Reports found that UV radiation levels increased significantly across most regions between 1990 and 2021, with notable rises across South America and Central Africa, regions that overlap substantially with the SAA footprint. In Southern Latin America, those UV increases tracked closely with rising melanoma incidence rates. The northern magnetic pole is drifting toward Siberia at 36 kilometres per year. The weakening is not localised. It is global. And it has a direct consequence for every human being alive today: greater UV radiation reaching the Earth's surface.

What is largely absent from public sun-safety messaging is the geomagnetic dimension. Standard UV monitoring tracks solar UV. It does not account for the particle radiation component that the SAA adds on top. The research community is beginning to close that gap. In October 2025, the EURAMET-BIOSPHERE project — a pan-European initiative specifically investigating the intersection of cosmic radiation and UV — published findings showing that skin cells are far more damaged when exposed to combined cosmic and UV radiation than either source alone far more damaged when exposed to combined cosmic and UV radiation than either source alone, exceeding what additive effects would predict. The interaction is synergistic. The whole, in other words, is worse than the sum of its parts.

For people with a personal or family history of melanoma — which is part of why this site exists — that synergy is worth taking seriously.

Beyond SPF — What the Research Suggests

If the effective radiation dose in SAA-affected regions is higher than standard UV measurements capture, the logical question is: what does adequate protection actually look like in those environments?

The partial answer from conventional photobiology is familiar — high-SPF broad-spectrum sunscreen, protective clothing, and avoiding peak UV hours. These remain essential. But if the radiation insult (damaging exposure to ionizing radiation, which causes immediate or delayed cellular, tissue, or systemic harm through DNA damage, oxidative stress, or inflammation) reaching skin cells includes a particle component that SPF does not address, then external photoprotection alone becomes insufficient by definition.

The research on cellular defence points in a complementary direction. Antioxidant pathways, mitochondrial integrity, and DNA repair mechanisms all have a role in how skin cells respond to radiation damage — not just at the surface, but at the biochemical level. When the radiation environment is more demanding, so too are the demands placed on those cellular systems. Supporting them becomes less of an optional extra and more of a physiological necessity.

The emerging picture is of a two-layer approach: external protection against solar UV, combined with internal cellular support designed to help the body respond to the full radiation environment it actually encounters. Science is beginning to address this gap directly, and that work has real implications for how photoprotection should be formulated for the regions most affected by the SAA.

We’ve been researching this intersection of geomagnetic science and photoprotection for some time. If you’d like to be among the first to know when a new approach becomes available, sign up using the form you'll find on this page at the top of the right hand column.