Earth faces many natural hazards, from hurricanes and cyclones to landslides, droughts, and earthquakes. But there’s another, often overlooked hazard in the space spectrum: “Solar Storms”, a unique natural hazard.

Recently, an “extreme” G5 Geomagnetic Storm (celestial event also called aurora borealis or a solar storm) reached Earth on May 10, 2024. G5 is the highest substantial level of a geomagnetic storm, on a scale from G1 to G5, that created stunning aurora and northern lights for three days across the Earth (sighted as far south as Puerto Rico).

Auroras are usually visible in northern Canada, Scandinavia, and Siberia at higher latitudes (see Figures 1 and 2). However, they can be also seen in low-latitude areas such as south-central Mexico, Cuba, Hawaii, Queensland, southern Japan, and China. Historical records of such storms show that major coronal mass ejections (CME) occurred on September 1, 1859, March 1989, October 28, 2003, and November 4, 2003.

How do Geomagnetic Storms Impact Earth’s Climate?

Geomagnetic Storms are classified as either “recurrent” or “non-recurrent.” Recurrent storms, corresponding with the sun’s rotation, occur every 27 days but rarely impact the Earth. The energetic particles penetrate the atmosphere and can change the chemical constituents. These changes in minor species such as nitrous oxide (NO) can have long-lasting consequences in the upper and middle atmosphere and, thus, impact Earth’s climate.

Scientists believe cosmic rays can create nucleation sites in the atmosphere, with seed cloud formation and create cloudier conditions. If this were true, then there would be a significant impact on ‘the Earth’s climate, which would be modulated by the 11-year solar cycle.

There is an average of 100 severe geomagnetic storms every solar cycle, but only three have been observed in the most recent cycle that began in December 2019. The most recent series of solar events started on May 9, 2024, when a large cluster of sunspots produced several moderate to intense solar flares. Solar flares are powerful bursts of radiation seen as bright areas on the sun’s surface, typically in active regions marked by strong magnetic fields. These bursts can last from minutes to hours and are the largest explosive events in the solar system. They occur when the evolving magnetic fields reach a point of instability and release energy in various forms. We usually see a solar flare by the photons (or light) it releases at almost every wavelength of the spectrum. The primary ways we monitor flares are in X-rays and optical light. Flares are also sites where particles (electrons, protons, and heavier particles) are accelerated. The area where the flares occurred on May 10 and 11, 2024 was 16 times the diameter of Earth. It measured about 198,000 km across and was one of this solar cycle’s largest and most active sunspots (Figure 3).

Solar storms and its linkages with disruptions over Earth

Solar flares produce high-energy particles and radiation that are dangerous to living organisms. However, on the surface of the Earth, we are protected from the effects of solar flares by the Earth’s magnetic field and atmosphere.

Harmful radiation from solar flares usually cannot pass through Earth’s atmosphere to physically affect humans on the ground. However, radiation from solar flares can disrupt the body’s circadian rhythm, nervous system, heart rate, and blood pressure, thus causing more difficulty sleeping than usual, unexplained bouts of nausea, dizziness, extreme exhaustion, or even difficulty remembering things. It has been experimentally established that weak and moderate geomagnetic storms do not cause significant changes in the brain’s bioelectrical activity and exert only stimulating influence. In contrast, severe disturbances of geomagnetic conditions cause negative influence by seriously disintegrating the brain’s functionality.

The Geomagnetic Storms have the potential of adversely impacting infrastructures using electromagnetic communication systems in near-Earth orbit and on Earth’s surface, potentially disrupting communications and GPS systems, the electric power grid, navigation, radio, and satellite operations primarily in high latitude regions.

Impacts of a recent solar storm on Earth

The May 2024 solar storm caused widespread Earth voltage control and protective system issues due to plasma and magnetic field explosions. Some grid systems experienced collapse or blackouts in Sweden and damaged transformers in South Africa. Radio transmissions and satellite navigation were also disrupted. A moderate solar radiation storm could expose people in high-flying aircraft to “elevated radiation risk” and cause infrequent issues with degradation or loss of HF radio transmission and satellite navigation signals, navigation system disruptions, and avionics errors. To alleviate these problems, most of the trans-polar flights were diverted as the adverse impacts of this storm were largely concentrated over high latitudes in the Pacific and America, and the Earth’s ionosphere was reported to be turbulent in these sectors.

India was less affected as the main hit of the storm happened in the early morning of May 11, when the ionosphere was not fully developed over India. Being at a lower latitude, India also did not experience widespread outages. No significant upsets or anomalies were reported in ‘India’s 30 GEO spacecraft or Earth Observation Satellites.

However, during this solar event, the increased atmospheric density at satellite altitudes created more drag on satellites due to heating and expansion of the upper atmosphere, gradually causing them to lose altitude. This effect is most pronounced for satellites in low-Earth orbit. For example, the orbit decay of EOS-07 at ~430 km with nearly 153 kg mass was observed to be 600 meters on May 11, 2024 (nominal 300 meters), and the orbit decay of Cartosat-2F at 505 km with a mass of nearly 688 kg on May 11, 2024, was observed to be 180 meters (nominal 35 to 40 meters). On May 11, 2024, the orbit decay of all satellites increased by 5 to 6 times compared to the expected value. India’s Aditya-L1 Spacecraft observed high-speed solar wind, high-temperature plasma, energetic ion flux, and disturbances in the interplanetary magnetic field. Chandrayaan-2 also observed many large solar flares and local high-intensity particle environments with dips due to ‘the spacecraft’s orbital motion around the Moon.

The G5 category storm is considered “severe” because it’s capable of causing technology issues and potential communication disruptions on Earth. With the ever-growing dependency on electricity and emerging technologies such as artificial intelligence, any disruption could lead to trillions of dollars of monetary loss and pose a risk to the countless lives that depend on these interconnected systems.