Cloudy skies may be a harbinger of something more ominous than rain. In a recent study, researchers found a positive correlation between the rise of rickets in Britain and decreased sunlight due to natural periodic changes in climate.

The lead author, Haris Majeed, a U of T Master’s student in Medical Imaging, collaborated with professor G. W. K. Moore from the Department of Physics at U of T to research the relationship between climate patterns and human health.This study is unique in its multidisciplinary approach to determining the basis of disease.

Rickets is a childhood disease caused by severe vitamin D deficiency, resulting in a defective calcification of bones and consequently, bone deformities. Vitamin D is essential for the absorption of calcium and inorganic phosphate, which aid in forming and maintaining bone mass and strength.

Around the mid-1990s, the UK saw a sudden increase in children suffering from rickets. The phenomenon led to theories about its probable causes, such as diet. Majeed proposed that the rise in rickets diagnoses was actually a result of “low-frequency variability” associated with the Atlantic Multidecadal Oscillation (AMO).

The AMO is the variation in sea surface temperatures that occurs naturally in the North Atlantic Ocean. Around six hours per month of sunlight exposure is crucial for proper vitamin D production, but a shift in the AMO results in a decrease of available sunlight.

The AMO goes through negative and positive phases. According to the paper, the negative phase is characterized by “high summer sea level pressures, reducing cloud cover and precipitation over the British Isles.”

As a result, there is less cloud cover over land and more available sunlight. In contrast, the positive phase involves a decrease in the duration of sunshine over Britain.

Each phase has a duration of approximately 60 to 80 years, and in the mid 1990s, the AMO shifted from its negative to positive phase. Cloud cover can inhibit up to 99 per cent of human vitamin D production.

According to Majeed’s research, because the positive phase of the AMO is expected to last for a few more decades, the UK will likely continue to see a sharp rise in rickets among children. Based on this multidisciplinary study, scientists can work on a solution that targets the high rate of childhood rickets that may be caused by the AMO’s positive phase.

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