A new study has found a link between climate-related events like extreme heat and humidity and people's mental health.

The study looked at the prevalence of depression and anxiety in Bangladeshi populations affected by climate-related shocks and stressors.

The findings of the study serve as a warning to other countries.

Flooding was also linked to an increased risk of co-occurring depression and anxiety.

Rising humidity was found to be associated with co-occurring depression and anxiety.

The South Asian country is ranked seventh in the world for its vulnerability to climate change, with frequent extreme flooding and cyclones.

The study, conducted by scientists at Georgetown University and colleagues at George Washington University and the World Bank in Bangladesh, was published in Lancet Planetary Health on February 5, 2023.

Syed Shabab, assistant professor in the Department of Global Health at Georgetown University's School of Health, said the study has now established a high-water mark for how climate can impact mental health in a highly vulnerable country.

"This should serve as a warning for other nations," he said.

Previous global research, he said in a statement, has discovered a link between these climate-related phenomena and negative mental health outcomes such as depression and anxiety.

"As climate change worsens, temperatures and humidity will continue to increase, as will natural disasters, such as extreme flooding, which portends worsening impact on our collective mental health, globally.”

Over a two-month period, the researchers measured climate-related variables at 43 weather stations in Bangladesh for changes in seasonal temperatures and humidity, as well as instances of flooding reported by study participants.

They stated that this was not enough time to see major climate change impacts, which could take many years to investigate, but it did show how even minor changes in weather events linked to climate change can impact mental health outcomes.

In addition, between August and September 2019 and January and February 2020, the researchers conducted two sets of surveys in both urban and rural areas to assess depression and anxiety in adults in representative households. Over 7,000 people responded with evaluable responses.

The researchers discovered that people who experienced one degree celsius higher temperatures in the two months preceding the study had a 21% higher likelihood of an anxiety disorder and a 24% higher likelihood of both depression and an anxiety disorder concurrently.

Similarly, one gram of moisture per cubic meter of air increase in humidity was found to increase the likelihood of anxiety and depression co-occurring by 6%. There were no links found between heat or humidity and depression alone.

Exposure to worsening flooding caused by climate change in the region was linked to an increase in the odds of all conditions: depression by 31%, anxiety by 69%, and the presence of both conditions by 87%.

The overall prevalence of depression in the Bangladeshi population was 16.3 percent, which is significantly higher than the 4.4 percent global estimate of depression found in other studies.

Aside from finding a large disparity in depression levels in Bangladesh compared to global estimates, they discovered anxiety levels of 6.0 percent in Bangladesh compared to global estimates of 3.6 percent.

"Our next steps are two-fold. We want to develop and evaluate community-based interventions that are culturally appropriate for Bangladesh, such as offering mental health services to climate-affected communities, of which there are many throughout the country. We also plan to conduct further research in Bangladesh and globally on the associations identified in this study using longer-term approaches to narrow down the causes and effects of climate changes on mental health."