GLOBAL WARMING ALTERS RAINFALL RHYTHM
What’s in news?
A study by a team of Indian and U.S. researchers has found that Global warming has altered a key weather system and that may be whetting cyclones in the Bay of Bengal, decreasing winter rain in north India and altering global rainfall patterns.
- The Madden–Julian Oscillation (MJO), as it’s called, is a moving band of rain clouds that travels around the globe spanning 12,000–20,000 km across the tropical oceans.
- In its journey, it interacts with surface waters of the Indo-Pacific ocean, the largest pool of warm water in the globe, and due to this, it is said that the lifecycle of the MJO gets affected.
- The MJO clouds on average are spending only 15 days, instead of 19, over the Indian Ocean.
- Over the west Pacific, it increased by five days (from an average of 16 days to 23 days).
- It is this change in the residence time of MJO clouds that has altered the weather patterns across the globe, according to the research paper.
- When the MJO appears in the Indian Ocean during the monsoon months of June-September, it can increase rains over India. This year, India was poised to receive below-normal monsoon rainfall in April but ended up with excessive rain partly due to the MJO.
- The changes in MJO behaviour have increased the rainfall over northern Australia, west Pacific, Amazon basin, southwest Africa and southeast Asia (Indonesia, Philippines and Papua New Guinea).
- At the same time, these changes have brought a decline in rainfall over the central Pacific, along the west and east coast of the U.S. (e.g., California), north India, east Africa and the Yangtze basin in China. The frequent California fires, droughts in Africa and East Asian floods and cyclones in the Bay of Bengal may be linked to these changes in global weather, the study noted.
- The MJOs haven’t been as extensively studied as say, the El Nino. This study shows that there is a need for better observation of the Indian Ocean and improved forecasts that can warn about a cyclone.
Links to note: