Facts for Prelims (FFP)
Source: TH
Context: A recent study suggests that a combination of global warming and the Pacific Decadal Oscillation (PDO), could lead to an increase in the frequency of tropical cyclones originating near the Equator.
- The PDO is a 20–30-year cycle that occurs in the Pacific Ocean, north of 20°N.The PDO is a pattern of ocean-atmosphere climate variability. During a “warm”, or “positive”, phase, the west Pacific becomes cooler and part of the eastern ocean warms. During a “cool”, or “negative”, phase, the opposite pattern occurs.
Global warming has led to an increase in sea surface temperatures, particularly in the Indian Ocean. Warmer sea surface temperatures have contributed to the formation and intensification of tropical cyclones in the region.
About Pacific Decadal Oscillation:
The Pacific Decadal Oscillation (PDO) is a natural climate pattern that affects the temperature of the Pacific Ocean and the weather patterns around it. The PDO shifts between warm and cool phases, with each phase lasting around 20-30 years
The PDO is often quantified by the use of an index, referred to as the PDO Index. The PDO Index is calculated by spatially averaging the monthly sea surface temperature (SST) of the Pacific Ocean north of 20°N
The PDO has been linked to slower global warming because cold phases of the PDO increase the mixing of colder, deep ocean waters with warmer surface waters. This temporarily reduces the rate of global warming caused by increasing greenhouse gas emissions.
The PDO also has impacts on the weather. A warm phase tends to cause heavy rains in the Eastern Pacific Ocean and droughts in Asia and Australia. A cold phase tends to cause droughts in the Eastern Pacific Ocean and floods in Asia and Australia.
