photo: Rameez Sadikot via flickr
An new study led by scientists from the University of Colorado at Boulder shows that rising sea levels in parts of the Indian Ocean appear to be, at least in part, amplified by rising levels of greenhouse gases in the atmosphere. That is, they're creating more sea level rise there than the global average.Some Areas to Have 'Significantly More' Rise Than Average
The research, published in the journal Nature Geoscience, found that the Indo-Pacific warm pool--an area of ocean stretching from East Africa to the International Date Line--has warmed about 0.5°C in the past 50 years due to rises in atmospheric greenhouse gases.
CU Boulder's Weiqing Han: "Our results from this study imply that if future anthropogenic warming effects in the Indo-Pacific warm pool dominate natural variability, mid-ocean islands such as the Mascarenhas Archipelago, coasts of Indonesia, Sumatra, and the north Indian Ocean may experience significantly more sea level rise than the global average." (Science Daily)
The patterns of sea level change are driven by the combined enhancement of two primary atmospheric wind patterns known as the Hadley circulation and the Walker circulation. The Hadley circulation in the Indian Ocean is dominated by air currents rising above strongly heated tropical waters near the equator and flowing poleward, then sinking to the ocean in the subtropics and causing surface air to flow back toward the equator.
The Indian Ocean's Walker circulation causes air to rise and flow westward at upper levels, sink to the surface and then flow eastward back toward the Indo-Pacific warm pool. "The combined enhancement of the Hadley and Walker circulation form a distinct surface wind pattern that drives specific sea level patterns," said Han.
Human Activity Major Cause of Regional Variability
The study also found evidence of distinct differences in current sea level rise throughout the region. While coast along the northern Indian Ocean are showing sea level rise of about half and inch per decade, the Seychelles Islands and Zanzibar are actually showing dropping sea levels.
The report authors conclude, "Our new results show that human-caused changes in atmospheric and oceanic circulation over the Indian Ocean region, which have not been previously studied, are the major cause of regional variability of sea level change."
More on Sea Level Rise:
25% Higher Sea Level Rise Than Predicted If West Antarctic Ice Sheet Melts
Two Meter Sea Level Rise Now Inevitable - But How Fast Will It Happen?
Sea Level Rise Forces Panama Islanders to Relocate
2 Foot Sea Level Rise Along US East Coast, Not Due to Global Warming