Review Evaluates the Evidence for an Intensifying Indian Ocean Water Cycle


Report calls for better integration of observations, models, and paleo proxies.

The Indian Ocean has been warming much more than other ocean basins over the last 50-60 years. While temperature changes basin-wide can be unequivocally attributed to human-induced climate change, it is difficult to assess whether contemporary heat and freshwater changes in the Indian Ocean since 1980 represent an anthropogenically-forced transformation of the hydrological cycle.

What complicates the assessment is factoring in natural variations, regional-scale trends, a short observational record, climate model uncertainties, and the ocean basin’s complex circulation.

A new review paper takes a broad look at whether heat and freshwater changes in the Indian Ocean are consistent with the increase in rainfall that is expected in response to anthropogenic global warming or whether these changes are due to natural variability on multi-decadal and other timescales along with other factors. That distinction has “big implications for climate risk assessment and for the densely populated regions around the Indian Ocean that are vulnerable to the effects of climate change,” says Caroline Ummenhofer, lead author of the paper, Heat and freshwater changes in the Indian Ocean region, published in Nature Reviews Earth & Environment.

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