Indo-Pacific warm pool may have been as hot during medieval times as it is today

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Washington, August 28 (ANI): A new 2,000-year-long reconstruction of sea surface temperatures (SST) from the Indo-Pacific warm pool (IPWP) suggests that temperatures in the region may have been as warm during the Medieval Warm Period as they are today.

The IPWP is the largest body of warm water in the world, and, as a result, it is the largest source of heat and moisture to the global atmosphere, and an important component of the planet's climate.

Climate models suggest that global mean temperatures are particularly sensitive to sea surface temperatures in the IPWP.

Understanding the past history of the region is of great importance for placing current warming trends in a global context.

In a joint project with the Indonesian Ministry of Science and Technology (BPPT), the study's authors, Delia Oppo, a paleo-oceanographer with the Woods Hole Oceanographic Institution, and her colleagues collected sediment cores along the continental margin of the Indonesian Seas and used chemical analyses to estimate water past temperatures and date the sediment.

"This is the first record from the region that has really modern sediments and a record of the last two millennia, allowing us to place recent trends in a larger framework," said Oppo.

Temperature reconstructions suggest that the Northern Hemisphere may have been slightly cooler (by about 0.5 degrees Celsius) during the 'Medieval Warm Period' (AD 800-1300) than during the late-20th century.

However, these temperature reconstructions are based on, in large part, data compiled from high latitude or high altitude terrestrial proxy records, such as tree rings and ice cores, from the Northern Hemisphere (NH).

Little pre-historical temperature data from tropical regions like the IPWP has been incorporated into these analyses, and the global extent of warm temperatures during this interval is unclear.

As a result, conclusions regarding past global temperatures still have some uncertainties.

According to Oppo, "Although there are significant uncertainties with our own reconstruction, our work raises the idea that perhaps even the Northern Hemisphere temperature reconstructions need to be looked at more closely."

The marine-based IPWP temperature reconstruction is in many ways similar to land temperature reconstructions from the Northern Hemisphere (NH).

Major trends observed in NH temperature reconstructions, including the cooling during the Little Ice Age (1500-1850 AD) and the marked warming during the late twentieth century, are also observed in the IPWP.

"The more interesting and potentially controversial result is that our data indicate surface water temperatures during a part of the Medieval Warm Period that are similar to today's," said Oppo. (ANI)

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