Patrick De Deckker Prof. Patrick De Deckker Department of Earth and Marine Sciences Australian National University Australia If you would like to interview this scientist, please contact Leah Christen. > biographical information > abstract > paper

Biographical Information:

Patrick De Deckker is a geologist with a PhD in zoology and a DSc in Quaternary geology. He commenced his carrier studying salt lakes, their biota, chemistry and paleoenvironments using the remains of many microscopic organisms. With others, he pioneered the study of the chemical composition of ostracods [= microcrustaceans with calcitic valves] for paleoenvironmental reconstruction, principally from salt lakes. Fifteen years ago, he diverged his interests and founded the Australian Marine Quaternary Program at the Australian National University, with the aim of reconstructing past oceanic changes in the Australasian region. He has conducted several multidisciplinary research cruises, including one studying the spectacular deep-sea canyons off the shores of southern Australia, from where superb paleoenvironmental records were recovered. His new interest is the study of aeolian dust in the Australian region, with emphasis on its chemistry, microbiology and effects on present and past climates.

Abstract:

The role of the Indo-Pacific Warm Pool on global climate change during the Quaternary

Tropical oceanic water that surrounds Southeast Asia and northern Australia is characterized today by constantly high (>28°C) sea-surface temperatures [SST], and a low-salinity and shallow ‘cap’ [= barrier layer] that prevents much exchange between the deeper ocean and the atmosphere. This region, called Warm Pool, sees the formation of high convective clouds that are critical to climate forcings on either sides of the Pacific and Indian Oceans. Today, the Warm Pool is the location of vast amounts of moisture and heat exchange between the atmosphere and the oceans, with ensuing contrasting monsoonal climates that affect the bordering land masses and its people and biota.

Any slight change in SST in the Warm Pool, and/or a change in the ocean to land ratio—the latter resulting from cyclic sea level changes so typical of the Quaternary—can have substantial consequences for climate, very likely on a global scale.

A reduction in deep convective clouds over the Warm Pool would:

(1) Increase the radiative loss to the upper atmosphere, thus causing its cooling, but also force sea-surface heating associated with strong diurnal temperature contrasts on land

(2) Change the precipitation/evaporation over the Warm Pool region and associated landmasses, and also change the moisture of the upper atmosphere

(3) Destabilize the upper layers of the oceans, and alter the freshwater flux to the global ocean

(4) Alter wind regimes, their strengths and patterns in the region

(5) Alter the poleward transport of heat and moisture, thus affecting the characteristics and formation of oceanic deep water, and lapse rates in the tropics

(6) Change the albedo ratio between land and ocean

In summary, the Warm Pool is the Planet’s HEAT ENGINE, and I will argue that subtle changes in SST occurred in this region during the Quaternary that were critical for global climate.

Paper:

The Role of the Indo-Pacific Warm Pool on Global Climate Change during the Quaternary

Lessons from the geological past call for international scientific monitoring of the oceans in SE Asia and north of Australia

Tropical oceanic waters that surrounds Southeast Asia and northern Australia today are characterised today by constantly high (>28°C) sea-surface temperatures, and a low-salinity and shallow ‘cap’ [= barrier layer] that prevents much exchange between the deeper ocean and the atmosphere. This region, called Indo-Pacific Warm Pool [Warm Pool for short], sees the formation of high convective clouds that are critical to climate forcing on either sides of the Pacific and Indian Oceans. Today, the Warm Pool is the location of vast amounts of moisture and heat exchange between the atmosphere and the oceans, with ensuing contrasting monsoonal climates that affect the bordering land masses and its people and biota.

Any slight change in sea-surface temperatures in the Warm Pool, and/or a change in the ocean to land ratio - the latter resulting from cyclic sea level changes so typical of the Quaternary - can  have substantial consequences for climate, very likely on a global scale. In other words, the modern-day conditions in the region of the Warm Pool are highly modulated and a slight change of conditions [e.g. a slight oceanic temperature change may  have dramatic consequences, such as occurred in 1997 with the major drought in Papua New Guinea [which affected over 500,000 people and required much aid from abroad] and the fires in Borneo, coincided with a significant El Nino event when sea surface temperatures in the Warm Pool had dropped in the western Pacific sector of the Warm Pool. The same could occur if sea-surface temperatures were to go over 31 degrees, the high convective clouds would not form and drought once again could ensue.

The only way one could predict such events to occur [and to prepare people against them] would be to monitor the oceans and other conditions on land, not only by satellite, but also by placing a vast array of monitoring systems such as buoys in the oceans. Equally, the destruction of rainforests and major fires have a major impact on atmospheric conditions that require monitoring. Hopefully, the destruction of forest which have a major role in soil and atmospheric moisture budgets will be stopped.

Possible scenarios with a reduction in deep convective clouds over the Warm Pool would engender the following:
(1) increase the radiative loss to the upper atmosphere, thus causing its cooling, but also force sea-surface heating associated with strong diurnal temperature contrasts on land;
(2) change the precipitation/evaporation over the Warm Pool region and associated landmasses, and also change the moisture of the upper atmosphere;
(3) destabilise the upper layers of the oceans, and alter the freshwater flux to the global ocean;
(4) alter wind regimes, their strengths and patterns in the region;
(5) alter the poleward transport of heat and moisture, thus affecting the characteristics and formation of oceanic deep water, and lapse rates in the tropics; and
(6) the albedo ratio between land and ocean.

In summary, the Warm Pool is the HEAT AND STEAM ENGINE FOR PLANET EARTH, and I will argue that subtle changes in sea-surface temperatures occurred in this region during the Quaternary that were critical for global climate and could be repeated in the future and have a significant impact on a large portion of the world’s population.