A serics of low-latitude marginal seas, ranging from the southern South China Sea in the north to the Arafura Sea in the south, are located within the Western Pacific Warm Pool. As shown by rnicropaleontological, isot...A serics of low-latitude marginal seas, ranging from the southern South China Sea in the north to the Arafura Sea in the south, are located within the Western Pacific Warm Pool. As shown by rnicropaleontological, isotopical and organic geochemical analyses, the sea surface temperatures in the marginal seas at the last glacial maximum were much cooler than those in the open Western Pacific Ocean. The emergence of extensive shelves of the marginal seas at the glacial low sea-level stand and the decrease of surface temperatures in their deeper water parts resulted in a remarkable reduction of the ability of vapor and heat transport to the atmosphere, causing variabilities to the Warm Pool in the glacial cycles. The intensification of winter monsoon at the glacial stages not only led to a decrease of the surface water temperature and hence to an enhanced seasonality, but also carried moisture from the sea to the tropical islands, giving rise to the downward shift of snowline and mountainous vegetation zones there. It may offer a new alternative in solution of the “Tropical Ocean Paleo-temperature Enigma”.展开更多
Based on the photosynthesis-respiration reversible reaction and the available statistics, we attempted to quantify the planetary seasonal exchanges of CO<sub>2</sub> between air and water from 1970 and com...Based on the photosynthesis-respiration reversible reaction and the available statistics, we attempted to quantify the planetary seasonal exchanges of CO<sub>2</sub> between air and water from 1970 and compared them to the glacial ACC cycles as reported from ice cores archives. In 2020, the overall continental absorption (AW) was 8.0 giga tonnes of carbon per year (GtC/y). Emissions into the atmosphere (EW) resulting from mineral degradation by respiration and combustion of biomass and fossil hydrocarbons were 14.7 GtC/y, an increase of 2.4% per year since 1970. The continental surplus balance (-AW+EW) of 6.7 GtC/y was shared between the atmosphere, which received 5.1 GtC/y (GATM), and the ocean which absorbed 1.6 GtC/y. This ocean contribution (OC) corresponded to 17% of the 9.2 GtC/y emissions by combustion of fossil hydrocarbons (EFOS). Analysis of the ACC oscillations during 2020 in the northern hemisphere showed that the ocean absorbed 11.1 GtC during the warm season and outgassed 9.5 GtC during the cold season. Assuming proportionality to world population, the ACC, 414 parts per million (ppm) in 2021, would reach 584 ppm in 2080, still growing at a rate of 0.6% per year. The gain of atmospheric CO<sub>2</sub> (GATM) and its absorption by the ocean (OC) were expected to peak at 7.0 and 2.2 GtC/y, respectively, in 2080. This increase in the availability of atmospheric CO<sub>2</sub> resulted in improved yields of agriculture which more than compensated for the reduction by half of food-producing areas per capita from 1970.展开更多
The preservation and dissolution of calcium carbonate (namely calcium carbonate pump) controls the pH of seawater in global oceans by its buffer effect, and in turn plays a significant role in global changes in atmosp...The preservation and dissolution of calcium carbonate (namely calcium carbonate pump) controls the pH of seawater in global oceans by its buffer effect, and in turn plays a significant role in global changes in atmospheric CO2 concentration. The results from measured carbonate con-tents over the past 2 Ma at ODP Site 1143 in the South China Sea provide high-resolution records to explore the process of the calcium carbonate pump during Quaternary glacial cy-cles. The results indicate statistically that the highest car-bonate accumulation rate leads the lightest d 18O by about 3.6 ka at transitions from glacials to interglacials, and that the strongest carbonate dissolution lags the lightest d 18O by about 5.6 ka at transitions from interglacials to glacials. The calcium carbonate pump releases CO2 to the atmosphere at the glacial-interglacial transitions, but transports atmos-pheric CO2 to deep sea at the interglacial-glacial transitions. The adjustable function of the calcium carbonate pump for the deep-sea 23CO- concentration directly controls parts of global changes in atmospheric CO2, and contributes the global carbon cycle system during the Quaternary.展开更多
文摘A serics of low-latitude marginal seas, ranging from the southern South China Sea in the north to the Arafura Sea in the south, are located within the Western Pacific Warm Pool. As shown by rnicropaleontological, isotopical and organic geochemical analyses, the sea surface temperatures in the marginal seas at the last glacial maximum were much cooler than those in the open Western Pacific Ocean. The emergence of extensive shelves of the marginal seas at the glacial low sea-level stand and the decrease of surface temperatures in their deeper water parts resulted in a remarkable reduction of the ability of vapor and heat transport to the atmosphere, causing variabilities to the Warm Pool in the glacial cycles. The intensification of winter monsoon at the glacial stages not only led to a decrease of the surface water temperature and hence to an enhanced seasonality, but also carried moisture from the sea to the tropical islands, giving rise to the downward shift of snowline and mountainous vegetation zones there. It may offer a new alternative in solution of the “Tropical Ocean Paleo-temperature Enigma”.
文摘Based on the photosynthesis-respiration reversible reaction and the available statistics, we attempted to quantify the planetary seasonal exchanges of CO<sub>2</sub> between air and water from 1970 and compared them to the glacial ACC cycles as reported from ice cores archives. In 2020, the overall continental absorption (AW) was 8.0 giga tonnes of carbon per year (GtC/y). Emissions into the atmosphere (EW) resulting from mineral degradation by respiration and combustion of biomass and fossil hydrocarbons were 14.7 GtC/y, an increase of 2.4% per year since 1970. The continental surplus balance (-AW+EW) of 6.7 GtC/y was shared between the atmosphere, which received 5.1 GtC/y (GATM), and the ocean which absorbed 1.6 GtC/y. This ocean contribution (OC) corresponded to 17% of the 9.2 GtC/y emissions by combustion of fossil hydrocarbons (EFOS). Analysis of the ACC oscillations during 2020 in the northern hemisphere showed that the ocean absorbed 11.1 GtC during the warm season and outgassed 9.5 GtC during the cold season. Assuming proportionality to world population, the ACC, 414 parts per million (ppm) in 2021, would reach 584 ppm in 2080, still growing at a rate of 0.6% per year. The gain of atmospheric CO<sub>2</sub> (GATM) and its absorption by the ocean (OC) were expected to peak at 7.0 and 2.2 GtC/y, respectively, in 2080. This increase in the availability of atmospheric CO<sub>2</sub> resulted in improved yields of agriculture which more than compensated for the reduction by half of food-producing areas per capita from 1970.
基金supported by the National Key Basic Research Development Project of China(Grant No.G2000078505)the National Natural Science Foundation of China(Grant Nos.49999560 and 40102010).
文摘The preservation and dissolution of calcium carbonate (namely calcium carbonate pump) controls the pH of seawater in global oceans by its buffer effect, and in turn plays a significant role in global changes in atmospheric CO2 concentration. The results from measured carbonate con-tents over the past 2 Ma at ODP Site 1143 in the South China Sea provide high-resolution records to explore the process of the calcium carbonate pump during Quaternary glacial cy-cles. The results indicate statistically that the highest car-bonate accumulation rate leads the lightest d 18O by about 3.6 ka at transitions from glacials to interglacials, and that the strongest carbonate dissolution lags the lightest d 18O by about 5.6 ka at transitions from interglacials to glacials. The calcium carbonate pump releases CO2 to the atmosphere at the glacial-interglacial transitions, but transports atmos-pheric CO2 to deep sea at the interglacial-glacial transitions. The adjustable function of the calcium carbonate pump for the deep-sea 23CO- concentration directly controls parts of global changes in atmospheric CO2, and contributes the global carbon cycle system during the Quaternary.
文摘托木尔河源于天山最大现代冰川作用中心托木尔峰西南坡的托木尔冰川,在第四纪冰期与间冰期的气候旋回中,遗留下了5套形态较为完整的冰川沉积.应用ESR测年技术对第一与第二级冰碛阶地(对应于第三套冰碛中地形较完整部分的冰碛,分布在托木尔河大桥与古库瓦河汇合口之间)以及第五套最高冰碛平台进行测年,依据初步的测试结果并结合地貌地层学原理可得出:5套冰碛分别形成于小冰期、新冰期、末次冰期、MIS6和MIS12,每次冰川作用过程中还包含着若干次级的冰川波动.根据现存的冰碛地形可推得:新冰期、末次冰期与MIS6时的冰川为山谷冰川,规模最盛时冰川长分别为47 km、60 km、≥70 km.
