O) maxima by 20°to 40°($1300 to 2600 years) at the precession band. The spectral differences in tropical paleoproductivity records from the Pacific and Indian oceans suggest that local processes (wind and circulation patterns driven by insolation) are dominant in driving productivity rather than large-scale tropical features. In the Timor Sea, productivity fluctuations over the last 460 kyr were strongly influenced by monsoonal wind patterns offshore NW Australia (23 and 19 kyr) and were also modulated by sea level-related variations in the intensity of the Indonesian Throughflow (100 kyr).

The evolution of the Australian monsoon in relation to high-latitude temperature fluctuations over the last termination remains highly enigmatic. Here we integrate high-resolution riverine runoff and dust proxy data from X-ray fluorescence scanner measurements in four well-dated sediment cores, forming a NE-SW transect across the Timor Sea. Our records reveal that the development of the Australian monsoon closely followed the deglacial warming history of Antarctica. A minimum in riverine runoff documents dry conditions throughout the region during the Antarctic Cold Reversal (15-12.9 ka). Massive intensification of the monsoon coincided with Southern Hemisphere warming and intensified greenhouse forcing over Australia during the atmospheric CO 2 rise at 12.9-10 ka. We relate the earlier onset of the monsoon in the Timor Strait (13.4 ka) to regional changes in landmass exposure during deglacial sea-level rise. A return to dryer conditions occurred between 8.1 and 7.3 ka following the early Holocene runoff maximum.

Spatiotemporal variations of Chinese Loess Plateau vegetation cover during 1981-2006 have been investigated using GIMMS and SPOT VGT NDVI data and the cause of vegetation cover changes has beenanalyzed, considering the climate changes and human activities. Vegetation cover changes on the Loess Plateau have experienced four stages as follows: (1) vegetation cover showed a continued increasing phase during 1981-1989; (2) vegetation cover changes came into a relative steady phase with small fluctuations during 1990-1998; (3) vegetation cover declined rapidly during 1999-2001; and (4) vegetation cover increased rapidly during 2002-2006. The vegetation cover changes of the Loess Plateau show a notable spatial difference. The vegetation cover has obviously increased in the Inner Mongolia and Ningxia plain along the Yellow River and the ecological rehabilitated region of Ordos Plateau, however the vegetation cover evidently decreased in the hilly and gully areas of Loess Plateau, Liupan Mountains region and the northern hillside of Qinling Mountains. The response of NDVI to climate changes varied with different vegetation types. NDVI of sandy land vegetation, grassland and cultivated land show a significant increasing trend, but forest shows a decreasing trend. The results obtained in this study show that the spatiotemporal variations of vegetation cover are the outcome of climate changes and human activities. Temperature is a control factor of the seasonal change of vegetation growth. The increased temperature makes soil drier and unfavors vegetation growth in summer, but it favors vegetation growth in spring and autumn because of a longer growing period. There is a significant correlation between vegetation cover and precipitation and thus, the change in precipitation is an important factor for vegetation variation. The improved agricultural production has resulted in an increase of NDVI in the farmland, and the implementation of large-scale vegetation construction has led to some beneficial effect in ecology.Loess Plateau, vegetation cover, climate changes, human activities, GIMMS The Chinese Loess Plateau is a famous area of serious water and soil loss and the fragile ecological environment. It is one of the key regions of water and soil conservation of China and the Yellow River sediment originated mainly from here. Vegetation is the connection of soil, atmosphere and water and serves as an indicator in global change research [1] . Vegetation cover represents the overall ecological environment to a large extent and its variation is the direct result of ecological environment change. The study of the spatiotemporal changes in vegetation cover of Loess Plateau is an important basis for further understanding the interactions among territorial ecosystems and the climatic systems

[1] Carbon isotope sequences at Ocean Drilling Program Site 1143, South China Sea, reveal a long-term cyclicity of $500 kyr that is superimposed on the glacial cycles and is present in long Cmax-III, which in turn were associated with expansion of the ice sheets. From a carbon perspective, therefore, the Quaternary period has passed through three major stages, and each appears to represent a further step in ice cap development.

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Abstract:Analysis of the sedimentary record has been used to determine the historical sedimentation rate in the lower Yellow River and the historical literature has been studied to obtain information on climate change and human activities. Based on the data obtained, the temporal variation in the sedimentation rate in the lower Yellow River over the past 2300 years has been studied in relation to climate change and the impact of human activities. The results indicate that the response of the sedimentation zone of Yellow River system to changes in the erosion zone are consistent with existing understanding. Changes in vegetation and land use, both related to climate change and human activities, are two major controls responsible for the increase in sedimentation rates. Additionally, the changing strategies for harnessing of the lower Yellow River are also responsible for such acceleration. With the trend of accelerated sedimentation in the past 2300 years, the period from the 7th to 10th centuries and the period since the mid-19th century have been identified as two periods in which abrupt changes occurred.

The beginning of the mid-Brunhes event ca. 430 ka coincided with the largest-amplitude change in ␦ 18 O in the global ocean over the past 6 m.y. This large ␦ 18 O change recorded a major ice-sheet expansion that cannot be explained by small changes in orbital forcing. Our recent studies at Ocean Drilling Program Site 1143 from the South China Sea show that this large ␦ 18 O change was preceded by a significant negative ␦ 13 C shift. A global survey of long deep-sea records has revealed periodic ␦ 13 C max episodes (i.e., maximum positive values of ␦ 13 C), and both major ice-sheet expansion events in the Pleistocene (the mid-Brunhes event and the middle Pleistocene revolution) were preceded by ␦ 13 C max episodes followed by negative ␦ 13 C shifts. This new finding suggests that disturbance in carbon reservoirs leads to major growth of ice-sheet size and challenges the prevalent concept of Arctic control of glacial cycles. Because Earth is now passing again through a ␦ 13 C max episode, it is crucial to understand the causal relationship between the successive ␦ 13 C changes and ice-sheet growth events.

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