Impacts of global climate change on terrestrial ecosystems are imperfectly constrained by ecosystem models and direct observations. Pervasive ecosystem transformations occurred in response to warming and associated climatic changes during the last glacial-to-interglacial transition, which was comparable in magnitude to warming projected for the next century under high-emission scenarios. We reviewed 594 published paleoecological records to examine compositional and structural changes in terrestrial vegetation since the last glacial period and to project the magnitudes of ecosystem transformations under alternative future emission scenarios. Our results indicate that terrestrial ecosystems are highly sensitive to temperature change and suggest that, without major reductions in greenhouse gas emissions to the atmosphere, terrestrial ecosystems worldwide are at risk of major transformation, with accompanying disruption of ecosystem services and impacts on biodiversity.

Modern typhoon data and historical documents from Guangdong Province, southern China, are analyzed and found to support the El Niño-Southern Oscillation (ENSO)-typhoon hypothesis. The hypothesis states that tropical cyclone formation during an El Niño event shifts eastward, with typhoons tending to recurve north, staying away from China. From the comprehensive but short modern record, typhoon tracks are grouped into 3 distinct clusters based on geographic position at maximum and terminal typhoon intensities. The majority of typhoons originate between 110 and 170°E longitude in the latitude belt between 8 and 25°N. In general, typhoons take 1 of 3 paths away from this genesis region -a westerly path between latitudes (straight moving), a west-northwesterly path (recurving), or a north-oriented path that keeps them out to sea. Straight-moving typhoons are a significant threat to the Philippines, southern China, and Vietnam, whereas recurving typhoons occasionally threaten Japan, Korea, and northern China. The number of straight-moving typhoons, when grouped by year, is found to be significantly positively correlated with the number of landfalls over China south of the Tropic of Cancer. Thus, the abundance of straight-moving typhoons is a good indicator of the typhoon threat to portions of southern China. Moreover, the number of straightmoving typhoons is correlated with the ENSO cycle. A long annual time-series (1600-1909) of typhoon landfall counts from Guangdong, extracted from historical documents together with treering proxy records of the ENSO cycle, provide data that independently support this relationship. KEY WORDS: Typhoons · Typhoon tracks · ENSO · Guangdong · Southern China · Cluster analysisResale or republication not permitted without written consent of the publisher

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We present a record of monsoon variations for the early and middle Holocene that is inferred from the geochemistry of sediment cores from Ahung Co, a lake in central Tibet. The resolution of this record is better than 50 yr and the age model is derived from radiocarbon ages of terrestrial charcoal, which eliminates errors associated with the lake hard-water effect. We made down-core geochemical measurements of % carbonate, % organic carbon, C/N and d 13 C of bulk organic matter, d 13 C and d 18O of carbonate, and % dolomite. Proxy calibration and modern water-balance reconstruction show that these are proxies for lake depth and the amount of monsoon precipitation. We find that lake level and monsoon precipitation have been decreasing at Ahung Co since the early Holocene (¨7500 cal yr B.P.). Superimposed on this trend are rapid declines in monsoon rainfall at 7000 -7500 and 4700 cal yr B.P. and seven century-scale wet -dry oscillations. The cores do not contain sediment from the last¨4000 yr. Surface sediments from the lake accumulated during the 20th century, however. From this, we argue that lake levels have risen again recently following a late Holocene dry period.

Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia.