Publications by authors named "Hugues Goosse"
Article Synopsis
- - The South American summer monsoon (SASM) significantly affects the climate in tropical South America, but its variability over long periods has been hard to understand and sometimes shows conflicting results in current climate models and data.
- - A new study utilized a paleoclimate data assimilation method that merged model findings with oxygen isotope data to create a detailed reconstruction of the region's summer hydroclimate over the last millennium, at a resolution of five years.
- - The researchers found that there was a notable intensification of the SASM during the transition from the Medieval Climate Anomaly to the Little Ice Age, linked to shifts in major atmospheric circulation patterns that need to be accurately modeled for future climate predictions.
Earth system models and various climate proxy sources indicate global warming is unprecedented during at least the Common Era. However, tree-ring proxies often estimate temperatures during the Medieval Climate Anomaly (950-1250 CE) that are similar to, or exceed, those recorded for the past century, in contrast to simulation experiments at regional scales. This not only calls into question the reliability of models and proxies but also contributes to uncertainty in future climate projections.
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- This study looked at how oak and beech forests grow in different climate change situations using a special model called HETEROFOR.
- The model was tested with data from many forest areas, showing it can predict how individual trees grow quite well.
- The results indicated that while climate change can help forest growth in some places, like continental and mountainous areas, factors like temperature and rainfall can also hurt growth, but rising CO levels generally help trees grow more.
The latitudinal temperature gradient between the Equator and the poles influences atmospheric stability, the strength of the jet stream and extratropical cyclones. Recent global warming is weakening the annual surface gradient in the Northern Hemisphere by preferentially warming the high latitudes; however, the implications of these changes for mid-latitude climate remain uncertain. Here we show that a weaker latitudinal temperature gradient-that is, warming of the Arctic with respect to the Equator-during the early to middle part of the Holocene coincided with substantial decreases in mid-latitude net precipitation (precipitation minus evapotranspiration, at 30° N to 50° N).
View Article and Find Full Text PDFThe recent thinning and retreat of Antarctic ice shelves has been attributed to both atmosphere and ocean warming. However, the lack of continuous, multi-year direct observations as well as limitations of climate and ice shelf models prevent a precise assessment on how the ocean forcing affects the fluctuations of a grounded and floating ice cap. Here we show that a +0.
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- The concept of feedback is crucial for understanding how changes in a system, like the climate, can be either intensified or reduced by the system's own mechanisms.
- In polar regions, climate is influenced by various interactions among the atmosphere, ocean, sea ice, ice sheets, and land surfaces, which are important for climate assessment.
- Accurately measuring these polar feedbacks is essential for improving climate models, understanding polar climate change processes, and reducing uncertainty in future climate projections.
Several processes have been hypothesized to explain the slight overall expansion of Antarctic sea ice over the satellite observation era, including externally forced changes in local winds or in the Southern Ocean's hydrological cycle, as well as internal climate variability. Here, we show the critical influence of an ocean-sea-ice feedback. Once initiated by an external perturbation, it may be sufficient to sustain the observed sea-ice expansion in the Ross Sea, the region with the largest and most significant expansion.
View Article and Find Full Text PDFWe present a sea-ice record from northern Greenland covering the past 10,000 years. Multiyear sea ice reached a minimum between ~8500 and 6000 years ago, when the limit of year-round sea ice at the coast of Greenland was located ~1000 kilometers to the north of its present position. The subsequent increase in multiyear sea ice culminated during the past 2500 years and is linked to an increase in ice export from the western Arctic and higher variability of ice-drift routes.
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