Author: W.M. WASHINGTONPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
High-latitude climate change in a global coupled ocean-atmosphere-sea ice model with increased atmospheric CO2
Author: W.M. WASHINGTONScientific Assessment of Climate Change
Author: Intergovernmental Panel on Climate ChangePublisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 388
Book Description
Linkages Between Arctic Warming and Mid-Latitude Weather Patterns
Author: National Research CouncilPublisher: National Academies Press
ISBN: 0309301912
Category : Science
Languages : en
Pages : 98
Book Description
The Arctic has been undergoing significant changes in recent years. Average temperatures are rising twice as fast as they are elsewhere in the world. The extent and thickness of sea ice is rapidly declining. Such changes may have an impact on atmospheric conditions outside the region. Several hypotheses for how Arctic warming may be influencing mid-latitude weather patterns have been proposed recently. For example, Arctic warming could lead to a weakened jet stream resulting in more persistent weather patterns in the mid-latitudes. Or Arctic sea ice loss could lead to an increase of snow on high-latitude land, which in turn impacts the jet stream resulting in cold Eurasian and North American winters. These and other potential connections between a warming Arctic and mid-latitude weather are the subject of active research. Linkages Between Arctic Warming and Mid-Latitude Weather Patterns is the summary of a workshop convened in September 2013 by the National Research Council to review our current understanding and to discuss research needed to better understand proposed linkages. A diverse array of experts examined linkages between a warming Arctic and mid-latitude weather patterns. The workshop included presentations from leading researchers representing a range of views on this topic. The workshop was organized to allow participants to take a global perspective and consider the influence of the Arctic in the context of forcing from other components of the climate system, such as changes in the tropics, ocean circulation, and mid-latitude sea surface temperature. This report discusses our current understanding of the mechanisms that link declines in Arctic sea ice cover, loss of high-latitude snow cover, changes in Arctic-region energy fluxes, atmospheric circulation patterns, and the occurrence of extreme weather events; possible implications of more severe loss of summer Arctic sea ice upon weather patterns at lower latitudes; major gaps in our understanding, and observational and/or modeling efforts that are needed to fill those gaps; and current opportunities and limitations for using Arctic sea ice predictions to assess the risk of temperature/precipitation anomalies and extreme weather events over northern continents.
Impact of Atmospheric CO2 and Atlantic-Arctic Gateway Evolution on Miocene Climate and Ocean Circulation Changes
Author: Akil HossainPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The Miocene (23.03-5.33 Ma) was a time period with a warmer climate than today. During this period, changes in ocean gateways and atmospheric CO2 levels largely control ocean circulation and climate changes. However, the underlying ocean processes and dynamics are poorly understood and it remains a challenge to simulate Miocene climate key characteristics such as pronounced polar warming and a reduced meridional temperature gradient. By applying state-of-the-art fully coupled atmosphere-ocean-sea-ice model approaches Miocene climate conditions at different atmospheric CO2 concentrations are simulated and thermohaline changes in response to the subsidence of Atlantic-Arctic gateways for various Greenland-Scotland Ridge (GSR) and Fram Strait (FS) configurations are investigated. For a singular subsidence of the GSR, warming and a salinity increase in the Nordic Seas and the Arctic Ocean is detected. As convection sites shift to the north of Iceland, North Atlantic Deep Water (NADW) is formed at cooler temperatures. The associated deep ocean cooling and upwelling of deep waters to the Southern Ocean surface can cause a cooling in the southern high latitudes. These characteristic responses to the GSR deepening are independent of the FS being shallow or deep. An isolated subsidence or widening of the FS gateway for a deep GSR shows less pronounced warming and salinity increase in the Nordic Seas. Arctic temperatures remain unaltered, but a stronger salinity increase is detected, which further increases the density of NADW. The increase in salinity enhances the contribution of NADW to the abyssal ocean at the expense of the colder southern source water component. These relative changes cause a negligible warming in the upwelling regions of the Southern Ocean. For a sill depth of ~1500 m, ventilation of the Arctic Ocean is achieved due to enhanced import of saline Atlantic water through a FS width of ~105 km. Moreover, at this width and depth, a modern-like three-layer stratification in the Arctic Ocean is detected. The exchange flow through FS is characterized by vertical separation of a low salinity cold outflow from the Arctic Ocean confined to a thin upper layer, an intermediate saline inflow from the Atlantic Ocean below and a cold bottom Arctic outflow. These characteristics are comparable to the present-day hydrography, in spite of significantly shallower and narrower FS configurations during the early Miocene, suggesting that the ventilation mechanisms and stratification in the Arctic Ocean have been similar. In simulations with different CO2 levels (280, 450 and 720 ppm) surface temperatures show the best fit to proxy reconstructions for atmospheric CO2 concentrations of 720 ppm, since in particular the high latitude cooling bias becomes least pronounced. For a CO2 increase from 280 to 450 ppm polar amplification is simulated in the northern high latitudes, which is stronger than for the same radiative CO2 forcing from 450 to 720 ppm. At higher CO2 levels the Miocene climate also shows a reduced climate sensitivity, since the warmest Miocene climate scenario with a CO2 level of 720 ppm is characterized by a seasonality breakdown in the Arctic Ocean. A pronounced warming in boreal winter is detected for a CO2 increase from 450 to 720 ppm, in contrast to a moderate boreal summer temperature increase. This change in the seasonal temperature signature is accompanied by a strong sea-ice concentration decline and enhanced moisture availability promotes cloud formation in the summer months. As a consequence the planetary albedo increases and dampens the temperature response to the CO2 forcing at a warmer Miocene background climate.
The Regional Impacts of Climate Change
Author: Intergovernmental Panel on Climate Change. Working Group II.Publisher: Cambridge University Press
ISBN: 9780521634557
Category : Science
Languages : en
Pages : 532
Book Description
Cambridge, UK : Cambridge University Press, 1998.
Antarctic Sea Ice Variability in the Southern Ocean-Climate System
Author: National Academies of Sciences, Engineering, and MedicinePublisher: National Academies Press
ISBN: 0309456002
Category : Science
Languages : en
Pages : 83
Book Description
The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970s, when satellite-based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region. Indeed, climate models, which incorporate our best understanding of the processes affecting the region, generally simulate a decrease in sea ice. Moreover, sea ice in the Arctic has exhibited pronounced declines over the same period, consistent with global climate model simulations. For these reasons, the behavior of Antarctic sea ice has presented a conundrum for global climate change science. The National Academies of Sciences, Engineering, and Medicine held a workshop in January 2016, to bring together scientists with different sets of expertise and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice variability and to discuss ways to advance understanding of Antarctic sea ice and its relationship to the broader ocean-climate system. This publication summarizes the presentations and discussions from the workshop.
Arctic amplification: Feedback process interactions and contributions
Author: Patrick Charles TaylorPublisher: Frontiers Media SA
ISBN: 2832517536
Category : Science
Languages : en
Pages : 177
Book Description
Global Climate Change
Author: The Global Cryosphere
Author: Roger G. BarryPublisher: Cambridge University Press
ISBN: 1108806708
Category : Science
Languages : en
Pages : 624
Book Description
Recent studies indicate that - due to climate change - the Earth is undergoing rapid changes in all cryospheric components, including polar sea ice shrinkage, mountain glacier recession, thawing permafrost, and diminishing snow cover. This book provides a comprehensive summary of all components of the Earth's cryosphere, reviewing their history, physical and chemical characteristics, geographical distributions, and projected future states. This new edition has been completely updated throughout, and provides state-of-the-art data from GlobSnow-2 CRYOSAT, ICESAT, and GRACE. It includes a comprehensive summary of cryospheric changes in land ice, permafrost, freshwater ice, sea ice, and ice sheets. It discusses the models developed to understand cryosphere processes and predict future changes, including those based on remote sensing, field campaigns, and long-term ground observations. Boasting an extensive bibliography, over 120 figures, and end-of-chapter review questions, it is an ideal resource for students and researchers of the cryosphere.
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