scholarly journals What causes the spread of model projections of ocean dynamic sea-level change in response to greenhouse gas forcing?

2020 ◽  
Author(s):  
Matthew P. Couldrey ◽  
Jonathan M. Gregory ◽  
Fabio Boeira Dias ◽  
Peter Dobrohotoff ◽  
Catia M. Domingues ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gas ◽  
Sea Level ◽  
North Atlantic ◽  
Ocean Dynamics ◽  
The Arctic ◽  
Large Temperature ◽  
Flux Change ◽  
Heat Uptake ◽  
Dynamic Sea Level

Abstract Sea levels of different atmosphere–ocean general circulation models (AOGCMs) respond to climate change forcing in different ways, representing a crucial uncertainty in climate change research. We isolate the role of the ocean dynamics in setting the spatial pattern of dynamic sea-level (ζ) change by forcing several AOGCMs with prescribed identical heat, momentum (wind) and freshwater flux perturbations. This method produces a ζ projection spread comparable in magnitude to the spread that results from greenhouse gas forcing, indicating that the differences in ocean model formulation are the cause, rather than diversity in surface flux change. The heat flux change drives most of the global pattern of ζ change, while the momentum and water flux changes cause locally confined features. North Atlantic heat uptake causes large temperature and salinity driven density changes, altering local ocean transport and ζ. The spread between AOGCMs here is caused largely by differences in their regional transport adjustment, which redistributes heat that was already in the ocean prior to perturbation. The geographic details of the ζ change in the North Atlantic are diverse across models, but the underlying dynamic change is similar. In contrast, the heat absorbed by the Southern Ocean does not strongly alter the vertically coherent circulation. The Arctic ζ change is dissimilar across models, owing to differences in passive heat uptake and circulation change. Only the Arctic is strongly affected by nonlinear interactions between the three air-sea flux changes, and these are model specific.

scholarly journals Regional Dynamic and Steric Sea Level Change in Response to the IPCC-A1B Scenario

2007 ◽  
Vol 37 (2) ◽  
pp. 296-312 ◽  
Author(s):  
Felix W. Landerer ◽  
Johann H. Jungclaus ◽  
Jochem Marotzke
Keyword(s):  
Climate Change ◽  
Southern Ocean ◽  
Sea Level ◽  
North Atlantic ◽  
Climate Change Scenario ◽  
The Arctic ◽  
Change Scenario ◽  
Sea Level Changes ◽  
The North ◽  
The North Atlantic

Abstract This paper analyzes regional sea level changes in a climate change simulation using the Max Planck Institute for Meteorology (MPI) coupled atmosphere–ocean general circulation model ECHAM5/MPI-OM. The climate change scenario builds on observed atmospheric greenhouse gas (GHG) concentrations from 1860 to 2000, followed by the International Panel on Climate Change (IPCC) A1B climate change scenario until 2100; from 2100 to 2199, GHG concentrations are fixed at the 2100 level. As compared with the unperturbed control climate, global sea level rises 0.26 m by 2100, and 0.56 m by 2199 through steric expansion; eustatic changes are not included in this simulation. The model’s sea level evolves substantially differently among ocean basins. Sea level rise is strongest in the Arctic Ocean, from enhanced freshwater input from precipitation and continental runoff, and weakest in the Southern Ocean, because of compensation of steric changes through dynamic sea surface height (SSH) adjustments. In the North Atlantic Ocean (NA), a complex tripole SSH pattern across the subtropical to subpolar gyre front evolves, which is consistent with a northward shift of the NA current. On interannual to decadal time scales, the SSH difference between Bermuda and the Labrador Sea correlates highly with the combined baroclinic gyre transport in the NA but only weakly with the meridional overturning circulation (MOC) and, thus, does not allow for estimates of the MOC on these time scales. Bottom pressure increases over shelf areas by up to 0.45 m (water column equivalent) and decreases over the Atlantic section in the Southern Ocean by up to 0.20 m. The separate evaluation of thermosteric and halosteric sea level changes shows that thermosteric anomalies are positive over most of the World Ocean. Because of increased atmospheric moisture transport from low to high latitudes, halosteric anomalies are negative in the subtropical NA and partly compensate thermosteric anomalies, but are positive in the Arctic Ocean and add to thermosteric anomalies. The vertical distribution of thermosteric and halosteric anomalies is highly nonuniform among ocean basins, reaching deeper than 3000 m in the Southern Ocean, down to 2200 m in the North Atlantic, and only to depths of 500 m in the Pacific Ocean by the end of the twenty-first century.

Climate Variability in the Context of Climate Change: El Niño and Other Oscillations

2008 ◽  
Author(s):  
Cynthia Rosenzweig ◽  
Daniel Hillel
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
North Atlantic ◽  
El Niño ◽  
El Nino ◽  
Global Climate ◽  
Climate System ◽  
The Arctic ◽  
The Pacific ◽  
Earth’S Climate

The climate system envelops our planet, with swirling fluxes of mass, momentum, and energy through air, water, and land. Its processes are partly regular and partly chaotic. The regularity of diurnal and seasonal fluctuations in these processes is well understood. Recently, there has been significant progress in understanding some of the mechanisms that induce deviations from that regularity in many parts of the globe. These mechanisms include a set of combined oceanic–atmospheric phenomena with quasi-regular manifestations. The largest of these is centered in the Pacific Ocean and is known as the El Niño–Southern Oscillation. The term “oscillation” refers to a shifting pattern of atmospheric pressure gradients that has distinct manifestations in its alternating phases. In the Arctic and North Atlantic regions, the occurrence of somewhat analogous but less regular interactions known as the Arctic Oscillation and its offshoot, the North Atlantic Oscillation, are also being studied. These and other major oscillations influence climate patterns in many parts of the globe. Examples of other large-scale interactive ocean–atmosphere– land processes are the Pacific Decadal Oscillation, the Madden-Julian Oscillation, the Pacific/North American pattern, the Tropical Atlantic Variability, the West Pacific pattern, the Quasi-Biennial Oscillation, and the Indian Ocean Dipole. In this chapter we review the earth’s climate system in general, define climate variability, and describe the processes related to ENSO and the other major systems and their interactions. We then consider the possible connections of the major climate variability systems to anthropogenic global climate change. The climate system consists of a series of fluxes and transformations of energy (radiation, sensible and latent heat, and momentum), as well as transports and changes in the state of matter (air, water, solid matter, and biota) as conveyed and influenced by the atmosphere, the ocean, and the land masses. Acting like a giant engine, this dynamic system is driven by the infusion, transformation, and redistribution of energy.

scholarly journals The EU and its Arctic spirit: Solving Arctic climate change from home?

European View ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 156-162
Author(s):  
Romain Chuffart ◽  
Andreas Raspotnik
Keyword(s):  
Climate Change ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Global Climate Change ◽  
Global Climate ◽  
Arctic Climate ◽  
The Arctic ◽  
Arctic Climate Change ◽  
Global Heating ◽  
The Eu

Dealing with climate change and developing the Arctic sustainably are often seen as both binary and contradictory sets of challenges. The EU is in a unique position in Arctic affairs: unlike non-Arctic states, it is part of and linked to the region. However, the EU is at risk of missing the opportunity to be a leader in setting standards for a coherent and sustainable approach for the region. The Arctic is often used as a symbol for global climate change and, conversely, climate change is also used as a reason for more Arctic engagement. Yet, the roots of global heating—greenhouse gas emissions—mostly originate from outside the region. This article asks whether the path towards more EU–Arctic involvement should start closer to home.

Rising Seas and Retreating Coasts: Implications for the Arctic

2020 ◽  
Vol 35 (3) ◽  
pp. 468-497
Author(s):  
Clive Schofield ◽  
Suzanne Lalonde
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Coastal Erosion ◽  
Legal Issues ◽  
The Arctic ◽  
Future Challenge ◽  
Legal Regime ◽  
Legal Responses ◽  
Key Aspects ◽  
Impacts Of Climate Change

Abstract This article addresses both the physical impacts and international legal issues arising from two interlinked stressors on Arctic coastlines: sea level rise and coastal erosion. Key aspects of the legal regime governing the baselines from which coastal States calculate the outer limits of their maritime zones are reviewed and a synopsis of the practice among the Arctic littoral States is provided. The article then turns to a discussion of the practical and international legal responses available to deal with the present and future challenge of rising seas and retreating coasts. The concluding section offers with some reflections on the way forward for a region experiencing some of the most devastating impacts of climate change.

scholarly journals Are the Transient and Equilibrium Climate Change Patterns Similar in Response to Increased CO2?

2020 ◽  
Vol 33 (18) ◽  
pp. 8003-8023
Author(s):  
Danqing Huang ◽  
Aiguo Dai ◽  
Jian Zhu
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Climate Models ◽  
Surface Air Temperature ◽  
The Arctic ◽  
The North ◽  
Temperature And Precipitation ◽  
Time Periods ◽  
The North Atlantic ◽  
Subtropical Oceans

AbstractAfter a CO2 increase, whether the early transient and final equilibrium climate change patterns are similar has major implications. Here, we analyze long-term simulations from multiple climate models under increased CO2, together with the extended simulations from CMIP5, to compare the transient and equilibrium climate change patterns under different forcing scenarios. Results show that the normalized warming patterns (per 1 K of global warming) are broadly similar among different forcing scenarios (including abrupt 2 × CO2, 4 × CO2, and 1% CO2 increase per year) and during different time periods, except for the first 50 years or so when warming is weaker over the North Atlantic and Southern Ocean but stronger over most continents. During the first 200 years, this consistency is stronger over land than over ocean, but is lower in midlatitudes than other regions. Normalized precipitation change patterns are also similar, albeit to a lesser degree, among different forcing scenarios and across different time periods, although noticeable differences exist during the first few hundred years with smaller increases over the tropical Pacific. Precipitation over many subtropical oceans and land areas decreases consistently under different forcing scenarios and over all time periods. In particular, the transient and near-equilibrium change patterns for both surface air temperature and precipitation are similar over most of the globe, except for the North Atlantic warming hole, which is mainly a transient feature. The Arctic amplification and land–ocean warming contrast are largest during the first 100–200 years after CO2 quadrupling but they still exist in the equilibrium response.

scholarly journals A Review of Ocean Dynamics in the North Atlantic: Achievements and Challenges

Climate ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 49
Author(s):  
Knut Lehre Seip
Keyword(s):  
Climate Change ◽  
Temperature Change ◽  
North Atlantic ◽  
Ocean Dynamics ◽  
Local Climate ◽  
The North ◽  
Local Climate Change ◽  
Global Temperature Change ◽  
The North Atlantic ◽  
Over Time

I address 12 issues related to the study of ocean dynamics and its impact on global temperature change, regional and local climate change, and on the North Atlantic ecosystem. I outline the present achievements and challenges that lie ahead. I start with observations and methods to extend the observations of ocean oscillations over time and end with challenges to find connections between ocean dynamics in the North Atlantic and dynamics in other parts of the globe.

scholarly journals Simulation of the Arctic—North Atlantic Ocean Circulation with a Two-Equation K-Omega Turbulence Parameterization

2018 ◽  
Vol 6 (3) ◽  
pp. 95 ◽  
Author(s):  
Sergey Moshonkin ◽  
Vladimir Zalesny ◽  
Anatoly Gusev
Keyword(s):  
Prandtl Number ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
Mixed Layer Depth ◽  
Ocean Dynamics ◽  
Dynamics Simulation ◽  
The Arctic ◽  
Buoyancy Frequency ◽  
Physical Factors

The results of large-scale ocean dynamics simulation taking into account the parameterization of vertical turbulent exchange are considered. Numerical experiments were carried out using k − ω turbulence model embedded to the Institute of Numerical Mathematics Ocean general circulation Model (INMOM). Both the circulation and turbulence models are solved using the splitting method with respect to physical processes. We split k − ω equations into the two stages describing transport-diffusion and generation-dissipation processes. At the generation-dissipation stage, the equation for ω does not depend on k. It allows us to solve both turbulence equations analytically that ensure high computational efficiency. The coupled model is used to simulate the hydrophysical fields of the North Atlantic and Arctic Oceans for 1948–2009. The model has a horizontal resolution of 0.25 ∘ and 40 σ -levels along the vertical. The numerical results show the model’s satisfactory performance in simulating large-scale ocean circulation and upper layer dynamics. The sensitivity of the solution to the change in the coefficients entering into the analytical solution of the k − ω model which describe the influence of some physical factors is studied. These factors are the climatic annual mean buoyancy frequency (AMBF) and Prandtl number as a function of the Richardson number. The experiments demonstrate that taking into account the AMBF improves the reproduction of large-scale ocean characteristics. Prandtl number variations improve the upper mixed layer depth simulation.

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