Most projections of greenhouse gas-induced climate change indicate a weakening of the thermohaline circulation (THC) in the North Atlantic in response to increased freshening and warming in the subpolar region. These changes reduce high latitude upper ocean density, and therefore weaken the THC. Using ensembles of numerical experiments with a coupled ocean-atmosphere model, it is found that thi...

The authors examine the key characteristics of the boreal winter extratropical circulation changes in response to anthropogenic aerosols, simulated with a coupled atmosphere–slab ocean general circulation model. The zonal-mean response features a pronounced equatorward shift of the Northern Hemisphere subtropical jet owing to the midlatitude aerosol cooling. The circulation changes also show st...

A simple model is developed of the lower limb of the meridional overturning circulation in the Southern Ocean based on residual-mean theory. It is hypothesized that the strength of the lower-limb overturning ( ) is strongly controlled by the magnitude of abyssal diapycnal mixing ( ) and that of mesoscale eddy transfer (K ). In particular, it is argued that K. The scaling and associated theory f...

8 Abstract One-third of the world’s coral reefs have dis9 appeared over the last 30 years, and a further third is under 10 threat today from various stress factors. The main global 11 stress factors on coral reefs have been identified as changes 12 in sea surface temperature (SST) and changes in surface 13 seawater aragonite saturation (Xarag). Here, we use a cli14 mate model of intermediate co...

A band of enhanced thermocline variability at 108–158N in the Pacific found in nature also occurs in an ocean general circulation model forced with observed fluxes of momentum, heat, and freshwater over the period 1958– 97. The variability in the model is primarily associated with long baroclinic Rossby waves characterized by periods in the decadal range (7–10 yr). The waves are forced by westw...

We have generated a high-resolution coral D14C record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950–1956) D14C values average -52‰. Values begin to increase in 1957, reaching a maximum in the early 1970s, about 10 yr after the atmospheric peak. There is a consistent 10-15‰ seasonal cycle whose relationship with vertical mixing evolves as a consequence of the pene...

The thermohaline hysteresis response to varying North Atlantic freshwater forcing is studied by means of a three-dimensional global ocean general circulation model (OGCM). The influence of vertical diffusivity is examined using a wide range of mixing coefficients. For sufficiently large vertical diffusivity the model shows a pronounced hysteresis behavior, so that two equilibrium states of the ...