No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Thermal Expansion
... Many of these effects already are being felt (Soja et al. 2007;Rowe et al. 2015;Trenberth et al. 2015). Temperatures are already rising, leading to the melting of polar ice caps and expanding water volume in the oceans (Gornitz et al. 1982;Mörner 2017;van den Broeke et al. 2016). These conditions put coastal areas at increased risk with entire ecosystems predicted to be lost or redistributed due to sea-level rise (Nicholls and Cazenave 2010). ...
Climate change will alter natural areas on a global scale within the next century. In areas vulnerable to climate change, scientists are regularly challenged to justify the resources needed for research and conservation. We face what may seem like a losing battle, especially in low-lying coastal areas where sea-level rise is predicted to severely degrade or destroy many ecosystems. Using sea-level rise in the low-elevation state of Florida, USA, as a case study, we argue that it is critical to remain engaged in the research, restoration, and conservation of natural areas threatened by climate change for as long as possible. These areas will continue to provide invaluable ecological and societal benefits. Additionally, uncertainty surrounding climate change forecasts and their ecological impact leaves room for optimism, research, and actions that are necessary for developing adaptation plans and mitigating further sea-level rise and other consequences of climate change. We urge scientists and particularly students beginning their careers not to forego research and conservation efforts of these imperiled lands but to face this unprecedented challenge with determination, creativity, and solution-based strategies.
The history and development of our understanding of sea level changes is reviewed. Sea level research is multi-fascetted and calls for integrated studies of a large number of parameters. Well established records indicate a post-LIA (1850-1950) sea level rise of 11 cm. During the same period of time, the Earth's rate of rotation experienced a slowing down (deceleration) equivalent to a sea level rise of about 10 cm. Sea level changes during the last 40-50 years are subjected to major controversies. The methodology applied and the views claimed by the IPCC are challenged. For the last 40-50 years strong observational facts indicate virtually stable sea level conditions. The Earth's rate of rotation records a mean acceleration from 1972 to 2012, contradicting all claims of a rapid global sea level rise, and instead suggests stable, to slightly falling, sea levels. Best estimates for future sea level changes up to the year 2100 are in the range of +5 cm ±15 cm.
Many variables control the changes in ocean level. The most significant parameters to drive a possible sea level rise today are the redistribution of water to the oceans by glacial melting (a process known as glacial eustasy) and the expansion of the water column by heating up the water (a process known as steric expansion). Both these parameters can be quantified as to maximum rates and amplitudes. Those values may even be used to define the frames, inside which one has values of possible changes and outside which one has values that are not anchored in physics of sea level variability. Additionally, the rate of postglacial melting of the big continental ice caps in mid-latitude position provides an excellent maximum value for all talk of what will happen in the next 100 years. This value provides with a tool of discriminating between realistic proposals and unrealistic claims that should be discarded or, at least, be taken with great care.
Sea-level change as recorded by tide gauges exhibits a complex spatial and temporal variability for a number of reasons, including tectonic movemenrs of changes in ocean volume and the adjusunent of the crust to major Late Pleistocene deglaciation, and to recent mountain glacier melting. Tide gaude records have been analysed by least sguares regression for secular trends and mean regional trends have been estimated for 10o x 10" areas. These have been expanded into a surface spherical harmonic series, yielding the global long wavelength pattern of sea-level change. The low degree rerms in this expansion represent a combination of tectonic change and local or regionai changes in sea-level. The eustatic rise, reflecting a change in water volume and corresponding to the zero degree harmonic, is estimated as 1.15 + 0.38 mm/year. The first degree terms in the expansion are negligibly small, indicating that there is no significant shifr in the cenue of mass of the ocean relative to the solid Earth. Of the second degree terms only the zonal coefficient is significant with an equatorial sealevel rise and a polar sea-level drop. The contributions from recent changes in mountain glacier volumes and postglacial rebound to the spatial variability are significant bur not for the very low degree terms. The separation of these contributions from the observed change yields a globally averaged secular steric change of about 0.5 mm/year but the uncertainties a¡e large. The mainly zonal geomery of the steric change implies greater thermal expansion effects in low latitudes than in high latitudes.
Postglacial transgressive maxima and second-order transgression of the southwest Pacific Ocean (ed) Earth rheology, isostasy and eustasy
- J Schofield
Secular sea-level changes (eds) Glacial isostasy, sea-level and mantle rheology
- Sm Nakibogul
- K Lambeck