Past and future sea level change Q1

Question 1

What is sea level rise?

Answer 1

Sea level rise is an increase in the level of the world’s oceans due to the effects of global warming

Question 2

What have trends in sea level rise shown?

Answer 2

IPCC projections of both high and low emissions show that sea levels will continue to increase

Question 3

How can we relate past sea level rise to future sea level rise?

Answer 3

we can use past sea level
variations during times when global temperature was similar to or
warmer than today to create models that can predict future changes in sea level

Question 4

what is The Geological Record?

Answer 4

Records of past sea level change

Question 5

What is the pliocene?

Answer 5

The Pliocene is the epoch in the geologic time scale that extends from 5.333 million to 2.58 million years ago

Question 6

describe sea temperatures during The Middle Pliocene

Answer 6

global mean surface temperatures
were 2°C to 3.5°C warmer than for pre-industrial climate (Church et al, 2013)

Question 7

what is the Marine Isotope Stage 11?

Answer 7

Marine Isotope Stage in the geologic temperature record, covering the interglacial period between 424,000 and 374,000 years ago

Question 8

describe sea temperatures during The Marine Isotope Stage 11

Answer 8

Antarctic ice
core and tropical Pacific paleo temperature estimates suggest that
global temperature was 1.5°C to 2.0°C warmer than pre-industrial (Church et al, 2013)

Question 9

what is the Last Interglacial period?

Answer 9

The Last Interglacial was a period of the Earth’s geological history (between 130 000 and 115 000 years BP)

Question 10

describe sea temperatures during The Last Interglacial period

Answer 10

global mean annual temperature was 1°C to 2oC warmer than pre-industrial
with peak global annual sea surface temperatures that were 0.7°C ± 0.6°C warmer (Church et al, 2013)

Question 11

what is the Holocene?

Answer 11

The Holocene is the current geological epoch. It began approximately 11,650 years Before Present ( c. 9701 BCE)

Question 12

describe sea levels during the Late Holocene

Answer 12

sea level began to rise above the late Holocene background rate
between 1905 and 1945 (Gehrels and Woodworth, 2013)

Question 13

describe an example of a future sea level prediction model

Answer 13

Geodynamic surface-loading models:
simulate the RSL response to past and contemporary changes in surface water and land ice mass redistribution and contemporary atmospheric pressure changes

Question 14

what is rsl?

Answer 14

Relative sea level (RSL) can be defined as the height of the ocean surface relative to the surface of the Earth

Question 15

how do changes in rsl occur?

Answer 15

RSL changes can be driven by processes that produce a change in height of either ocean or Earth surface

Question 16

how is temperature related to sea level rise?

Answer 16

as the oceans warm due to an increasing global temperature, seawater expands—taking up more space in the ocean basin and causing a rise in water level.

Question 17

describe eustasy

Answer 17

refers to changes in ocean mass and is time depen­dent. This can result from either the direct addition or the
removal of water to and from the ocean (e.g., by ice-sheet growth and decay) or volumetric changes (or steric effects)
which result from changes in water density (caused by varia­tions in temperature and salinity) and gravitational change produced by changing ocean–ice mass flux

Question 18

what is isostasy?

Answer 18

movements of land relative to the ocean
and is variable over time and space

Question 19

how does isostasy impact rsl?

Answer 19

The melting of ice on land transfers load to the ocean. This process
deforms ocean basins and their margins and is known as hydro-isostasy
Close to, and beneath, centres of ice loading, the weight of ice presses the solid crust of the Earth down into
the visco-elastic mantle, which subsequently rebounds as the
weight is lifted off commensurate with melting. This is termed ‘glacio-isostasy’

Question 20

what are the limitations of using models based on ice sheet history?

Answer 20

Knowledge of ice sheet history and Earth rheology is imprecise and consequently outputs from various models differ and must be tested and refined by comparing the results with observations (Plater and Kirby, 2011)
many factors involved in sea level rise therefore models based on only one or a few components may not be accurate and therefore reliable to use