Sea-Level changes.

Slides:



Advertisements
Similar presentations
In the Beginning… Ice Age: period of time when freezing temperatures created ice sheets across continents. Glaciers covered most of.
Advertisements

Paleoclimate indicators. Rock types as indicators of climate.
1 Sea-Level changes. What causes the sea level to change over time? Questions:
GEOS 112 Lecture Topics 4/28/03 Read Chapter 12 (Glaciers) Final Exam – Monday, May 5 1:00pm 1.Types of Glaciers; 2.Glacier Formation, Mass Balance, and.
Explore p  4. At a rate of 2 cm/second how long did it take your plate to move across your work table?  About 75 seconds, or 1 minute 15.
News stories often link climate change to rising sea levels. Throughout Earth’s history sea level has constantly changed and, indeed, it is these very.
Mr. Burton 2.3 Notes Please Grab: 1. Your folder. 2. Writing Utensil. 3. Answer the following question: How does the surface of the earth move?
The Last Glacial Maximum (LGM)
Climate and Climate Change 17 January How and Why Does Climate Change? Climate changes over a broad range of time scales – Years, decades, centuries,
Paleo-precipitation and water isotopes10/14/10 Archives of interest : 1)ice cores 2)deep-sea sediments 3)lake sediments 4)corals 5)speleothems 6)groundwaters.
Fossils, Paleoclimate and Global Climate Change. Global Warming CO 2 levels in the atmosphere rising Average global temperature is rising Polar ice caps.
Exploring the inner and outer shells of earth. Earth consists of a series of concentric layers or spheres which differ in chemistry and physical properties.
Reading Material See class website “Sediments”, from “Oceanography” M.G. Gross, Prentice-Hall.
Glacial Rebound Glacial Rebound Studies depend on many factors. What are they ? Ice load History of the load Ocean water load on coastlines and globally.
Topic: The Sea Also Rises Changes in Sea Level Broadcast 6: February 21, 2001 Mrs. Joan Linsley.
What Controls Ice Sheet Growth?
Geographic Datums Y X Z The National Imagery and Mapping Agency (NIMA) and the Defense Mapping School Reviewed by:____________ Date:_________ Objective:
1 Global Climate: Estimating How Much Sea Level Changes when Continental Ice Sheets Form Over the last few million years, Earth has experienced numerous.
Floodplain Management SESSION 2
Composite of Sea Level – for last 600 k years. Note that SL was not always extremely low during glacial periods. From Rabineau et al, EPSL, 2006.
1 Sea-Level changes. 2 Learning Objectives The shape of the planet: difference between Geoid and Ellipsoid The concept of Mean Sea Level Article:
The Last Glacial Maximum (LGM) Lesson 1 Starter Slides on the nature and timing of the LGM.
Reading Material See class website “Sediments”, from “Oceanography” M.G. Gross, Prentice-Hall.
Sea Level Rise – A Global Problem in Your Backyard ESI.
Formation  Snow accumulation  More winter snowfall than summer melt  Glacier formation is similar to sedimentary rock formation.
Topic 2: Frozen Water Grade 8 Science. Distribution of water on earth Groundwater = 0.63% Rivers/Lakes/Ponds = 0.02% Glaciers/Ice sheets = 2.15% Oceans.
Greenhouse Earth: 100 Ma GEOL Paleoclimate Research Two components –Observations i.e. fossils, sediments, chemical proxies –Modeling using observations.
What Controls the Size of Ice Sheets?
Proxy Records Ice Cores Dendrochronology Sediment records
Multi-year time scale variations El Nino and La Nina are important phenomena Occur every ~2 to 7 years when typical ocean-atmosphere circulation breaks.
OC 450: Orbital Controls on Climate (Chaps 8 and 10) Main Points: Small cyclic variations in the earth’s orbital characteristics affect the distribution.
The Cretaceous Hot House – a Greenhouse Gas-Rich World First, the break-up of Pangea; the most recent MegaContinent.
Sea Level Change Concept Maps. Overview Overarching Concept: Changes in sea level have occurred in the past, are occurring now, and will continue to occur.
Geology Unit: Sea level history
Glacial Processes and Landforms What is a glacier? How do glaciers form?
Plate Tectonic and Ocean Bathymetry. Effects of Volcanic eruptions on the solar incoming radiation Agung 1963 Pinatubo 1991 Chichón 1982 Pinatubo.
Characterizing and understanding the Quaternary Glacial/Interglacial cycles Earth’s Climate and Environment: Past, Present, and Future GEOL 3100.
EARTH Third Rock From The Sun.
Greenhouse Climate September 11, Earth 100 Mya -Global sea level 100m higher than today -No permanent ice -Middle Cretaceous -Dinosaurs, turtles,
Long-Term Changes in Global Sea Level Craig S. Fulthorpe University of Texas Institute for Geophysics John A. and Katherine G. Jackson School of Geosciences.
Ocean Topography Main Features.
Lecture 27: Climate Change in the Last Years Ch. 13.
Lecture 6 The Greenhouse Earth Last 100 Myr (Chapter 5)
Glacial Erosion.
Oxygen isotopes and climate. The long term average of temperature and precipitation (30 years)
Chapter 21: The Glacier Systems and the Ice Age Presentation.
An introduction to where, how, and why glaciers form
Tom Wilson, Department of Geology and Geography tom.h.wilson tom. Department of Geology and Geography West Virginia University Morgantown,
Isotope Chemistry in Oceanography
Earth’s Internal Structure
Glacial Landscapes.
How The Last Ice Age Shaped Canada
Paleoclimate: oxygen isotopes in foraminifera and corals The JOIDES Resolution drillship.
The Surface of the Ice-Age Earth
ISOSTASY A Plate Tectonic Process of Equilibrium.
Glaciers Chapter 3 Section 4 Pages Objective: Describe the causes and types of glaciers, how they impact land features, and analyze their role.
Grade 8 Science Unit 1: Water Systems on Earth. Effects of Water? Churchill River.
Why ocean bathymetry?. How do we measure bathymetry? Why is ocean bathymetry important? Questions:
Glaciers. Formation of glaciers Glaciers – a large mass of moving ice. At high elevations and in polar regions, snow can remain on the ground year-round.
Lesson 1: The Continental Drift Hypothesis
Geological Features at Sea and on Land. Pangea Nearly 100 years ago Alfred Wegner thought that the map looked like a giant jigsaw puzzel. Nearly 100 years.
The relationship between average annual surface temperature, accumulation and ablation rates, and glacial mass balance.
But, classic Plate Tectonics do not explain everything…
Hydrosphere All the water on earth
Coastal Forcing Coasts are the ribbons that form the interface between regions dominated by terrestrial and marine surface processes, respectively, and.
Chapter 21.
DO NOW Turn in Review #8. Pick up notes sheet..
However Sources of heat to our planet:
Glaciers Glaciers are a part of both the hydrologic cycle and rock cycle Glacier – a thick mass of ice that forms over land from the compaction and recrystallization.
Sea-Level changes.
Presentation transcript:

Sea-Level changes

Learning Objectives   The shape of the planet: difference between Geoid and Ellipsoid The concept of Mean Sea Level Article: http://www.esri.com/news/arcuser/0703/geoid1of3.html Processes that control the Mean Sea Level and its changes Sea level changes over millions of year Sea level changes over the recent geologic past

What does it mean to be at an altitude of 4000 m?

What does it mean to be at an altitude of 4000 m? It means that I am 4000 m above the Mean Sea Level (MSL)

Model of the shape of the Earth geoid: The equipotential surface of the Earth's gravity field which best fits, in a least squares sense, global mean sea level (MSL) http://www.ngs.noaa.gov/GEOID/geoid_def.html

The height of the Earth surface

by definition: Mean Sea Level = 0 m = equilibrium level Changes in volume of water Changes in shape and volume of ocean basins Changes are measured as relative changes to a reference datum This reference datum can be a fixed one (e.g. distance from the center of the earth) or local (coastline).

A change in volume of seawater in one ocean will affect the level in all others. Any such world-wide change in sea-level is called EUSTATIC SEA-LEVEL change A change in local sea level measured with respect to a land reference point is referred to as a RELATIVE SEA-LEVEL change

Sea Level Change ?

Other effects of plate tectonics e.g. Upper Cretaceous (90 Ma) MSL > 300 m

Summary of spatial-temporal scale of processes contributing to Mean Sea Level (D) Plate Tectonics 100 m (C) Melting of ICE Load from ice sheets deforms crust Thickness and area of continental crust Thermal state (age) of crust sediment loading MSL (meters) 10 m (A) Exchange of water with continents (Groundwater, Lakes, etc.) (B) Temperature expansion 1 m NOTE: A,B,C  change in volume of water D  change in shape of container 1 cm 1 day 100 1000 100 Ka 10 Ma 100 Ma TIME (years)

Other processes complicating the study of mean sea level (ice or sediment loads) The concept of Post Glacial Rebound (PGR) !!!

All this ice caused a EUSTATIC sea level drop of 125m Last Glacial Maximum: 20 thousand years ago Laurentide Ice Sheet, 3-4km thick All this ice caused a EUSTATIC sea level drop of 125m How do we know this?

Aerial view of glaciated Bylot Island, Canada U-shaped valley Glacial Striations Glacial Flow

OK, so we’ve mapped the extent of glaciation. Now what?

Date coral samples from various paleo-sea levels. Barbados is the “dipstick” for eustatic sea level reconstruction Now what?

From corals we know that Corals for paleo-sea level reconstruction From corals we know that LGM sea level was -125m

The world looked different during the LGM

Rate of change in Sea Level The subsidence of the Northern Sea (associated with relaxation from glacial loading) Rate of change in Sea Level mm/year Scandinavia Northern Sea Great Britain

Geological proxy for sea level change: 18O/16O in foraminifera Oxygen has two stable isotopes: 16O (99.8%) and 18O (0.2%) Rainfall and Ice are very depleted in 18O (lots more 16O) So when you build ice sheets, ocean loses 16O, becomes 18O-rich Forams record ocean 18O/16O ratio in shells 21,000 ybp

Take-home points: eustatic vs. local sea level lots of new, young, hot crust means higher sea level; tectonic changes on 10-100Ma timescales  Wilson cycle glacial cycles have several impacts on sea level: 1) ice sheets remove water  lower sea level 2) glacial loading/unloading reshapes crust under and surrounding ice sheets - changes occur on 10-100ky timescales tools for studying sea level change through geologic time: 1) radiocarbon-date marine shells & corals found at known elevation (above MSL) and depth (below MSL) 2) deep-sea sediment 18O record