CLIMATE CHANGE In Norfolk Jökulsarlon, Iceland Please refer to the Microsoft Word and Adobe PDF documents available on the website for the further information required to present this PowerPoint presentation. The information in this presentation refers to the text in the document called “Climate Change”. Jökulsarlon, Iceland © NERC 2005, AM Jarrow

Introduction Norfolk’s location and low lying coast vulnerable to climatic changes Natural glacial-interglacial cycles for last 2.6 million years (Quaternary) Not a recent trend caused by us But humans are having an affect too

North Norfolk Quaternary (2.6 million years ago to present) interglacial stages (warmer) warmer than present - Costa del Cromer glacial stages (colder) like present day Antarctica These climatic changes have affected Norfolk’s coastline and appearance

Norfolk during glacial stages During a glacial stage glaciers grow around the world take water from the seas lower global sea levels coastline moves outwards Norfolk increases in size If glaciers grow and reach Norfolk glaciers cover Norfolk and change the land’s appearance

During interglacial stages Opposite during interglacials global sea levels rise No solid high cliffs to keep sea out coastline migrates inland To simplify the Quaternary we will split it into two…

2.6 million years ago to 900,000 years ago Coastline further inland (sea levels) S England joined to France creating a land bridge Warmer climate Small oscillations Small sea-level changes Ever-changing coastline © NERC 2006, JR Lee

2.6 million years ago to 900,000 years ago Landscape similar to today saltmarshes, tidal creeks, estuaries, beeches sands, gravels and muds laid down during this time are called ‘crags’ by geologists An ancient beach deposit at Norton Subcourse in southern Norfolk. These sands and gravels are called the Wroxham Crag. © NERC 2005, JR Lee

900,000 years ago to present A large climatic shift occurred Climate dominated by extremes Global, not just felt in Norfolk About 10 shifts from glacial to interglacial Several identified in geology of Norfolk

900,000 years ago to present Several occasions – Norfolk covered by ice or near ice margin At maximum extent – British Ice Sheet reached London. about450,000 years ago known as the Anglian Glaciation

How Norfolk changed Each of the glaciations had a dramatic affect on Norfolk glaciers smear sediment on land surface Sediment laid down by glacier in this way geologists call this deposit Till usually clayey, also some sand and gravel depends on what glacier is ‘carrying’ depends on which rocks ice has travelled over Reason many fields in Norfolk are clayey

How Norfolk changed When the glaciers retreat northwards due to global warming water released from the ice lots of sand and gravel carried by water this is deposited as water slows down Reason there are many sandy fields and quarries/pits in Norfolk

Layer cake Geologists think of Norfolk as a cake with many layers till sands and Gravels etc… The cliffs at Happisburgh, showing deposits laid down during a glaciation. Two tills are separated and overlain by sands that were deposited within a glacial lake. © NERC 2005, JR Lee

Coastline variations These large-scale climate changes = large-scale changes in sea level change of several 10s of metres © NERC 2006, JR Lee

Rivers River pathways affected by glaciations glaciations erode and bury earlier landscapes change direction of river drainage can destroy whole river systems glaciers melt and drainage of the meltwater uses old river pathways modern day drainage network is based on ancient drainage pattern

Drivers of climate change Fjallsjokull, Iceland © NERC 2005, AM Jarrow

Drivers of climate change 1 Distribution of land and water on the Earth thermohaline circulation

Drivers of climate change 2 Solar radiation orbital shape or eccentricity axial tilt or obliquity axial orientation or precession © NERC 2006, JR Lee

Climate change record Present 2.6 million years ago © NERC 2006, JR Lee