Warmup How has global climate change affected the biosphere?  In the polar zone?  In the temperate zone?  In the tropical zone?

Warm-up Take 10 minutes to finish your Ecosystem Role Card posters. Due today, must be colored.

Ocean Acidification and Sea Level Rise 2.6.4B & 2.6.4C

Ocean acidification is the name given to the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO 2 ) from the atmosphere. Remember the pH scale!

How does the Acid get into the Ocean in the first place?

Since the industrial revolution began, it is estimated that surface ocean pH has dropped by slightly more than 0.1 units on the logarithmic scale of pH, representing an approximately 29% increase in H +, and it is estimated that it will drop by a further 0.3 to 0.5 pH units (an additional doubling to tripling of today's post-industrial acid concentrations) by These changes are predicted to continue rapidly as the oceans take up more anthropogenic CO 2 from the atmosphere. Ocean AcidificationOcean Acidification

Over the last decade, scientists have discovered that this excess CO2 is actually changing the chemistry of the sea and proving harmful for many forms of marine life. This process is known as ocean acidification.

Effects on Wildlife Corals, mussels, snails, sea urchins and other marine organisms use calcium (Ca) and carbonate (CO3) in seawater to construct their calcium carbonate (CaCO3) shells or skeletons. ShellsShells As the pH decreases, carbonate becomes less available, which makes it more difficult for organisms to secrete CaCO3 to form their shells.

A more acidic ocean could wipe out species, disrupt the food web and impact fishing, tourism and any other human endeavor that relies on the sea.

The growing acidification of the oceans is a threat to corals. Bleaching Animation

This relatively healthy coral community on Australia's Great Barrier Reef represents the current situation, with atmospheric CO2 concentration of 375 ppm. Mass bleaching has been observed in many places around the world, and coral reefs struggle to survive. Coral cover is currently at 60 percent or less of what it once was.

At an atmospheric CO2 concentration of ppm (which could be reached before 2050 based on current trends), the accelerated rate of coral erosion would lead to an overall decline worldwide, as in this location on the Great Barrier Reef. Coral cover will drop to less than 10 percent of what it once was. (Projections from 2007 paper in Science.)

Once the atmospheric CO2 concentration exceeds 500 ppm, reef ecosystems will be exceedingly rare or non- existent, robbing many marine organisms of the habitat they need to survive. Coral reefs worldwide will collapse into rubble, as in this reef that once grew in an inshore region of the Great Barrier Reef. (Projections from 2007 paper in Science.)

National Geographic Reading… The Acid Sea The carbon dioxide we pump into the air is seeping into the oceans and slowly acidifying them. One hundred years from now, will oysters, mussels, and coral reefs survive?

Warmup How does CO2 concentrations make the oceans more acidic? Describe how ocean acidification affects marine organisms. Why should we care?

Changes in Sea Level

Sea Level and Climate change Between 1870 and 2004, Global average sea levels have risen 17 cm. Two main factors contributed to observed sea level rise. The first is thermal expansion: as ocean water warms, it expands. The second is from the contribution of land-based ice due to increased melting. The major store of water on land is found in glaciers and ice sheets Glacier Calving

Over the last several decades, evidence of people's influences on climate change has become increasingly clear and compelling. Warming of the climate system is well-documented-- evident from increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising sea levels. el el

This Aug photo shows a flooded road on Hatteras Island, N.C., after Hurricane Irene swept through the area the previous day cutting the roadway in five locations. From Cape Hatteras, N.C., to just north of Boston, sea levels are rising much faster than they are around the globe.

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Extra Extra…now hear this! In the news! North Carolina tries to wish away sea-level rise US state proposes new law that would ignore grim projections of a one-metre sea-level rise by the end of the century Some lawmakers will go to great lengths to deny the reality of climate change. However, North Carolina lawmakers reached new heights of denial, proposing a new law that would require estimates of sea level rise to be based only on historical data— not on all the evidence that demonstrates that the seas are rising much faster now thanks to global warming. Keep reading…

Is this possible?

Warmup How much is the sea level off the coast of North Carolina predicted to rise by 2100? What are the two main factors that have contributed to observed sea level rise?

2.6.4D ANALYZE HOW SEA LEVEL HAS BEEN AFFECTED BY OTHER EARTH PROCESSES SUCH AS GLACIATIONS AND TECTONIC MOVEMENTS. CONSIDER LONG- AND SHORT- TERM CHANGES. Historical Sea Level Changes

Glaciation Sea water removed to form glaciers; glaciers melt to add water to ocean Rate: 1-15 mm/yr Volume change: water Can result in changes of up to 200m! During Pleistocene glaciation, a drop of 106m occurred. Melting of Greenland and Antarctic would produce a sea-level rise of 60m.

Glacial Isostasy Sea shelf sinks under ice; rebounds when ice melts Rate: 0.5-5mm/yr Volume change: basin

Change in water temperature Approximately 2m change in sea level for one degree change in surface water temperature Rate: slow Volume change: water During Pleistocene, temperatures were 5`C lower than today, accounting for 10m lower sea levels just from thermal contraction.

Juvenile water Addition of new water from volcanic activity; one- way change Rate: very slow Volume change: water

Shelf Margin sinks/rises Affects broad areas, but not worldwide Rate: <0.02mm/yr Volume change: basin 1964 earthquake in Alaska raised the coast by more than 5m!

Change in rate of spreading Rate of seafloor spreading controls volume of ocean basin Rate: <0.02mm/yr Volume change: basin The early Atlantic was shallow (thin layer, “floated”) until the late Cretaceous (layer thicken with time, “sunk”)

Sediment transfer to oceans Reduces basin size; Typically a one-way change, sediments can be returned to continents through the subduction zone Rate: very slow Volume change: basin

Subduction Loss of sediment to the mantle or plastered to continental block; one-way change Rate: very slow Volume change: very slow

Project work time Draft out your project (Do Something)  What are you doing?  How do you plan on doing it?  Why are you doing it (anticipated effect? Personal connection?)  Obstacles you anticipate.