Lecture 15 (Review) Ocean’s Role in Climate and Climate Change by Instructor: Dr. Charles Dong at El Camino College

Questions? What are the ocean’s roles in the climate? What kind of situation of the global climate are we facing now? As an individual living on the earth village, what should we do to help stabilize the global climate change?

Ocean’s roles in Climate and Climate Change The ocean acts as a global climate system adjustor with its large heat capacity 2. The ocean acts as a global climate system by regulating the concentration of carbon dioxide (CO2) in the atmosphere.

Basic Facts of Earth’s Oceans Cover 70.8% of Earth’s surface; Huge size and volume, as a reservoir, contain 97% of Earth’s water; Water has higher heat capacity than rocks (amount of energy to raise one gram of material 1 degree higher).

Ocean surface currents Red lines carry warm water and blue lines carry cold water: it is noted that the warm water is carried to cold areas and cold water to warm areas

Coastal Moderate Climate Solar heating Different heat capacities of land and water Sea breeze From ocean to land Land breeze From land to ocean Fig. 6.13

Exe. 16-01 List the two primary roles of ocean in the global climate How does the oceanic circulation adjust the climate? Why do the coastal areas have the moderate weather?

How a greenhouse works Sunlight (visible and UV) passes through the clear covering of a greenhouse It is converted to longer wavelength heat energy (IR) Heat (and IR) cannot pass through the covering and is trapped inside Fig. 6.24

Greenhouse gases in the atmosphere Absorb longer wave radiation from Earth Water vapor Carbon dioxide (CO2) Other trace gases: methane, nitrous oxide, ozone, and chlorofluorocarbons

The heating of Earth’s atmosphere

Earth’s average temperature is rising Earth’s average surface temperature has risen at least 0.6°C (1.1°F) in the last 130 years May be related to increase in atmospheric carbon dioxide Arctic ice sheet breaking up Glaciers throughout the world melting Fig. 6-28

Carbon dioxide is increasing in the atmosphere Fig. 6.27

Sea Ice Coverage Declines in Arctic Ocean Sea ice extent reached a record minimum in summer 2005, and the past four summers (2002-2005) has been among the lowest on record. Fig. 6.22

Global warming and changing sea level About 0.6oC (1.1oF) warmer over last 130 years Sea level rose 10-15 cm (4-10 in) over past 100 years If global warming continues, higher sea level due to water expansion and ice melting Fig. 10.15

Exe. 16-02 What is the major greenhouse gas due to human activities? When did the global temperate start to increase sharply? Why does the sea level rise with the global warming?

Ocean’s role in reducing the greenhouse effect The oceans absorb vast amount of carbon dioxide from the atmosphere What happens to the carbon dioxide that enters the ocean? Biological Pump (next slice)

Nutrient cycling: Photosynthesis, Biological Pump and Upwelling. Fig. 13.16

Possible consequences of global warming Melting glaciers Shift in species distribution Warmer oceans More frequent and more intense storms Changes in deep ocean circulation Shifts in areas of rain/drought Rising sea level

Reducing greenhouse gases Greater fuel efficiency Alternative fuels Re-forestation Eliminate chlorofluorocarbons Reduce CO2 emissions Intergovernmental Panel on Climate Change (4 reports 2007 Nobel Peace Prize for IPCC) Kyoto Protocol 1997 Copenhagen UN Climate Change Conference(ongoing)

Discussion What should we do to help stabilize the climate change?