22.3 Climate Change CHAPTER 22

Studying Climate Changes  Done by Climatologists – use past climate history to predict future climate changes  Use:  Ice Cores – (gas concentrations) high CO₂ levels = warm climate  Sea Floor Sediment – (18 O Concentration) High 18O = cool water  Fossils – (Pollen/leaves/animals) broad leaves = warm climates; waxy leaves = cool climate  Tree Rings – (Width) thin = cool weather  Speleothems – (cave mineral deposits) high 13C = El Nino; Low 18O = hurricanes  Also, computers are used to create models called General Circulation Models (GCMs) that simulate climate change.

So, what causes climate change? Possibilities:  Plate Tectonics – As continents move, wind flow & ocean currents change which in turn brings changes to temp & precip. Levels.  Orbital Changes – Milankovitch Theory ◦Eccentricity: Earth’s orbit changes elongation ◦Tilt: varies between o, the greater the tilt-the more energy the poles receive. ◦Precession: Earth also “wobbles” on its tilt…this happens as a cycle every approx. 100,000 41,000 and 26,000 years.

Possibilities Continued… Human activity: emissions—(transportation/industry releases CO 2 into atmosphere) land use--(deforestation removes the natural CO 2 removal from vegetation). Volcanic activity: sulfur/ash released into atmosphere reflects sunlight back into space.

Potential Impacts  Global Warming—gradual increase in global temps 1 o C/100 yrs. o Leads to increase in evaporation—areas become drier, ice at poles melt—sea levels could rise.  Sea level changes—scientists predict 2-4 o C increase this century…thermal expansion of oceans and ice melting can cause shorelines to shift inland.

How can we reduce effects?  International laws to reduce pollution  Individuals can reduce, reuse, recycle public transportation, fuel efficient cars (hybrids)…