Climate Change Chapter 22 Section 3

How do we know if the climate is changing?

How do we know if the climate is changing? It’s easy to measure the temperature right now. Estimating the temperature thousands of years ago is tricky.

Studying Past Climates Ice Cores Shows gas concentrations for hundreds of thousands of years High CO2 = warm climate

Hundreds of thousands of years. Sea Floor Sediments O concentration High O = cool water Hundreds of thousands of years. 18 18

Studying Past Climates cont. … Fossils – millions of years Pollen, leaves, animals Broad leaves means warm climates, waxy leaves mean cool climates Tree Rings – hundreds to thousands of yrs Thin rings means cool weather, thick rings mean warm weather

Speleothems Cave deposits  stalagmites & stalactites High C = El Nino events low O = hurricanes 13 18

Studying Past Climates cont. … General Circulation Models Computers are used to simulate climate conditions based on available data

So what causes climate change?

Possible causes are - Plate Tectonics As continents move, wind flow & ocean currents change and affect temperature & precipitation

Orbital Changes / Milankovitch Theory Eccentricity: Earth’s orbit changes becomes more or less elliptical in 100,000 year cycles. Tilt: varies between 22 – 24 *, the greater the tilt – the more energy the poles receive – 41,000 year cycles

Precession: Earth also “wobbles” on its tilt … this happens as a cycle of every ~26,000 years

Volcanic Activity: Sulfur/ash released into atmosphere, reflects back sunlight into space (cooling effect)

Human Activity: Emissions – transportation, industry releasing CO2 into air Land use – deforestation removes natural CO2 from vegetation

Looking at data: The planet is getting warmer.

Global Temperature and CO2 Levels are both increasing.

Temperature Change is Natural for the Earth

BUT the temperature has been STABLE for all of recorded human history.

Predictions from Climate Models

Potential Impacts of Climate Change

Global Warming Gradual increase in global temperatures, 1o C in the last 100 years Climate models predict a temperature rise of 2 to 4o C in this century.

Global Warming Effects Ice at poles is melting. Liquid water absorbs more heat than ice.

Ice on Greenland and Antarctica adds to the ocean when it melts.

Sea level will rise – but how much, and how fast? Water expands with temperature Ice on Greenland & Antarctica melts Sea level has risen about a foot in the last century.

Global Warming Effects Low lying areas will be affected by sea level rise. New Orleans and South Florida are the lowest lying areas in the USA.

A 6 meter rise in sea level would be very bad for South Florida.

Annual high tides are flooding Miami Beach and Ft. Lauderdale Annual high tides are flooding Miami Beach and Ft. Lauderdale. Miami Beach is raising roads and installing pumps.

How can we reduce potential effects of global warming? International Laws to reduce greenhouse gas emissions. Individuals can reuse, reduce, and recycle. Public transportation, fuel efficient cars/hybrids. Limit air travel 