Climate change

Ch. 19Climate change basicsChanges in the ozone layer

Changes to the greenhouse effectAtmospheric changes lead to climate changeThe ozone layer blocks UV radiation (high energy radiation from the sun).

UV is dangerous because it causes skin cancer, cataracts, immune system problems and kills plants and animals.

UV kills phytoplankton.The ozone problemA hole in the ozone layer has developed over the south pole.

It was primarily caused by human use of CFCs, which were used as propellants in aerosolsand in cooling systems such as air conditioning and refrigeration.Why is there an ozone problem?The Montreal protocol banned the use of CFCs and our production is nearly zero now.

CFCs are persistent and remain in the atmosphere to react with and break down ozone for a long period of time.

CFCs are bannedWe are now shifting gears.

Forget about the ozone problem for a minute.

Now were going to look at the greenhouse effect.Heat is molecular motion.

Earths atmosphere naturally absorbs some lower energy (infrared) radiation from the sun. This energy is absorbed by the molecules and causes them to vibrate faster. These vibrations transmit heat to the surface of the earth.The greenhouse effectSome naturally occurring molecules in the atmosphere absorb the IR heat better than some others.These are called the greenhouse gases.atmosphereWater vaporCarbon dioxideMethane (CH4)Nitrous oxide (N2O)Ozone (O3)Which gases?CFCs and HCFCs are entirely manmade, but absorb/radiate heat in the same way.

These are not natural parts of the atmosphere, nor are they produced much anymore, yet they are very persistent so must be considered.Some are manmadeAfter many years of research by thousands of scientists, the verdict is in.

Humans have increased the concentrations of greenhouse gases in the atmosphere and are causing the climates around the planet to change.Scientific consensusIn the United States, the discussion of anthropogenic global warming has recently been politicized.

It has become a popular position to be a skeptic and to suggest that AWG is not real or is a hoax.

The evidence for a warming climate and the human cause of it is overwhelmingly strong. The scientific community is not divided on this issue.politicsRachel Pike: The science behind a climate headline .

James Balog explains why he is worried.How do we do science?