Transcript Chapter 19

Chapter 19
Adam Brooks
19-1 How Might the Earths
Temperature and Climate Change
in the Future
Weather and Climate Are Not the
Same
• Weather is short term changes in the
atmospheric variables like wind, temperature,
precipitation and barometric pressure in a
certain area over a period of hours or days.
Climate is the average weather conditions of
the earth or of a particular area. Temperature
and precipitation that is measured over a long
period of time. The time can range from
decades to centuries to thousands of years.
Climate Change is Not New
• Over the past 3 billion or more years, the planet’s climate
has been altered by a lot of things. These factors include
changes in the sun’s output of energy, impacts by large
meteorites that throw large amounts of dust into the
atmosphere, and slight changes in the earth’s orbit around
the sun. The climate on earth is also affected by global air
circulation patterns that reflect incoming solar energy and
helps to cool the atmosphere, various concentrations of the
different gases that make up the atmosphere and the
changes in ocean currents. The atmosphere has had long
periods of global cooling and global warming over the past
900,000 years. These cycles of freezing and thawing are
called glacial and interglacial periods.
The Climate and Our Lives and
Economics Depend on the natural
Greenhouse Effect
• Greenhouse effect affects the earths climate because it
warms the earth’s lower atmosphere and surface. About
1% of the earth’s lower atmosphere is made up of
greenhouse gases, especially water vapor (H2O), carbon
dioxide (CO2), methane (CH4), and nitrous oxide (N2O).
Heat radiated into the atmosphere by the earth causes
molecules of these gases to vibrate and release infrared
radiation with an even longer wavelength into the lower
atmosphere. As this radiation interacts with molecules in
the air, it increases their kinetic energy and warms the
lower atmosphere and the earth’s surface, which over time
affects the earth’s climate. It is thought that without the
natural greenhouse effect, earth would be frigid and
uninhabitable place.
19-2 What Are Some Possible
Effects of a Warmer Atmosphere
Enhanced Atmospheric Warming
Could Have Serious Consequences
• Most historic changes in the temperature of the lower
atmosphere took place over thousands of years. What
makes the current problem urgent is that we are faced
with a rapid projected increase in the average
temperature of the lower atmosphere during this
century. This is probably going to quickly change the
mild climate that we have had for the past 10,000
years. What we are facing is very rapid climate change.
These changes will affect where we can grow food and
how much we can grow. It will also affect what areas
will have problems with increased drought and which
will have increased flooding. It will also affect what
areas people and wildlife can live.
More Ice and Snow Are Likely to Melt
• Climate models project that the worlds polar regions
will be most affected by climate change because of the
warming of the climate. The ice and snow in these
areas help to cool the earth by reflecting solar energy.
When the ice and snow melts it exposes darker land
and sea areas. These areas reflect a lot less sunlight
and absorb more solar energy. The atmosphere above
the poles would warm faster. Mountain glaciers are
important to the water cycle because they store water
as ice during cold wet seasons and release it slowly to
streams during warmer dry seasons. If these glaciers
continue to shrink people in many countries could be
faced with major water, power and food shortages.
Severe Drought Is Likely to Increase
• Drought happens when evaporation from increased temperatures exceeds
precipitation for a long period of time. Southern Australia has
experienced a severe drought for a decade, and the western United States
is experiencing its worst drought in 500 years. A 2007 study by climate
researchers at NASA’s Goddard Institute for Space Studies predicts that by
2059 up to 45% of the world’s land area could be experiencing extreme
drought. When droughts increase and spread it affects the growth of trees
and other plants, the growth declines. When the forests and grasslands
dry out the chances of wildfires increase and this adds CO2 to the
atmosphere. Other problems caused by drought are declining stream
flows and less available surface water. It will also cause water tables to fall
with more evaporation. This will get worse because farmers will irrigate
more to make up for drier conditions. It will cause the lakes, reservoirs and
inland seas to shrink. Some of these effects will probably going to
accelerate atmospheric warming and lead to even more drought.
19-3 What Can We Do to Slow
Projected Climate Disruption
Dealing with Climate Disruption Is
Difficult
• One of the main things we can do is do everything we
can to avoid any and all climate tipping points. The
climate tipping points are points where natural systems
can change beyond a chance to go back. The problem
is global. Dealing with this threat will require
international cooperation. The problem is a long-term
political issue. Voters and elected officials generally
respond better to short- term problems than to longterm threats. Most of the people who could suffer the
most serious harm from projected climate disruption
during the latter half of this century have not been
born. The projected harmful and beneficial impacts of
climate disruption are not spread evenly.
Prevent and Reduce Greenhouse Gas
Emissions
• Preventions- Cut fossil fuel use. Shift from coal to natural gas. Improve
energy efficiency. Shift to renewable energy resources. Transfer energy
efficiency and renewable energy technologies to developing countries.
Reduce deforestation. Use more sustainable agriculture and forestry. Put a
price on greenhouse gas emissions. Reduce poverty. Slow population
growth
• Reduce- Remove CO2 from smokestack and vehicle emissions. Store CO2
by planting trees. Sequester CO2 in soil by using no-till cultivation and
taking cropland out of production. Sequester CO2 deep underground.
Sequester CO2 in the deep ocean. Repair leaky natural gas pipelines and
facilities. Use animal feeds that reduce CH4 emissions from cows
Collect Greenhouse Gas Emissions and
Stash Them Somewhere
• One way is to increase the uptake of CO2 by starting a global tree-planting
program.
• Restore wetlands where they have been drained for farming. Wetlands are
good at taking up CO2 and provide other natural services.
• Another way is to plant plants in large areas of degraded land. Plants like
perennial plants that are fast growing and remove CO2 from the air and
store it in the soil.
• Another way is to help the natural uptake and storage of carbon by
preserving natural forest.
• Seeding the oceans with iron to promote the growth of more marine algae
and other phytoplankton. Marine algae and phytoplankton absorb large
amounts of CO2 from the atmosphere as they grown.
• Remove CO2 from the smokestacks of coal-burning power and industrial
plants to store it somewhere. This is called carbon capture and storage.
19-4 How Have We Depleted
Ozone in the Stratosphere and
What Can We D About It
Our Use of Certain Chemicals
Threatens the Ozone Layer
• Around 95% of the sun’s harmful ultraviolet radiation is kept from
reaching the earths surface by a layer of ozone in the lower stratosphere.
The ozone depletion in the stratosphere is a serious threat to humans,
animals and plants that use the sunlight to support earth’s food webs.
CFCs, more commonly known as Freon’s, was thought to be a dream
chemical. It is odorless, nonflammable, nontoxic and chemically
unreactive. Because it is very inexpensive to manufacture it was used a lot
as coolants in refrigerators and air conditioners, as a cleaner for electronic
parts like computer chips, propellants in aerosol spray cans, as gases used
to make insulation and packaging and fumigants for granaries and ships
cargo holds. It was proven in 1974, by chemists Sherwood Rowland and
Mario Molina, that CFCs are chemicals that destroy protective ozone in
the stratosphere. These are not the only ozone depleting chemicals
though. Some of the others are methyl bromide which is a fumigant,
hydrogen chloride which is released in the stratosphere by space shuttles,
halons and hydrobromoflurocarbsons, used in fire extinguishers and some
cleaning solvents.
Why Should We Worry
about Ozone Depletion?
• Ozone depletion should be a concern for us
because there are many problems that can be
caused by this. This will cause worse sunburns,
eye cataracts and increased skin cancers. The
increase in UV radiation could destroy
phytoplankton. Phytoplankton plays an
important role in removing CO2 from the
atmosphere.
We Can Reverse Stratospheric Ozone
Depletion
• A lot of researchers think that we should stop producing all
ozone-depleting chemicals. Even if we did it would take a
long time for the earth’s ozone layer to recover the levels of
ozone it had years ago. The goal of the Montreal Protocol
was to cut emissions of CFCs by about 35% between 1989
and 2000. After getting news that seasonal ozone thinning
above Antarctica representatives from 93 countries had
more meetings in 1992 and adopted the Copenhagen
Protocol. This accelerated the phase-out of key ozonedepleting chemicals. Finally companies and nations agreed
to work together to solve this global problem. If nations
keep following agreements on stratospheric ozone the
levels should return to 1980 levels by 2068.