Transcript global climate change II

Global Climate Change
Past Climate Change
• Large climate changes have occurred in the
past
– Eruptions of various volcanoes, including Mount
Pinatubo in 1991 alter the climate by sending a
cloud of gas and ash high into the atmosphere
• Initial cooling due to interference of light from particles
in the atmosphere
• Followed by warming period
• These changes were observed after the volcanic
explosion of 1991
• Many different models have shown that
global temperatures are likely to rise
several degrees this century
– Will have many different effects on humans and
ecosystems
Natural Climate Change
• Main alterations in the climate
come from volcanic eruptions,
changes in solar input, moving
continents, meteor strikes, and
other factors
• Over the past 1,000 years, the Earth
has experienced fairly stable
temperatures, with a rise becoming
noticeable during the last century
• Major hypotheses about changing
climate:
– Change in the Earth’s elliptical orbit about
every 100,000 years
– Change due to tilt on Earth’s axis every
40,000 years
– Ice ages could have been caused by
wobbling of Earth on its axis (every 26,000
years)
– 11-year sunspot cycles and 22-year solar
magnetic cycles
PAST CLIMATE AND THE
GREENHOUSE EFFECT
Figure 20-2
Analyzing Past Climate
• According to measurements of
carbon dioxide and other gases in
ice core samples, changes in
troposphere levels of CO2
correlate fairly closely with
variations in the average global
temperature during the past
160,000 years
– This demonstrates that CO2 has a
direct effect on global temperature
• In 2005, an ice core showed that
CO2 levels in the troposphere are
the highest they have been in
650,000 years
• May 9, 2013 – 400 ppm milestone!
The Natural Greenhouse Effect
• Three major factors shape Earth’s climate
1.
2.
The sun
The natural greenhouse effect: greenhouse gases in the
atmosphere warm the surface and lower troposphere
-Chemist Svente Arrhenius first recognized in 1896
-Four major greenhouse gases are water vapor, carbon dioxide, methane (CH4), and
nitrous oxide (N2O)
-These gases have always been present in the troposphere in varying
concentrations
-Fluctuations in these concentrations (along with changes in solar output) are the
major cause of changes in tropospheric temperature over the past 400,000
years
3. Ocean cycles and natural cooling processes
-oceans store carbon dioxide and heat
-Evaporate and receive water as part of the hydrologic cycle
-Move stored heat around the globe through currents
-natural cooling process occurs as heat causes water to
evaporate from the surface of the ocean, condensing and forming
droplets in clouds and releasing their stored heat higher in the
atmosphere
Climate Change and Human Activities
• The basics: the idea is that a variety of human
activities, most notably burning fossil fuels,
increases the concentration of gases like carbon
dioxide (which trap and hold solar heat and cause
an increase in surface temperature) to such an
extent that the entire climate of the planet can be
affected
• Since the beginning of the Industrial Revolution
(about 275 years ago), human actions have lead
to a major increase in three of the greenhouse
gases (CO2, CH4, and N2O)
– Burning fossil fuels adds CO2 and CH4
– Clearing and burning forests adds CO2 and N2O
– Planting rice and using inorganic fertilizers releases N2O
• Plants emit 10-30% of the greenhouse gases
present in the atmosphere, but since this has
been going on for hundreds of thousands of
years, it cannot be responsible for the current
drastic increase in global temperatures
Global GHG Emissions
• United States has 4% of the world’s
population and emits 25% of its
anthropogenic carbon dioxide (22% of
total GHG emissions)
– China emits 14%, EU 13%, Russia 6%, Japan
5%, and India 4%
– China’s emissions increased 88% between
1990 and 2004; U.S. emissions rose 19% during
that same period.
• China’s total emissions are expected to surpass U.S. by
2025 due to increasing population and coal burning;
increased vehicle use and ownership
• Other developing countries will likely follow
• U.S has not signed onto Kyoto protocol; China and
India are not required to reduce their emissions due to
economic and growth status
• Still, average American releases 10 times as much CO2
as average Chinese person
• Per capita emissions in E.U. and Japan are about half of
those for Americans
Climate Change and Human Activities
• Humans have been emitting CO2 and CH4
from agriculture for over 11,000 years
•
The
IPCC
1988: U.N. forms the Intergovernmental Panel on Climate
Change (IPCC) to document past and current climate changes
and to predict future trends
– Includes 2000 climate experts from 70 countries
– Their report, which was a compilation of 12 years worth of study,
was that there is a 90-99% probability that the troposphere is
warming
– “There is new and stronger evidence that most of the warming that
has occurred over the last 50 years is attributable to human
activities.”
– Has published 4 reports since then, the next one is due in October,
2014
•
Major findings of the reports published by the IPCC:
– 90-99% confidence that the Earth is the hottest it has been in 400
years and 66-89% confident that it is hotter than it has been in the
past 1,000 years
– Since 1900, the average global temperature has risen 0.6 C (1.1 F)
over the entire globe and 0.8 C (1.4 F) over the continents
• Most of this increase has taken place since 1980
– 10 warmest years since 1861 have occurred since 1990 (top five
hottest: 2010, 2005, 1998, 2003 & 13 (tie), 2002, 2006, 2009, 7, 4 12
(all tie)
– Arctic temperatures have risen almost twice as fast as the rest of
the world over the last 50 years
– Glaciers and sea ice melting and shrinking at increasing rates
– Warmer temperatures in Alaska and Russia are causing melting of
permafrost, which releases carbon dioxide and methane
– During the last century, the average sea level has risen by 4-8
inches
• Due to thermal expansion and melting glaciers/land-based ice
The Critics
• Healthy skepticism is good- it’s an important
part of the scientific process
• Some scientists have legitimate concerns
about the “consensus” and particulars of
climate change theory, and point to
incomplete data on some projections. This
is valid.
• Others are industry-funded groups that have
a financial interest in preventing regulatory
action on climate change
The Response
• Although many sources claim that there is no
“consensus on global warming,” the following
was signed onto by the national science
foundations of Brazil, Canada, China, France,
Germany, India, Italy, Japan, Russia, the
United Kingdom and the United States:
– The atmospheric concentration of carbon dioxide is the
highest it has been in the period of time as far back as
reliable measurements can be made (400,000 years)
• Have increased from 280 ppm in 1750 to 400 ppm in 2013
– The planet will, with a 90-99% degree of certainty,
experience an average surface temperature increase of
1.5-4.8°C by 2100
– Due to developing economies and population increases,
global energy demand is expected to increase 60% in the
next 25 years
• Fossil fuels are expected to provide 85% of this demand
– Cost-effective and long-lasting solutions need to be taken
to address the clear anthropogenic effects on the global
climate
Scientific Modeling and Consensus
• Mathematical models used to
project the effects of increasing ghg
concentrations on global
temperatures and climate systems
– Coupled general circulation models
(CGCMs) take into account sunlight,
clouds, land masses, oceans and their
currents, concentrations of ghg and
pollutants, and positive and negative
feedback loop systems
Sun
Troposphere
Greenhouse
gases
Aerosols
Warming
from
decrease
Cooling
from
increase
CO2 removal
by plants and
soil organisms
CO2 emissions
from land
cleaning, fires,
and decay
Heat and
CO2 removal
Heat and
CO2 emissions
Ice and snow cover
Shallow ocean
Land and soil biotoa
Long-term
storage
Natural and human emissions
Deep ocean
Stepped Art
Fig. 20-6, p. 469
The Scientific Consensus about
Future Climate Change
• Measured and
projected changes in
the average
temperature of the
atmosphere.
• 90-99% probability
that Earth’s
temperature will
increase by 2.4-5.4 C
(4.5-9.7 F) by 2100
– IPCC, U.S. National
Academy of Sciences,
American Geophysical
Union have reached
similar projections
Global Climate Change
• There is a difference between “global warming”
and “global climate change”
• Global warming: the temperature increase in the
troposphere, which can cause global climate
change
– Global climate change refers to the changes in any
aspects of the earth’s climate, including
temperature, rainfall and other precipitation patterns,
storm intensity, and desertification/biome shift
• Scale of problem of increase in troposphere
temperature also dependent on how fast it occurs
– Worst-case scenario: it is too late to reverse climate
change, and eventually ecosystems will collapse,
low-lying cities will flood, forests will be consumed
in fires, grasslands will become deserts, wildlife will
disappear, coastal storms will wipe out cities,
tropical diseases will become pandemics
• Referred to as the tipping-point- have we passed it?
Factors Affecting Climate
-Climate feedback systems
•
•
Positive feedback systems can
amplify (increase) changes in the
tropospheric temperature. These
are harmful, and unfortunately more
common than negative feedback
systems
Negative feedback systems can
decrease changes in the
tropospheric temperature. These
are corrective.
Climate Factors: Oceans
• Oceans moderate Earth’s
temperature by storing heat
and removing almost half of
the excess carbon dioxide
human activities release into
the atmosphere
Climate Factors: Clouds
• This is a major unknown factor, because
clouds could either warm or cool the
troposphere
• What is known is that warmer
temperatures will cause an increase in
could formation
– Could cause warming effect (positive
feedback) by absorbing and releasing heat
into the troposphere
– Could cause cooling effect (negative
feedback) by reflecting more sunlight back
into space
– Could also decrease surface warming by
reflecting and blocking more sunlight
Climate Factors: Outdoor Air Pollution
• Aerosol pollutants and soot
produced by human activities can
warm or cool the atmosphere, but
such effects will decrease with any
decline in outdoor air pollution
– Aerosols are microscopic
droplets and solid particles of
various air pollutants
Other Climate Effects
• Effects of higher carbon dioxide levels on
photosynthesis: larger amounts of carbon
dioxide could actually increase the process of
photosynthesis, eventually leading to a drop in
carbon dioxide as plants absorb it at a higher rate
• Effects of a warmer troposphere on methane
emissions: warmer air can release methane
stored in bogs, wetlands, and tundra soils to
accelerate global warming
– Since methane has a low boiling point, a small increase
in temperature can release it
– Methane is 25 times more potent as a greenhouse gas
than carbon dioxide
– Large stores of methane are locked in wetlands and as
icy methane hydrates under permafrost, but will be
released as ice melts
Effects of Global Warming
• In general: some areas will benefit
because of less severe winters, more
precipitation in dry areas, less
precipitation in wet areas, and increased
food production; but other areas will
benefit due to excessive heat, lack of
water, and decreased food production
– According to the IPCC, poor people and
wildlife species will suffer the most (as
usual)
– Most climate changes are too complex to
predict what will happen to a specific area;
only general trends can be predicted
Rising Sea Levels
• Sea levels rise and fall naturally
• IPCC: world’s sea level will rise 4-35
inches (9-88 cm) over the next century
(90-99% probability)
Changing Ocean Currents
• Ocean currents are extremely important to Earth’s
climate
– Move carbon dioxide and heat to and from the deep
sea
– Transfer hot and cold water between the tropics and
the poles
– Cycle works because water in the North Atlantic is
saltier and more dense due to lower temperature,
and creates current
Changes in Precipitation and Weather
Extremes
• Climate changes will shift patterns of precipitation by
altering the rate and distribution of water in the
hydrologic cycle
– Some areas will get more water; others will get less
– This will affect where crops can be grown, and increase pressure
on arable land for food production
– Severe water shortages in areas already short of water
• Severe weather events will become more intense and
frequent
– Droughts will intensify and last longer, causing famine and
desertification to increase
• National Center for Atmospheric Science reported that the area of
Earth’s surface affected by drought increased from 15% to 30%
between the 1970’s and 2002 due to reduced precipitation and higher
temperatures
– Heat waves will increase
• 2003 heat wave in Europe killed 54,000 people and devastated crop
production
• The hurricane question
– No conclusive evidence established, but basic scientific theory
predicts stronger storms due to increased ocean temperatures
• Peak intensity and wind duration of average hurricanes increased 50%
between 1970 and 2004
Effects on Biodiversity
• Warmer climate could expand ranges and populations
of warm-weather adapted plant and animal species
– Includes many weeds, insect pests, and diseasecarrying organisms
• 1 million other species could face extinction (UN)
– Specialized niches or narrow temperature tolerance
– Most likely to suffer are coral reefs, polar seas, coastal
wetlands, arctic and alpine tundra, mountaintop
ecosystems
– Increased incidence of forest fires (also increases
carbon dioxide)
• Agriculture and fish stocks could also be
affected
– Climate shifts and hydrologic cycle changes could
completely disrupt human agricultural system
• Rice-producing areas flooded
• Northward shift of ideal food-growing climate from
Midwestern U.S. to Canada, where soils are far less
fertile
• Decreased snow mass would cause a sharp decline
in China and India, due to reduction of irrigation
water from Yangtze River (which is fed by summer
melt from the Himalayas)
Effects on People
• Heat stress will become more frequent and
prolonged
– Increase death and illness, especially among
older people and urban poor
• Fewer people will die from cold weather
(more people typically die from cold than
heat)
• Incidences of tropical infectious diseases
like malaria, yellow fever, and dengue fever
will rise
– Could increase death rate in sub-Saharan
Africa from tropical diseases to 185 million
people by the end of the century
• Flooding of coastal areas will lead to mass
displacement of people
Dealing With Global Warming:
Solutions
• Two basic strategies for dealing with global
warming:
– Mitigation: reducing greenhouse gas emissions,
learning more about the global climate and shift
to non-carbon energy options
– Adaptation: recognizing global warming as
inevitable and devise strategies to reduce its
harmful effects
– Most think a mix of both approaches is needed
• Reducing the threat of global warming
(mitigation):
– Improve energy efficiency, rely on carbon-free
renewable energy resources, find ways to keep
anthropogenic carbon dioxide out of the
atmosphere
• Strategies would all be enhanced by reducing
population and reducing poverty
Carbon Sequestration
• Carbon sequestration is the process of capturing
and storing carbon dioxide emissions
• Many different methods available:
– Planting trees that sequester and remove
atmospheric carbon dioxide
– Soil sequestration- plants such as switchgrass can
remove carbon dioxide from the air and store it in
the soil
– Reducing emissions of carbon dioxide and nitrous
oxide from the soil- use no-till cultivation and set
aside depleted crop fields
– Remove carbon dioxide from smokestacks- carbon
dioxide is pumped deep underground or injected
deep into the ocean
• Problems: expensive, limited amount of carbon
dioxide can be removed, would increase cost of
electricity, could upset global carbon cycle and deepsea life
Solutions
Global Warming
Prevention
Cut fossil fuel use (especially
coal)
Shift from coal to
natural gas
Cleanup
Remove CO2 from smoke stack
and vehicle emissions
Store (sequester)
CO2 by planting trees
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
Limit urban sprawl
Reduce poverty
Sequester CO2 deep underground
Sequester CO2 in soil by using
no-till cultivation
and taking cropland out
of production
Sequester CO2 in the deep ocean
Repair leaky natural gas pipelines
and facilities
Use animal feeds that reduce CH4
emissions by belching cows
Slow population growth
Fig. 20-14, p. 481
Government Role in Reducing Climate Change
•
Could reduce using three major methods:
– Carbon taxes/energy taxes- taxes on each unit of carbon
dioxide emitted by fossil fuels or each unit of fossil fuel
burned
• Could offset cost by decreasing taxes on income, labor, and
profits
– Level economic playing field- greatly increase government
subsidies for energy-efficient technologies, carbon-free
renewable energy technologies, carbon sequestration, and
sustainable agriculture
• Reduce subsidies and tax-breaks for non-renewable energy
•
•
– Technology transfer- governments of developed countries
give renewable-energy technology to developing countries
U.N. Environment Program- projected global warming will cost
the world economy more than $300 million annually by 2050
– Implementing strategies might cost more in the short-term,
but would cost less in the long-term dealing with harmful
effects
Critics of plans say taking measures to combat global climate
change will hurt the economy too much to be useful
– Problems: do not take into account savings from using
renewable energy sources, underestimate ability of
marketplace to respond to economic initiatives,
underestimate potential costs of disasters and disease
from climate change
The Kyoto Protocol
•
1997: First negotiations of international legislation to reduce
greenhouse gas emissions took place in Kyoto, Japan
– 2,200 delegates from 161 countries
– Drafted the Kyoto Protocol, a resolution to cut emissions of
methane, nitrous oxide, and carbon dioxide by 5.2% of their
average levels (by country) by 2012
– 38 countries initially signed on
– Developing countries excluded because reducing emissions
might curb growth
– 2005: Phase 2 negotiations for after 2012
•
Protocol allows for “carbon trading,” which gives credits to
countries that reduce their emissions
– Can then use credits to avoid reducing emissions in other areas,
save for future use, or sell to other countries
•
•
U.S. did not sign onto Kyoto Protocol, citing harm to the U.S.
economy and exclusion of developing countries that have
high emissions (China, India, Brazil)
U.S. and Australia the only two “first world” countries that
have not signed on, although the U.S. in particular could use
its technology and leadership to set an excellent example in
progressive climate change action
Beyond Kyoto
•
•
Some believe excluding high-emissions developing countries will make the Kyoto
Protocol ineffective
– Call for new treaty, including emissions trading program, that includes those
countries
– Or other, faster and more drastic alternatives
Many countries, states, cities, businesses, schools, and individuals are taking their
own actions
– EU to increase use of renewable energy and cut energy use by 20% by 2020
– Japan to lead technological development of extremely energy-efficient
appliances
– Canada closing coal-burning power plants
– Chinese phasing out coal subsidies, shutting down inefficient plants, and
increasing energy efficiency and use of renewable energy
– California has goal of reducing ghg emissions to pre-1990 levels by 2020 and to
80% below 1990 levels by 2050
– Half of U.S. states have climate action programs
– Many companies setting goals for reducing emissions
• Including oil companies (BP spent $20 million to reduce ghg emissions to
1990 levels and saved $250 million, 32 times original investment)
• GE, Shell, Duke Energy, Wal-Mart pushed for Congress to regulate carbon
dioxide and impose mandatory emissions caps
Think Globally, Act Locally
• Ways to for businesses, schools, and individuals to
reduce emissions
– 25 Pennsylvania colleges joined to purchase wind power
for use on campuses
– Building energy-efficient new buildings and renovating old
ones
– Drive fuel-efficient cars, or walk, bike, carpool, or use
mass transit
– Use energy-efficient windows, appliances, lights, and
insulation
– Reduce garbage by recycling and reuse
– Insulate hot water heater and set no higher than
120°F/49°C
– Plant trees to shade house during summer
– Wash laundry in warm or cold water
– Use low-flow showerhead
– Buy products from companies that are trying to reduce
their climate impact
– Demand that the government make climate change a
priority
Preparing for Climate Change
• The world would need a 60% cut in
emissions of ghg to stabilize their
concentrations in the troposphere by 2050
• Wise to have some preparation (adaptation
strategy)
– Connect wildlife reserves with corridors
– Move hazardous materials storage tanks away
from the coast
– Expand existing wildlife reserves toward poles
– Stockpile supply of key foods
– Prohibit new construction in low-lying coastal
areas
– Waste less water, and develop crops that need
less water