Chapter 30: Global Climate Change

Madrona, A.

1

Chemical compounds naturally

present in the Earths atmosphere:

Water vapor (H20)

Carbon dioxide (CO2)

Ozone (O3)

These compounds absorb thermal

radiation emitted by the Earths

surface and atmosphere

Greenhouse effect

Average surface air temp of

Earth is about 30C or higher

than it would be w/o

atmospheric absorption and

reradiation of thermal

energy.

Gases responsible for this

effect: greenhouse gases

Amount of energy incoming from

the sun = amount radiated back

into space

Industrial period conc. Of

greenhouse gases increased

dramatically

Major concern is the rise of CO2

levels

Atmospheric conc. has risen

by >30% over the past 100

years

2008, >70% of total CO2

emissions from burning fossil

fuels came from developed

countries (China = 22% of

total emissions)

Deforestation

A major cause of rising

atmospheric CO2

Average annual amount of C released

to the atmosphere in 1990 = 8.5Gt

Approx. 6.3Gt = fossil fuels

2.2Gt = forest clearing

Direct measurements of atm.

CO2 is only 3.2Gt

5.3Gt must have flowed from

the atmosphere into the main

pools I the global carbon

cycle: oceans and terrestrial

ecosystems

Diffusion

Controls the uptake of CO2

from the atmosphere into the

oceans

Net uptake of terrestrial

ecosystems (o.7Gt) =

Any possible net uptake of

carbon by terrestrial

ecosystems may result from

reforestation in temperate

regions of the Northern

hemisphere

Diffusion gradient

Difference in concentrations

Rate of diffusion from the

atmosphere to the surface

waters of the ocean

Rise in atmospheric conc. of

CO2 = rise in diffusion of

CO2 into surface waters

Ocean

Functions as two layers:

1. Surface waters

2. Deep waters

(Thermocline transition bet. 2

layers)

Ave. depth: 2000 m

Intercepted solar radiation

warms the surface waters

Zone of warm water 75-200 m in

depth

Ave. temp of surface: 18C

Ave. temp of deep: 3C

Mixing bet. surface and deep

depends on deep ocean currents

Emissions from

Fossil fuels

(6.3 Gt)

Atmospheric

Increase

(3.2 Gt)

Ocean

Uptake

(2.4 Gt)

- -

Chapter 30: Global Climate Change

Madrona, A.

2

caused by the sinking of surface

waters as they move toward the

poles

The amount of CO2 that can be

absorbed by the oceans over the

short term is limited

Elevated CO2 conc. has two direct,

short term effects on plants:

1. Increase rate of

photosynthesis

CO2 fertilization effect

higher rates of diffusion

and photosynthesis under

elevated atmospheric conc.

of CO2

2. Causes stomata to partially

close, reducing water loss

due to transpiration thus

increasing plants water

efficiency

C3 plants respond

most strongly to

elevated CO2, ave.

increase in biomass of

47%

CAM plants 21%

C4 plants 11%

In some studies, enhanced effects

of CO2 in plant growth have been

short-lived

Downregulation

- Some plants produce less

of rubisco, reducing

photosynthesis.

Some plants produce fewer

stomata on the leaf surface

to reduce water loss, total

carbon uptake, and growth

rate

Elevated CO2 resulted in

consistent increase in NPP

(net primary productivity)

Over the past 100 years

Earths ave. surface temp

increased by approx. 0.74C

1995-2010 rank among the

warmest years (actually

nabasa ko na 2014 warmest

year yet Pero olds na tong

book na to so yeah.)

Greenhouse gasses that

increase due to human

activity:

o CO2

o Methane CH4

o CFCs

o HCFCs

o Nitrous oxide N2O

o Ozone O3

o Sulfur oxide SO2

General circulation models (GCMs)

- Used in determining how

increasing conc. of

greenhouse gases influence

large-scale patterns of

global climate

- General patterns of an

increase in average global

temperature as well as global

precipitation are observed

o Consistent qualitative

predictions of GCMs lead

scientists to believe that

rising concentrations of

atmospheric CO2 will

significantly affect global

climate

Changes in climate will affect

ecosystems at many levels

o Self-explanatory na naman

siguro ito. Puro expt and

studies lang to

Changing climate will shift the

global distribution of ecosystems

o Migration rates depend on how

well a species physiology,

dispersal ability, and

competitive interactions with

other tree species let it

Chapter 30: Global Climate Change

Madrona, A.

3

respond to changes in climate

o Deforestation

- is the single major cause

of species extinction in

the tropics

Climate change would raise sea

level and affect coastal

environments

- Glaciers melted, sea level

rose

- Rises at a rate of 1.8mm/year

- Direct inundation of low-

lying wetlands and drylands

- Erosion of shorelines through

loss of sediments

- Increased salinity of

estuaries and aquifers

- Rising coastal water tables

- Increased flooding and water

surges

Climate change will affect

agricultural production

- Most crop species will

benefit from a rise in CO2

conc.

- Negative effects are to some

extent compensated for by

increased productivity

resulting from elevated

atmospheric concentrations of

CO2

Climate change will directly and

indirectly affect human health

Direct: increased heat

stress, asthma, and other

cardiovascular and

respiratory ailments

Indirect: increased incidence

of communicable diseases,

increased mortality and

injury due to increased

natural disasters, changes in

diet and nutrition due to

changed agricultural

production

Global ecology

- Needed to understand the

effect of rising atmospheric

concentrations of greenhouse

gases and global climate

change

Tropical rain forests

- most productive terrestrial

ecosystems on the planet

- when shrunk, atmospheric CO2

rises and thus will increase

the greenhouse effect