温室效应英文

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英文演讲稿

环保

温室效应

Here are some tips :

1.

Change the light

Replacing one regular bulb with a compact fluorescent light bulb will save 150 pounds of carbon

dioxide a year.

2.

Recycle more

It is said that in Japan, people are requested to separate the waste in different kinds. And the trash

man would only collect one kind of waste each day. That can be a perfect way to recycle.

3.

Use less hot water

It takes a lot of energy to heat water. Use less hot water by installing a low flow showerhead and

washing your clothes in cold or warm water.

4.

Adjust your air conditioner

Moving your air conditioner just 2 degrees in winter and up 2 degrees in summer. You could save

about 2,000 pounds of carbon dioxide a year with this simple adjustment.

5.

Plant a tree

A single tree will absorb one ton of carbon dioxide over its lifetime.

6.

Turn off electronic devices

Simply turning off your television, DVD player and computer when you’re not using them will

save you thousands of pounds of carbon dioxide a year.

Global warming has already been a very serious problem

in the world. Even in our generation,

varieties of birds singing are silenced, beautiful coral reefs are no longer be seen. It is a real pity

that

when

I’m

telling

my

son

about

the

dream

when

I

was

young.

He

can

never

know

a

place

named Great Barrier Reef.

Thank you very much.

英文资料

-

温室效应

!

The Greenhouse Effect

The greenhouse effect is a naturally occurring process that aids in

heating

the

Earth's

surface

and

atmosphere.

It

results

from

the

fact

that

certain atmospheric gases, such as carbon dioxide, water vapor, and

methane,

are

able

to

change

the

energy

balance

of

the

planet

by

absorbing

longwave radiation emitted from the Earth's surface. Without the

greenhouse effect life on this planet would probably not exist as the

average

temperature

of

the

Earth

would

be

a

chilly

-

18°

Celsius,

rather

than the present 15° Celsius.

As energy from the sun passes through the atmosphere a number of things

take place (see Figure 7h-1). A portion of the energy (26 % globally) is

reflected or scattered back to space by clouds and other atmospheric

particles.

About

19

%

of

the

energy

available

is

absorbed

by

clouds,

gases

(like ozone), and particles in the atmosphere. Of the remaining 55 % of

the

solar

energy

passing

through

the

Earth's

atmosphere,

4

%

is

reflected

from the surface back to space. On average, about 51 % of the sun's

radiation reaches the surface. This energy is then used in a number of

processes, including the heating of the ground surface; the melting of

ice and snow and the evaporation of water; and plant photosynthesis.

The

heating

of

the

ground

by

sunlight

causes

the

Earth's

surface

to

become

a radiator of energy in the longwave band (sometimes called infrared

radiation). This emission of energy is generally directed to space (see

Figure

7h-2).

However,

only

a

small

portion

of

this

energy

actually

makes

it back to space. The majority of the outgoing infrared radiation is

absorbed by the greenhouse gases (see Figure 7h-3 below).

Figure 7h-3: Annual (1987) quantity of outgoing longwave radiation

absorbed in the atmosphere.

(Image created by the CoVis Greenhouse Effect Visualizer).

Absorption

of

longwave

radiation

by

the

atmosphere

causes

additional

heat

energy to be added to the Earth's atmospheric system. The now warmer

atmospheric greenhouse gas molecules begin radiating longwave energy in

all

directions.

Over

90

%

of

this

emission

of

longwave

energy

is

directed

back

to

the

Earth's

surface

where

it

once

again

is

absorbed

by

the

surface.

The heating of the ground by the longwave radiation causes the ground

surface

to

once

again

radiate,

repeating

the

cycle

described

above,

again

and again, until no more longwave is available for absorption.

The

amount

of

heat

energy

added

to

the

atmosphere

by

the

greenhouse

effect

is controlled by the concentration of greenhouse gases in the Earth's

atmosphere. All of the major greenhouse gases have increased in

concentration since the beginning of the Industrial Revolution (about

1700

AD).

As

a

result

of

these

higher

concentrations,

scientists

predict

that

the

greenhouse

effect

will

be

enhanced

and

the

Earth's

climate

will

become warmer. Predicting the amount of warming is accomplished by

computer modeling. Computer models suggest that a doubling of the

concentration of the main greenhouse gas, carbon dioxide, may raise the

average

global

temperature

between

1

and

3°

Celsius.

However,

the

numeric

equations of computer models do not accurately simulate the effects of

a

number

of

possible negative

feedbacks.

For

example,

many

of the

models

cannot

properly

simulate

the

negative

effects

that

increased

cloud

cover

would have on the radiation balance of a warmer Earth. Increasing the

Earth's temperature would cause the oceans to evaporate greater amounts

of water, causing the atmosphere to become cloudier. These extra clouds

would

then

reflect

a

greater

proportion

of

the

sun's

energy

back

to

space

reducing

the

amount

of

solar

radiation

absorbed

by

the

atmosphere

and

the

Earth's surface. With less solar energy being absorbed at the surface,

the effects of an enhanced greenhouse effect may be counteracted.

A number of gases are involved in the human caused enhancement of the

greenhouse effect (see Table 7h-1 below). These gases include: carbon

dioxide (CO2); methane (CH4); nitrous oxide (N2O); chlorofluorocarbons

(CFxClx); and tropospheric ozone (O3). Of these gases, the single most

important

gas

is

carbon

dioxide

which

accounts

for

about

55

%

of

the

change

in the intensity of the Earth's greenhouse effect. The contributions of

the other gases are 25 % for chlorofluorocarbons, 15 % for methane, and

5 % for nitrous oxide. Ozone's contribution to the enhancement of

greenhouse effect is still yet to be quantified.

Concentrations of carbon dioxide in the atmosphere are now approaching

360 parts per million

(see Figure 7a-1).

Prior to 1700,

levels of carbon

dioxide

were

about

280

parts

per

million.

This

increase

in

carbon

dioxide

in

the

atmosphere

is

primarily

due

to

the

activities

of

humans.

Beginning

in 1700, societal changes brought about by the Industrial Revolution

increased

the

amount

of

carbon

dioxide

entering

the

atmosphere.

The

major

sources of this gas include fossil fuel combustion for industry,

transportation, space heating, electricity generation and cooking; and

vegetation

changes

in

natural

prairie,

woodland,

and

forested

ecosystems.

Emissions

from

fossil

fuel

combustion

account

for

about

65

%

of

the

extra

carbon

dioxide

now

found

in

our

atmosphere.

The

remaining

35

%

is

derived

from

deforestation

and

the

conversion

of

prairie,

woodland,

and

forested

ecosystems primarily into agricultural systems. Natural ecosystems can

hold 20 to 100

times more

carbon dioxide per unit area than agricultural

systems.

Artificially created chlorofluorocarbons are the strongest greenhouse

gas per molecule. However, low concentrations in the atmosphere reduce

their overall importance in the enhancement of the greenhouse effect.

Current measurements in the atmosphere indicate that the concentration

of

these

chemicals

may

soon

begin

declining

because

of

reduced

emissions.

Reports of the development

of ozone holes over

the North and

South Poles

and

a

general

decline

in

global

stratospheric

ozone

levels

over

the

last

two decades has caused many nations to cutback on their production and

use of these chemicals. In 1987, the signing of the Montreal Protocol

agreement

by

forty-six

nations

established

an

immediate

timetable

for

the

global reduction of chlorofluorocarbons production and use.

Since 1750, methane concentrations in the atmosphere have increased by

more than 140 %.

The primary

sources for the additional methane

added to

the atmosphere (in order of importance) are rice cultivation, domestic

grazing animals, termites, landfills, coal mining, and oil and gas

extraction. Anaerobic conditions associated with rice paddy flooding

results in the formation of methane gas. However, an accurate estimate

of

how

much

methane

is

being

produced

from

rice

paddies

has

been

difficult

to

obtain.

More

than

60

%

of

all

rice

paddies

are

found

in

India

and

China

where scientific data concerning emission rates are unavailable.

Nevertheless, scientists believe that the contribution of rice paddies

is

large

because

this

form

of

crop

production

has

more

than

doubled

since

1950. Grazing animals release methane to the environment as a result of

herbaceous digestion. Some researchers believe the addition of methane

from

this

source

has

more

than

quadrupled

over

the

last

century.

Termites

also release methane through similar processes. Land-use change in the

tropics, due to deforestation, ranching, and farming, may be causing