Lecture 4: Global Warming and the Greenhouse Effect

Question 1

What is the greenhoues effect?

Answer 1

Some sunlight that hits the earth is reflected, some becomes heat. Greenhouse gases in the atmosphere trap heat, keeping the earth warm.

Question 2

What are the greenhouse gases?

Answer 2

Carbon dioxide, methane, nitrous oxide, CFC (chloro fluoro carbons)

Question 3

Basic elements of the global warming problem

Answer 3

1. Emissions of greenhouse gases
2. increases in the atmospheric concentration
3. increase in radiative forcing
4. increases in average temperature
5. Changes in global climate

Question 4

Stefan boltzman law:

Answer 4

Q max = sigma * A * T^4

Question 5

Climate vs weather

Answer 5

Climate is the average weather conditions of a place over a long period of time
Weather is the day to day conditions of the earth’s atmosphere at a particular place and time

Question 6

What fraction of the outgoin radiation form the earth is blocked by the atmosphere?

Answer 6

around 30% of the solar radiation is reflected by the atmosphere, 70% is absorbed.

Question 7

Troposhere

Answer 7

80% of gases
drives substantial air mixing. and movements
temp lowers are you go up

Question 8

strato sphere

Answer 8

protective ozone layer, increasing temp with altitude

Question 9

Greenhouse effect:

Answer 9

If we were to increase the concentration of gases such as CO2
, CH4
, N2O, and H2O in the
atmosphere ➔more absorption ➔ making the atmosphere’s ratio of outgoing to incoming
transparency decline.
• In turn, the average temperature of the earth would rise, thus producing the so-called greenhouse
effect.
• The group consisting of CO2
, CH4
, N2O, etc. are collectively called greenhouse gases

Question 10

Indicators of global warming

Answer 10

Global temperature rise
warming oceans
shrinking ice sheets, glacia retreat
sea level rise
extreme weather
ocean acidification

Question 11

1) Global temperature rise:

Answer 11

• Earth’s average surface temperature has risen about 0.9 degrees Celsius since the late
19th century, a change driven largely by increased CO2 and other anthropogenic
emissions into the atmosphere.
• Most of the warming occurred in the past 35 years

Question 12

2) Warming oceans

Answer 12

The oceans have absorbed much of this increased heat, with the top 700 meters
(about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since
1969
• The warming of the oceans has widespread effects. -
→ It causes marine heat waves that kill fish and coral reefs, fuels hurricanes and
coastal downpours, spawns harmful toxin-producing algal blooms

Question 13

3) Shrinking ice sheets, glacial retreat

Answer 13

Mountain glaciers all over the world are in retreat.

Question 14

4) sea level rise

Answer 14

• Melting ice sheets and glaciers
• Expansion of seawater with temperature increase
• Global sea level rose about 8 inches in the last century. The rate in the last two decades is
nearly double that of the last century.

Question 15

5) extreme weather

Answer 15

Heat waves
• Drought
• Heavy downpours
→ The increase in evaporation (fairly uniform globally) implies an increase in precipitation (not
uniform), because the atmosphere can’t store water vapor indefinitely
• Floods
• Hurricanes
• Increased winter storm in Easter North America

Question 16

6) ocean acidification

Answer 16

Ocean acidification is the ongoing decrease in the pH of the Earth’s oceans, caused by the uptake
of CO2
from the atmosphere.
• Seawater is slightly basic (meaning pH > 7), and ocean acidification involves a shift towards pHneutral conditions rather than a transition to acidic conditions (pH < 7).
• An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere
dissolves into oceans, rivers and lakes. Some of it reacts with the water to form carbonic acid

Question 17

CO2 Emissions and energy use

Answer 17

Most of the energy used throughout the world is in the form of fossil fuels: oil, coal and
natural gas.
• Fossil fuels supply energy for transportation and industrial processes.
• Fossil fuels account for 75 % of the world’s annual energy consumption

Question 18

The lifetime of Greenhouse gases

Answer 18

THe atmospheric concentration of GHG will undergo an exponetial decay. THe longer the atmospheric lifetime, the slower and more gradual the depletion

Question 19

stabilization scenarios

Answer 19

They show how atmospheric CO2 concentrations migh tbe stablilized at levels from 450 to 1000 ppmv CO2. THis process is assuemd to take 75 -400 years, and it requires a substantial reduction in anthropogenic CO2