Global warming (2011)

— Debating the issues Summary: “Examines two sides of the global warming debate and whether or not human activities are causing it; defi nes global warming; explains the science of clima

GLOBAL WARMING

Sharon

Debating Global Warming

Debating Global Warming

No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or

by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission

of the copyright owner Request for permission should be addressed to the Publisher, Marshall Cavendish Corporation, 99 White Plains Road, Tarrytown, NY 10591 Tel: (914) 332-8888, fax: (914) 332-1888.

Website: www.marshallcavendish.us This publication represents the opinions and views of the author based on L H Colligan’s personal experience, knowledge, and research The information in this book serves as a general guide only

The author and publisher have used their best efforts in preparing this book and disclaim liability rising directly and indirectly from the use and application of this book.

Other Marshall Cavendish Offi ces:

Marshall Cavendish International (Asia) Private Limited, 1 New Industrial Road, Singapore 536196 • Marshall Cavendish International (Thailand) Co Ltd 253 Asoke, 12th Flr, Sukhumvit 21 Road, Klongtoey Nua, Wattana, Bangkok 10110, Thailand • Marshall Cavendish (Malaysia) Sdn Bhd, Times Subang, Lot 46, Subang Hi-Tech Industrial Park, Batu Tiga, 40000 Shah Alam, Selangor Darul Ehsan, Malaysia

Marshall Cavendish is a trademark of Times Publishing Limited All websites were available and accurate when this book was sent to press.

Library of Congress Cataloging-in-Publication Data Colligan, L H.

Global warming / L.H Colligan.

p cm — (Debating the issues) Summary: “Examines two sides of the global warming debate and whether or not human activities are causing it; defi nes global warming; explains the science of climate change, and its potential effects on the planet.”—Provided by the Publisher.

Includes bibliographical references and index.

ISBN 978-0-7614-4971-3 (print)—ISBN 978-1-60870-664-8 (ebook)

1 Global warming—Juvenile literature I Title

QC981.8.G56C58 2012 363.738’74—dc22 2010039299 Editor: Peter Mavrikis Publisher: Michelle Bisson Art Director: Anahid Hamparian Series design by Sonia Chaghatzbanian Photo research by Alison Morretta

Front cover: Paul Souders/Getty Images.

Associated Press: NASA, 27; Stephanie Krell/Record-Courier, 30; Diana Haecker, 42; Jeff Gentner, 51;

Toby Talbot, 52 Bridgeman Art Library: Yale Center for British Art/Paul Mellon Collection, 21 Getty Images: Bernhard Lang, 9; StockTrek, 12; Vin Morgan/AFP, 17; Andrew Harrer/Bloomberg, 24; Gordon

Wiltsie, 26; David McNew, 34; Ashley Cooper/Visuals Unlimited, 36; U.S Geological Survey, 41; Bates

Littlehales/National Geographic, 45; Paul Souders, 48; George Rose, 54 Nancy Sabato: 15, 38 NASA:

Goddard Institute for Space Studies, 10 Superstock: age fotostock, 1, 2-3, 4-5, 6; Design Pics, 13; Science

Faction, 18; Science and Society, 23, 29; Ambient Images, 46.

Back cover: Mark S Wexler/Getty Images.

Printed in Malaysia (T) 135642

Sharon

Debating Global Warming

5 T able of C

Chapter 1 Is It Getting Hotter or Not? 7

Chapter 2 One Side: Human Activities

Are Not Causing Global Warming 19

Chapter 3 The Other Side: Human Activities Are

the Main Cause of Global Warming 35

Chapter 4 You Decide 49

Global Warming Debate Summary 56

Debating Global Warming

Chapter 1

Droughts are always a threat in California, which receives little rainfall The state must depend on unpredictable snowmelt from the Sierra Nevada because rain is often scarce during the spring planting season

Imagine that you are growing up on a central California farm fi fty years from now Crops from the farm once traveled to customers all over the country, but not anymore Because

of droughts (long dry spells), the consequent drying out of the soil,

and the multiplication of agricultural pests, the land now grows barely enough food for your family

Annual melting snows slowed to a trickle before you were born

The rivers and reservoirs that watered your valley dried up, too The farm’s fruit trees burned in a wildfi re that grew out of control during a severe drought several years ago When storms do come, they are so intense that the water runs off and washes away valuable topsoil

Your family is thinking of moving to Alaska or Canada Long ters are mainly a thing of the past up north Some northern areas now have the longest growing seasons in the world However, Canada and

win-Alaska have plenty of problems, too Not only people are migrating

northward Disease-causing insects that sicken people, animals, and plants have moved north as well Bark-eating beetles have killed huge numbers of trees, as have forest fi res

Plant scientists developed heat- and insect-resistant fruit trees and nut trees and other crops suitable for dry climates Your family was the

fi rst to try out the experimental plants These new crops began to fl ish on all the farms in your valley Engineers also fi gured out new ways

our-to capture, sour-tore, and recycle water

People told stories about how hot it was during the fi rst half of the twenty-fi rst century Then people began to live in houses designed for

coolness in summer and warmth in winter Solar (sun-powered)

cool-ing and heatcool-ing systems became so affordable that most houses had them With plenty of drought- and disease-resistant trees surrounding your house, the heat was not too hard to take

In addition, the climate changed Average world temperatures

start-ed to drop a bit So what happenstart-ed to global warming? It turnstart-ed out that most scientists in the late twentieth century and the early twenty-

fi rst were wrong about what caused it Most scientists thought that

Sharon

Debating Global Warming

burning fossil fuels—oil, coal, and gas—had caused the earth to warm

up However, a small number of skeptical scientists believed that

natu-ral events were increasing ocean and land temperatures Then natunatu-ral events caused the earth to cool down again Could either of these two imaginary situations happen?

What Is Global Warming?

Global warming is not the local weather forecast, a summer heat wave,

or a few warm winters Global warming is the rise in average land and

ocean temperatures on the planet Earth Since about the mid–1800s, the worldwide average temperature has been going up—about 1.4 de-grees Fahrenheit (1.4°F), or 0.8 degrees Celsius (0.8°C)—much of it

after 1970 During that upward trend, many cold and warm periods

have come and gone However, the warm extremes have come twice

as often as the cold extremes In 2010, an environmental professor

The use of solar power in homes and power plants has been increasing about 40 percent a year in the last decade

Sharon

Debating Global Warming

GLOBAL WARMING

at Oberlin College, David Orr, said, “We’re setting climate records

at a record-setting pace More hottest hots, driest dries, wettest wets, windiest wind conditions.” These extremes are happening just as the

overall temperature trend is up.

Do a couple of degrees really matter? About twenty thousand years ago, when the earth’s average temperature was just a few degrees cold-

er than it is now, much of the planet was covered with thick ice sheets

That is something that matters The few extra degrees of warmth the

earth is experiencing now are coming at the same time as melting

gla-ciers, ice sheets, and ice shelves, along with rising sea levels, record

droughts, wild storms, and wildfi res Climatologists (climate scientists)

are asking, “What is causing these climate-related events?”

Over half of the earth’s average temperature rise since 1880 has taken place since 1980.

Sharon

Debating Global Warming

IS IT GETTING HOTTER OR NOT?

Running Hot and Cold

The earth’s climate is always changing Throughout its

four-and-a-half-billion-year history, natural events called climate forcings have

some-times made Earth colder and somesome-times warmer than it is now Natural

forcings include the sun, Earth’s orbit around the sun, ocean currents,

volcanoes, clouds, and gases

One major climate forcing is the earth’s sun The planet has a

pro-tective atmosphere made up of gases that has allowed in the ideal

amount of sunlight for life on the earth to fl ourish

Slight orbit changes are another climate forcing Earth’s orbit affects how much sunlight reaches it If less sunlight hits the oceans, for ex-ample, ocean currents can change Like warm and cold rivers, currents

fl ow within the world’s oceans Sunlight, temperatures, wind, and the salt in ocean water all affect the temperature and movements of ocean currents and the air above them

Natural disturbances in Earth’s atmosphere are other climate ings Weather forecasters often talk about El Niño and La Niña These are two disruptions in the ocean and atmosphere that, like a lamp or an appliance, switch on and off every few years When El Niño is active, it warms the ocean and air It is linked with droughts and other undesir-able weather events around the world La Niña is less disruptive and is linked with cooler ocean and air temperatures

forc-Exploding volcanoes are another kind of climate forcing Volcanic particles refl ect the heat of the sun and can cool the planet for a couple

of years after a huge volcano explodes

Sharon

Debating Global Warming

GLOBAL WARMING

Who Turned Up the Heat?

Some climatologists and environmentalists who measure the earth’s

health say the biggest, most damaging climate forcing ever is taking place now This forcing, they say, is not the sun, ocean currents, earth-quakes, or volcanoes—it is the human race

Other scientists contend that humans are not powerful enough to change something as big as the climate The two sides are arguing

about greenhouse gases These heat-trapping substances protect the

planet from the sun and cold almost the way an enclosed greenhouse protects its contents

Fortunately for the human race, natural climate forcings have kept the earth’s climate fairly steady for about twelve thousand years Dur-ing that time, people learned to farm and raise animals Societies built villages and cities, pyramids and cathedrals, factories and universities

Ash from the Philippines’ 1991 Mount Pinatubo volcano, along with another eruption, temporarily cooled the earth’s temperature by 1.8°F (1°C) for about two years

Sharon

Debating Global Warming

IS IT GETTING HOTTER OR NOT?

As natural forcings made the planet a comfortable place to live, mans invented everything from the wheel to computers

hu-Living in a Greenhouse

Anyone who has ever walked through a greenhouse on a sunny day has noticed how hot and humid it gets in there, even when it is cold outside Sunlight alone is enough to heat up the plants, people, and other living organisms inside The moisture and gases they give off fi ll the greenhouse

If someone built a wood fi re inside the greenhouse, the mix of gases would change The temperature would rise, and the living things

Everything on Earth releases heat and energy called infrared radiation For the last two hundred years or so, gas levels have been building up in the atmosphere and trapping more infrared and solar radiation the way a greenhouse traps water vapor.

Sharon

Debating Global Warming

GLOBAL WARMING

might overheat Within the earth’s enclosed atmosphere, a similar kind

of greenhouse effect occurs.

Helpful Heat Trappers

Earth’s most abundant greenhouse gas is water vapor It comes from

oceans, rivers, lakes, streams, soil, and all other living things when they

warm up As temperatures rise, water evaporates into the atmosphere,

where it is seen as fog, mist, rain, snow, ice, clouds, or gas, depending

on the temperature

Carbon dioxide—often simply called CO2—is the second most common greenhouse gas It is a waste product that all living cells pro-duce When a dead organism—an animal, human, insect, fl ower, tree,

fi sh, or microscopic creature—decays or burns, all the carbon energy

stored in its cells is released

For billions of years, countless plant organisms took in the sun’s

ener-gy while they were alive After they died, their carbon remains

eventual-ly wound up at the bottom of the oceans or covered with soil Immense heat and pressure deep in the planet “cooked” these ancient carbon remains into coal, oil, and natural gas These substances are called fossil fuels (a fossil is a remnant of an organism that died off ages ago) Re-lease of stored carbon energy into the atmosphere sped up when people started to cut down and burn forests and make use of fossil fuels

The planet’s atmospheric greenhouse, which is about

75 miles (120 kilometers)

D I D Y O U K N O W ?

The earth’s stored carbon energy, in the form of coal,

oil, and natural gas, built up over millions of years

Much of this carbon has been released in the last

few hundred years as people burned fossil fuels.

Sharon

Debating Global Warming

IS IT GETTING HOTTER OR NOT?

deep, is a busy place Gases and chemicals constantly mix tures go up and down Since about 1900, the mix of gases in the at-mosphere has changed There is more carbon dioxide than in the past

Tempera-owing to deforestation and

the burning of fossil fuels

hap-pens to trap heat more

ef-fi ciently than water vapor and other greenhouse gases

do, and it stays in the

Many climate scientists have reached the same conclusion after looking at the data: the earth warmed up noticeably as soon as people

D I D Y O U K N O W ?

During the steamboat era of the 1800s, loggers cut down and burned wood from forests along the Mississippi and other rivers to power steamboats and factories This deforestation and burning

Water Vapor 36%-72%

Methane

4%-9%

Ozone 3%-7%

Nitrous Oxide and other 9%-18%

Carbon Dioxide 9%-26%

Carbon dioxide lasts over a hundred years longer in the atmosphere than water vapor, which

is the largest greenhouse gas.

Sharon

Debating Global Warming

GLOBAL WARMING

started burning huge quantities of fossil fuels Was this rise in ture a coincidence?

tempera-A 2007 report issued by the UN Intergovernmental Panel on Climate

no coincidence “Warming of the climate system is unequivocal [without

a doubt] Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic [human-caused] greenhouse gas concentrations.”

levels and warmer temperatures appeared at the same time, they reply, it does not mean that one thing caused the other You might just as well say that the sun caused an earthquake that took place on a sunny day

An observer reading these two opinions might fi nd it hard to lieve that these two sets of experts are describing the same planet

be-WHAT DO YOU THINK?

Have you ever talked to older family members about what the general climate was like when they were your age? If so, what did they have to say about differences in the climate between then and now?

Why do you think that climate experts who study the same evidence come up with different opinions?

Sharon

Debating Global Warming

IS IT GETTING HOTTER OR NOT?

HOW COOL IS THAT?

To discover what temperatures were in the past, climatologists examine tree rings in old forests to see which periods had more or less rain and higher or lower

temperatures To learn what plants grew or died out as a result of cold or heat, they dig deep into the earth and oceans to study sands and mud from millions

of years ago Researchers also study ice cores drilled out from ice sheets that

formed millions of years ago, when new layers of snow pressed down on old ones and formed ice.

In the early 1950s, a Danish scientist named Willi Dansgaard realized that each air bubble trapped in ice was a clue to the planet’s past climate These air bubbles enclosed the gases, chemicals, and particles present in the atmosphere

at the time the ice formed Over the next decades, engineers carved out a great many ice cores to study them.

The cores provided information about past temperatures, space dust,

precipitation, solar activity, and pollution Some contained ash particles from

volcanic explosions, including the very famous explosion of Mount Vesuvius,

in the ancient Roman city of Pompeii,

in the year 79 CE

In 2008, climatologists who examined ice-core samples from Antarctica that were about 800,000 years old reported their fi ndings in Nature, a science magazine These samples showed that high levels of carbon dioxide and warm global tem- peratures appear together throughout Earth’s history, whether humans were

on the scene or not.

Coal dust and greenhouse gases from the start of the Industrial Revolution appear in ice-core samples dating from the 1700s and 1800s.

Sharon

Debating Global Warming

Debating Global Warming

Some climate engineers have been trying to duplicate the cooling effects of volcanic ash that sometimes blocks the sun’s heat and lessens the effects of global warming.

at least a hundred years So what are they arguing about?

The debate comes down to this: are human activities that increase

causing global warming?

Among the scientists who answer no is Richard Lindzen, a

profes-sor of atmospheric science at Massachusetts Institute of Technology

(MIT) In 2006, he wrote the following in the Wall Street Journal:

Three claims have widespread scientifi c support: Global ture has risen about a degree since the late 19th century; levels of

tempera-CO2 in the atmosphere have increased by about 30 percent over the same period; and CO2 should contribute to future warming These claims are true However, what the public fails to grasp is that the claims [do not] establish man’s responsibility for the small amount of warming that has occurred.

So why is the earth getting warmer? Look to nature, say Lindzen and many others

Sharon

Debating Global Warming

GLOBAL WARMING

GLOBAL COOLING AND THE LITTLE ICE AGE

For hundreds of winters, ice-skaters glided along Amsterdam’s canals in the Netherlands In 1536, England’s King Henry VIII traveled by sleigh along the frozen Thames River near London For a long period of time, Londoners gathered at annual

“frost fairs” set up on the frozen Thames During the same especially cold period, the Golden Horn harbor in Istanbul, Turkey, froze over and shut down the winter shipping trade Glaciers slowly growing down from Swiss mountaintops crushed villages and farms below Near Africa’s Sahara Desert, snow covered certain high mountain peaks where snowfalls have not been recorded since In North America in 1608, Lake Superior was iced in until June In 1780, New York City’s harbor froze between Manhattan and Staten Island New Yorkers could walk from one island to the other.

What was going on with the weather during the roughly fi ve hundred cold years that began around 1300 and ended around 1850? Climatologists call that period the Little Ice Age During most of those centuries, the average temperature drop is thought to have been about 1.8°F (1.0°C).

That drop in average worldwide temperatures may seem small, but its negative effects lasted for centuries Early on, the abnormally cold weather led to malnutrition and even starvation Because of starvation, exposure to cold, sickness, wars, and, most of all, a plague called the Black Death, the population of Asia and Europe fell by over 100 million people in the fourteenth century.

What caused the Little Ice Age? The majority of today’s climatologists think the causes were low solar activity, high volcanic activity, and a drop in the greenhouse gas carbon dioxide (CO2) This drop in carbon dioxide may have come about because the world lost about a quarter of its population early on, around 1350, due

to famine, disease, and wars The Little Ice Age dropped the average temperature

by 1.8°F (1°C) That meant millions fewer people cut down trees for farming or burned them for warmth and cooking As forests grew back and trees absorbed more CO2, temperatures cooled Some theorize that the Little Ice Age ended when increased solar radiation began to warm the globe again After that, the human population increased steeply Others think that certain human activities, such as deforestation and, later, manufacturing, led to raised CO2 levels, which in turn may have warmed up the earth

Sharon

Debating Global Warming

ONE SIDE: HUMAN ACTIVITIES ARE NOT CAUSING GLOBAL WARMING

London’s Thames River regularly froze over during winters from the 1600s to the early 1800s Warmer temperatures and changes to the river since then ended the celebrations

of London’s winter frost fairs

Natural Events, Not People, Are to Blame

Scientists point out that temporary natural climate forcings always change global temperatures Big climate changes happened long be-fore humans cut down forests or burned fossil fuels So how can people alone be responsible for today’s global warming?

Tad Murty, a Canadian oceanographer at the University of Ottawa, made this point in 2005: “The atmosphere hasn’t changed much in 280 million years, and there have always been cycles of warming and cooling.”

Sharon

Debating Global Warming

GLOBAL WARMING

In 2007, Reid Bryson, a professor of meteorology at the University

of Wisconsin, said, “Of course [the temperature is] going up It has gone up since the early 1800s, before the Industrial Revolution, be-cause we’re coming out of the Little Ice Age, not because we’re putting more carbon dioxide into the air.”

THE SUN

Some climatologists who study solar activity think that the sun causes global warming, not hu-

fuels A Russian space scientist, Habibullo Abdusamatov, says that increased solar activity warmed world temperatures in the last cen-tury until about thirty years ago

He says that the sun is still causing temperature change, only in the other direction In early 2008, Ab-dusamatov predicted that reduced solar activity over the last thirty years would bring about a drop in global temperatures for some time to come Abdusamatov says that this relatively lower level of solar activity

Low sunspot activity since the early twenty-fi rst century

means temperatures should have been cooler than they are.

Sharon

Debating Global Warming

oceanog-do State University, argues, “This small warming is likely a result of the natural alterations in global ocean currents, which are driven by ocean salinity [salt level] variations Humankind has little or nothing to do with the recent temperature changes We are not that infl uential.”

WATER VAPOR AND CLOUDS

Water vapor is the largest greenhouse gas, and some climate experts say that it has been paid far too little attention A Canadian water vapor

Natural and human-generated water vapor make up the biggest greenhouse gas Unlike other greenhouse gases, though, water vapor evaporates quickly.

Sharon

Debating Global Warming

GLOBAL WARMING

triggers the major greenhouse gas, water vapor, which may eventually cool the planet, not warm it up.”

A 2008 study published in the Journal of Climate argued that natural

changes in clouds cause temperature changes, not the other way around

The article also suggests that researchers on the “human-caused” side of the global warming debate do not understand the importance of clouds

Global Warming Problems

Climate news often sounds deliberately depressing Ice shelves are

breaking off in the Arctic and Antarctic polar regions Sea levels are

ris-ing around the world Arctic ice is beris-ing lost, and polar bears are ing in their search for food The world’s oceans are absorbing dangerous

in a way that leaves the impression that they are happening more often than ever before

Are people really to blame? A majority of climate scientists say that

if human-caused global warming is not stopped, these environmental problems will destroy our way of life Other climate scientists view these problems differently or reject their signifi cance altogether

ONE SIDE: HUMAN ACTIVITIES ARE NOT CAUSING GLOBAL WARMING

any computer models had predicted With less white ice covering the

ocean, its dark surface would soak up more solar heat This feedback

loop could make the earth hotter.

However, skeptical scientists point out that a reduction in Arctic ice might produce a positive economic effect with the opening of shorter shipping routes Exploration for oil and gas sealed under the ice could also begin

levels and temperatures increase because of human activities, then why did sea ice loss go down in 2008? The same scientists who ask that question also point out that ice is growing in parts of Antarctica and possibly in the center of Greenland’s huge ice sheet

RISING SEA LEVELS

Sea levels rise for several reasons As ocean temperatures warm up, the seawater’s volume expands Also, warmer temperatures melt more land ice and bring more storms, both of which raise sea levels (In fact, melting sea ice does not raise sea levels any more than the ice cubes

in a drink cause the liquid to overfl ow as they melt.)Some experts worry that rising sea levels might cause major coastal cities, such as Miami and New York, to disappear Others do not think seas will rise nearly that much and point out that similar predictions made just a few decades ago were wrong Sea levels have gone up only about a foot since 1860 Experts skeptical about global warming claims point to poor water and river management, not the burning of

Sharon

Debating Global Warming

GLOBAL WARMING

Hunting and access to ice affect polar bear populations in the Arctic Hunting regulations boosted their populations about fi fty years ago, but now melting ice poses a threat to their health and survival.

Sharon

Debating Global Warming

ONE SIDE: HUMAN ACTIVITIES ARE NOT CAUSING GLOBAL WARMING

loss along rivers

STORMS, DROUGHTS, AND WILDFIRES

wildfi res to be more severe now than in the past? Some climatologists

say yes, others say no According to a 2009 article in Science Daily,

“Clemson University researchers have concluded that the number of hurricanes and tropical storms in the Atlantic Basin is increasing, but there is no evidence that their individual strengths are any greater than

The massive ice island four times the size of Manhattan shown in the right photo broke away from the Petermann Glacier in Greenland just a week after the photo on the left was taken on July 28, 2010 Greenland’s ice melting season in 2011 lasted fi fty days longer than historical averages

Sharon

Debating Global Warming

GLOBAL WARMING

storms of the past or that the chances of a U.S strike are up.” One hurricane expert, William M Gray, has pointed out that from 1900 to 1949, a somewhat cool period, there were 101 hurricanes From 1957 to 2006, a warmer period, there were only 83

Droughts were part of history long before people began burning fossil fuels On the skeptical side of the global warming debate, experts

D I D Y O U K N O W ?

More people die during prolonged cold spells than

during long heat waves.

Rising sea levels make hurricanes such as Katrina in New Orleans more damaging because

of storm surges that travel farther inland than in the past.

Sharon

Debating Global Warming

ONE SIDE: HUMAN ACTIVITIES ARE NOT CAUSING GLOBAL WARMING

link droughts to overpopulation, outdated farming methods, and poor

are normal and natural ways to burn off old, dry forest tracts If people did not live as close to forests as they often do, if they managed water and forests better, then wildfi res would be less destructive and give birth to young, healthy forests, experts say

DISAPPEARING ANIMAL AND PLANT LIFE

A number of animal biologists have predicted that global warming will

lead to the disappearance of many animal species These arguments do

not impress those who contend that overpopulation, overfi shing, and

Not only do southern magnolias bloom earlier than in the past, but warmer temperatures have made it possible to grow them farther north than ever before

Sharon

Debating Global Warming

GLOBAL WARMING

overhunting harm mals more than global warming does or will

ani-do Why, they ask, are there more polar bears

in the world today than

in the 1960s? Their answer is that stricter hunting regulations helped boost polar bear populations

Skeptics further point out that many changes in wildlife habits are positive, not negative, effects of warmer global temperatures Red squirrels in Canada breed earlier in the spring than they did in the past Certain plants are fl owering earlier than they once did Some plants, animals, and birds are moving to other locations In Scotland, certain wild sheep are getting smaller as food conditions change What

is wrong with those changes?

Patrick Michaels, an environmental scientist at the University of Virginia, is less worried about global warming than about changes in land use In 2005 he said that “ if you turn forest into farmland—

that will have more severe effects on wildlife than merely changing the temperature a degree or two.”

Skeptical Experts Look at the Future

How do those who reject human-caused global warming see the ture? Some point out something that ought to be obvious: people have built successful societies in places with huge temperature differences

fu-D I fu-D Y O U K N O W ?

Certain warm-climate plants grown in the United

States, including the southern magnolia tree and

the kiwi fruit, can now be grown well north of

the warm southern states where they once grew

exclusively.

Sharon

Debating Global Warming

ONE SIDE: HUMAN ACTIVITIES ARE NOT CAUSING GLOBAL WARMING

The predicted rise in average temperatures is far less than the whopping 40°F (22°C) average temperature difference between cold Alaska and tropical Singapore

What Should Be Done?

Skeptical scientists argue that humans are an adaptable species New technologies can help humans adjust to climate change that may come

In the United States of a hundred years ago, Florida, Texas, and

Arizo-na, and other very warm places were lightly populated and considered almost unliveable for a good part of the year Since then, thanks to the invention of air-conditioning, the population of those states and many others has boomed

To the environmental writer and problem solver Bjorn Lomborg, global warming is a major problem with the potential to cause world-wide hardship He views poverty and disease the same way These are the solutions he suggests:

• Invest in new ways of growing food to help solve world hunger

in a warmer, drier world

• Do a better job of managing Northern Hemisphere forests and Southern Hemisphere tropical rain forests than the nations they belong to do now Growing more carbon-absorbing trees

slowing down manufacturing or lowering living standards in developing countries

Sharon

Debating Global Warming