How Global Warming Works

Technical English for Native German Speakers

How Global Warming (Erderwärmung) Works
by Ed Grabianowski and Jonathan Strickland (from “How Stuff Works”)
(German translations of word stems added by Utech)

Global warming was once an uncommon (ungewöhnlich) term used by a few
scientists who were growing concerned over the effects of decades (Dekaden) of
pollution (Umweltverschmutzung) on long-term weather patterns.
Global warming can be defined as a significant (erheblich) increase in the Earth's
climatic (klimatisch) temperature over a relatively (verhältnismäßig) short period
of time as a result of the activities of humans. An increase of 1 or more degrees
Celsius over a period of one hundred to two hundred years would be considered
global warming.
To understand what this means in more detail, let's start by reviewing the
difference between weather and climate.
Weather and Climate (Klima)
Weather is local and short-term. If it snows in the town where you live next
Tuesday, that's weather. Climate is the average (durchschnittlich) weather
conditions in a region over a long period of time. If the part of the world you live
in has cold winters with lots of (viel) snow, that would be part of the climate for
the region you live in. If the winters there will have been cold and snowy for as
long as weather has been recorded, we know how to describe the climate.
It's important to understand that when we talk about climate being long-term, we
mean really long-term. Even a few hundred years is pretty (ziemlich) short-term
when it comes to climate. In fact, changes in climate sometimes take tens of
thousands of years. That means if you happen to have a winter that isn't as cold as
usual, with not very much snow -- or even two or three such winters in a row --
that does not signal a change in climate. That's just an anomaly
(Absonderlichkeit)--an event that falls outside of the usual statistical range
(Reichweite) but doesn't represent (darstellen) any permanent, long-term change.
It's also important to understand that even small changes in climate can have
major effects. When scientists talk about "the Ice Age," you probably envision (sich
vorstellen) the world frozen, covered with snow and suffering (erdulden) from frigid
(eisig) temperatures. In fact, during the last ice age (ice ages recur roughly every
50,000 to 100,000 years), the earth's average temperature was only 5 Celsius
degrees cooler than modern temperature averages.
Global warming is a significant increase in the Earth's climatic temperature over a
relatively short period of time as a result of the activities of humans.
The Intergovernmental Panel on Climate Change (IPCC), a group of over 2,500
scientists from countries across the world, convened (einberufen) in Paris in
February, 2007 to compare (vergleichen) and advance (voranbringen) climate
research. The scientists determined that the Earth had warmed 0.6 degrees Celsius
between 1901 and 2000. When the timeframe is advanced by five years, from 1906

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to 2006, the scientists found that the temperature increase was .74 degrees
Celsius.
Other observations from the IPCC include:
• Of the last 12 years, 11 have ranked (Rank einnehmen) among the
warmest years since 1850.
• The warming trend of the last 50 years is nearly double that of the last 100
years, meaning that the rate of warming is increasing.
• The ocean’s temperature has increased to depths of 3,000 meters (over
9,800 feet); the ocean absorbs (aufnehmen) more than 80 percent of all
heat added to the climate system.
• Glaciers (Gletscher) and snow cover have decreased in regions in both the
Northern and Southern hemispheres, which has contributed to the rise of
sea levels.
• Average Arctic temperatures increased by nearly twice the global average
rate over the last 100 years (the IPCC also noted that Arctic temperatures
are highly variable from decade to decade).
• The area covered by frozen ground in the Arctic has decreased by
approximately 7 percent since 1900, with seasonal decreases of up to 15
percent.
• Precipitation (Niederschlag) has increased in eastern regions of the
Americas, northern Europe and parts of Asia; other regions such as the
Mediterranean and southern Africa have experienced drying trends.
• Westerly winds have been growing stronger.

• Droughts (Dürre) are more intense, have lasted (dauern) longer and have
covered (einbeziehen) larger areas than in the past.
• There have been significant changes in extreme temperatures – hot days
and heat waves (Hitzewelle) have become more frequent while cold days
and nights have become less frequent.
• While scientists have not observed an increase in the number of tropical
storms, they have observed an increase in the intensity of such storms in
the Atlantic correlated (einander entsprechen) with a rise in ocean
surface temperatures.
The Greenhouse (Treibhaus) Effect
Global warming is caused by an increase in the greenhouse effect. The greenhouse
effect is not a bad thing by itself--it's what allows Earth to stay warm enough for life
to survive.
Although it's not a perfect analogy, you can think of the Earth sort of like (etwas
Derartiges) your car sitting out in a parking lot (Parkfläche) on a sunny day.
You've probably noticed that your car is always much hotter inside than the outside
temperature if it has been sitting there for a while. The sun's rays enter through
your car's windows. Some of the heat from the sun is absorbed by the seats, the
dashboard (Armaturenbrett) and the carpeting (Teppichbelag) and floor mats



(Autofußmatte). The result is a gradual (langsam) increase in the temperature
inside your car.
The greenhouse effect is a little more complicated than your hot car. When the
sun's rays hit the Earth's atmosphere and the surface of the Earth, approximately
70 percent of the energy stays on the planet, absorbed by land, oceans, plants and
other things. The other 30 percent is reflected into space by clouds, snow fields and
other reflective surfaces. But even the 70 percent that gets through doesn't stay on
earth forever (otherwise the Earth would become a blazing fireball). The Earth's
oceans and land masses radiate heat back out. Some of this heat makes it into
space (All). The rest of it ends up (letztendlich so kommen) getting absorbed when
it hits certain things in the atmosphere, such as carbon dioxide, methane (Methan)
gas and water vapor. The heat that doesn't make it out through Earth's atmosphere
keeps the planet warmer than it is in outer space, because more energy is coming
in through the atmosphere than is going out. This is the greenhouse effect that
keeps the Earth warm.
Global Warming: What is Happening?
The greenhouse effect happens because of certain naturally occurring substances
in the atmosphere. Unfortunately, since the Industrial Revolution, humans have
been pouring (gießen) additional amounts of those substances into the air.
Carbon dioxide (CO2) is a colorless gas that is a by-product (Beiprodukt) of the
combustion (Verbrennung) of organic matter. It makes up (zusammenbringen) less
than 0.04 percent of Earth's atmosphere, most of which was put there by volcanic
activity very early in the planet's life. Today, human activities are pumping huge
(riesig) amounts of CO2 into the atmosphere, resulting in an overall (insgesamt)
increase in carbon dioxide concentrations (Konzentration). These increased
concentrations are considered the primary factor in global warming, because
carbon dioxide absorbs infrared (infrarot) radiation. Most of the energy that
escapes (ausbrechen) Earth's atmosphere comes in this form, so extra CO2 means
more energy absorption and an overall increase in the planet's temperature.
Nitrous oxide (NO2) is another important greenhouse gas. Although the amounts
being released by human activities are not as great as the amounts of CO2, nitrous
oxide absorbs much more energy than CO2 (about 270 times as much). For this
reason, efforts to curb (bremsen) greenhouse gas emissions have focused on NO2 as
well. The use of large amounts of nitrogen fertilizer (Düngemittel) on crops
(Gesamternte) releases (abgeben) nitrous oxide in great quantities, and it is also a
by-product (Beiprodukt) of combustion.
Methane is a combustible (brennbar) gas, and it is the main component of natural
gas (Erdgas). Methane occurs naturally through the decomposition
(Zersetzungsprozess) of organic material and is often encountered in the form of
"swamp gas (Sumpfgas)." Man-made processes produce methane in several ways:
• By extracting (gewinnen) it from coal

• From large herds of livestock (i.e., digestive (Verdauungs-) gases)

• From the bacteria in rice paddies (Reisfeld)

• Decomposition of garbage (Müll) in landfills (Deponie)



Methane acts much like carbon dioxide in the atmosphere, absorbing infrared
energy and keeping heat energy on earth. While there isn't as much methane as
carbon dioxide in the atmosphere, methane can absorb and emit twenty times more
heat than CO2. Some scientists even speculate that a large-scale venting (Abzug) of
methane into the atmosphere (such as from the release of huge chunks of methane
ice locked under the oceans) could have created brief periods of intense global
warming that led to some of the mass extinctions (Aussterben) in the planet's
distant (entfernt) past.
Effects of Global Warming: Sea Level
We have seen that an average drop of just 5 degrees Celsius over thousands of
years can cause an ice age; so what will happen if the Earth's average
temperature increases a few degrees in a few hundred years? There is no clear
answer. Even short-term weather predictions are never perfectly accurate
(akkurat) because weather is a complex phenomenon. When it comes to long-
term climate predictions (Vorhersage), all we can manage are educated guesses
(auf Sachkenntnis gestützte Vermutung) based on our knowledge of climate
patterns through history.
Glaciers (Gletscher) and ice shelves around the world are melting (schmelzen). The
loss of large areas of ice on the surface could accelerate (beschleunigen) global
warming because less (weniger) of the sun's energy would be reflected away from
Earth to begin with (zu Anfang). An immediate result of melting glaciers would be a
rise in sea levels. Initially, the rise in sea level would only be an inch or two (2.5 to
5 cm). Even a modest rise in sea levels could cause flooding problems for low-lying
coastal (Küsten-) areas. However, if the West Antarctic Ice Sheet were to melt and
collapse (einstürzen) into the sea, it would push sea levels up 10 meters, and many
coastal areas would completely disappear (verschwinden) beneath the ocean.
The IPCC estimates (abschätzen) that sea levels rose 17 centimeters (or about 6.7
inches) in the 20th century. Scientists project (abbilden) rising sea levels to
continue through the 21st century, with levels increasing between 7 and 22 inches
(17 and 55 cm) by 2100. Sea levels will likely be greater than these projections, but
we can't be sure by how much until more data can be gathered about the effect of
global warming on ice flows (Eisgang).
With a rise (Anstieg) in the overall (insgesamt) temperature of the ocean, ocean-
borne (Ozeanertragen) storms such as tropical storms and hurricanes, which get
their fierce (wuchtig) and destructive energy from the warm waters they pass over,
could increase in force.
If the Polar Ice Caps Melt
Are the polar ice caps in danger of melting (schmelzen) and causing the oceans to
rise? This could happen, but no one knows when.
The Earth's main ice-covered landmass (Landmasse) is Antarctica at the South
Pole, with about 90 percent of the world's ice (and 70 percent of its fresh water).
Antarctica is covered with ice an average of 2,133 meters (7,000 feet) thick. If all of
the Antarctic ice melted, sea levels around the world would rise about 61 meters
(200 feet). But the average temperature in Antarctica is -37°C, so the ice there is in
no danger of melting. In fact, in most parts of the continent it never gets above
freezing.



At the other end of the world, the North Pole, the ice is not nearly as thick as at the
South Pole. The ice floats on the Arctic Ocean. If it melted, sea levels would not be
affected.
There is a significant amount of ice covering Greenland, which would add another 7
meters (20 feet) to the oceans if it melted. Because Greenland is closer to the
equator than Antarctica, the temperatures there are higher, so the ice is more likely
(wahrscheinlicher) to melt. Scientists from the Universities of London and
Edinburgh say that ice loss in Antarctica and Greenland together contribute
approximately 12 percent of the rise in sea levels.
But there might be a less dramatic reason than polar ice melting for the higher
ocean level -- the higher temperature of the water. Water is most dense (dicht) at 4
degrees Celsius. Above and below this temperature, the density of water decreases
(the same weight of water occupies a bigger space). So as the overall temperature of
the water increases, it naturally expands (ausbreiten) a little bit, making the
oceans rise.

Effects of Global Warming: Seasons and Ecosystems
Less abrupt (plötzlich) changes would occur around the world as average
temperatures increased. In temperate (gemäßigt) areas with four seasons, the
growing season would become longer with more precipitation. This could be
beneficial (wohltuend) in many ways for these areas. However, less temperate parts
of the world would likely see an increase in temperature and a sharp decrease in
precipitation, causing long droughts (Trockenperiode) and potentially creating
deserts (Wüste).
Because the Earth's climate is so complex, no one is really sure how much a
change to one region’s climate will affect other regions. For example, scientists at
the University of Colorado theorize that the decrease in sea ice in the Arctic could
reduce snowfall in Colorado because Arctic cold fronts would be less intense. This
could impact everything from farmlands to the ski industry.
The most devastating (verheerend) effects, and also the hardest to predict, are the
effects on the world's living ecosystems. Many ecosystems are very delicate
(gebrechlich), and the slightest (geringste) change can kill off several species as
well as any other species that depends on them. Most ecosystems are
interconnected, so the chain reaction (Kettenreaktion) of effects could be
immeasurable (unermesslich). The results could be something like a forest
gradually dying off and turning to grassland or entire coral reefs (Korallenbank)
dying. Many species of plants and animals would adapt (anpassen) or move
(umlegen) to deal with (mit etwas fertig werden) the shift in climate, but many
would become extinct (ausgestorben).
Some ecosystems are already changing drastically due to a shift in climate. The
University of Alberta reports that much of what once was tundra in northern
Canada is turning into forests. They also noticed that the change from tundra to
forest wasn't linear; instead, it seems that the change happens in sudden spurts.
The human cost of global warming is hard to quantify. Thousands of lives per year
could be lost as the elderly (die Alten) or ill (die Kranken) suffer from heat stroke



(Hitzschlag) and other heat-related trauma. Poor and underdeveloped nations
would suffer the worst effects, since they would not have the financial resources to
deal with the problems that come with an increase in temperature. Huge numbers
of people could die from starvation (Hungersnot) if a decrease in precipitation limits
(begrenzen) crop growth and from disease if coastal flooding (Überflutung) leads to
widespread (großflächig) water-borne (durch Wasser übertragen) illness.
The Carnegie Institution estimates (einschätzen) that around $5 billion in crop
losses per year are due to global warming. Farmers see a decrease of about 40
million metric tons of cereal grains (Getreide) like wheat (Weizen), barley (Gerste)
and corn each year. Scientists discovered that an increase of 1 degree Fahrenheit in
average temperature results in a 3 to 5 percent drop in crop yields.
Is Global Warming a Real Problem?
Despite a scientific consensus on the subject, some people don't think global
warming is happening at all (überhaupt). There are several reasons for this:
• They don't think the data show a measurable upward trend (Tendenz) in
global temperatures, either because we don't have enough long-term
historical climate data or because the data we do have isn't clear enough.
• A few scientists think that data is being interpreted incorrectly by people
who are already worried about global warming. That is, these people are
looking for evidence of global warming in the statistics, instead of looking
at the evidence objectively and trying to figure out (herausfinden) what it
means.
• Some argue (vorbringen) that any increase in global temperatures we are
seeing could be a natural climate shift, or it could be due to other factors
than greenhouse gases.
Most scientists recognize that global warming does seem to be happening, but a few
don't believe that it is anything to be worried about. These scientists say that the
earth is more resistant to climate changes on this scale than we think. Plants and
animals will adapt to subtle (subtil) shifts in weather patterns, and it is unlikely
anything catastrophic will happen as a result of global warming. Slightly longer
growing seasons, changes in precipitation levels and stronger weather, in their
opinion, are not generally disastrous (fatal). They also argue that the economic
damage caused by cutting down (reduzieren) on the emission of greenhouse gases
will be far more damaging to humans than any of the effects of global warming.
In a way, the scientific consensus may be a moot (irrelevant) point. The real power
to enact significant change rests in the hands of those who make national and
global policy (Strategie). Some policy-makers in the United States are reluctant to
propose and enact (verordnen) changes because they feel the costs may outweigh
any risks global warming poses (darlegen). Some common concerns, claims and
complaints include:
• A change in the United States' policies in emissions and carbon production
could result in a loss of jobs.
• India and China, both of which continue to rely (sich verlassen auf)
heavily on coal for their main source of energy, will continue to cause



environmental problems even if the United States changes its energy
policies.
• Since scientific evidence (Beweis) is about probabilities (Wahrscheinlich-
keit) rather than certainties (Gewissheit), we can't be certain that
human behavior is contributing to global warming, that our contribution
is significant, or that we can do anything to fix it.
• Technology will find a way to get us out of the global warming mess, so any
change in our policies will ultimately be unnecessary and cause more
harm than good.
What's the correct answer? It can be hard to figure out. Most scientists will tell you
that global warming is real and that it is likely to do some kind of harm, but the
extent (Ausmaß) of the problem and the danger posed by its effects are wide open
for debate.
Can We Stop Global Warming?
• Though scientists warn that global warming will likely continue for
centuries because of the long natural processes involved, there are a few
things we can do to decrease the effects. Basically, they all boil down to
(auf etwas hinauslaufen) this: Don't use as much of the stuff (Kram)
that creates greenhouse gases.
To really stem (eindämmen) the emission of greenhouse gases, we need to
develop non-fossil fuel (nicht fossiler Brennstoff) energy sources. Hydro-
electric power, solar power, hydrogen (Wasserstoff) engines and fuel cells could
all create big cuts in greenhouse gases if they were to become more common.
At the international level, the Kyoto treaty (Staatsvertrag) was written to reduce
CO2 and other greenhouse gas emissions worldwide. Thirty-five industrialized
nations have committed to reducing their output of those gases to varying degrees
(unterschiedlich). Unfortunately, the United States, the world's primary
(vorrangig) producer of greenhouse gases, did not sign the treaty.


How Global Warming Works

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How Global Warming Works