Global Warming Test: The Real Answers

Lisa MooreThis post is by Lisa Moore, Ph.D., a scientist in the Climate and Air program at Environmental Defense Fund.

There’s an email making the rounds lately – an invitation to take a Global Warming Test. It starts off reasonably enough (yes, global warming is real), but then quickly devolves into ridiculousness – ridiculousness presented in a way that looks misleadingly "scientific".

For those interested in truth, here are the real answers to the Global Warming Test.

1) "Global warming" is a real phenomenon: Earth’s temperature is increasing. (True/False)

Correct Answer: True

Today’s temperature is probably higher than it’s been in at least 1300 years – mostly due to human activities.

2) The "Greenhouse Effect" is real. (True/False)

Correct Answer: True

A background greenhouse effect is natural to the Earth. Without it, the Earth’s average temperature would be an uninhabitable 0°F. But human activities have increased the greenhouse effect, causing rapid global warming.

3) The main cause of Global Warming is:

a) pollution from factories and automobiles
b) orbital eccentricities of Earth and variations in the Sun’s output
c) the Greenhouse Effect

Correct Answer:  a) pollution from factories and automobiles, and c) the Greenhouse Effect

Today’s rapid global warming is caused by increased concentrations of greenhouse gases in the atmosphere. The additional greenhouse gases come from human activities such as industrial pollution and tropical deforestation. It is not caused by orbital eccentricities or variations in the Sun’s output.

4) The Greenhouse Effect is caused primarily by:

a) water vapor
b) carbon dioxide
c) ozone-destroying aerosol sprays

Correct Answer: b) carbon dioxide

Although water vapor traps more heat than carbon dioxide (CO2), increasing greenhouse gases like CO2, not water vapor, is what drives global warming. Air warmed by CO2 holds more water vapor, enhancing the effect. To interrupt this vicious cycle and stop global warming, we must control the emission of greenhouse gases like CO2.

5) Which most accurately describes the effects of Global Warming in the United States over the last 100 years?

a) temperatures have risen > 5° C
b) temperatures have risen > 2° C
c) temperatures have risen < 1° C

Correct Answer: c) temperatures have risen < 1° C

Global temperatures have increased by about 0.75°C over the past 100 years (see this chart from NASA). U.S. temperatures have risen by nearly the same amount.

It may sound like a small number, but the impacts on Earth systems and global climate are already dramatic. Scientists predict much more warming in the future unless we cut greenhouse gas emissions.

6) How much carbon dioxide (CO2) is in Earth’s atmosphere today?

a) 10% or greater
b) 2% to 10%
c) less than 1/10th of 1%

Correct Answer: c) less than 1/10th of 1%

CO2 is about 0.038 percent of the Earth’s atmosphere. This sounds insignificant, but even small concentrations of greenhouse gases can have a large effect.

Since the start of the industrial revolution, CO2 levels have risen about 33 percent, and the level of methane (a more potent greenhouse gas) has more than doubled.

7) Carbon dioxide from coal-fired power plants damages forests. (True/False)

Correct Answer: True

Nearly 20 percent of global CO2 emissions come from cutting down forests, which certainly counts as damage!

Rising levels of CO2 from industrial emissions have a complex effect on forests and other plants. In the western U.S., warming and drying have encouraged widespread beetle outbreaks and increasing wildfires. Some plants respond to CO2 by growing more rapidly, but scientists also have found that many crops grown in high CO2 conditions have lower nutritional value.

8) Which answer below provides the best explanation for the following temperature record?

< graph of Medieval Warm Period and Little Ice Age temperatures, origin unknown >

a) Industrial pollution from factories, power plants, and cars caused global warming
b) Natural variations in global temperatures may occur in roughly 500-years cycles
c) Global cooling occurred as a result of the Renaissance Period

Correct Answer: N/A, data in graph not accurate

The actual temperature record is not depicted in this graph. The "Medieval Warm Period" wasn’t as warm as temperatures are today, and it may not have been a global phenomenon. Like the "Little Ice Age", it’s most prominent in records from Europe. Scientists think the cooler temperatures between the 14th and 19th centuries may have been caused by changes in solar energy and/or the Gulf Stream. But natural factors like these have not contributed much to today’s warming trend.

9) Which of the following is not true about an increasing greenhouse effect?

a) the consensus of scientists is that the problem warrants drastic action
b) nighttime temperatures may increase, but daytime temperatures will not
c) the coldest, driest regions of the planet will warm first

Correct Answer: b) nighttime temperatures may increase, but daytime temperatures will not, and c) the coldest, driest regions of the planet will warm first

Both daytime and nighttime temperatures are already increasing. Northern areas are warming more quickly, but global warming is evident around the world. Scientists are calling for prompt action to cut greenhouse gas emissions.

10) Which temperature measuring method most accurately measures global warming?

a) ground-based thermometers
b) orbiting weather satellites
c) weather balloons

Correct Answer: a) ground-based thermometers, and b) orbiting weather satellites

All of these measurement techniques are useful, and the results consistently show warming. Some people point to an old discrepancy in satellite records as evidence that global warming isn’t happening. But the discrepancy was resolved more than two years ago in a federal report describing mistakes in initial data processing. Balloon measurements are less reliable than thermometers and satellites because of sparse coverage and inconsistencies among instruments. For more on this topic, see Myth #2 in this report [PDF] by James Wang and Michael Oppenheimer.

You can read more corrections of misinformation on our Myths and Facts page.

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  1. Posted April 19, 2008 at 2:00 pm | Permalink

    Hey — where are the ridiculousnesses? I want entertainment, not facts! :)

    For an interesting view on the results of global warming, see this post.

    Warming in the western US will be 50% greater

  2. Posted April 22, 2008 at 10:40 am | Permalink

    If you want to see the ridiculousness, click the link in the first paragraph.

  3. mikes
    Posted April 24, 2008 at 5:41 am | Permalink

    Unfortunately, there are a number of scientifically incorrect answers in this Test.

    #1. The earth’s temperature is NOT increasing. World air temperatures peaked in 1998. The more important measure, ocean temperatures, have been falling for four years.

    #8. “But natural factors like these have not contributed much to today’s warming trend.” While correlation does not prove causation, there is increasing evidence that solar trends, combined with a change in instrumentation for measuring surface temperature, caused the warming of the 1990’s The sun has become quite inactive recently and temperatures have correspondingly dropped.

    #9. It may be a “consensus” of “scientists” believes dramatic action must be taken but it is clear there is no consensus among meteorologists, the scientists that understand the most about weather and atmosphere. Many meteorologists are deeply skeptical of the IPCC’s case for AGW.

  4. Posted April 24, 2008 at 5:14 pm | Permalink

    mikes – Obviously we think you’re wrong about this (and so does most of the world).

  5. mikes
    Posted April 24, 2008 at 9:22 pm | Permalink

    Hi Sheryl,

    Thanks for your comment but I am surprised to learn there is any dispute about what I wrote.

    #1. Here is the graph of world temperatures: Are you disputing the peak in temperatures occurred in 1998 or that temperatures have been dropping over the past year?

    The story of the cooling oceans: While one can interpret the meaning of the data in various ways, there is zero doubt ocean temperatures are falling.

    #8. Not sure what you are disputing. The sun has been very inactive the last year or so. See a live image for yourself:

    It has been interesting to watch the solar forecasts modified after the fact (!) as demonstrated in this animation:
    Note that the forecasts kept forecasting too much solar activity compared to what has actually occurred.

    As I stated, correlation does equal causation but it is interesting that atmospheric and ocean temperatures have fallen so dramatically during this period of “quiet sun” and further work is clearly needed.

    There was a very significant change in NOAA’s instrumentation during the 1990’s that appears to have introduced a warm bias. There is evidence this is true in a number of other nations. There is so much to cite here that one link will not do it justice but here goes: and scroll down to see what climate stations used to look (white Stephenson screens away from buildings, etc.) and what they often look like now. The net warm bias introduced by the installation of MMTS stations is indisputable.

    #9. Again, don’t know what you believe is incorrect. I am a meteorologist and I can state — without reservation — that many, and perhaps most, meteorologists have serious issues with the IPCC reports and, especially, the contention the science is “settled.” But don’t take my word for it, here is an excerpt from an email from Eric Berger, science reporter for the Houston Chronicle, to me written just last week: “What I do find interesting is that a large proportion of meteorologists — as opposed to climate scientists — are deeply skeptical of global warming.”

    At the top of your web page, the words “Strong Science” appear. I am disappointed in your reply that “we think you’re wrong about this (and so does most of the world).” Science is not about what people “think” or “believe.” It is about facts and about theories that can be proven.

    I was motivated to write because I believe that a posting titled: “Global Warming Test: The Real Answers” should have answers that are scientifically accurate.

    As a person who considers himself to be an environmentalist, I intend for this information to be helpful. I hope that it has been.


  6. mikes
    Posted April 24, 2008 at 9:24 pm | Permalink

    Typo in #8. Correlation does NOT equal causation.

  7. Posted April 28, 2008 at 11:05 am | Permalink

    mikes – if you are surprised that anyone disagrees with you, then you aren’t following the news.

  8. mikes
    Posted May 2, 2008 at 6:06 pm | Permalink

    Hi Sheryl,

    OK, but what does “the news” have to do with science?

    Especially from an organization that proclaims, “Strong Science Guides Our Work”?


  9. whamo
    Posted August 13, 2008 at 8:44 pm | Permalink

    Obviously science has little to nothing to do with the “manmade global warming” sales pitch.
    Public opinion is all that counts. If more people buy into it, the environmental defense fund makes more money.