Climate quiz answers
Here are the answers. If you haven’t taken the quiz yet, take the quiz first.
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Now for the answers:
1. What percent of the earth’s atmosphere is CO2?
A) 40 percent
B) 4 percent
C) 1.4 percent
D) 0.4 percent
E) 0.1 percent
F) 0.04 percent
G) 0.01 percent
H) 0.004 percent
F. 0.04 percent. Four percent of one percent. This is what 420 parts per million means. The last two digits are technically insignificant.
2. How thick is the CO2 layer in the atmosphere?
A) About 1 cm
B) Less than 10 cm
C) Less than 30 cm
D) Less than 1 m
E) About 1,000 m
F) None of the above
F. CO2 is a well-mixed gas
3. Where is the CO2 in the atmosphere?
A) It’s at the top of the troposphere, about 10km up.
B) It’s more concentrated at the top of the troposphere — there’s more as you go up.
C) It’s mostly in the stratosphere, above 10km.
D) It’s mostly in the first kilometer above ground level.
E) None of the above.
E. CO2 is a well-mixed gas.
4. How does the greenhouse effect work?
A) Where the lapse rate is positive, it delays longwave photons as they escape, raising the emission height and shifting the curve toward higher surface temperatures; where the lapse rate is negative, it accelerates the escape of longwave radiation and shifts toward lower surface temperatures.
B) It’s pretty much exactly like a greenhouse — it reflects heat back down to earth that would otherwise escape.
C) It concentrates more heat in the oceans.
D) Same as A but without the negative pole nonsense.
E) It’s not like a greenhouse, it’s like a blanket, trapping heat. It’s an insulator.
F) None of the above
A. The greenhouse effect shifts the lapse rate to the positive, especially over the tropics, and the process works in reverse to cool the poles.
5. At what CO2 concentration do commercial greenhouses operate?
A) Below 250 PPM
B) 250 — 500 PPM
C) 500 — 1,000 PPM
D) 1,000 — 1,200 PPM
E) 1,200 — 5,000 PPM
F) Above 5,000 PPM
D. Between 1,000 and 1,200 PPM.
6. What is the earth’s average surface temperature today?
A) 30 degrees C
B) 23.6 degrees C
C) 18.2 degrees C
D) 16 degrees C
E) 15 degrees C
F) 12.5 degrees C
E. NASA
7. What’s the best estimate for the earth’s average surface temperature 90 million years ago?
A) 30 degrees C
B) 28 degrees C
C) 23.6 degrees C
D) 18.2 degrees C
E) 16 degrees C
F) 14.5 degrees C
B. Global Mean Surface Temperatures for 100 Phanerozoic Time Intervals
8. What was the average ocean temperature 20 years ago?
A) 1 degree K
B) 3.7 degrees K
C) 0 degree C
D) 3.8 degrees C
E) 8 degrees C
F) 16 degrees C
B. It is generally believed that the average temperature of the oceans is 3.7–3.9 degrees C. Ask GPT4 or see Andy May’s analysis.
9. What is the average ocean temperature today?
A) 1.2 degree K
B) 3.9 degrees K
C) 0.5 degree C
D) 3.8 degrees C
E) 8.6 degrees C
F) 23 degrees C
D. The average ocean temperature has hardly budged in 20 years. It’s less than 1/10th of one degree C higher now, but that’s within the range of error of measurement, especially since we measure better now than we did in the past. So we really can’t say ocean temperatures have increased except at the surface. See this post.
10. Probably the most difficult question on this page: According to researcher Javier Vinos, the most influential Milankovitch factor for earth’s climate today is:
A) Eccentricity
B) Obliquity
C) Precession
B. See his book, chapter 2. Also see Clive Best.
11. According to a 2021 blog post by Chris Landsea and Eric Blake at the National Hurricane Center in Miami, the number of hurricanes has risen from 1878 to today because …
A) CO2 added to the atmosphere by humans
B) A combination of CO2 and natural factors
C) Better determination and counting methods
C. See their blog post.
12. According to the same article, total cyclone energy, which is a measure of all cyclone strength per year combined, after adjusting for technology and measurement bias, has …
A) Risen dramatically in the last 20 years
B) Risen a bit
C) Been flat
D) Oscillated up and down over a 50-year cycle with no discernable difference between the end of the 19th century and early 21st.
E) Trended down consistently
13. About 38,000 years ago, in the largest Dansgaard-Oeschger event #8, north Atlantic temperatures rose dramatically over a period of less than 120 years. According to a 2014 peer-reviewed investigation, how big was the temperature rise?
A) 1–2 degrees C
B) 2–4 degrees C
C) 4–8 degrees C
D) 10–13 degrees C
E) 15–17 degrees C
D. Researchers find temperatures rose 11.8 degrees +/- 1.8 degrees C in under 140 years. The rise was natural and had nothing to do with CO2.
14. According to the IPCC AR6 chapter 11, the future occurrence of low-likelihood, high-impact events linked to climate extremes is given:
A) High confidence
B) Medium confidence
C) Low confidence
C. Low confidence. See Box 11.2 of the AR6.
15. According to the IPCC, the effects of greenhouse gas forcing on changes in atmospheric dynamic and associated changes in drought occurrence is …
A) High confidence
B) Medium confidence
C) Low confidence
C. Low confidence. See section 11.6.1 of the AR6.
16. According to the IPCC, general statements attributing changes in global flood events to anthropogenic climate change have:
A) High confidence
B) Medium confidence
C) Low confidence
C. Low confidence. See section 11.5.4 of the AR6.
17. According to the International Union for the Conservation of Nature, whose job it is to count polar bears, the number of polar bears on earth in 1960 was under 10,000. Roughly how many are alive today?
A) 6,000–8,000
B) 8,000–12,000
C) 12,000–16,000
D) 16,000–22,000
E) 22,000–32,000
F) 32,000–40,000
G) 40,000–50,000
E. Approximately 22,000–31,000 bears in the last count, though there could be more.
18. According to a peer-reviewed paper citing data from the Polar Bear Specialist Group, what’s the mininum number of polar bears shot and killed by hunters each year?
A) None
B) Fewer than 100
C) 100–400
D) 400–800
E) 800–1,000
F) 1,000 — 1,200
F) More tha 1,200
E. Polar Bear Harvest Patterns Across the Circumpolar Arctic
19. Is East Antarctica warming?
A) Yes, significantly, and that warming is accelerating.
B) Yes, significantly since 1980, though not accelerating
C) Yes, a bit, but not much
D) No, it has stayed the same
E) No, it has cooled a bit
D. “Beyond the Antarctic Peninsula there has been little significant change in temperature,” and Antarctica is losing ice from below, not from above.
20. Approximately how warm were temperatures in the Medieval Warm Period (900 - 1300 AD)?
A) Fake question. This is referred to as the Medieval Ice Age, everyone knows it was much colder then.
B) Less than today’s temperatures by about 2 degrees C
C) Less than today’s by about 1 degree C
D) At least as warm as temperatures today
E) Significantly warmer than today by at least 1 degree C
F) Significantly warmer by at least 2 degrees C
D. About the same as today, perhaps a bit warmer. See Moberg et al.
21. According to a peer-reviewed article in the journal Cryosphere, from 2009 to 2019, Antarctica’s ice shelves …
A) Lost 2,500 GT of ice
B) Lost 844 GT of ice
C) Been stable
D) Gained 661 GT of ice
E) Gained 1744 GT of ice
See also NASA’s evaluation of Antarctic ice.
22. What role do clouds play in the atmosphere?
A) They provide the tipping points that heat the earth to extreme levels.
B) Troposphere (lower-atmosphere) clouds generally reflect heat during the day and retain heat at night, while stratospheric (upper-atmosphere) clouds are made of ice and reflect sunlight away.
C) Water-rich low clouds over the tropical ocean have the greatest cooling effect and low-water ice clouds at high altitudes have the strongest warming effect. Overall, the cooling effect is greater.
D) Troposphere (lower-atmosphere) clouds greatly accelerate the greenhouse effect of CO2, while stratosphere (upper-atmosphere) clouds have no effect on temperature.
C. Interview with Bjorn Stevens, cloud expert.
23. If you condensed 100 percent of all the water vapor in the atmosphere, you’d get a layer of water that is how thick?
A) Less than 1mm
B) About 1mm
C) About 5mm
D) About 1cm
E) About 4cm
F) None of the above
A. Interview with Bjorn Stevens, cloud expert.
24. What has been the trend of Arctic sea-ice extent for the last 15 years?
A) Significant decrease
B) Gradual decrease
C) Flat
D) Increase
E) Significant increase
C. Flat. What does 45 years of daily arctic sea-ice data tell us?
25. What is the polar vortex?
A) The polar vortex has little to do with climate but is responsible for the Northern Lights.
B) The polar vortex is a circular band of strong westerly winds in the stratosphere between about 10 and 30 miles above the North Pole, is strongest in winter, and can lose energy and change the jetstream.
C) The polar vortex is a band of fast-moving cold air in the upper troposphere. It is where jets fly.
D) The polar vortex is an irregular pattern of air above the north pole caused and influenced by greenhouse gases. It has grown tremendously in the last 50 years.
B. Video explainer.
26. According to a 2021 paper analyzing Greenland’s mass balance from 1992 - 2020, Greenland shed approximately 200 gigatons of ice per year, causing global sea level to rise by 0.4 millimeters per year. At this rate, how long until all the ice in Greenland is gone?
A) 10 years
B) 20 years
C) 50 years
D) 150 years
E) 1,500 years
F) 15,000 years
F. Paper.
27. At that rate (see previous question), how much will Greenland cause sea level to rise by 2100?
A) 40mm = 4cm = less than 2 inches
B) 400mm = 40cm = 16.75 inches
C) 4,000mm = 400cm = 13 feet
D) 10,000mm = 10m = 33 feet
A) This is simple math.
28. The lowest 10km or so of the atmosphere is called the:
A) Atmosphere
B) Mezosphere
C) Lithosphere
D) Stratosphere
E) Troposphere
E. UCAR.
29. The earth’s albedo is roughly:
A) 1 percent
B) 8 percent
C) 18 percent
D) 30 percent
E) 44 percent
F) Nonexistent. Venus has an albedo, but earth doesn’t.
D. NASA.
30. The water in the earth’s atmosphere originally came from:
A) Deep underground.
B) Space. Water is relatively abundant in space.
C) It was created by heat and pressure on oxygen and hydrogen molecules.
D) It precipitated out of the original rocks.
E) None of the above.
31. The CO2 in the earth’s atmosphere originally came from:
A) It was manufactured by animals breathing in oxygen supplied by plants.
B) It was created deep in the earth and came out through volcanoes.
C) Mostly from decaying plant and animal material buried underground.
D) Space. CO2 is fairly common in space.
E) None of the above.
32. Has the Arctic Ocean been essentially ice-free in summer in any time during the past 10,000 years?
A) No; the last time the Arctic was ice-free was about 90 million years ago.
B) No; there was less ice 8,000 years ago, but no, not ice-free in summer.
C) Absolutely. In fact, the Arctic sea was ice-free in summer for a few decades in the 1600s.
D) Probably; the best studies we have point toward very little ice, and possibly no summer ice for hundreds of years in the range 6,000 — 10,000 years before present.
D. See Jakobsson, Jakobsson, and Stein.
33. This is a MODTRAN database graph showing the frequencies at which CO2 and methane are most effective as a greenhouse gas. What does it say?
MODTRAN data visualization by William Happer
A) That CO2 is rising over time.
B) That CO2 went down 600 years ago and has now peaked.
C) That doubling CO2 will have a negligible effect on the emissivity and, therefore, surface temperatures.
D) That doubling CO2 will block all the energy shown by the black curve.
E) That with no CO2 the earth would be 360 degrees cooler (green line).
C. Greenhouse gas paper by Happer and Van Wijngaarden. There’s a good Video explainer by Happer.
34. For current concentrations of greenhouse gases, the radiative forcing at the tropopause, per added CH4 molecule, is about 30 times larger than the forcing per added carbon-dioxide (CO2 ) molecule. If we could instantly double the amount of CH4 in the atmosphere from 2 parts per million to 4 parts per million, and disregarding feedbacks, how much would that raise the surface temperature?
A) About 1-2 tenths of 1 degree C.
B) About a half of 1 degree C.
C) About 2.5 degrees C.
D) About 5 degrees C.
E) About 30 degrees C.
A. Methane paper by Happer and Van Wijngaarden. Here’s a good video explainer by Van Wijngaarden.
35. This is a record of all max temps in Parker, Arizona (a very remote weather station) since 1893.
What story does this tell?
A) In this location, temperatures have been rising dramatically.
B) In this location, temperatures have been relatively steady for 130 years.
C) In this location, temperatures have fallen.
B. Steady. The two ultra-low temperatures could have been mechanical error but are correlated with extremely strong La-Nina cooling events. Learn more about US remote thermometer data.
36. Is this (see previous question) station anomalous?
A) Yes, most thermometers around the US show a dramatic rise in temperatures, including most rural stations.
B) No. This station represents the vast majority of rural stations recording since the early 1900s.
C) Rural and urban weather stations report substantially the same temperature trend for the entire period, and this is representative.
D) Rural and urban weather stations report substantially the same temperature trend for the entire period, and it doesn’t look anything like this.
B. Take the max-temperature quiz, for yourself.
37. Here’s data from a very remote weather station in Iceland that has been recording temperature since 1798:
How much warming does it show in 230 years?
A) About 6 degrees C.
B) About 3 degrees C.
C) Less than 2 degrees C.
D) About 0.2 degrees C.
C. Less than 2 degrees in 220 years. That’s less than 1 degree C per century, and the 1820s were about the same as the 1920s and the early 2000s on a relative basis.
38. What does this graph show?
A) The Roman Warm Period, which was about as warm as temperatures are today, followed by a bit of cooling, then the Medieval Warm Period, during which temperatures were as high or higher than today (Greenland was settled then, and they grew corn, which can’t grow there now), followed by the very cold Little Ice Age, and now 200 years of natural warming continuing the cycle.
B) This graph is fake, fake, fake. There are no peer-reviewed scientific articles that support this graph.
C) This is only European temperatures. The rest of the world didn’t do this.
D) That temperatures now are far higher than any point in the last 200,000 years.
A. See Moberg et al — Nature, 2005.
39. What phase is the Atlantic Multidecadal Oscillation in now?
A. Neutral
B. Warm
C. Cold
D. None of the above, that’s not how the AMO works.
B. Since the mid-1990s, we have been in a warm phase.
40. What happened 33 million years ago?
33 million years ago, temperatures fell off a cliff and the poles went into a deep freeze in short order. What caused this?
A) A sudden rise in oxygen concentration.
B) Sunspots stopped for a period of about 1 million years.
C) Trees took over the landscape, sucking in all the CO2.
D) Mammals flourished, providing more CO2.
E) The Isthmus of Panama closed.
F) None of the above, they are all silly.
E) The Isthmus of Panama closed, changing the flow of water and heat to the poles. Also note that CO2 and temperatures have rarely been in sync and are often out of sync.
41. What solar cycle are we in now?
A) 18
B) 22
C) 23
D) 24
E) 25
F) 26
G) Solar cycles use names, not numbers.
42. This map uses data from the US Historical Climate Network:
One of these maps shows data from 1936, the other from 2023. Which is which?
A) The data is all faked and cherrypicked, it’s not from the USHCN.
B) A is 1936.
C) B is 1936.
B. 1936 remains the US’s hottest year on record, but there are ways to count that slant the table in favor of more recent years.
43. According to NOAA’s tide-gauge network, the rate of sea-level rise since 1800 is:
A) Accelerating
B) The same
D) Slowing down
B. No acceleration in sea-level rise since 1880 (and since 1800 for tide gauges that have been keeping records that long).
44. Since 1968, temperatures have generally been rising. Has the rate of that rise generally:
A) Accelerated - the temperature curve is going up and bending upward even more
B) Been flat, no acceleration, linear increase
C) Declined - the temperature curve is going up but bending downward
C. See Fig 12.11 in Javier Vinos’s book.
45. Recorded temperatures in Adelaide, Austrailia:
One of these shows the temperature record for 1920, the other for 2020. Can you tell which is which?
A) The gray one is obviously 1920.
B) The orange dotted one is obviously 1920.
C) I can’t tell.
D) This is ridiculous. It’s totally fake data.
C. One of these — it turns out to be the orange dotted line — is actually 2020, but there is no way to know. Is this what the IPCC says should happen? More such city graphs available at the Climate Discussion Nexus website.
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