Here are the ten true/false questions. Find the correct answers and explanations below. Have fun! 🙂

  • 1. Without humans there would be no greenhouse effect.
  • 2. The ozone hole is the main cause of the greenhouse effect.
  • 3.  CO2 is more harmful to the climate than the same amount of methane.
  • 4. Water vapor is a greenhouse gas.
  • 5. The global rise in temperature in the last century was the biggest within the last 1.000 years.
  • 6. The 1990s were the warmest decade of the 20th century.
  • 7. In the last century, warming in Austria was significantly lower than the global average.
  • 8. If the current greenhouse gas content in the atmosphere was stabilized, the climate would nevertheless continue to warm up for at least 100 years.
  • 9. A diesel vehicle generates more CO2 emissions per person and kilometer than a comparable petrol vehicle.
  • 10. The production of 1 kg of pork produces more greenhouse gas emissions than the same amount of wheat.

1. Without humans there would be no greenhouse effect.

As the graphic shows, there exists a natural greenhouse effect that enables life on Earth by keeping incoming and outgoing radiation in balance (radiation budget). In contrast to this, the anthropogenic greenhouse effect describes an overflow of greenhouse gas emissions in the atmosphere due to human activities such as burning fossil fuels. This leads to more heat being trapped and therefore to warming of the Earth’s surface, bringing the radiative budget out of balance.1 [FALSE]

2. The ozone hole is the main cause of the greenhouse effect.

This is one of the most common misconceptions regarding climate change (Ungar, 2000). In general, the ozone layer functions as a protection shield in the stratosphere that keeps dangerous UV radiation from reaching the Earth’s surface. An ozone hole simply means that through certain substances (such as aerosol can sprays, etc.) this layer is reduced, and more dangerous radiation can come through. As a result of CFC bans following the Montreal Protocol in 1987, the ozone layer has begun to recover.1 [FALSE]

3.  CO2 is more harmful to the climate than the same amount of methane.

According to the global warming potential (GWP), that measures the strength of greenhouse gases (radiative forcing) compared to CO2 as a reference value over a specific time horizon, methane has a bigger effect (value of 28 for a 100 year period). Still, methane is more short-lived than CO2 at the same time, meaning it remains in the atmosphere for about 12.4 years. Therefore, exact effects and relative strength between the greenhouse gases depend both on the time horizon and the metric used.2 [FALSE]

4. Water vapor is a greenhouse gas.

Water vapor is a greenhouse gas and has an important role in the natural greenhouse effect. It is mainly coupled to temperature (when temperature rises, more water vapor is in the air, leading again to an increase in temperature), where its effect is often described as a positive (enhancing) feedback effect. Although it is not an initial forcing, such as CO2, its amplifying role makes it a fundamental factor of climate change.3 [TRUE]

5. The global rise in temperature in the last century was the biggest within the last 1.000 years. & 6. The 1990s were the warmest decade of the 20th century.

The following graph shows temperature anomalies relative to the mean temperature of 1961-1990. The last decade (2010 -2019), breaking all temperature records, is not included.4 [BOTH TRUE]

7. In the last century, warming in Austria was significantly lower than the global average.

“In Austria, the temperature in the period since 1880 rose by nearly 2 °C, compared with a global increase of 0.85 °C. The increased rise is particularly observable for the period after 1980, in which the global increase of about 0.5 °C is in contrast to an increase of approximately 1 °C in Austria.”

APCC, 2014

Warming in Austria in the last century was higher than the global average: The picture shows, similar to the figure above, the deviation from annual mean temperatures compared to the mean for the period 1961–1990 globally (blue) and for Austria (red).5 [FALSE]

8. If the current greenhouse gas content in the atmosphere was stabilized, the climate would nevertheless continue to warm up for at least 100 years.

Some greenhouse gases, especially CO2, are very long-lived and tend to stay in the atmosphere for decades before they vanish again. This means even if no new greenhouse gases would accumulate in the atmosphere anymore, still it would take some time for the already existent ones to vanish, where they would still lead to warming in the meantime.6 [TRUE]

9. A diesel vehicle generates more CO2 emissions per person and kilometer than a comparable petrol vehicle.

In general, diesel vehicles have a higher fuel efficiency, leading to a lower amount of CO2 being emitted per kilometer than comparable petrol vehicles. Still, at the same time diesel cars emit more NOX emissions and other air pollutants, such as fine dust.7 This was underlined throughout the VW “Dieselgate” scandal in 2015, when manipulations were uncovered that reduced NOX emissions below the legal limit. [FALSE]

10. The production of 1 kg of pork produces more greenhouse gas emissions than the same amount of wheat.

In general, animal products are often connected to higher GHG emissions, where beef takes the lead due to the methane emissions of cows. The overall impact is also very dependent on the performance throughout the supply chain beginning with land use changes for cultivation up to emissions related to food packaging8. [TRUE]

Have a look on the following figure to get an overview for different food products:

AbbreviationsFull terms
APCCAustrian Panel on Climate Change
CO2Carbon Dioxide
CFCChlorofluorocarbons
GHGGreenhouse Gas
GWPGlobal Warming Potential
IPCCIntergovernmental Panel on Climate Change
NOXNitrogen oxide
UVUltraviolet (radiation)

1Austrian Assessment Report 2014 (AAR14), Volume 1: Climate Change in Austria: Drivers and Manifestations, Volume 1 Chapter 1: The Global Climate System and Causes of Climate Change

2 AR5 Synthesis Report: Climate Change 2014

3 Climate Change 2013: The Physical Science Basis, Chapter 8: Anthropogenic and Natural Radiative Forcing

4Finnish Meteorological Institute, the Finnish Ministry of the Environment, and Climateguide.f based on IPCC (2013)

5https://www.zamg.ac.at/cms/de/klima/informationsportal-klimawandel/klimavergangenheit/neoklima/lufttemperatur

6https://earthobservatory.nasa.gov/features/GlobalWarming/page5.php

7https://www.umweltbundesamt.at/umweltsituation/verkehr/kraftstoffe/)

8https://www.visualcapitalist.com/visualising-the-greenhouse-gas-impact-of-each-food/