Climate change: Questions and answers

What is the greenhouse effect? Is climate change really caused by human activity? Interesting facts in a nutshell.

1. Is climate change caused by human activity?

The Intergovernmental Panel on Climate Change (IPCC) concluded in its fifth report (2013) with over 95 % probability based on wider scientific analysis that global warming in the last 50 years is mainly the result of human activities. Nothing else could even come close to explaining the global warming of recent decades.

2. How does the greenhouse effect work?

Solar radiation is absorbed by the earth’s surface which in turn releases heat radiation into the atmosphere. Greenhouse gases in the atmosphere absorb this radiation and send some of it back to earth. It is due to this reflection that the earth's surface and the lowest layer of the atmosphere heat up. The higher the concentration of greenhouse gases the greater this additional warming.

Schematic explanation:

1. Short-wave solar radiation is absorbed by the earth’s surface.

2. The earth's surface emits long-wave infrared radiation.

3. Greenhouse gases absorb a part of the infrared radiation (each greenhouse gas has a different wavelength range) and in turn emit infrared radiation.

4. A part of the radiation emitted by greenhouse gases reaches back to the earth's surface and causes a warming of the earth's surface and the lowest layer of the atmosphere (troposphere).

This natural greenhouse effect makes life on earth possible. Without greenhouse gases in the atmosphere the average temperature on earth would be about minus 18 degrees Celsius.

The greenhouse gases emitted by humans disrupt the natural balance between radiation and emission. Today over 40% more CO2 can be measured than at the beginning of the industrial age. The share of other greenhouse gases released by human activity has also increased. As a result the earth’s surface has become warmer by 1 °C since the beginning of industrialisation in the mid-19th century.

Regeneration in the climate system

The warming of the earth causes various regeneration processes that affect changes in the climate system. Increased concentration of water vapour in the atmosphere and the decrease in surface covered with snow and ice cause additional warming. Changes in cloud cover and of the carbon cycle are effects whose impacts on the climate still cannot be estimated.

3. What is meant by the natural carbon cycle?

Carbon dioxide is constantly released by vegetation, the oceans and the soil and absorbed again - this is known as the carbon cycle. In a state of equilibrium carbon flows in and out of the atmosphere are about even. The quantity of CO2 caused by human activity disrupts this natural equilibrium. Because oceans, soil and vegetation absorb only a part of the additional CO2 caused by human activity (currently about half), this creates an excess of CO2 emissions. As a direct consequence the CO2 concentration in the atmosphere increases at a speed never observed before.

4. Are the effects of climate change already detectable to us?

A number of insidious changes that are clearly linked to climate change can be observed. Several examples have been published in a study by the FOEN:

Climate models show that an increase in greenhouse gases leads to an increase in temperature and increased water vapour in the atmosphere. Higher water vapour content, in particular, can manifest itself in higher precipitation intensities and in the intensity of storms. Intense precipitation events, such as those that occur about once a month, have increased in Switzerland by 20 to 40% over the past century.

The rapid retreat of glaciers is also already highly visible. The release of large amounts of debris and the formation of unstable glacial lakes can threaten settlements and have already resulted in high costs for protective measures (e.g., drainage tunnels for the glacial lake in Grindelwald).

Climate change in Switzerland (Management Summary)

Cover Klimawandel in der Schweiz

Indicators of driving forces, impact and response. 2020

5. How much CO2 does Switzerland emit?

Switzerland emits around 50 million tonnes greenhouse gases per year (system parameters in accordance with the UN Framework Convention on Climate Change). This corresponds to per capita emissions of approx. 5.8 tonnes.

These values, however, include only greenhouse gases that are emitted within the country’s borders. If imported goods and services are taken into account, per capita emissions in Switzerland increase to the European average of around 12 tonnes.

CO2 is the main greenhouse gas. The Swiss emit around 5 tonnes CO2 per capita (without imputation of imports). This value is low compared to that of some developed countries (USA; Australia: around 17 tonnes per person), but high compared to that of African developing countries (Ethiopia, Eritrea: less than 0.1 tonnes per capita). The global average is around 4.5 tonnes CO2 per capita. The Federal Council intends to decrease Switzerland’s per capita emission to between 1 and 1.5 tonnes CO2 by 2050.

6. What can we do?

Reducing greenhouse gas emissions is paramount. The greatest potentials lie in transport, heating and hot water consumption, and food production. Using public transport or more energy-efficient vehicles, renewable energy for household use, and a diet of mostly seasonal and plant-based products would already accomplish a lot.

Because global warming can at best be limited to 1.5 °C, adaptation to the impacts of climate change is becoming increasingly important. While adaptation measures are required in the private sector, they are especially required in the public domain.

7. How much CO2 is produced for ...?

... heating of an old house (100 m2) per year: 7200 kg

... heating of a Minergie home (100 m2) per year: 1200 kg

... car-kilometres travelled on average per person per year (10,000 km) in an average passenger vehicle: 1800 kg

... travelling the same route by train (Switzerland): 70 kg

... travelling the same route by plane (economy) (e.g., Zurich-Dakar roundtrip): 1200 kg

... the production of 50 kg meat that is consumed annually on average per capita: 500 kg

Annual average footprint per person in Switzerland: 12,800 kg [ROR1] CO2eq (Basis: life cycle assessment data from Ecoinvent)

CO2-Emissionsfaktoren des schweizerischen Treibhausgasinventars (PDF, 316 kB, 15.04.2019)Zusammenstellung der CO2-Emissionsfaktoren und Energieinhalte verschiedener Energieträger, die im Treibhausgasinventar verwendet werden (in German, also available in French and Italian).

Die Auswirkungen der Flugverkehrsemissionen auf das Klima (PDF, 2 MB, 11.06.2020)(available in German or in French) Faktenblatt über die Klimawirkung der Flugverkehrsemissionen und deren Bewertung
Akademien der Wissenschaften Schweiz, mit Unterstützung des BAFU.

8. How climate-friendly is the Swiss energy supply?

The energy produced in Switzerland is low in emissions because very little is generated using fossil fuels. The energy consumed in Switzerland however clearly produces higher emission because the CO2 emissions of imported energy must be taken into account. The figures for the various Swiss energy mixes are as follows:

  • Production energy mix: 29.6 g CO2eq/kWh
  • Delivery energy mix (according certificate of origin for electricity): 54.7 g CO2eq/kWh
  • Average renewable energy mix: 15.7 g CO2eq/kWh
  • Average consumer mix (based on production and electricity trade): 128.0 g CO2eq/kWh

9. What is the CO2 levy?

The CO2 levy is imposed on fossil fuels (surcharge of CHF 96 per tonne CO2, equivalent to CHF 0.25 per litre heating oil). It is an incentive tax, encouraging people to use fossil fuels such as heating oil or natural gas sparingly, and increase their use of CO2 neutral or low CO2 energy sources.

Almost two thirds of the revenue from the levy is redistributed in a consumption-neutral manner to the public and companies through health insurers and the OASI compensation offices. A third is available for the buildings programme, which supports energy-efficient renovations, the use of renewable energies, and geothermal projects. A small proportion flows to the technology fund.

Energy-intensive companies can be exempted from the CO2 levy if they commit to reducing their greenhouse gas emissions. Companies that participate in the emissions trading system are likewise exempt from the CO2 levy.

10. What has emissions trading contributed to climate?

Emissions trading sets an upper limit for the emission of greenhouse gases. An emission allowance entitles the emission of 1 tonne CO2 and can be traded within the system. Issuers receive a corresponding number of emission allowances and decide whether to reduce the emissions of the company itself or whether they want to acquire emission allowances from other issuers.

From a business perspective, it is logical that they will be reduced where the costa are lowest. Through emissions trading the economic efficiency of climate protection is increased, ensuring at the same time that the ecological objectives can be achieved.

11. How can CO2 emissions be compensated?

If greenhouse gas emissions are emitted in one location, they can be compensated by savings in another location.

The CO2 Act obliges distributors of fossil motor fuels and operators of fossil-thermal energy plants to CO2 compensation. In part this is fulfilled through projects for reducing domestic emissions, so-called domestic compensation projects.

The FOEN may on application register domestic compensation projects and after submission of a report (monitoring), issue attestations. Attestations are only issued for voluntary measures that are not already legally required or encouraged.

Compensation of CO2 emissions abroad

The FOEN compensates emissions (e.g., flight emissions) - for the services of its own office as well as on behalf of other federal agencies. The type and quality and quality of the CO2 certificates are thus standardised: They must fulfil the criteria of the CO2 Ordinance and create an additional benefit with regard to the environment, economy, technology and society (Gold Standard or detailed proof of the fulfilment of comparable requirements).

Last modification 02.10.2018

Top of page