Forests and climate change

What do we mean by the climate change?

The greenhouse effect means, that the atmosphere retains some of the sun’s radiation reflected back from the surface of the Earth and then reflects some of it back on to the Earth. As a result, the climate becomes warmer. The phenomenon is necessary for life on Earth in its present state, as the Earth would be considerably colder without it.

Gases, which retain and reflect heat are called greenhouse gases (GHG). The most common of them is carbon dioxide. Thus, carbon dioxide is not a pollutant, but a gas which normally belongs to the atmosphere.

Strengthening of greenhouse effect, or climate change, is caused by the fact that the content of greenhouse gases in the atmosphere is increasing. This leads to the warming up of the climate. This is mostly caused by carbon dioxide, which is always formed through the combustion of matter containing carbon.

Forests are neutral or positive in regard to the climate change

Forests and forestry play a role in the natural circulation of carbon in various ways. During growth, atmospheric carbon is sequestered by forest plants. The process where atmospheric carbon is sequestered in a carbon store outside the atmosphere is called a carbon sink. Carbon is sequestered not only in trees but in all vegetation as well as in the soil.

On the other hand, carbon is released from this store when the plants decompose either naturally or when timber taken into use after felling is burned or otherwise decomposed. Emissions of carbon sequestered in the soil is also increased after loggings. This all is called a carbon emission.

Generally, drainage also leads to a change in the carbon content of forest. The exhaust gases of forestry machinery cause carbon emissions into the atmosphere, but their impact is very small compared with the carbon flows caused by forest growth and felling.

Since the growth of forest plants decreases the amount of atmospheric carbon, one might conclude that forests prevent climate change. However, forests also release carbon into the atmosphere. Therefore forests can only act as carbon sinks if the amount of carbon released from them is smaller than the amount of carbon sequestered in them through growth.

Fossil carbon accelerates greenhouse effect

The greenhouse effect is accelerated by carbon which is brought to the carbon circle from somewhere else. Most of all this has taken place due to the industrialisation and the use of fossil fuels – coal, oil, natural gas – in traffic and energy production, i. e. their burning.

However, the burning of biomass – which means plants and fuels made of them – is not considered to accelerate the climate change, although when burned they create exactly same kind of carbon dioxide as it is with fossil fuels. It is said that biofuels – like forest energy products – are neutral with regard to the climate change.

According to a fresh research forests also produce fine particles called aerosols while growing. These particles reflect the sunlight back to space and control the climate change in this way. In Finland this effect may be as large as one quarter of that of the use of fossil fuels. However, there is not sufficient information of this phenomenom.

Sources for climate change related forest.fi pages:

  • Crill ym.: The role of peat in Finnish greenhouse gas balances. Ministry of Trade and Industry of Finland, Studies and Reports 10/2000, 2000.
  • Kauppi, Pekka: Metsien hiilitalous ja kestävyyden periaate [Carbon dynamics in forests and the principle of sustainability, available only in Finnish]. Maa- ja metsätalousministeriö [Ministry of Agriculture and Forestry in Finland], julkaisuja 10/1997 .
  • Kauppi, Pekka ym.: Carbon reservoirs in peatlands and forests in the boreal regions of Finland. Silva Fennica 31: 13 25, 1997.
  • Liski, Jari: Carbon storage of forest soils in Finland. Helsingin yliopisto [University of Helsinki], 1997.
  • Liski, Jari: Millainen kiertoaika eduksi metsien hiilitaloudelle? [Optimal rotation period and carbon economy of forest, available only in Finnish] Metsätieteen aikakauskirja 4/2000. Metsäntutkimuslaitos [Finnish Forest Research Institute], 2000.
  • Metsien hiilinielujen todennettavuus Kioton pöytäkirjan soveltamisessa [Verifiability of carbon sinks of forests in adapation of the Kyoto Protocol]. Indufor, 2000.
  • Metsät ilmastosopimuksessa ja Kioton pöytäkirjassa [Forests in climate treaty and Kyoto protocol, available only in Finnish]. Maa- ja metsätalousministeriö (Ministry of Agriculture and Forestry in Finland), julkaisuja 1/2000.
  • Mäkipää, Raisa ja Tomppo, Erkki: Suomen metsät ovat hiilinielu – vaikka Kioton ilmastosopimuksen mukaan muulta näyttää [Finnish forests are a carbon sink – although the Kyoto Protocol does not admit it, available only in Finnish]. Metsätieteen aikakauskirja, 2/1998. Metsäntutkimuslaitos [Finnish Forest Research Institute], 1998
  • Pingoud, Kim ym.: Greenhouse impacts of the Finnish forest sector including forest products and waste management. Ambio25 (5): 318–25, 1996.
  • Pingoud K., Perälä A.-L., Pussinen A.: Carbon Dynamics in Wood Products. Mitigation and Adaptation Strategies for Global Change, 6: 91-111, 2001.
  • Tomppo, Erkki: National forest inventory of Finland and its role estimating the carbon balance of forests. Biotechnol. Agron. Soc. Environ. 4 (4): 281–284, 2000.
  • Tomppo, Erkki: Arvio Kioton pöytäkirjan artiklan 3.3 mukaisten toimenpiteiden (metsittäminen, uudelleen metsittäminen ja metsien hävittäminen) määrällisistä vaikutuksista Suomelle vuosina 2008–2012 [Estimation of the quantitative effects of measures defined by the Kyoto Protocol (afforestation, reforestation, deforestation) on Finland in 2008–2012, available only in Finnish]. Maa- ja metsätalousministeriö [Ministry of agriculture and forestry in Finland], 2006.
  • Uusiutuvien energianlähteiden ympäristövaikutukset [Environmental effects of renewable energy sources, available only in Finnish]. KTM:n raportti [Report of Finnish Ministry of trade and industry], 1999.
  • Value added creation in the European pulp and paper industry and bio-energy sector. Pöyry Forest Industry Consulting, 2006.

Updated on the 5th of January, 2016.