Climate neutrality

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The then Indian "Minister for Oil and Gas " Veerappa Moily presented a "Carbon Neutrality Initiative" at the 11th International Oil & Gas Conference and Exhibition ( PETROTECH 2014 , "International Oil and Gas Conference and Exhibition ") in Noida , Uttar Pradesh

Actions and processes through which greenhouse gases are released have an effect that intensifies global warming , that is to say, to put it simply, "harmful to the climate". In contrast to this, actions and processes that do not cause greenhouse gas emissions or whose emissions can be fully offset have no impact on the climate; they are simply referred to as climate neutral or greenhouse gas neutral . In a modification of this, the English term “Climate-positive” (“Climate-positive”, Climate Positive Development Program ) is established for actions and processes that counteract global warming in order to keep it at the same level or (absolutely) to reduce it .

A distinction must be made between climate neutrality and zero emissions , which means that no greenhouse gas emissions occur and therefore do not have to be compensated. The term CO 2 -neutral can have a different meaning from climate-neutral . In a narrow sense, a CO 2 -neutral action does not increase the CO 2 concentration in the atmosphere, but it can have other influences on the climate, for example by emitting other greenhouse gases such as nitrous oxide or - in the example of air traffic - by reducing cloud cover to change.

Target size and options for action

The climate-damaging effect of other greenhouse gases than CO 2 can be converted into the effect of a corresponding amount of CO 2 ( CO 2 equivalent ) and then removed from the world using the technical or biotic compensation method described.

Differences in the large-scale horizontal, small-scale horizontal, vertical and temporal distribution of climate-relevant gases in the atmosphere are neglected for the sake of simplicity. The conversion of the economy with the goal of climate neutrality is called decarbonization .

Since the total content of greenhouse gases in the atmosphere alone is decisive for the extent of global warming, actions and processes can still be made climate-neutral through so-called climate compensation if greenhouse gas releases were not avoided or were not (yet) avoidable during their implementation. On the one hand, this is possible through appropriately dimensioned emission avoidance at another location (e.g. through the co-financing of a project to generate renewable energy), i.e. through technical compensation . Likewise, is biotic compensation by so-called sink projects possible: It is somewhere on earth an additional, permanent carbon sink financed, for example, an additional afforestation, whose area should be such that the newly growing trees for after. B. ten years a CO 2 amount will have withdrawn from the air, which corresponds to the CO 2 emission amount to be compensated .

In principle, all climate protection measures that reduce the CO 2 footprint of consumed goods or services to zero are suitable for achieving climate neutrality. The most consistent form of climate-neutral energy use is the use of greenhouse gas-free energy sources such as solar, wind and water energy. The use of plant-based, non- fossil fuels (such as bioethanol , rapeseed oil ) can also be climate-neutral, since the growth of plants (equivalent to CO 2 removal from the air), the release of CO 2 when they decompose or burn and the regrowth of a Plants of the same size represent a closed cycle through which the CO 2 concentration in the air is not significantly changed (for information on the climate neutrality of wood pellets, see non-fossil fuels ).

In order to achieve the desired climate neutrality, comprehensive balancing and controls are necessary for all compensation measures in order to be able to ensure that the CO 2 compensation amount to be booked technically or biotically corresponds to the actual emission amount and that the compensation measure has just as much a healing effect on the greenhouse gas problem as one corresponding emission avoidance. In the case of biotic compensation, a good concept is also required in order to secure the carbon sequestration in the forest areas.

Actors can combine the options for avoiding and offsetting within their budget in such a way that their own climate neutrality is secured with minimal costs.

Non-fossil fuels

When energy is released through the combustion of carbon-containing fuels, the same amount of CO 2 is always initially produced, regardless of whether it is fossil fuels such as coal, natural gas or crude oil or non-fossil fuels from biomass such as wood; in both cases the energy is biochemically stored Solar power. There are differences due to the different maximum combustion efficiency levels of the fuel-specific combustion technologies and heating systems .

The combustion of biomass is only climate-neutral if the resulting amount of CO 2 was previously bound by the growth of the plants in the biomass. However, the following should be included in the CO 2 balance:

  • the balance sheet date to which the CO 2 balance relates
  • the time required to bind released CO 2 . A CO 2 neutrality therefore always relates to a period of time.
  • CO 2 emissions from binding or releasing humus
  • CO 2 emissions from processing and transporting the biomass
  • Biomass as a CO 2 storage location and carbon sink .

Disregarding these framework conditions can lead to serious misjudgments.

The (small) proportions of energy losses for processing and transporting the biomass reduce the net effect somewhat, but do not question the method. Much more important is the influence of biomass use on biomass stocks. If biomass is taken from the supply, in which, for example, an existing forest is burned as biomass, it is easy to understand that this does not lead to a reduction, but to an intensification of the greenhouse effect. Use is only climate-neutral if the same amount of biomass to be used later grows elsewhere, in roughly the same period of time (and this offspring is only included once in the overall balance). Such an economy, called sustainable, is therefore a prerequisite for climate neutrality.

Surprisingly for many, however, it is not yet a guarantee. This is due to indirect effects. For example, a change in land use leads to changes not only in the biomass of plants but also in that of the humus reserve in the soil. If, for example, a grassland area is plowed up in order to grow energy maize on it , a multiple of the biomass is released from the soil through humus reserve depletion (see also soil erosion ), as can be saved through the annual use of the harvest. This “carbon debt” can only be paid off after decades of use, until then the balance is negative. In contrast, if a field is afforested, the positive effect is correspondingly greater. If a forest that has existed for a long time is used, the effect in this form does not matter. But here too, the effects of the biomass supply must be taken into account. For example, old, primeval forest-like forests have a higher stock of wood than commercial forests, but the effect of not using it appears under German conditions to be very small. Even in its current state, the biomass supply in Europe's forests has increased by a factor of 1.75 over the past 50 years, so that, according to the majority of experts, using wood from commercial forests for energy does not have to reduce the carbon supply in the system in the long term.

In addition to the direct balance, the resulting indirect effects must also be taken into account; In addition, whether even greater effects could be achieved through changed measures ( opportunity costs of measures). For example, the substitution effect of wood biomass on fossil fuels is higher when short-rotation plantations are established than when forests are used. Long-term storage, for example in construction timber, can achieve greater effects than burning or leaving it in place (where the biomass is ultimately always mineralized sooner or later through natural degradation processes). Calculating the actual climate footprint of a measure can therefore be a demanding task.

literature

  • S. Bode and F. Lüdeke: CO 2 -neutral company - what is it? UmweltWirtschaftsForum, 2007, vol. 15, no. 4, 265–273
  • Michael Bilharz: Living climate-neutrally: Consumers get started with climate protection . Ed .: Federal Environment Agency. July 2015 ( Umweltbundesamt.de ).
  • Study by WWF Germany on CO 2 offsets: window dressing or effective climate protection? (2008, abstract )
  • Wolters, Stephan; Katharina Nett, Dennis Tänzler, Kristian Wilkening, Markus Götz, Jan-Marten Krebs and Dana Vogel 2015: Updated analysis of the German market for voluntary offsetting of greenhouse gas emissions . In: Climate Change 02/2015. Dessau-Roßlau: Federal Environment Agency.

Web links

Individual evidence

  1. ^ Main report WBGU, p. 146
  2. Federal Institute for Building, Urban and Spatial Research and Competence Center for Sustainability in the Real Estate Industry at the IRE BS International Real Estate Business School at the University of Regensburg (ed.): CO 2 -neutral in the city and district - the European and international perspective (=  BBSR online publication . No. 03/2017 ). January 2017, ISSN  1868-0097 , 3.1 Definitions in the context of decarbonization ( bund.de [PDF; 4.7 MB ]).
  3. Bernhard Pötter: The fairy tale of climate-neutral flying. In: taz. August 21, 2019, accessed August 31, 2019 .
  4. NASA Maps Shed Light on Carbon Dioxide's Global Nature. NASA, September 8, 2008, accessed October 6, 2016 .
  5. ^ John A. Taylor and James C. Orr: The Natural Latitudinal Distribution of Atmospheric CO 2 (=  Climate and Global Change Series . ANL / CGC-002-0400). April 2000 ( anl.gov [PDF]).
  6. Peter von Sengbusch: Nutrient Cycles. Archived from the original ; accessed on October 6, 2016 .
  7. Timothy D. Searchinger, Steven P. Hamburg, Jerry Melillo, William Chameides, Petr Havlik, Daniel M. Kammen, Gene E. Likens, Ruben N. Lubowski, Michael Obersteiner, Michael Oppenheimer, G. Philip Robertson, William H. Schlesinger , G. David Tilman (2008): Fixing a Critical Climate Accounting Error. Science 326: 527-528. doi: 10.1126 / science.1178797
  8. ^ Daniel Klein, Christian Wolf, Andre Tiemann, Gabriele Weber-Blaschke, Hubert Röder, Christoph Schulz (2016): The “Carbon Footprint” of warmth from wood. LWF current 1/2016: 58-61.
  9. Bernhard Zimmer (2010): Ecological balance for wood chips. LWF currently 74/2010: 22-25.
  10. Joseph Fargione, Jason Hill, David Tilman, Stephen Polasky, Peter Hawthorne (2008): Land Clearing and the Biofuel Carbon Debt. Science 319: 1235-1238. doi: 10.1126 / science.1152747
  11. Sebastiaan Luyssaert, E.-Detlef Schulze, Annett Börner, Alexander Knohl, Dominik Hessenmöller, Beverly E. Law, Philippe Ciais, John Grace (2008): Old-growth forests as global carbon sinks. Nature 455: 213-215. doi: 10.1038 / nature07276
  12. Weingarten P., Bauhus J., Arens ‐ Azevedo U., Balmann A., Biesalski HK., Birner R., Bitter AW., Bokelmann W., Bolte A., Bösch M., Christen O., Dieter M. , Entenmann S., Feindt M., Gauly M., Grethe H., Haller P., Hüttl RF., Knierim U., Lang F., Larsen JB., Latacz ‐ Lohmann U., Martinez J., Meier T. , Möhring B., Neverla I., Nieberg H., Niekisch M., Osterburg B., Pischetsrieder M., Pröbstl ‐ Haider U., Qaim M., Renner B., Richter K., Rock J., Rüter S. , Spellmann H., Spiller A., ​​Taube F., Voget ‐ Kleschin L., Weiger H. (2016): Climate protection in agriculture and forestry as well as the downstream areas of nutrition and wood use. Reports on Agriculture. Special issue 222. (Report of the Scientific Advisory Board for Agricultural Policy, Nutrition and Consumer Health Protection and the Scientific Advisory Board for Forest Policy at the Federal Ministry of Food and Agriculture. 399 pages.)
  13. P. Ciais, MJ Schelhaas, S. Zaehle, SL Piao, A. Cescatti, J. Liski, S. Luyssaert, G. Le-Maire, E.-D. Schulze, O. Bouriaud, A. Freibauer, R. Valentini, GJ Nabuurs (2008): Carbon accumulation in European forests. Nature Geoscience 1: 425-429. doi: 10.1038 / ngeo233