Climate Change Mitigation and Water
Climate change can be viewed from two perspectives:
1) What is causing climate change, and
2) What can we as humans do about it
Both natural and anthropogenic processes contribute significantly to climate change. Among the natural processes are changes in the energy emitted from the sun, the distance between the sun and the earth, and eruptions from volcanoes. The main anthropogenic processes include emissions of greenhouse gasses such as methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) (Solomon et al, 2007). Greenhouse gasses will in general result in increased global average temperatures near the surface of the earth. Reduction of emissions of greenhouse gasses is generally referred to as mitigation of climate change.
The sensitivity of the earth’s atmosphere to these emissions is not clearly established, but there is little to no doubt that humans are currently making the earth less optimal for future humans to inhabit (Stern, 2006; Lomborg, 2008). The main concern is not the heating itself, but the corresponding changes in the water content of the atmosphere. This will jeopardize human settlements because they are situated where there is an appropriate amount of water; enough to ensure a stable supply of water to sustain the settlement and little enough to ensure that flooding can be avoided. That is why climate change is a key driver in water resource management and thus to water professionals.
Climate change will lead to increased probabilities of extremes such as floods and droughts and therefore the anticipated changes are likely to have a significant cost to society. However, the costs can in many cases be reduced significantly by changing the design of infrastructure to mitigate the impacts of climate change. This is known as climate change adaptation. Studies show that both sea level rise and increased precipitation extremes will contribute to significantly higher costs in some regions unless adaptation measures are carried out now, even if the actual changes in the design parameters are highly uncertain.
- Sector-specific mitigation measures
- Effects of water management on GHG emissions and mitigation
- References
- Related Articles
- Links
Sector-specific mitigation measures
Sector-specific mitigation measures can have various effects on water, which are explained in this section. The following table shows the Influence of sector-specific mitigation options on water quality, quantity and level. Positive effects on water are indicated with [+]; negative effects with [−]; and uncertain effects with [?]. Numbers in round brackets refer to the notes below.
Notes:
(1) Carbon capture and storage (CCS) underground poses potential risks to groundwater quality; deep-sea storage (below 3,000 m water depth and a few hundred metres of sediment) seems to be the safest option.
(2) Expanding bio-energy crops and forests may cause negative impacts such as increased water demand, contamination of underground water and promotion of landuse changes, leading to indirect effects on water resources; and/or positive impacts through reduced nutrient leaching, soil erosion, runoff and downstream siltation.
(3) Biomass electricity: in general, a higher contribution of renewable energy (as compared to fossil-fuel power plants) means a reduction of the discharge of cooling water to the surface water.
(4) Environmental impact and multiple benefits of hydropower need to be taken into account for any given development; they could be either positive or negative.
(5) Geothermal energy use might result in pollution, subsidence and, in some cases, a claim on available water resources.
(6) Energy use in the building sector can be reduced by different approaches and measures, with positive and negative impacts.
(7) Land-use change and management can influence surface water and groundwater quality (e.g., through enhanced or reduced leaching of nutrients and pesticides) and the (local) hydrological cycle (e.g., a higher water use).
(8) Agricultural practices for mitigation can have both positive and negative effects on conservation of water and on its quality.
(9) Reduced tillage promotes increased water-use efficiency.
(10) Afforestation generally improves groundwater quality and reduces soil erosion. It influences both catchment and regional hydrological cycles (a smoothed hydrograph, thus reducing runoff and flooding). It generally gives better watershed protection, but at the expense of surface water yield and aquifer recharge, which may be critical in semi-arid and arid regions.
(11) Stopping/slowing deforestation and forest degradation conserve water resources and prevent flooding, reduce run-off, control erosion and reduce siltation of rivers.
(12) The various waste management and wastewater control and treatment technologies can both reduce GHG emissions and have positive effects on the environment, but they may cause water pollution in case of improperly designed or managed facilities.
(13) As conventional oil supplies become scarce and extraction costs increase, unconventional liquid fuels will become more economically attractive, but this is offset by greater environmental costs (a high water demand; sanitation costs).
Further information about each sector-specific mitigation measure can be found in the IPCC report "Climate Change and Water" (chapter 6).
Effects of water management on GHG emissions and mitigation
Water management policies and measures can have an influence on GHG emissions associated with different sectors, and thus on their respective mitigation measures. The following table shows the influence of water management on sectoral GHG emissions. Increased GHG emissions are indicated with [−], (because this implies a negative impact) and reduced GHG emissions with [+]. Numbers in round brackets refer to the notes provided after the table.
Notes:
(1) Hydropower does not require fossil fuel and is an important source of renewable energy. However, recently the GHG footprint of hydropower reservoirs has been questioned. In particular, methane is a problem.
(2) Applying more effective irrigation measures can enhance carbon storage in soils through enhanced yields and residue returns, but some of these gains may be offset by CO2 emissions from the energy used to deliver the water. Irrigation may also induce additional CH4 and N2O emissions, depending on case-specific circumstances.
(3) Residue returned to the field, to improve water-holding capacity, will sequester carbon through both increased crop productivity and reduced soil respiration.
(4) Drainage of agricultural lands in humid regions can promote productivity (and hence soil carbon) and perhaps also suppress N2O emissions by improving aeration. Any nitrogen lost through drainage, however, may be susceptible to loss as N2O.
(5) Depending on the design and management of facilities (wastewater treatment and treatment purification technologies), more or less CH4 and N2O emissions – the major GHG emissions from wastewater – can be emitted during all stages from source to disposal; however, in practice, most emissions occur upstream of treatment.
(6) Desalinisation requires the use of energy, and thus generates GHG emissions.
(7) Using geothermal energy for heating purposes does not generate GHG emissions, as is the case with other methods of energy production.
Further information about each sector-specific mitigation measure can be found in the IPCC report "Climate Change and Water" (chapter 6).
References
Bates, B.C., Z.W. Kundzewicz, S. Wu and J.P. Palutikof, Eds. 2008. Climate Change and Water. Technical Paper VI. IPCC Secretariat, Geneva
Karsten Arnbjerg-Nielsen, Technical University of Denmark, Department of Environmental Engineering (kan@env.dtu.dk)
- Lomborg, B. (2007): Cool it. Knopf Publishing Group. ISBN 978-0307266927.
- Solomon, S., D. Qin, M. Manning, R.B. Alley, T. Berntsen, N.L. Bindoff, Z. Chen, A. Chidthaisong, J.M. Gregory, G.C. Hegerl, M. Heimann, B. Hewitson, B.J. Hoskins, F. Joos, J. Jouzel, V. Kattsov, U. Lohmann, T. Matsuno, M. Molina, N. Nicholls, J. Overpeck, G. Raga, V. Ramaswamy, J. Ren, M. Rusticucci, R. Somerville, T.F. Stocker, P. Whetton, R.A. Wood and D. Wratt, 2007: Technical Summary. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
- Stern, N. (2007): The economics of climate change. The Stern Review. Cambridge University Press. ISBN 978-0-521-70080-1
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