Greenhouse gases and climate change 79 3.1. Greenhouse gases and climate change Global and European annual mean air temperatures have increased by 0.3-0.6°C since Main findings 1900. 1998 was globally the warmest year on record. There is augmenting evidence that emissions of greenhouse gases (GHGs – mainly carbon dioxide (CO2)) are causing air temperature increases resulting in climate change. Climate models estimate further increases, above 1990 levels, of about 2°C by the year 2100. It is unlikely that stable, potentially sustainable, atmospheric greenhouse gas concentrations will be realised before 2050. An immediate 50-70% reduction in global CO2 emissions would be needed to stabilise global CO2 concentrations at the 1990 level by 2100. The issue of climate change is being addressed through the United Nations Framework Convention on Climate Change (UNFCCC). The EU’s commitments are to stabilise CO2 emissions by 2000 at 1990 levels and to reduce emissions of the main six greenhouse gases by 8% in 2008-2012 from 1990 levels (Kyoto Protocol). EU CO2 emissions decreased by 1% between 1990 and 1996, due to relatively low economic growth, increases in energy efficiency, economic restructuring of the new Länder in Germany and fuel switching from coal to natural gas in the UK. However, CO2 emissions are projected to increase under the pre-Kyoto baseline scenario by 8% above 1990 levels by 2010 with transport sector emissions increasing by 39% while industrial sector emissions decline by 15%. The shift from solid fuels to gaseous fuels is projected to continue. Total EU GHG emissions are projected to increase 6% above 1990 levels by 2010 – clearly missing the 8% reduction target. Additional policies and measures will therefore be necessary to meet the Kyoto Protocol commitment. In the Accession Countries CO2 and GHG emissions are projected to decrease by 8% and 11% respectively between 1990 and 2010. This would imply a 2% increase in GHG emissions for an enlarged EU – still well short of the existing EU’s 8% reduction target. EU action thus far includes target sharing between Member States, an agreement with the car industry to reduce CO2 emissions from new passenger cars, and energy/CO2 taxes at national level but not – as yet – EU-wide. Consideration is being given to uses of the so-called ‘Kyoto mechanisms’ - emission trading, joint implementation, and the ‘clean development mechanism’, although the total technical reduction potential for measures with costs below 50 euro/tonne CO2 equivalent is estimated to be more than what is needed to achieve the EU 8% reduction target. Forest carbon sinks in the EU are estimated to be only up to 1% of the 1990 EU CO2 emissions. 1. An issue under international scrutiny The greenhouse effect of the Earth’s atmos- phere is a natural phenomenon, without 1.1. From greenhouse gases to climate change which the Earth’s temperature would be Climate change is widely recognised as a much lower, whereby atmospheric concen- serious potential threat to the world’s envi- trations of water vapour and carbon dioxide ronment. The problem is being addressed (CO2) trap infrared radiation. through the United Nations Framework Convention on Climate Change (UNFCCC), Over the past century there have been most recently at the fourth Conference of increases in atmospheric concentrations of the Parties at Buenos Aires in November anthropogenic greenhouse gases – carbon 1998 (UNFCCC, 1999). It has been identi- dioxide (CO2), methane (CH4), nitrous fied by the EU as one of the key environmen- oxide (N2O), as well as halogenated com- tal themes to be tackled under the Fifth pounds such as CFCs, HFCs and PFCs. Over Environmental Action Programme (5EAP). the same period a considerable increase, in 80 Environmental Issues historic terms, in global mean temperature the extent to which consequences of climate has been observed. There is augmenting change can be minimised by adaptation evidence that emissions of greenhouse gases measures. Decreased emissions of green- from human activities are causing an en- house gases can have other beneficial effects hanced greenhouse effect in the form of (see also Chapters 3.4 and 3.11), such as: global warming) (IPCC, 1996; IPCC, 1997a and 1997b). • reduction in CO2 emissions from fuel combustion by – for example – fuel Fossil-fuel combustion resulting in CO2 switching to natural gas or by increased emissions is the dominant human activity use of renewables, which also helps to (driving force) causing the enhanced green- reduce the emissions of other pollutants house effect. Other activities that contribute that cause acidification, troposheric to greenhouse gas emissions are agriculture ozone and reduced air quality; and land-use changes including deforesta- • reduction in methane emissions also tion, certain industrial processes such as helps to reduce the general background cement production, landfilling of wastes, levels of tropospheric ozone. refrigeration, foam blowing and solvent use. 1.2. Current indications and impacts of climate Climate change resulting from the enhanced change greenhouse effect is expected to have widespread consequences, causing: Temperature increase Global mean surface air temperature has • sea-level rise and possible flooding of increased by about 0.3-0.6°C since the late low-lying areas; 19th century (IPCC, 1996). The year 1998 was • melting of glaciers and sea ice; globally the warmest year on record. In • changes in rainfall patterns with implica- Europe similar increases in temperature have tions for floods and droughts; been observed, although the natural varia- • changes in the incidence of climatic tions in regions are larger than those that extremes, especially high-temperature occur for the global average (Figure 3.1.1). extremes. The warming effect is more prominent at These effects of climate change will have higher latitudes in the northern hemisphere impacts on ecosystems, health, key economic (Figure 3.1.2). sectors such as agriculture, and water re- sources. An observed sea level rise Global warming causes oceans to warm and There is now general recognition that policy therefore expand, and increases the melting action is needed to curb greenhouse gas of glaciers and sea ice. Climate change can emissions and that it is important to identify thus affect sea levels which have increased by Figure 3.1.1 Observed global and European annual mean temperature deviations from 1856 to 1998 Between 1856 and 1998, the yearly deviations from the 1961-1990 global average World Europe and European temperature (in addition smoothed to 1.5 1.5 show 10 yearly variations in C) Normal mean Normal mean C) o temperature) show an 1.0 Smoothed o 1.0 Smoothed increase of 0.3° C to 0.6° C. The year 1998 was globally 0.5 0.5 the warmest year on record, and 1997 the warmest before 0.0 0.0 that. This is partly due to the 1997/1998 El Niño/Southern Oscillation (ENSO), which -0.5 -0.5 was the largest on record Temperature change ( (Hadley Centre/The Met. -1.0 Temperature change ( -1.0 Office, 1998a). The ENSO phenomenon is a cycle of -1.5 -1.5 natural fluctuations of Pacific 1850 1875 1900 1925 1950 1975 1998 1850 1875 1900 1925 1950 1975 1998 ocean temperatures resulting in large-scale changes in tropical rainfall and wind patterns. Source: CRU, 1998; Hadley Centre, 1998a Greenhouse gases and climate change 81 135˚ 90˚ 45˚ 0˚ 45˚ 90˚ 135˚ Global mean temperature deviations in the 1990's 60˚ 60˚ Temperature in cells 5˚ x 5˚ 30˚ 30˚ +1.00 – +5.00 ˚C 0˚ 0˚ +0.50 – +1.00 ˚C increase +0.25 – +0.50 ˚C +0.25 – -0.25 ˚C -0.25 – -0.50 ˚C -0.50 – -1.00 ˚C 30˚ 30˚ decrease -1.00 – -5.00 ˚C 60˚ 60˚ no data 135˚ 90˚ 45˚ 0˚ 45˚ 90˚ 135˚ Figure 3.1.2 The mean annual temperatures in the 1990s 10-25 cm in the past 100 years, the range UNFCCC were about 18 Gt (CO2-equivalent) are well above the mean reflecting differences in different parts of (UNFCCC, 1998) (Figure 3.1.3), although annual temperatures from the world and uncertainties in the measure- this is subject to uncertainty and the IMAGE 1961 to1990. ments. The rate of increase does not appear model (see section 1.3) assumes a higher Source: CRU, 1998; Hadley to be changing but it is significantly higher figure (21 Gt). However, between 1990 and Centre, 1998a than that averaged over the past few thou- 1995 the aggregate emission of all green- sand years (IPCC, 1996). house gases of industrialised countries, excluding carbon removals/sinks (see Box Greenhouse gas concentrations 3.1.3 in section 5), has decreased slightly and global emissions increase (5%), mainly due to decreases from central There has been a marked upward trend in atmospheric concentrations of CO2, CH4 and N O since pre-industrial times. The so-called Greenhouse gases: concentration changes, contri- 2 Table 3.1.1. ‘new greenhouse gases’ (the halogenated bution to global warming (GW) and main sources substances HFC, PFC and SF ) entered the 6 Gas Concentration Contribution Main anthropogenic sources atmosphere only after mankind started using increase (%) since to global them in the past few decades. Table 3.1.1 about 1750 warming (%) * shows the estimated contributions of these CO2 30% 64% Fuel combustion, gases to global warming. deforestation and land-use change, cement production In addition to these gases, tropospheric CH4 145% 20% Energy production and use ozone (O3) may also augment global warm- (including biomass), animals, rice ing, by a further 16% (IPCC, 1996). paddies, sewage, organic waste in landfills Aerosols, consisting of small particles or N2O 15% 6% Use of fertilisers, land clearing, droplets either emitted directly (primary adipic and nitric acid production, aerosols) or formed in the atmosphere from biomass burning, combustion of fossil fuels sulphur dioxide (SO2), nitrogen oxides HFCs not applicable Refrigeration, air conditioners, (NOx) and ammonia (secondary aerosols), can have a cooling effect (see also Chapter chemical industry 3.4 ).