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L’énergie dans le développement de la Nouvelle-Calédonie

 | 
Yves Le Bars
, 
Elsa Faugère
, 
Philippe Menanteau
, 
et al.

Emissions and the reduction of greenhouse gas emissions in New Caledonia

The climate issue and greenhouse gas emissions

Texte intégral

1It was the intergovernmental panel on climate change (IPCC) that in its 1990 report alerted the international community to the need to take action in order to limit climate change caused by greenhouse emissions.

The intergovernmental panel on climate change (IPCC)
The IPCC was established in 1988 under the aegis of the United Nations by the World Meteorological Organisation (WMO) and the United Nations Environment Programme (UNEP). It presents findings regarding the climate issue for the benefit of political decision-makers: on climatology (Group 1), on the impacts of, and how to adapt to, climate change (Group 2), on how to mitigate these changes while reducing greenhouse gas emissions (Group 3) and on methods to determine these emissions (Group 4). An architecture at several levels guarantees the quality and independence of scientific assessments. The IPCC received the Nobel Peace Prize in 2007 jointly with Al Gore.
There are three special reports to be noted in relation to New Caledonia; one on the capture and geological sequestration of CO2, one on storing carbon in vegetation and one on fluorine gas emissions which are also considered under the Montreal protocol (www.ipcc.int).

2Concentrations of greenhouse gases in the atmosphere have gone from 280 ppm at the start of the industrial revolution to almost 400 ppm today. According to recent studies (Ramstorf 2009), average sea levels could rise by a metre between now and 2100 if we continue with our current pace of greenhouse gas emissions.

3Current global emissions would need to be halved in order to stabilise the climate by 2050. By 2050, temperatures would thus be around 2°C hotter than at present. In fact, even if we put a sudden stop to all anthropic green-house gas emissions, the world would continue to heat up for around thirty years because of the excess gas already accumulated in the atmosphere. The hope is that by halving these emissions, we can at least avoid even greater changes before the end of the century. Thus the heads of state that attended the G8 summit in Hokkaido, Japan, in July 2008 adopted this objective of stabilising the climate on behalf of the international community.

CLIMATE CHANGE

4Higher temperatures as the result of an increase in the greenhouse effect will have very different implications, either directly on temperatures or indirectly on rainfall and seawater levels. The small islands in the Pacific which are situated at a low elevation could disappear. All the coastal areas, which are generally heavily populated, will be affected; there will be less land that can be cultivated and saline intrusions could become more of a threat.

5Rainfall levels will decrease in other parts of the globe. This, combined with higher temperatures and potentially higher evapotranspiration, will make certain regions more arid. In yet other places, at high latitudes for example, conditions could become more favourable for plant production as the result of a longer growing season.

Climate change and the small islands

6The small islands are particularly vulnerable to the effects of climate change, rising sea levels and extreme climatic events (including cyclones). In the Caribbean and Pacific islands, 50 % of the population lives less than 1.5 km from the coast. Increased sea levels will most likely make floods, storms and coastal erosion worse. Air, maritime and industrial infrastructures will be affected as well as roads running mainly alongside the coast. In every scenario, rain levels will fall in the summer and will be compensated by higher levels in the winter.

7Commercial and local fishing, an important resource for many of the islands, will also be affected by the frequency and intensity of El Niño. Agriculture in coastal areas is also under threat from rising sea levels, saline intrusions and reduced water resources. Further away from the coast, agriculture will probably also be affected by extreme events such as droughts and floods.

8At low latitudes, tourism could suffer as a result of these changes, while there is an increased risk of certain diseases becoming more prevalent (dengue, malaria, elephantitis, schistosomiasis, etc.). At high latitudes, conditions could, conversely, become more favourable.

Climate change in Australia and New Zealand

9Since 1950, the average temperature has increased by 0.3 and 0.7°C. Heatwaves are more frequent, and frosts less common. Rainfall has increased in the north-west of Australia and in the south-east of New Zealand: on the other hand, it has decreased in the south and east of Australia and in the north-east of New Zealand. Droughts have become more intense in Australia. Glaciers have altered as has the snow cover which has had an effect on rain patterns, ecosystems and agriculture.

10During the course of the 21st century, temperatures will most probably increase as will the intensity and frequency of heatwaves and droughts. That could lead to a worsening water situation in the two countries by around 2030, bringing with it a decline in agricultural and forestry production and, in certain regions, a loss of biodiversity from 2020.

Carbon dioxide emissions

11Alongside the concentration of water vapour in the atmosphere, over which we have little influence, carbon dioxide is the most prevalent green-house gas. Net carbon dioxide emissions are generated primarily from fossil fuels in the northern hemisphere and changes in land use in developing countries – deforestation, changes to grazing where the land is cultivated, urbanisation, artificial or spontaneous reforestation and cultivated land which is then abandoned, etc.

Carbon cycles

12Whether or not CO2 emissions into the atmosphere increase depends on our use of fossil fuels, how we substitute these with plant biomass and other forms of renewable energy, variations in vegetation carbon stocks and geological sequestration of CO2. The complexity borne of these different cycles overlapping often results in partial approaches, which are sometimes far removed from reality. For the atmosphere, what counts are the quantity and the net variations in CO2. It is for this reason that we felt it would be useful to include a series of diagrams in the longer article which appears on the CD-ROM.

CO2 emissions differ according to the circumstances below

The use of fossil fuels or plant biomass

13The role of energy production using plant biomass and fossil fuels varies whether or not the carbon dioxide emitted by power plants is captured and stored geologically. Where CO2 emissions are captured and stored geologically, the net balance of CO2 emissions from fossil fuels could become zero, while the net balance of bio-energy could become negative, i.e. it could be expressed as a net withdrawal of CO2 from the atmosphere.

Changes in land allocation

14When there are changes in land use, stocks of carbon in the vegetation and in the ground’s organic matter also vary. For example, turning a forest into a meadow means an average of 60 t of carbon (220 t of CO2) is lost per hectare from the vegetation. If the land is adapted to cultivation, organic matter is also lost from the ground – which means around 25 t of carbon per hectare – albeit more slowly.

15Deforestation results in a rapid loss within just two to three years of stocks of organic matter in the vegetation. The loss of organic matter from the ground is far slower, however, at around 1 t per hectare per annum. With deforestation, carbon stocks in the vegetation increase, albeit slowly.

16Average carbon stocks in a forested area may also vary without any changes in land allocation. The average carbon stock in an under-utilised forest may increase over a certain number of years. But in the long-term, the stock in a forest which is not worked and not affected by fire, storms or damaging insects will hardly increase at all. Conversely, the carbon stock in an over-worked forest will decline.

Substituting plant biomass for fossil energy sources

17Using plant biomass in place of fossil fuels, oil and coal in particular, enables greenhouse gas emissions from fossil fuels to be reduced. By dedicating a small additional area of land to producing extra biomass, it is even possible to achieve plant biomass with neutral energy and greenhouse gas emissions.

18Unlike fossil fuels, plant biomass production requires an extensive land area. This is a key difference and one it is particularly important to emphasise for countries such a New Caledonia where there is little land area that can be cultivated agriculturally and small areas of workable forest. A way therefore needs to be found of using the land - in order to avoid deforestation when food and non-food biomass production needs to increase – and fossil energies, as efficiently as possible.

19It should also be noted that increases in food plant biomass production require either an increase in agricultural returns or for meadows or forests to be cleared. Nevertheless, annual greenhouse gas emissions from cultivation, even with heavy use of fertilisers, are generally low (one hundredth) compared with emissions from changes in carbon stocks subsequent to deforestation. In terms of the climate, therefore, the need is to seek to maximise agricultural and forest production per unit of surface area, provided this is acceptable to the local environment and human health.

The dynamics of carbon stocks in different parts of the world

20Annual net CO2 emissions are set to increase to almost 10 billion tC, or 36.7 billion tonnes of CO2: around 7.5 billion tC would come from fuel consumption and other fossil products, and 1.5 billion tC from land clearance. However, net annual absorptions by global vegetation would then increase to around 2.6 billion tC, or around 29 % of net total emissions. Net absorptions from the ocean would reach 26 %. The rest – around 26 % – would remain in the atmosphere where it would contribute towards increasing the greenhouse effect.

21Increased carbon stocks in forests (generally known as ‘sinks’) and geological stores of CO2 in the earth’s crust should enable part of the excess which accumulates in the atmosphere to be absorbed. Geological storage will certainly be more expensive than avoiding deforestation or increasing stocks in forests, but potentially also more costly than increasing carbon stocks in forests.

OTHER GREENHOUSE GAS EMISSIONS

Methane

22Over 100 years, its global warming potential (GWP) is weight for weight 23 times greater than that of CO2, but over 20 years, this GWP rises to 62 times greater. Over 50 years – the new perspective introduced in 2001 along with the obligation to stabilise the climate (halve global greenhouse gas emissions) – this GWP is 42 times greater than that of CO2, or almost double what was previously considered when taking a perspective of 100 years.

23The objective of reducing methane emissions from landfill, mines and livestock is thus becoming increasingly important.

Nitrogen oxide

24Over 100 years, the impact of this gas, which has a life similar to that of carbon dioxide is, weight for weight, 296 times greater than that of CO2. Large emissions of this gas are created during the manufacture of nylon and from the nitrates industry, where they can be reduced by consuming slightly more energy or by properly treating the manure from industrial livestock farming.

25It should be emphasised that where there are changes in land use, nitrogen oxide emissions from agricultural sources are relatively low compared with CO2 emissions, and compared to reductions in fossil fuel emissions achieved by converting all phytomass harvests to replace these fossil fuels. Often too, land clearance can be avoided when agricultural production needs to be increased by, for example, increasing land efficiency (productivity of areas already cultivated or number of heads of livestock per hectare). In the case of plant biomass, the balance on the scale of all rural space and across the entire planet should be taken into consideration. Approaches which consider only variations at the field level lead to erroneous diagnostics for the climate.

26Thus, increasing wheat yields in France slightly increased nitrogen oxide and CO2 emissions due to the production and transport of manure. But without these increased yields, it would have been necessary to clear more than 13 million hectares of land in order to increase total wheat production to the same degree and this would have resulted in emissions of more than 4 billion tonnes of CO2 and the elimination of all annual wood harvests. A way thus needs to be sought to reduce emissions of this gas by using better organic or mineral fertilisers, but not to the detriment of yields and, more generally, land efficiency.

CFCs, HFCs and other synthesis gases

27Chlorofluorocarbons (CFC) from the refrigeration industry and insulating foams, hydrofluorocarbons (HFCs) which, like perfluorocarbons (PFCs), are manufactured to replace CFCs (because they are less harmful to the ozone layer), and sulphur hexafluoride (SF6) used in the electronics industry are synthesis gases with a warming potential much lower than that of the gases referred to above. However, they are gradually being phased out because of the commitments agreed under the Montreal protocol, and being replaced by HFCs. HFCs are less harmful to the ozone layer, but also have a very high GWP and are included under the climate change convention.

The tropospheric ozone

28It is also important to consider the tropospheric ozone. However this gas is not included on the list of gases to be reduced under the Kyoto protocol because it is difficult to predict when it will form. The carbon monoxide produced when cars are poorly incinerated, from boilers and, in particular, that is generated from forest and savanna fires is partly responsible for this gas forming.

29Nitrogen oxide emissions, synthesis gases (except those, like CFCs, included under the Montreal protocol) and tropospheric ozone emissions are thought to have been responsible, in 1990, for around 20 % of the additional greenhouse effect recorded under the climate change convention.

Other factors (aerosols, albedos)

30Aerosols are fine particles (between 0.01 and 10 µm) in suspension in the air which also change the planet’s thermal balance: they include sulphates emitted by volcanoes, sodium crystals and chlorine formed by drying out sea spray, particles emitted by heat generating plants, savanna and forest fires, etc. Black soot or dust absorbs their radiation and thus contributes to global warming. Unlike greenhouse gases, however, aerosols do not accumulate in the atmosphere and generally have a life of just a few days because they are eliminated by rainfall. Their direct impact is, on balance, negative, and their indirect affect on clouds has not been properly quantified; this is why aerosols have not been included in the initial commitment period under the Kyoto protocol.

31Black masses absorb all the radiation they receive whereas white surfaces (snow, white roofs on the houses in hot regions) reflect a large proportion: this is known as albedo. If the ice caps disappear, global warming will increase as this reflection decreases. Changes in vegetation covering the ground at the same time alter the albedo and evaporation, thus affecting the local thermal balance.

GREENHOUSE GAS EMISSIONS FROM NEW CALEDONIA

32The calculation of greenhouse gas emissions from France under the United Nations framework convention on climate change (UNFCCC), put together by the Interprofessional Technical Centre for Studies in Atmospheric Pollution (Citepa), includes mainland France, the Overseas Departments (DOM), the Territorial Overseas Communities (COM), French Polynesia and New Caledonia. However only mainland France and the Overseas Departments (DOM) fall within the perimeters set by the Kyoto protocol.

33With a GDP of 5.8 billion euros, New Caledonia accounted for 0.3 % of total GDP which in 2007 was 1 938.4 billion euros, or virtually half of the GDP for “New Caledonia plus the Territorial Overseas Communities” (NC+COM).

34Between 1990 and 2007, greenhouse gas emissions fell by 5.6 % across the regions subject to the constraints of the Kyoto protocol (mainland France + DOM), and by 6.5 % in mainland France; however, they increased by 73.4 % in the Overseas Departments and by 63.5 % in the “New Caledonia + COM” group. Within this round-up, the main increase can be attributed to rising emissions of carbon dioxide (+ 1.7 Mt), i.e. to industry, transport and electricity production. There was little change in methane emissions from landfill and enteric fermentation in ruminants. HFC emissions, included in the climate convention, increased by the equivalent of 0.1 million tonnes of CO2.

35Per habitant (although this indicator should be used with caution for small areas such as Iceland, Greenland and New Caledonia where intensive coal mining dominates), greenhouse gas emissions fell sharply between 1990 and 2007: by 13.6 % across all the regions subject to the constraints of the Kyoto protocol (mainland + DOM) and by 20.6 % in mainland France. Conversely, emissions increased by 36.8 % in the DOM and by 10.7 % in the “New Caledonia + COM” group. They changed from 9.6 to 8.3 teqCO2 within the Kyoto perimeter, from 9 to 7.2 teqCO2 in mainland France, from 5.7 to 7.8 teqCO2 in the Overseas Territories (DOM) and from 6 to 6.6 teqCO2 in the “New Caledonia + COM” group.

36It can be seen that emissions from all the overseas territories and New Caledonia declared under the Kyoto protocol accounted for less than 1 % of total emissions from “mainland France plus DOM”. In 1990, they accounted for just 0.5 % of these emissions. However within this group, 70 to 90 % of CO2 emissions most probably come (“according to expert opinion”) from New Caledonia.

37We should add here that it would be advisable to also include emissions from imports of foodstuffs and to deduct emissions associated with nickel production which is clearly not used by the habitants in the Territory, but rather exported. Indeed, the list of greenhouse gas emissions in the United Nations format which is designed to enable verifiable reductions to be achieved should not be confused with the list of actual average emissions per habitant in any given country or region.

38For a detailed presentation of emissions of the six greenhouse gases included under the Kyoto protocol – in mainland France, in the Overseas Territories and in the Territorial Overseas Communities plus New Caledonia – please see the full report which appears on the CD ROM enclosed.

© IRD Éditions, 2010

Conditions d’utilisation : http://www.openedition.org/6540