Title of paper

3.3 Limitations for climate change prediction

The following factors provide limitations in modelling of climate change, as it was experienced during the Vulnerability and Adaptation Assessment:

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  Uncertainty and lack of agreement in General Circulation Models.
  
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  Understanding the complexity of nature, natural processes (including variability in the case of Namibia) and the contribution of human factors to these.
  
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  The diminishing availability of long-term primary data across Namibian weather stations necessitated vast interpolation of results which do not lend themselves to accurately project future changes.
  
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  Limited technical capacity in climate change as well as modelling in the country.
  

4. Global warming and climate change

Global warming is defined as the increase in the average temperature of the earth’s atmosphere and the oceans over decades.
Greenhouse effect is a natural process caused by the presence of gases that trap heat from the sun in the earth’s atmosphere so that it is unable to escape back into space.



Figure 6: Layers of stratosphere

The sun’s energy enters the earth’s atmosphere. It is absorbed by the earth’s surface. The earth’s surface warms up and gives off heat. The greenhouse gases in the atmosphere absorb the heat and reflect some of it back down to the earth’s surface. This causes the earth to get hotter = global warming!

Figure 7: The green house effect

So, is global warming and climate change the same?
Climate change refers to long term changes in the statistical distribution of weather patterns over time periods ranging from decades to millions of years.
Global warming refers to surface temperature increases.
Climate change includes global warming and everything else that increasing greenhouse gas levels will affect.

5. Causes of climate change

There is an ongoing debate on the causes of climate change. The United Nations Framework Convention on Climate Change has accepted that climate change is caused by both anthropogenic (human induced) causes and natural processes such as movement of continents, large eruptions of volcanoes and differences in ocean currents.

The main greenhouse gases (GHG) are:

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  Water vapour
  
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  Excess carbon dioxide
  
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  Methane
  

Others include nitrous oxide and hydrofluorocarbons.

These gases form a layer - a type of a ‘blanket’ which keeps the surface of the earth warm.

Human activities (e.g. land use, deforestation, burning of fossil fuels) lead to an increase in greenhouse gases in the atmosphere. This process brings about changes to the earth’s climate. In recent years it is believed that the concentration of carbon dioxide (CO₂) has increased by 25% as a result of human factors. Methane is considered as a much more powerful greenhouse gas than CO₂. The main sources of methane are fermentation of food in animal’s stomachs and landfills. Nitrous oxide can last in the atmosphere for about 150 years and comes from the use of artificial nitrogen fertilisers as well as burning of fossil fuels. Chlorofluorocarbons (CFCs) are produced by industries mainly in the processes of producing coolants, fridges, air conditioners and spray cans. CFCc can last in the atmosphere for up to 130 years and are very efficient at trapping heat.

Water vapour is produced by evaporation of lakes, rivers and oceans. Water vapour contributes significantly to the greenhouse effect and consequently to climate change. The exact contribution is estimated to be between 30-70% of the greenhouse effect.

6. Greenhouse gas inventory for Namibia

A greenhouse gas (GHG) inventory is a summary of emissions³ from source categories as well as removals by carbon sinks.

A carbon sink is a natural or artificial reservoir that accumulates and stores some carbon containing chemical compound for an indefinite period.

The process by which carbon sinks remove carbon dioxide (CO₂) from the atmosphere is known as carbon sequestration.

All the countries that are signatory to United Nations Framework Convention on Climate Change are required to submit greenhouse gas inventories as part of their reporting to UNFCCC. Namibia’s first inventory was prepared in 1994 and the second in 2008 (for the year 2000). The Ministry of Environment and Tourism is currently working on the third report to the UNFCCC and an updated inventory is expected from this process.

The greenhouse inventory is a comprehensive review of the anthropogenic sources and sinks for greenhouse gases in Namibia. It is important to note that the inventory does not account for greenhouse gas emissions occurring

1) in other countries resulting from electricity imported to Namibia,

2) in Namibia, international open space or other countries resulting from international airplane flights to or from Namibia, or

3) in other countries resulting from the manufacture of consumer goods in other countries that are imported to Namibia.

The inventory is broken down into six sectors which have been prescribed by the IPCC’s Revised 1996 Guidelines for National Greenhouse Gas Inventories. Overall, it is shown that Namibia is a net sink for greenhouse gases. This means that it absorbs CO₂ as a result of increasing woody biomass in the rangelands and it does not emit significant greenhouse gases on global standards.
The results for CO₂-equivalent emissions and removals indicate that the agriculture and energy sectors are most important with respect to emissions, and the land-use change and forestry sector (LUCF) is most important with respect to removals. Table 1 shows calculated greenhouse gas emissions and removals, disaggregated by major sector and compared with the 1994 inventory.

Table 1: Calculated greenhouse gas emissions for Year 2000 and comparison of results with Year 1994. Source: MET, 2011.

The largest differences in emissions and removals between the 1994 and 2000 inventories occur in the agriculture and land-use change and forestry sectors. The primary reason for the change (increase) in the agriculture sector greenhouse gas emission is that improved emission factors were utilised to calculate emissions from farm animals in the 2000 inventory. The improved emission factors are generally higher than those utilised in the 1994 inventory. The primary reason for the change (increase) in land-use change and forestry sector greenhouse gases removal is that new data was available regarding the extent of the bush encroachment problem and the annual increase in biomass resulting from the growth of invader bush.
Greenhouse gases inventories provide an understanding on trends and emissions. It is therefore useful for policy making as well as in formulation of mitigation and adaptation measures.
A few detailed recommendations have been formulated in the second national communication that both would improve future greenhouse gas inventories, and would provide cross-cutting benefits related to carbon credit applications, promotion of renewable energy, and finding solutions to the bush encroachment problem. The recommendations are summarised as follows:

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  Establish a greenhouse gas data collection unit within a government body such as the National Planning Commission (NPC) Central Bureau of Statistics or the Ministry of Environment and Tourism – Department of Environmental Affairs (MET-DEA).
  
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  Conduct scientific studies that will significantly improve the understanding of the impact of invader bush encroachment on Namibia’s greenhouse gas profile.
  
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  Clarify the details of pre-anthropogenic baseline ecological conditions in Namibia.