Human actions that produce environmental change 
A variety of human land uses and activities lead to environmental change. Examples include agriculture, forestry, fishing, mining, urbanisation, industry, tourism and recreation. All of these activities involve specific actions which cause changes to occur to the source, sink, service and spiritual functions of the earth’s environment. 

Causes of Environmental Changes

Some of these specific actions include: 
• vegetation clearance 
• channelling of streams 
• draining of wetlands 
• irrigation 
• application of fertilisers and pesticides 
• ploughing 
• covering land with hard surfaces 
• building on sand dunes 
• extraction of ground water
• planting of exotic forests
• use of off-road vehicles. 

Biophysical processes involved in environmental change 
Biophysical processes are interconnected sequences of cause and effect relationships. As a result of the specific human actions described above, the environment responds accordingly. For example, as a result of vegetation clearance, rising water tables can produce salinity, and because of the application of fertilisers, run-off into water bodies can cause eutrophication (algal blooms).  

Other biophysical processes include:  
• acidification of soils 
• accelerated soil erosion 
• beach erosion 
• weed invasion  
• enhanced greenhouse effect 
• heat island effect 
• climate change 
• decline in biodiversity. 

Activities 
1. In your own words, distinguish between the human actions that cause environmental change, and the biophysical processes involved in environmental change. 

2. Investigate the cause and effect relationships involved in the biophysical processes listed above. 

Causes and Effect of Climate and Environmental Changes 
In a broad sense, climate and environmental changes is the after mat of so many human activities and some natural occurrences.  Some natural causes of climate change are referred to as ‘’climate forcing’’ or ‘’forcing mechanisms’’. Changes in the state of this system can occur externally (from extraterrestrial systems) or internally (from ocean, atmosphere and land systems), through any one of the described components.

However, some climatologists are of the opinion that only a limited number of factors are primarily responsible for most of the past episodes of climate change on the Earth. 

These factors include; 
- Variations in the Earth’s orbital characteristics  Atmospheric carbon dioxide variations. 
- Volcanic eruptions. 
- Variation in solar output. 
- Plate Tectonics 
- Thermohaline Circulation.  

Climate and Environmental changes  
Climate change refers to a long change in the average weather pattern over a specific region/and a significant period of time. It is also seen as a change in the statistical distribution of weather patterns when that change lasts for an extended period of time (i.e. decades to millions of years). The most general definition of climate change is a change in the statistical properties of the climate system when considered over long period of time.

Some scientific journals are of the opinion that’’ global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels will affect’’ climate change is also seen as a change in global or regional climate patterns, in particular, a change apparently from the mid to late 20th century onwards and attributed largely to the increased level of atmospheric carbon dioxide (CO2). 

Environmental changes have to do with changes caused by the variation in the occurrences of some climatic factors; rainfall, temperature, light wind: biotic factors; predators, parasites, soil micro-organism, pest and diseases: and edaphic factors; soil pH, soil texture, soil structure etc. when environmental changes occur as a result of the actions of man and other natural phenomena, lives and properties are adversely affected. 

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