The Meaning of Climate
- Climate is the average weather in a given area over a longer period of time, typically averaged over a period of 30 years. Or,
- Climate is the average weather conditions of an area observed and recorded over a long period of time (about 30 years)

Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation.

In a broader sense, climate is the state of the components of the climate system, which includes the ocean and ice on Earth. The climate of a location is affected by its latitude, terrain, and altitude, as well as nearby water bodies and their currents.

The scientific study of climate is called climatology and a person who studies climate is called climatologist.

Climate change is any systematic change in the long-term statistics of climate variables such as temperature, precipitation, pressure, or wind sustained over several decades or longer. Climate change can be due to natural external forcings (changes in solar emission or changes in the earth’s orbit, natural internal processes of the climate system) or it can be human induced.

Good Climate

The weather should not be equated with climate, though they are very closely related to each other in the study of meteorology and climatology.

Weather is the conditions of the atmosphere which occur at a place at specific time period from hour to hour or day to day. The weather should not be equated with climate, though they are very closely related to each other in the study of meteorology and climatology. For example when we say climate of Tanzania is hot wet equatorial climate that is the summing up of the average everyday weather conditions of the country throughout the year.

Climate is the average weather conditions of an area observed and recoded over a long period of time (about 30 years). This involves systematic observation, recording and processing of the various elements of climate such as rainfall, temperature, humidity, air pressure, winds, clouds and sunshine before any standardization of the climatic means or average can be arrived at.

The Difference between Weather and Climate

The difference between weather and climate is a measure of time. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere "behaves" over relatively long periods of time.

When we talk about climate change, we talk about changes in long-term averages of daily weather.

For example: Today, children always hear stories from their parents and grandparents about how snow was always piled up to their waists as they trudged off to school. Children today in most areas of the country haven't experienced those kinds of dreadful snow-packed winters, except for the Northeastern U.S. in January 2005. The change in recent winter snows indicate that the climate has changed since their parents were young.

The table below summarizes these differences.

a.Describes the atmospheric conditions at a specific place and time.Describes the average atmospheric conditions of a place over a specific period of time.
b.Weather is defined as the day to day state of the atmosphere, and it is short-term (minutes to weeks) variation.Climate is defined as statistical weather information that describes the variation of weather at a given place for a specified time interval.
c.Weather conditions are measured over a short period e.g. a few hours or days.Climate conditions are measured over many years, e.g., 30 years.
d.Determined by real time measurements of atmospheric pressure, wind speed and direction, humidity, precipitation, cloud cover, and other variables.Determined by averaging weather data over periods of 30 years.
e.Weather changes abruptly within a short period.Climate changes slowly and gradually over many years.
f.Weather varies from one place to another within a region.Climate remains uniform over a large area.
g.Most weather elements are measured by weather instruments.Climatic elements are not measured but calculated from the recorded weather data.
Bad Climate
Factors Influencing Climate
1. Latitude - Influences temperatures on the surface of the earth whereby the areas nearer to the Equator experience higher temperature than those far away. -Shifting of the overhead position of the sun is determined by latitudes and has an influence on climate.
2. Altitude - Influences temperature and pressure of a region. Low altitude regions are warmer and experience high atmospheric pressure while high altitude areas are cooler and have low pressure.
3. Distance from the sea - Has an influence in both temperature and rainfall of a region. During summer onshore winds have cooling effect on the land which is warm. During winter the sea is warmer than the land.
4. Aspect - Aspect refers to the direction in which a slope faces e.g: in The Northern Hemisphere, the Southern ward slopes are warmer than the North ward facing slopes. This is because the North slopes never receive direct sunshine as the sun in this region never gets overhead. Windward slopes of highlands receive much higher rainfall than the Leeward slopes.

5. Ocean Currents - Current flowing along the Coasts tend to modify the climate of the Coastal regions. Where onshore wind blow over a cold ocean current are cooled from the below and the moisture they are carrying is condensed and dropped over the sea as rain.

6. Prevailing Winds - Wind is a medium of transfer of heat and moisture over the land. If wind is blowing from a warm region, it has the warming effects over the region it is blowing across and if wind will blow from cold region it will be cold and will cool the land over which it is blowing.

7. Human Activities - Like development of settlements, agriculture and construction of dams and creation of manmade lakes have influence on climate. In recent times we are realizing the effects of human activities in causing climate change, caused by:
- clearing of forests
- draining and cultivating swamp areas
- emission of Chlorofluorocarbons and
- other gases from factories and motor vehicles.

Relationship between Climate and Human Activities
Climate has many impacts to human activities. Various economic activities conducted by man in different parts of the world are governed by the type of climate experienced in a particular region. For example, people living in deserts and semi-arid regions do not practice much agriculture because their environment does not favour crop cultivation or animal husbandry. In these regions, however, a very limited agriculture and animals rearing is conducted. The animals kept include camels, goats, sheep, donkeys and other hardy animals. Only drought resistant crops such as dates are grown in deserts and arid areas.
In tropical and equatorial regions, a lot of agriculture is carried out. The inhabitants of these regions take part in cultivation of crops and keeping of animals. Crops grown include cocoa, banana, horticultural crops and grains. The animals kept in these climatic zones include cattle, pigs, donkeys, horses, poultry and other farmyard animals. Specific types of various economic activities carried out in each climatic region will be discussed in detail in the section below.
Good climate supports agriculture

Climate is not the uniform across the World, climate varies from one place to another. Mainly variation of temperature and rainfall influences different climatic characteristics. This gives rise to various climatic regions around the globe.

Natural Regions are geographical areas with uniform physical characteristics that distinguish it from other natural regions. The four types of climate are hot, warm, cool, and cold climates. Each of these climates is further subdivided into different subtypes as it will be explained in detail below:

These are the type of climates found within the tropics, mainly between 23½° north and 23½° south of the equator. Hot climates include the following climate sub types:

1. Equatorial climate
2. Tropical continental climate
3. Tropical monsoon climate
4. Tropical marine climate
5. Tropical desert climate
Location. The region is found between 0° and 5° north and south of the equator but in some regions it may extend up to 10° north or south of the equator. Examples of areas found within this region include the Amazon basin, Congo basin, the southern Ivory Coast, south Ghana, western coastal Nigeria, and eastern coastal Malagasy Republic.
Equatorial Climate
Climatic Characteristics

1. There are no marked seasons of the year
2. High temperature about 270C throughout the year
3. The annual temperature range is about 3°C.
4. The daily mean temperatures are about 26°C all the year round.
5. The daily temperature range is rarely more than 8°C because of the thick cloud cover.
6. Rainfall is heavy and is usually convection rain.
7. Rainfalls usually occur in the afternoons and they are accompanied by lightning and thunder.
8. The annual rainfall is about 2000mm
9. High humidity and intensive cloud cover throughout the year.

Crops grown are cassava, groundnuts, maize, millet, beans, bananas.
Human activities: Plantation agriculture, fishing, cultivation, peasantry sedentary agriculture.
Common animals found: Monkey, gorillas, crocodiles, and hippopotamus.
NB: But areas located in highlands within the equatorial region have their temperatures modified by altitude. The temperature of some of these highland areas, e.g., the East African Highlands, is lowered to about 15°C. These regions are said to have a modified equatorial climate. Variations on the basic type of climate occur in the highland regions of equatorial Africa. The climate of most of these regions has an equatorial rainfall pattern.

Equatorial Rain forest

This climate is also known as Sudan type or Savannah climate. In the interior of the continents it is referred to as tropical continental climate.

Location: the region is found between 5° - 15° north and south though it may extends to 250 north or south of the equator. Area found: East and Central Africa, Brazilian plateau, Venezuela, Africa and N. Australia. Climate: hot wet summer season, warm dry winter, rainfall is moderate. Torrential rainfall associated with thunderstorms in annual range of temperature increases with the distance from equator.

Tropical Climate

Climatic Characteristics
1. High temperature, in hot summers (320C) and cooler winters (200C).
2. The annual temperature range is about 110 C.
3. The highest temperatures occur just before the rainy season begins.
4. Heavy rains, mainly convection, occur in the summer.

5. Total annual rainfall is around 765mm, though this increases in the areas lying close to the equatorial climate region. Similarly, rainfall decreases towards the tropical deserts.
6. Humidity is high during the hot, wet season.

This climate is characterized by tall grass and trees which are more numerous near the equatorial forest region.

The savannah region is suitable for herbivores animals such as giraffes, elephants, buffaloes, rhino, zebras, antelopes, wildebeests and many other animals. There are also carnivorous animals such as lions, leopards, hyenas, etc. The region also supports a variety of species of birds, reptiles and insects.

Tropical or Savannah Climate
Human Activities
People living in this region mainly engage in livestock keeping, cultivation and tourism. Also lumbering is practiced. Many tourists come from foreign countries to view the wildlife that live in the vast grassland. Numerous national parks have been established in this region. In Tanzania, for example, there are established national parks such as Serengeti, Mikumi, Selous, Tarangire, Ruaha, Saadani, Ngorongoro, Katavi and Manyara. The major crops grown in this region are maize, millet, groundnuts, beans, onions, cotton, tobacco, sugarcane, sisal, rice and coffee.


Location. The areas which mainly experience monsoon type of climate are South East Asia, Northern Australia, Southern China, and the Indian subcontinent. This type of climate is most marked in India.

Tropical Monsoon Climate

Climatic Characteristics

1. Seasonal reversal of winds (monsoon winds); onshore during one season and offshore during another season.
2. Onshore wind brings heavy rain to coastal regions while offshore winds bring little or no rain, except where they cross a wide stretch of the sea.
3. Temperatures range from 32oC in the hot season to about 25oC in the cool season, giving an annual range of about 7oC.
4. Annual rainfall varies greatly, depending on relief and the angle at which onshore winds meet the highlands (aspect).
5. There are three marked seasons: cool, dry season; hot, dry season; and hot, wet season. This climate can generally be described as having a hot, wet season and cool, dry season.

Human Activities
The main human activities carried out in areas experiencing this type of climate include rice growing and livestock husbandry. Apart from rice, the other crops grown are wheat, millet, maize, and sorghum. Sugarcane, cotton and juice are important lowland crops grown in India, Pakistan and Bangladesh. The other crops grown are tea (Sri-lanka, Bangladesh and India) and rubber in Malaysia. Animals kept in this climatic region include pigs, cattle, buffalos, sheep, goats, and poultry.

Location. Regions with this type of climate are located on the east coasts of regions lying between 100N and 250N and 100S and 250S. These areas are under the influence of onshore trade winds. The main areas are the east coasts of Brail and Malagasy, the lowlands of Central American and the west indies the coast of Queen land (Australia) and the southern Islands of the Philippines.

Tropical Marine Climate

Climatic Characteristics
1. Temperature characteristics are similar to those of the equatorial climate.
2. Hot season temperature is 290C and cooler season temperature is 210C.
3. Annual temperature range is about 80C.
4. Total annual rainfall varies from 1000 mm to 200 mm depending on the location.
5. Rainfall is both convection and topographic (brought by onshore trade winds).
6. Maximum rainfall occurs in the hot season.
7. High humidity throughout the year. This climate can generally be described as hot and humid throughout the year. However, the climate is cooled by the onshore winds blowing almost everyday.

Human Activities
The main human activities carried out in this climatic region include crop cultivation, lumbering and animal rearing. The crops grown include sugarcane, rice, banana and wheat. The animals kept are such as cattle, pigs, sheep, goats and poultry.

Location.The tropical desert climate occurs on the western margins of landmasses between latitude 200 to 300 north and south of the equator. The climate is experienced in all the major tropical deserts of the world. The hot deserts occupy about one third of the earth’s surface. The principal tropical deserts occur on the continents as follows:

1. Africa: Sahara, Kalahari and Namib Deserts
2. Asia: the desert of Jordan, Syria, Iran, Iraq, Saudi Arabia and Israel, and the desert of India.
3. North America: Mohave, Colorado and Mexican Deserts.
4. South America: Atacama Desert
5. Australia: Great Australian Desert

Hot Desert Climate
Vegetation - Hot deserts have clumps of vegetation in which mostly consist of thorny scrub bushes and cacti.
Animals - the camel is a typical example of a desert animal adapted to its environment. Other animals which can be found in hot deserts include donkeys, goats, sheep etc
Human Activities
The bushmen from Kalahari Desert and Aborigines of Australia engage in collecting fruits and hunting. They also eat lizards, insects, snakes and other small animals. People in hot deserts also practise agriculture, irrigation is practised where oases are found. Some main crops include maize, millet, rice and wheat. Other human activities are weaving mats, trading, making tents and ropes
Cacti in the Desert

Warm climates border the hot tropical deserts. They occur between 300 and 400 north and south of the equator. There are four broad types of warm climates:

1. Warm temperature western margin.
2. Warm temperature continental.
3. Warm temperature eastern margin.
4. Warm temperature desert.

This is also known as the Mediterranean climate
Location. This type of climate occurs between 300 N and 450 N and 300 S and 400 S on the western sides of the continents. Places experiencing the Mediterranean climate are on the coastal lands around the Mediterranean Sea (the Maghreb, Spain, Italy, Greece, Egypt and Israel), the western sides of north and South America (central California and central Chile), South Australia (Perth and Adelaide) and South Africa (Cape Province).

Mediterranean climate

General Characteristics
1. Temperatures range from 210 C in the summer to 100 C (or below) in the winter.
2. Mean annual temperature is about 150C.
3. Annual total rainfall varies from 500 to 900 mm.
4. Hot, dry summers and cold, wet winters. This is because westerly winds blow off shore in the summer and on shore in the winter.

The Mediterranean climate can generally be described as having hot, dry summers and middy, rainy winters. The climate permits a wide range of crops to be grown, which include fruits and cereals. It is in this region that much of the world’s citrus fruits are grown. Citrus fruits include oranges, lemons, grapes and limes.

Other fruits grown here are peaches, apricots, plums, cherries, olives, almonds and pears. The cereals include maize, wheat, rice and barley. Agriculture has given rise to specialized industries such as wine-making, flour-milling, fruit canning and food processing industries.

Fruit Trees (Mediterranean climate)

This type of climate is also known as warm temperate interior region
Location. It occurs in the interior of the continents, between 200 and 350 north and south of the equator. The best examples of the areas having this climate are Murray-Darling lowlands of Australia; The high Veldt of South Africa; and the central Paraguay and central Argentina (both in South America); central lowlands of north America (Oklahoma and Texas and in northern Mexico), central European lowlands, and the plains of Manchuria.

Steppe Climate

Climatic Characteristics
1. Temperatures range from 26oC in the summer to 10oC in the winter.
2. The annual rainfall varies from 380 to 700 mm, depending on the distance from the sea.
3. Rainfall is convectional type and falls mainly in spring and early summer.

Human Activities
The main economic activities carried out in this region are cattle rearing and crop growing. Tourism is also practiced.

Location. It occurs in the eastern sides of the continents between latitudes 230 and 350 north and south of the equator. The countries having this type of climate are central China, south eastern USA, and southern Brazil, eastern part of Argentina, South Africa, southern Brazil, and eastern part of Argentina, South Africa, southern Japan, and south eastern Australia.

China Type Climate
Climatic Characteristics
1. Temperatures are about 26°C in summer and 13°C in the winter.
2. The total annual rainfall varies is about 1000 mm.
3. The rain is convectional and torrential type and it mostly falls in the summer.

Human Activities
Temperatures and rainfall in this type of climate make it possible to grow crops and keep animals. Lumbering is also practiced in the forested areas. The crops grown include rice, maize, cotton, sugarcane and tobacco. Animals are extensively kept in Argentina and Australia. The animals produce products such asmeat, milk, butter and cheese for consumption and export.

This type of climate is also called mid-latitude desert climate. The areas having this type of climate include Nevada and Utah states of North America and Pentagonia in South America. It is also found in regions that extend from Turkey, northern Iran, across the Caspian sea and Aral areas into former USSR. It is also experienced in the Gobi desert of Mongolia.

These climates are experienced in regions between 350 north and 600 south of the equator. They are characterized by definite seasonal variations in temperature. There are four types of cool climates:
1. Cool temperate continental (British type).
2. Cool temperate continental (Siberian type).
3. Cool temperate eastern margin (Laurentian type).
4. Temperate desert.

Location. It occurs on the western sides of the continents between 450 and 600 north and south of the equator. Areas with this type of climate include North West Europe, British Columbia in western Canada, Southern Chile, Tasmania, and the south Island of New Zealand.

British type Climate

1. Winter temperatures range between 20 C and 70 C, while summer temperatures range from 130 C to 150 C.
2. The annual temperature range is between 80 C and 110 C.
3. Rain falls throughout the year, with maxima in winter.
4. The total annual rainfall is about 760 mm.
5. The rain is both convectional and cyclonic in nature.

Human Activities
People living in this region engage in a myriad of economic activities which include agriculture, mining, lumbering, manufacturing and commerce. Agriculture is of extensive type and includes keeping of beef and dairy cattle and sheep and the growing of wheat, barley oats, vegetables and fruits. In British Columbia lumbering is an important economic activity. In Tasmania and New Zealand, sheep rearing for wool and mutton is an important activity. Fruit farming, especially apples, is practiced throughout the region.

Location. This type of climate is found extensively in the northern hemisphere. It occurs in the interiors of North America and Eurasia between 350 and 600N

Siberian Climate

Climatic Characteristics
1. Moderately warm summers (180) and very cold winters (-190C).
2. The annual temperature range is very high (370C).
3. Most of the rain falls in the summer.
4. The rain is convectional type and is often accompanied with thunder.
5. The annual precipitation (rain plus snow) ranges from 400 to 500 mm.

Human Activities
The main human activities in this region include lumbering fishing, mining and some agriculture.

Location. It occurs on the eastern sides of the continents between 350N and 500N, and south of 400S. It is experienced mainly on the eastern sides of North America and Asia

Laurentian Climate

Climatic Characteristics
1. Winter temperatures range from -100C to 40C.
2. Summer temperatures range from 120C to 240C.
3. The annual temperature range is large and averages 240C.
4. Precipitation (in the form of rain and snow) is distributed throughout the year.
5. Annual precipitation varies between 700 and 1000 mm.
6. Rainfall is both convectional and cyclonic.

Human Activities
The main economic activities in this region are farming, mining, and manufacturing. The crops grown include wheat, maize, millet and soya beans. Sheep farming is important in Patagonia. Mining and manufacturing are practiced where minerals are found.

Location. This climate occurs in the interiors of Eurasia and North America, and in Patagonia (South America).
Climatic Characteristics
1. Winters are very cold with temperatures often below -70C.
2. Summer temperatures vary between 250C and 370C.
3. Diurnal temperature range is about 350C while the annual temperature range is about 400C.
4. Precipitation is very low, it averages about 250 mm.
5. Most of the rain falls in late winter and early spring.
Autotrophs in Temperate Deserts
Human Activities
The human activities carried out in this region include mining, animal rearing and some agriculture. The animals reared are such as camels, donkeys, sheep and goats. The main crops grown in this region are date palms, oil palms, and millet. Agriculture is mostly practised in oases and along river valleys. iv.

Cold climates are mainly experienced in regions between latitudes 600 N and 680 N. There are three types of cold climates:
1. Cold temperate western margin.
2. Cold temperate eastern margin.
3. Cold temperate continental.

Location. This climate is confined to coastal areas of Scandinavia and Alaska.
Cold Temperate Western Margin

Climatic Characteristics
1. Cold and long winters with temperatures ranging between -340 C and -450 C.
2. Warm and short summers with average temperatures up to 210 C.
3. Annual rainfall is about 750 mm.
4. Rain falls in most months except the winter when show falls.

Human Activities
The main economic activities practiced in this region include agriculture, mining and manufacturing. A dairy cattle farming is mainly practiced in the Scandinavian countries such as Norway Denmark and Sweden.
Location. This climate occurs between 550N and 680N in the interior of America and Eurasia.

Cold Temperate Climate

Climatic characteristics

1. Cold and long winters with temperatures ranging between -340 C and -450 C.
2. Warm and short summers with average temperatures up to 210 C.
3. Annual precipitation is very low, about 380 mm.
4. Most of the rainfalls in summer, but in winter, precipitation is in the form of snow.


This climate occurs in the north east pacific of Russia.

Climatic Characteristics

1. Long, cold winters with an average temperature as low as -200 C or below.
2. Short, hot summers with an average temperature up to 210 C or higher.
3. Total annual rainfall varies between 500 and 1000 mm.

These types of climates are experienced in regions beyond the Arctic Circle (661/20 N) and around Arctic Ocean. They are also known as polar deserts.

The main features of these climates are:
1. Low amounts of precipitation (rain)
2. Mild summers
3. Very cold winters.
Arctic climates comprises of
a) Tundra
b) Polar climates

Location This region occurs in the northern coast of North America, southern coast Greenland and the Arctic coast of Europe and Asia.

Tundra Climate

Climatic Characteristics
1. Very long, cold winters with temperatures ranging between -290 C and – 400 C.
2. Short, cool summers with temperatures of about 100 C.
3. Annual precipitation is 250 mm; some of it falls as snow in winter and as rain in summer.

Ice in Tundra Climate
Location. It occurs in the interiors of Iceland, Greenland and Antarctica.
Polar Climate

Climatic Characteristics
1. Temperatures are permanently below 00 C.
2. Precipitation is in the form of blizzards (now storms).
3. The winters consist of continuous night, and summers of continuous day.

Bear in Polar Climate

Human Activities
Because temperatures are very low, most these regions are uninhabited and hence limited human activities take place here. The natural occupations are hunting, fishing and herding of reindeer.
This type of climate occurs in the main mountain areas of the world. The areas that experience such climates include the East Africa Mountains, the Ethiopian highlands, the mountains and plateaus of central Asia, the Alps of Europe, the Andes of South America and the Rockes of North America.

Climatic Characteristics
1. Pressure and temperature generally decrease with increase in altitude.
2. Precipitation increases with altitude.
3. In areas around mountains within the tropic, temperatures may range from high at the foot of a mountain to very cold at the peak, e.g. Mount Kilimanjaro.

Mountain Climate

Characteristics of these Regions
1. They experience similar problems.
2. They have same geographical back ground.
3. Are unified by the same certain latitudes which help in locating them over.
4. Tend to have almost the same type of soil and vegetation cover.
5. They have the same occupation such as a mining, agriculture and animal husbandry.

We have seen how particular climatic conditions influence human activities. Now, let us see how specific climatic conditions are suitable for given human activities:

Agriculture is strongly influenced by weather and climate. The nature of agriculture and farming practices in any particular location depends on the type of climate experienced in that location.
Crops thrive well in any area with a fertile soil and which receives sufficient rainfall as well as optimum temperature conditions. In such areas both commercial and subsistence crops may be grown.
The equatorial region receives high rainfall and experiences high temperature throughout the year. This climate is suitable for crops that can thrive well in moist and hot conditions. The crops that can be grown in this region include cocoa, banana, rubber, sugarcane and yams.
Livestock rearing can be practised in the tropics where rainfall permits the growth of pastures. This area also supports the cultivation of a variety of tropical crops such as fruits, tobacco, sugarcane, tea, maize, rice and a variety of horticultural and cereal crops

Cooler climates also support crops which grow better in climates like barley, wheat, oats, sugar beet, and fruits such as apples, peaches and apricots. These areas also support the rearing of dairy animals.
In semi desert and desert climates where very little rainfall is received, there are reduced agricultural activities. However, drought-resistant crops like millet, date palms, oil palms and sorghum can be grown. The keeping of hardy animals such as sheep, camels, donkeys and goats can be done.


People like to establish settlements in areas with favourable climates and which support a variety of agricultural activities. Such areas are often well-populated. Very hot or extremely cold areas are usually sparsely populated because their climatic conditions are unfavourable for human settlement.
Forests thrive well in areas that receive ample rainfall and which have adequate temperatures. Dense forests of the world are concentrated in the equatorial and tropical climates which experience high rainfall and temperature throughout the year. The presence of forests in these regions stimulate lumbering and growth of other industries such as paper-making and carpentry.

Most of the world’s fishing grounds are in cooler regions. The cooler water is thought to support the growth of water plants called plankton on which fish feed. Tropical areas are not suitable for fish as compared to regions with temperate climates.


For tourism industry to flourish, the climate in the host countries must be favourable enough to attract the tourists to visit them. Tropical countries, like Tanzania, are often visited by tourists from cooler climates during winter in their home countries to enjoy the warmth of the tropical countries where they swim in warm waters and sunbath in tropical beaches.


The establishment and growth of industries strongly correlate to the climatic conditions. Most industries are established in areas where raw materials are adequately available. For instance, milk, tea, tobacco, meat, fish and fruit processing industries are often located where raw materials are found. Likewise, lumbering industries are built close to forests.


Development of the transport systems in some climatic regions is very difficult. For example, the tropical and equatorial regions, which receive much rainfall throughout the year, have poorly developed roads. Routes passing through areas with clay soils become muddy and slippery when it rains. This makes it hard to travel on earthy and murram roads. Roads in desert regions may be blocked by sand blown onto them, making the roads impassable. In very cold regions, precipitation in the form of snow may cover roads, making them impassable during winter.
Climate change is a large-scale, long term shift in the planet’s climate (weather patterns and temperatures). The overall effect of climate change is termed as global warming.

What is Global Warming?
Global warming refers to increase of the earth’s average surface temperature due to effects of the greenhouse gases. These gases trap heat that would otherwise escape from the earth. The greenhouse gases include:
- Water vapour (H2O),
- Carbon dioxide (CO2),
- Methane (CH4), dinitrogen oxide or
- Nitrous oxide (N2O),
- Ozone (O3) and
- Chlorofluorocarbons (CFCs).
Since the early 20th century, the global air and sea surface temperature has increased by about 0.8°C, with about twothirds of the increase occurring since 1980. Each of the last three decades has been successively warmer at the earth’s surface than preceding decades since 1850.

The recent rapid warming was caused by human activities which contribute to the production of greenhouse gases, such as carbon dioxide, that trap heat in the earth’s
atmosphere. It is predicted that the continuation of these activities will result in 1.8–4°C average temperature increase over the next century.

Global Warming

Causes of Global Warming
Scientific understanding of the cause of global warming has been increasing. Global warming is mostly caused by:
1. Increasing concentrations of greenhouse gases in the atmosphere. The following greenhouse gases which are the main contributors to global warming:
a) Carbon dioxide
Carbon dioxide is the main greenhouse gas. The gas contributes over 50% of the greenhouse effect. It is because of this reason that man is struggling to reduce carbon dioxide emissions.

The following are some of the man-made sources of carbon dioxide in the atmosphere:
i) Deforestation
Green plants absorb carbon dioxide gas from the atmosphere and use it to manufacture their food through the process of photosynthesis. Cutting down trees means that a few trees are left to absorb carbon dioxide gas from the air. This has led to the increase in the amount of carbon dioxide in the atmosphere.
ii) Combustion of fuel
Burning of fossil fuel such as wood, coal, petroleum and natural gas, releases carbon dioxide into the atmosphere. The gas is produced during combustion of these fuels in car engines, power stations, industries, etc.

Producing Carbon dioxide

b) Methane
The main source of methane is from agricultural activities. It is released from wetlands such as rice fields and from animals, particularly cud-chewing animals, like cattle. The emission of methane gas into the atmosphere, therefore, increases with increase in agricultural activities. Since 1960s the amount of methane in the air has increased by 1% per year, twice as fast as the build-up of carbon dioxide.Methane is also produced by the decomposition of waste materials by bacteria. It is the major component of natural gas.The gas is also produced during the mining of coal and oil (as natural gas) and when vegetation is burnt.

Producing Methane

c) Nitrous Oxide (Dinitrogen Oxide, N2O)
Niitrogen oxide is produced from both man-made and natural processes. Human activities which produce dinitrogen oxide include combustion of fossil fuels in vehicles and power stations, use of nitrogenous fertilizers and burning of vegetation and animal waste. During combustion of fuel in automobile engines, the air gets so hot that nitrogen reacts with oxygen to form dinitrogen oxide. The gas is also produced by digesting bacteria, and is part of the nitrogen cycle, one of the most important natural processes on earth.

Producing Nitrous Oxide

d) Chlorofluorocarbons (CFCs)
The sources of CFCs in the atmosphere include refrigerators, air conditioners and aerosols. CFCs are extremely effective greenhouse gases. One CFC molecule is about 10,000 times more effective in trapping heat than a carbon dioxide molecule. Some of them are up to 14,000 times effective than carbon dioxide, the main greenhouse gas.

Producing Chlorofluorocarbons 

Effects of Global Warming
Global warming is expected to have far-reaching, longlasting and, in many cases, devastating consequences for planet earth.The following are some effects of global warming:

1. Increase in Average Temperatures
One of the most immediate and obvious impacts of global warming is the increase in temperatures on the world. The average global temperature has increased by about 0.8°C over the past 100 years. Scientists predict that the earth’s average temperature will increase by between 1.4 and 5.8°C by the year 2100. Increase in global temperature will affect both the land and the ocean environments. The average temperature of the oceans has increased significantly in the past few decades, causing negative effects on marine life. When the ocean water gets warm, the algae in the ocean tends to produce toxic oxygen compounds called superoxides which are damaging for the corals. Global warming is threatening the coral reefs to a great extent, and the fact is that if coral reefs are wiped off the planet, it will affect one third of planet’s marine biodivers

Increase in Average Temperatures

2. Extreme Weather Events
Extreme weather events include record-breaking high or low temperatures, floods or intense storms, droughts, heat waves, hurricanes and tornadoes, etc. These are effective measures of climate change and global warming. Scientists project that extreme weather events, such as heat waves, droughts, blizzards and rainstorms will continue to occur more often and with greater intensity due to global warming.
Other effects of extreme weather events include:
i) Higher or lower agricultural yields
ii) Melting of arctic ice and snowcapes- this causes landslides, flash slides and glacial lakes
iii) Extinction of some animal and plant species
iv) Increase in the range of dseases vectors, that is, organism cause diseases like mosquitoes

Extreme Weather Events 

3. Change in World’s Climate Patterns
It is forecasted that global warming will cause climate patterns worldwide to experience significant changes. Climate change resulting from increasing temperatures will likely include changes in wind patterns, annual precipitation and seasonal temperature variations. Climatic patterns in most parts of the world have already changed. Rains fall when least expected and at irregular intervals. This has greatly affected the timing of planting and harvesting activities. Sometimes the rains fall so heavily to cause floods, or too little leading to drought.

Most of the arable land that once used to be productive is slowly turning arid. With time, farmers will run short of the land for cultivation, a fact that will result in famine. Because high levels of greenhouse gases in the atmosphere are likely to remain high for many years, these changes are expected to last for several decades or longer.

Change in World’s Climate Patterns

4. Rise in Sea Levels
Continued increase in the global temperature will cause the melting of ice caps in the poles and mountain glaciers. Melting polar ice and glaciers are expected to raise sea levels significantly. Global sea levels have risen about 8 inches since 1870 and the rate of increase is expected to accelerate in the coming years. If current trends continue, many coastal areas will eventually be flooded. Scientists predict that by the year 2100 the sea level will raise by at least 25 m, leading to coastal flooding that will displace millions of people. Small islands in the Caribbean, South Pacific, Mediterranean and Indian Ocean will be totally covered by ocean waters.

Rise in Sea Levels

5. Ocean Acidification
As levels of atmospheric carbon dioxide increase, the oceans absorb some of it. This increases the acidity of seawater. Since the Industrial Revolution began in the early 1700s, the acidity of the oceans has increased about 25%. Because acids dissolve calcium carbonate, seawater that is more acidic has a drastic effect on organisms with shells made of calcium carbonate, such as corals, mollusks, shellfish and plankton. The acid water is likely to dissolve the carbonaceous shells, thus endangering the lives of these sea creatures. Change in ocean acidity will also affect fish and other aquatic animals and plants. If current ocean acidification trends continue, coral reefs are expected to become increasingly rare in areas where they are now common.

Ocean Acidification

6. Effects on Plants and Animals
The effects of global warming on the earth's ecosystems are expected to be profound and widespread. Many species of plants and animals are already moving their range northward or to higher altitudes as a result of warming temperatures. Additionally, migratory birds and insects are now arriving in their summer feeding and nesting grounds several days or weeks earlier than they did in the 20th century.

Warmer temperatures will also expand the range of many disease-causing pathogens that were once confined to tropical and subtropical areas, killing off plant and animal species that formerly were protected from disease. These and other impacts of global warming, if left unchecked, will likely contribute to the disappearance of up to one-half of the earth's plants and one-third of animals from their current range by 2050.

Deaths of Animals

7. Effects on Humans
As dramatic as the effects of climate change are expected to be on the natural world, the projected changes to human society may be even more devastating. Agricultural systems will likely be affected badly. Though growing seasons in some areas will expand, the combined impacts of drought, severe weather, lack of snowmelt, greater number and diversity of pests, lower groundwater tables and a loss of arable land could cause severe crop failures and livestock shortages worldwide.

This loss of food security might, in turn, create havoc in international food markets and could spark famines, food riots, political instability and civil unrest worldwide. The effect of global warming on human health is also expected to be serious. An increase in mosquito-borne diseases like malaria and dengue fever, as well as a rise in cases of chronic conditions like asthma, are already occurring, most likely as a direct result of global warming.


The Relationship between Human Activities and Climate
Human activities are human undertakings which are done to earn a living, they include, fishing, lumbering, hunting and gathering and manufacturing. Climate influences human activities directly.E.g In agriculture, different crops have different requirements of temperature and rainfall as the major climatic element. Therefore it is not advisable to cultivate permanent crops in deserts.

Ways of Solving Climatic Problems
There are natural and man-made causes of climatic change that bring about climate problems. There are possible solutions to climatic problems such as:
1. Education,
2. Avoidance of bad methods of farming,
3. Application of good farming methods,
4. Application of appropriate technologies,
5. Land reforms,
6. Afforestation,
7. Laws and rules,
8. Reduction of carbon dioxide emissions from industries.