Earth’s Dynamic Climate
Climate change is a natural part of Earth’s history.
• For example, .
Increased Temperature
• In the last 100 years
• Eleven of the twelve years (1995-2006)
• There is a risk that by the end of the 21st Century temperatures could rise by between 1.1 and 6.4°C.
Weather
• Weather .
• Weather .
• Weather is thought of as
Climate
• Climate is .
• Climate is defined as
• It is the weather of a locality averaged over some period (usually 30 years) plus statistics of weather extremes.
Temperature and Climate
• The Earth is surrounded by
• Without this envelop,
• So how is heat energy transferred?
Heat
• Heat is always transferred
• There are three types of heat transfer:
• Conduction
• The transfer of heat between substances
• The better the conductor the more rapidly the heat will transfer.
• Convection
• The
• As a gas/liquid is heated As it rises and expands, it cools and falls.
• Radiation
• .
Climate Systems
• The Earth’s climate system is affected by the interactions of different subsystems such as the atmosphere, the lithosphere the hydrosphere (oceans and rivers) and the biosphere (forests, plants and soil).
• The lithosphere is the rocky layer that covers the earth.
• The atmosphere is the air that surrounds the earth.
• The hydrosphere is all the water on or near the earth’s surface.
Factors Affecting Climate Change
· The Sun
o The sun is all “atmosphere” because it is all gas. When people refer to the “surface” of the sun, .
o Some regions on the sun are cooler than their surrounding and therefore appear to be darker.
o Near sunspots are where violent solar flares occur, sending streams of high energy subatomic particles into space. .
o Heat produces .
o The Sun produces a variable amount of energy.
o When the number of sunspots is high,
o Some scientists believe that changes in solar output are .
· The Earth
o Earth rotates
o The Earth also
o Another important detail is that the Earth’s
o The amount of solar energy that reaches Earth depends on
o The seasons are created by Earth’s revolution and its tilted axis.
o A crucial feature of the climate system is that the energy coming from the sun
o Due to the shape of the Earth, .
o This non-uniform energy distribution leads to
o Earth’s outer layer is made of massive pieces of solid rock,
o Earth has about 12 major plates The plates carry the continents with them as they move.
o This means that the shape of the oceans and continents is always changing.
· Most volcanoes are
· Plate movement affects climate
· During a volcanic eruption,
o Aerosols:
§ reflect
§ scatter light
§ Some volcanic eruptions can .
· The Atmosphere
o The Earth’s atmosphere is like a big blanket that surrounds the globe, keeping humans warm. If it was suddenly stripped off, .
o It is mostly made of , very low concentrations of other gases and particles of solids.
o The greenhouse effect occurs because the Sun’s shortwave radiation .
o This warm surface then
o The greenhouse gases
o Any change to the volume of greenhouse gases therefore It is a bit like putting an extra blanket on your bed – it traps more of your body heat under the covers.
o Greenhouse gases
§ The main gases are nitrogen, oxygen and argon.
§ There are also trace gases such as .
§ These are called the .
o Wind
§ Wind is caused by
§ The air moves .
§ It is the .
o As air masses of different densities move across the Earth’s surface, they interact.
o When air masses .
o The rising air cools and .
o Currents
§ Winds start the ocean currents flowing, but two other factors influence the patterns of flowing waters – continents and the Coriolis effect.
· Ocean currents turn right in the Northern Hemisphere and turn left in the Southern Hemisphere.
· The difference in atmospheric temperature cause the . These currents transport heat from the warm tropics to the cold Polar Regions and back again.
· The Hydrosphere
o Two thirds of the Earth is covered by oceans.
o The hydrosphere includes
o On Earth water is found in many forms:
§ vapour and clouds of water droplets in the atmosphere
§ liquid in the oceans, seas, and smaller bodies of water
§ ice and snow in temperate and colder regions
o Specific Heat Capacity
§ Oceans and lakes act as heat reservoirs.
§ Large bodies of water influence
§ Specific heat capacity .
§ Water has a large specific heat capacity. This means of 1 g of water by 1oC than it does to do the same to many other substances.
§ The higher the heat capacity,
§ Ice and snow reflect heat
§ The light colour of ice and snow allow them to reflect solar radiation.
§ Because as we know, light-coloured surfaces reflect energy, and dark surfaces absorb energy.
· Human Activity
o In the past, scientists have had great difficulty understanding and predicting changes in climate.
o Recently though, reliable evidence has emerged on how subsystems interacted and produced past climatic changes.
o Using and improving complex climate models with sophisticated computer programs, scientists have been able to simulate weather and climate. Scientists are now able to predict climate changes that could follow from human actions.
o Over the past century major changes have occurred in agriculture, manufacturing and transportation, most notably since the middle of the 19th century and the Industrial Revolution.
o One major change is the replacement of organic fuels
o With the exception of water vapour,
o The concentration of carbon dioxide (CO2) in the atmosphere has been increasing rapidly since the Industrial Revolution as
o Scientists have concluded that human activities are the main cause of the increase in CO2 in the atmosphere.
o In addition to burning fossil fuels, clearing of forests and releasing industrial gases such as refrigerants, have also contributed to the enhanced greenhouse effect.
o Another of the main greenhouse gases is methane (CH4), which is 25 times more effective a greenhouse gas than CO2. This means that although methane is less abundant than CO2,
o The analysis of ice cores indicates that changes in methane concentrations in the atmosphere over time .
o Ultraviolet radiation is a part of the solar radiation spectrum. It causes sun-burn and is deadly to living organisms, including humans.
o Ozone can absorb the most lethal type of ultraviolet rays and is therefore crucial to life on Earth.
o Since 1980, the ozone in the atmosphere has been depleting because of pollutants emitted by human manufacture.
· The issue of ozone depletion is an entirely different process to the greenhouse effect.
· The two are commonly confused, but they are, simply, two destructive processes occurring in the atmosphere in response to human activities.