THE CARBON CYCLE AND ENERGY SECURITY

OVERVIEW:

How much Carbon is there?

Types of Carbon?

Fluxes and balances?

OVERVIEW:

How much Carbon is there?

Types of Carbon?

Fluxes and balances?

amnt of carbon on earth =gigatonnes (Gt) + Each Gt Carbon=one billion tonnes. It’s estimated that 180Gt of carbon has been added to the atmosphere as a result of burning fossil fuels . Whilst this is tiny compared to the amounts transferred naturally, its enough to alter the conc. of greenhouse gases in the atmosphere, and to trigger climate change.

Carbon comes in 3 forms:

-Inorganic ( found in rocks such as carbonate)= the Earth’s largest carbon store.

-Organic (found in plant material).

-Gaseous (found as CO2, CH4 and CO)

Flux=exchange between carbon stores . Inorganic carbon is released by chemical weathering very slowly, over decades or hundreds of years, but fluxes between the Earth’s surface, plants, and atmosphere are much faster (matter of months/ seasons).

Variation in carbon fluxes: Fast and Slow

-The quickest cycle

-Organic matter in soils

As well as adding carbon to the atmosphere, the Earth’s carbon reservoirs also remove it into carbon sinks in a series of fluxes. The speed of fluxes between these sinks varies, both globally and over time:

-The quickest cycle is completed in seconds, as plants take carbon from the atmosphere through photosynthesis+ release it in respiration. Sunlight, temp+ moisture affect the speed of these processes + low levels of CO2 in the atmos. also reduce the speed of the cycle.

-Dead organic material in soils may retain carbon for many years (even centuries), waiting to be broken down. Some organic materials may become buried so deeply that they don’t decay at all- instead transforming into sedimentary rocks such as limestone/ coal or hydrocarbons. CO2 is only then released when these are burned, or when limestone is used industrially.

The earth’s spheres

(6)

1)Lithosphere- Land

2)Hydrosphere- Water

3)Biosphere- Living things

4)Atmosphere- Air

5)Cryosphere - Ice

6)Pedosphere- Soil

Variation in carbon fluxes: Geographical patterns

-Regional climates influence rates of photosynthesis and respiration, thus influencing CO2 fluxes according to latitude. Levels are always higher in the Northern hemisphere, bc greater landmasses+ greater temp variations

Geological Carbon Cycle

Natural cycle that moves carbon between the land, oceans and atmosphere- involves a number of chemical reactions that create new stores which trap carbon for significant periods of time.

There tends to be a natural balance between carbon production and absorption in this cycle (with some short term disruptions before equilibrium is restored such as by volcanic eruptions)

Co2 dissolves in water in clouds to form carbonic acid, which reacts to form calcium carbonate (limestone). Volcanic outgassing, and plate subduction = C02 released to atmosphere.

LONG TERM

The bio-geochemical carbon cycle

The role of living organisms is critical in maintaining the running of the system: They control the balance between storage, release, transfer and absorption.

— Through photosynthesis ( plant growth), respiration(animals), decomposition (breakdown of organic matter) and combustion(of biomass and fossil fuels).

SHORTER-TERM

-Carbon stores?

-Choke points?

-Combustion?

-Decomposition?

-Places where Carbon accumulates for a period of time such as rocks and plant matter.

-Points in the logistics of energy and fuel that are prone to restriction.

-The process of burning a substance, in the presence of oxygen, to release energy.

-The break down of matter, often by a decomposer which releases Carbon Dioxide often through their own respiration.

-Energy Mix

-Energy security

-Energy pathway

-Energy players

-The composition of a country’s energy resources

-The ownership and full control of a country’s energy source, production and transportation.

-The movement of energy from its extraction/ source, through pipes, freight logistics or cabling.

-Key companies and individuals who own, distribute and sell energy and energy sources.

-non-renewable

-Nuclear fusion

-Carbon neutral

-A source of energy that can be used only once to generate electricity or takes thousands of years to replace ( eg/ Fossil Fuels)

-The process of joining atomic nuclei together, to produce energy

-A process that has no net addition of carbon dioxide into the environment

-Outgassing

-Photosynthesis

-Phytoplankton

-Primary energy

-The release of dissolved Carbon Dioxide ( eg/ at plate boundaries, warming the oceans).

-The process of converting carbon dioxide and water into glucose and oxygen. All plants and some organisms rely on this process to survive.

-Small organisms that rely on photosynthesis to survive, so intake carbon dioxide from the atmosphere.

-The initial source of energy, as it is naturally found. This could be natural ores, water, crops or radioactive material.

-Renewable

-Respiration

-Secondary energy

-Sequestration

-Primary energy that can be re-used to produce electricity or has a short lifetime, therefore any used can be replaced quickly ( eg/Hydroelectric, biomass,solar).

-The process of converting glucose and oxygen into carbon dioxide and energy. Some organisms rely on respiration to survive.

-The product of primary energy, mostly electricity

-The transfer of carbon from the atmosphere to stores elsewhere

-Tipping point

-Thermohaline circulation

-A critical threshold after which any changes to a system are irreversible.

- Thermohaline circulation (‘ocean conveyor belt’) is a global system of surface and deep ocean currents driven by differences in temp. and salinity. It moves warm water from the equator to the poles and cold water from the poles back to the equator.

thermohaline circulation role in the carbon cycle

The colder the water, the greater the absorption of CO2. This means that as warm water is transported towards the poles ,it cools -absorbing more CO2. As it does the salinity also increases and as a results it sinks (down welling) taking CO2 from the surface ocean to the deep ocean. This allows more diffusion to occur, regulating the carbon store in the atmosphere.

The biological carbon pump

It takes millions of years for carbon to move through the carbon cycle (Annually, 100 million tonnes moves through it).

The part of the cycle at the surface of the ocean moves faster— There’s always an exchange of CO2 and its known as the biological carbon pump.

How the carbon pump works

The ocean’s surface layer contains tiny phytoplankton: They contain chlorophyll, need sunlight to live. They have shells and , sequesterCO2 through photosynthesis.

Phytoplankton require nutrients in vast quantities , and existing ocean temps and currents maintain a constant supply. The recycling of particles that sink in deep waters by upwelling current is critical. The global movement of water through thermohaline circulation maintains the pump.

Slight changes to water temp, or pollution and turbulence (which reduce light penetration) alter the flow and slow the pump down (all of these factors are vulnerable to climate change).

Is the gulf stream failing?

CASE STUDY

04- some alrm amongst ocean+ climate scientists when the northeasterly Atlantic current, Gulf Stream, appeared to stall for 10 days. Hypothesis of cause:

-Melting Arctic sea ice was increasing the amnt of freshwater entering the atlantic.The Ocean’s salinity was declining as a result, preventing cold water from sinking there.This meant there was nowhere for the warm waters of the gulf stream to go- North Atlantic was losing its pulling effect.

Research since 04 has suggested that the Gulf Stream has slowed by 6 million tonnes of water per second over 12 years.

Terrestrial stores?

=(land-based)

primary producers sequester carbon through photosynthesis. As plants grow, they release CO2 into the atmosphere through respiration. Organisms known as primary consumers- bugs, beetles, larvae and herbivores- depend and feed on producers + return carbon to atmos. (respiration).

The role of trees in the carbon cycle

95% of a tree’s biomass is made up from the CO2 that it sequesters and converts into cellulose ( a carbon compound). Carbon fixation turns gaseous carbon into living organic compounds that grow . The amount of carbon stored within a tree depends on the balance between photosynthesis and respiration

Mangroves and the role of soil in the carbon cycle

Biological carbon can be stored in soils in the form of dead organic matter, or returned to the atmosphere though decomposition. Depending on the nature of the soil this process can be quick, or as in tundra soils, slow. Deforestation and land use change can release carbon stores rapidly.

Mangrove forests are found in tropical and sub-tropical tidal coats in Aus, Africa, Asia+ the Americas.They’re vital processors, sequestering almost 1.5 metric tonnes of carbon per hectare annually.

Undisturbed mangrove forests grow quickly and absorb large amounts of carbon. Submerged below high tides twice a day, their soils are anaerobic so decomposition of plant matter is slow= little carbon can be respired back to the atmosphere. ( If cleared, carbon released).

— If 2% of the world’s mangroves are lost. the amount of carbon released will be 50 times the natural sequestration rate.

Tundra soils

Permanently frozen regions contain ancient carbon. Microbe activity is only active when soil layer thaws- the rest of the time the roots and dead and decayed organic matter are frozen, locking any carbon in an icy store. Tundra soil contains carbon that has been trapped for hundreds of thousands of years.

Tropical rainforests as carbon stores

(4)

-Huge carbon sinks , but they’re fragile.

-Carbon stored in trees, plant litter and dead wood.

-Soils are relatively thin + lacking in nutrients.

-Tropical rainforests absorb more atmospheric CO2 than any other terrestrial biome.

The natural greenhouse effect

• Energy is received as incoming solar radiation (light) from the sun.

• Dark surfaces on Earth absorb this radiation and radiate it back as heat.

• Release of CO2+ other green house gases forms a layer which absorbs and reflects back some of the radiated heat from the Earth’s surface = warm enough to sustain life.

Enhanced greenhouse effect:

key stats

conc. of greenhouse gases in the atmosphere have increased 25% since 1750 (industrialisation). Since 1980s, 75% of carbon emissions have come from burning fossil fuels= increased global temperatures.

Said to be caused by human activities

Climate patterns-

temperature (2) and precipitation (5)

C02 & other greenhouse gases naturally helped to maintain the Earth’s temp.- and also determine the distribution of temp and precip. Changing their conc. = alteration of these distribution patterns.

TEMP: amnt. of solar radiation (solar insolation) reaching Earth’s surface varies at diff. locations= influences temp. Angle of the sun’s rays make solar insolation intense at the equator, but dispersed over a wider area at the poles. Diff. Characteristics of the Earth’s surface (eg/ light/dark) also affect how much heat is absorbed/ reflected ( the albedo affect)- snow reflects heat and dark forests absorb it.

PRECIP:

-BC solar insolation is most intense at equator, convection and low-pressure systems dominate there= Rainfall high all yr.

-As air pressure rises around 30° N & S of equator= precip. decrease, clouds rarely form.

-Mid Latitudes= air masses of diff. characteristics meet+ low pressure systems bring rainfall.

-Nearer Poles, precip falls as the air is cools, dense+ dry= polar deserts.

-Regional +seasonal variations also occur (effects of relief, migration of global pressure patterns + wind systems).

Why do oil prices fluctuate ?

+ The USA’s energy security

They reflect political and economic factors, but particularly market demand

PAST: if demand suddenly rose, OPEC producers tended to increase oil production in order to prevent a sharp rise in prices,or vice versa.

NOW: world’s largest oil market is the USA, which drives much of what happens to oil price. US oil prices fallen sharply since ‘12 (large new supplies of oil and shale gas from USA and Canada). OPEC producers often cut prices to compete +maintain market share.

The USA became energy secure in oil and gas in ‘15. New Canadian sources came from tar sands and fracking. Fracked gas emits less CO2 than coal when used to generate electricity. As a result, between 08 and ‘15, the USA’s carbon emissions fell by 7.7% even though its oil consumption grew by 9%.

Fossil fuels: India

CASE STUDY

-Depends on coal for 66% of its energy needs. Just one day after the ‘15 Paris Climate Conference agreed to reduce global CO2 emissions, India declared that it intended to double its coal output by 2020.

-Accounts for 6% of global CO2 emissions+ 3rd largest emitter after China + USA. Wants to reduce its dependence on imported fuel, such as oil + gas= more use of domestic coal.

New infrastructure,expanding middle class + 600 million new users of electricity =development+ demand for coal. BUT Child labour in India’s coalmines=cost of coal low and promotes economic growth, (suffering and keeping the children out of education).

regulating the composition of the atmosphere

(4)

Photosynthesis is a vital process in regulating composition of the atmosphere:

-biological carbon pump. terrestrial photosynthesis, tropical rainforests, coral reefs and mangroves sequester large amounts of CO2.

-Anything affecting level of phytoplankton in oceans/ area of land covered by forest, will have an impact on carbon sequestration+ the comp. in the atmosphere.

-Deserts are of sparse vegetation= little CO2 absorbed.

-Increased melting of Arctic sea ice= greater expanses of ocean open to direct sunlight, bc seasonal thaws here last longer. Increasing photosynthesis by phytoplankton is now causing algal blooms in the Arctic waters + more carbon is being absorbed there.

Soil and carbon

• why is carbon vital in soils?

• What does the amount of carbon stored depend on?

• What are the features of healthy soil?

Carbon is vital in soils- without it the nutrient and water cycles couldn’t operate properly ( it supports microorganisms that maintain the nutrient cycle, break down organic matter, provide pore spaces for infiltration, enhance plant growth).

The amount of carbon stored depends on the system.

Healthy soils usually are: Dark, crumbly and porous. Contain many worms and other organisms. Provide air, water and nutrients for microorganisms and plants to thrive +Contain organic matter. Sequester carbon. Retain moisture.

Fossil fuel combustion

Fossil fuels= long term carbon stores, comprising carbon locked away within the remains of organic matter. When burnt to generate energy, the stored carbon is released, primarily as CO2, into the atmosphere+ it has severe implications (disrupts the balance of the carbon cycle)

Fossil fuel combustion: Varied Implications for the climate

(3)

-Across Europe, annual average land temps are projected to increase by more than the global average.

-Annual precip. is projected to increase in Northern Europe and decrease in Southern Europe.

-Extreme weather events are also more likely to increase in intensity and frequency.

Fossil fuel combustion: Artic Amplification

CASE STUDY

The Arctic region is warming twice as fast as the global average. This phenomenon is called Arctic Amplification. Melting permafrost released CO2 and CH4, increasing the conc. of these greenhouse gases in the atmos. =increased global temps + further melting.

Climate change is altering the Arctic Tundra ecosystem. Rapid warming has contributed to extensive melting of sea ice in summer months, as well as greatly reduced snow cover and permafrost. Shrubs and trees, prev. unable to survive in the tundra have begun to establish themselves. The same is true of animals.

Fossil fuel combustion: Implications for the hyrdrological cycle

(3)

• Precip. in form of snow diminishing + rainfall patterns changing.

• River discharge patterns changing ( greater flooding in winter+ drought in summer).

• Alpine glaciers melt, water flows lead to inc. sediment yield. Glacier retreat= discharge + sediment yield fall & water quality falls.

Energy consumption:

Urban (London) + Rural (Peru)

(Energy consumption depends on lifestyle, climate, technology, availability and need+ tends to rise as countries economically develop):

LONDON (Urban consumption): Cities consume 75% of world’s energy + produce 80% of greenhouse gas emissions. London generates 1.7 million tonnes of carbon per yr, with it resident pop. averaging 1.8 tonnes of carbon per capita.

PERU (Rural consumption): National programme of solar panel installation= electricity made available to 500,000 ppl in remote villages across Peru (‘06 -‘15)- a sustainable source. == Increased energy consumption, sustainable development.

Factors affecting energy consumption: UK + Norway

-Physical availability, Cost, Technology, Political decisions, economic development and Environmental Priorities.

-PHYSICAL ABILITY: Until 70s UK depended heavily on domestic coal from North + S Wales and was a global leader in nuclear tech 50s-70s, discovery of North sea oil and gas greatly altered UK’s energy mix. Norway’s mountains, valleys+ rainfall = HEP is a natural energy choice. Oil + natural gas largely exported.

-COST: UK= North sea reserves became ‘secure’ alt. to depend. on M Eastern oil, when price there inc., but N Sea oil is expensive to extract+ if global prices fall, it becomes less viable. Norway= Norsk Hydro runs over 600 HEP sites+ costs are low once capital invest. is complete, but transfer to rural regions is expensive.

-TECHNOLOGY: UK=150 yrs of coal reserves left, but current tech + environ policy makes its extraction unrealistic+ expensive.Norway= deep water drilling tech enabled both N + UK to dev. North Sea Oil+ gas extraction.

-POLITICAL DECISIONS: UK= Increased reliance on imported energy sources= decreased energy security, a political issue. Norway= Gov. has an intervention approach= foreign comp. cannot own primary resources.

-ECONOMIC DEVELOPMENT: UK= GDP per cap. US$41 200, Norway US$61 500 (‘15) +UK Energy use per capita 2752 kg oil equivalent, Norway 5854 kg (‘14)

-ENVIRON. PRIORITIES: Uk= “‘15 committed to a 40 % reduc. in domes. greenhouse gas emissions by 2030, compared to 1990”& intends to broaden its energy mix. + Norway is the 3rd largest exporter of hydrocarbons, expanding output.

Energy players:

TNCs

OPEC

National gov.

Consumers

Key players often have roles in securing energy pathways:

-Energy TNCs = explore, exploit and distribute resources+ respond to market conditions to secure profits for their shareholders (Shell, BP)

-OPEC(OPEC producers control 81% of proven world oil resources).

Role= coordinates and unifies petroleum policies of its members + ensures stabilisation of oil markets eg/ OPEC has prev. set production quotas to respond to economic conditions such as from ‘12- 16 it maintained output at high levels to compete w USA’s increased produc. from fracking, which caused a collapse in global oil prices.

-National gov. Meets international obligations while securing supplies for the nation’s demands + regulate the role of private companies, set environ. policies.

-Consumers= Create demand

Fossil fuel demand

development= global demand for energy resources growing. fossil fuels still make up 86% of global energy mix.

Energy pathways:

ESPO pipeline

-4188km ESPO ( East Siberia Pacific Ocean) pipeline exports crude oil from Russia to China, South Korea and Japan. It was built by the Russian energy company, Transneft, and was completed in ‘12. ESPO is an energy pathway.

Efficiency of transporting gas by pipeline

-Transporting gas by pipeline= efficient+ international. Some of the world’s pipelines carry billions of cubic metres of gas over thousands of km. These pathways depend on multilateral (between many countries) and bilateral agreements.

For security reasons, when companies like Russia’s Gazprom export 80% of their gas to Europe, they try to avoid transit states whenever they can. EG/ the Nord Pipeline runs 1200km along the bed of the Baltic sea, and the South stream runs under the Black sea to Bulgaria.

Trade flows and shipping routes

About half of the world’s oil is moved by tankers traveling on fixed shipping routes + goes through chokepoints.

EG/ 20% of world’s oil passes through the Strait of Hormuz, a 39km wide stretch of water between the Gulf of Oman and the Persian Gulf. If choke points are blocked or threatened, even temporarily, energy prices can rise quickly. Oil transit points are a crucial element of global energy security.

Political conflict on energy pathways : The Syrian Conflict

CASE STUDY

Ongoing Syrian conflict has involved two superpowers and their allies:

-One side , Russia and its Shia non-fundamentalists allies + Other USA and its fundamentalist Sunni allies.

=in a battle for control over Syrian territory. Many argue that for the two superpowers the key reason is the proposed construction of oil and gas pipelines through Syria to supply fuel into Europe, the world’s largest energy market. Recent decades= oil and gas have freq. been at the root of international tension +proxy wars have been common.

-- Russia is the world’s biggest supplier of oil and gas, but Iran (its ally) wants a share of the European market, which Russia supports. Having Iran onside gives Russia control over European energy, while strengthening a non fundamentalist block between Asia and the Middle East. Iran wants to export its gas via pipelines through Syria, which explains why it defends the Syrian Government against those trying to overthrow and replace President Assad.

—Sunni Qatar and Saudi Arabia also seek to become Europe’s main suppliers of oil and gas. Each would also need to be pipelined through Syria. Qatar and Saudi Arabia are US allies=the USA and its allies are happy for Al’Qaeda and other jihadists to conquer a strip through Syria over which US companies would build pipelines, allowing other US companies such as Exxon to market Middle Eastern oil and gas to Europe.

Peak Oil and unconventional fossil fuels

Geologists have been predicting ‘peak oil’ (the global peak of oil production, then a sharp decline) for many yrs. The argument is that the world has finite resources of oil, coal and natural gas, so fossil fuels may be reaching an end.

However, Canada now exploits tar sands to boost its energy security, and an abundance of shale gas in the USA ( produced by fracking) has brought an energy boom. Also, geopolitics can make access to resources difficult/ cause oil + gas prices to inc., making unconventional fuels like shale gas more economically viable.

Canadian tar sands

CASE STUDY

Canada has the world’s largest resources of tar sands, w three major deposits in Alberta ( The Athabasca, Cold lake, and Peace river). Together, they cover an area larger than England. Extracting the oil is expensive and difficult, but it helps to improve Canada’s energy security.

Tar sands are extracted by opencast mining. The extracted material is crushed and mixed with water, and the bitumen is separated before it can be used. Tar sands can also be pumped out- high pressure steam is injected underground to separate bitumen from the sand.

Canadian Tar sands : Key Players

(3)

-Alberta regional gov. and Canada’s national gov. promote tar sands for energy security and economic development.

-Environmental pressure groups: Greenpeace called for an end to the “industrialisation of indigenous territories, forests and wetlands in Northern Alberta”.

-Local communities experience costs and benefits: New jobs+ trade benefit for local businesses, but also disruption to traditional ways of life (inhabited by many indigenous people), Fears over pollution into the Athabasca River, housing crisis due to many new workers migrating there.

Tar sands: Implications for the carbon cycle and consequences for the environment.

(4)

• Carbon emissions rise due to their extraction, production and use.

• Carbon absorption falls due to deforestation.

• Large-scale opencast mining destroys forests and peat bog, causing loss of ecosystem and habitats.

• Caribou populations have declined sharply in the areas of oil extraction. They’ve become easy prey for wolves, which are now culled to protect the caribou. Even so, the local population is expected to be extinct by 2040.

Renewable (5) and Recyclable energy (2) sources

Renewable:

-Biomass (heat energy from wood, plants, animal and general waste).

-Solar power(energy from the sun generating electricity via photovoltic cells).

-Wind energy(moving air turns a propellor- driven generator)

-Wave and tidal energy (moving water flows through a barrage, driving turbines).

-Hydroelectric power (The vertical release of water turns a turbine to drive a generator).

Recyclable:

-Nuclear power ( use of atomic reactions to obtain heat, in turn heating water and generating steam to drive a turbine).

-Heat recovery systems (heat from inside a building/underground in a garden is used to warm air drawn from outside).

The growth of biofuels

Brazil Case study

Brazil was the 1st country to produce biofuel from sugar cane in the 70s. The bio-ethanol it produced was cheaper than petrol, and was used as a vehicle fuel. Brazil has since become the world’s leading producer of bio-ethanol, and a leader in cutting carbon emissions. Cars running on bio-ethanol emit 80% less CO2 than petrol-driven cars.

Other countries have followed suit: Forests cleared in Malaysia to plant oil palms (for bio-diesel) + Oilseed Rape in the EU and Maize in the USA. The motivation is to reduce carbon emissions, but the downside is deforestation- and in Brazil, social unrest has occurred ( farm workers have lost land to grow sugar cane and cannot grow food for themselves + many farm workers end up moving to the cities).

This ‘green fuel’ has reinforced rural inequalities. Swiss, Swedish and American companies have been buying land to grow sugar and soy- inflating land prices.

pros and cons of biofuels

+(2) -(2)

+:

1)Renewable, lower emissions than fossil fuels, Bio-degradable, easily-grown and no need for heavy machinery.

2)Rural inward investment, positive multiplier effect in rural regions, earns export income, Infrastructure improvements often provided by growers.

-

1)Takes land from food production, needs pesticides and fertilisers which use fossil fuels in their production (so they’re not carbon neutral), req. large vol. of water+ clearing forests for this crop means the loss of carbon sink and inc. CO2 emissions from deforestation

2) contaminates water resources w overuse of fertiliser/ pesticides, food shortages occur which increase prices.

Other approaches to reducing carbon emissions:

Carbon Capture and Hydrogen Fuel cells.

1)Carbon Capture and Storage (CCS): Uses technology to capture CO2 emissions from coal-fired pwr stations.The gas is transported to a site where its stored, compressed and transported by pipeline to an injection well, where its injected in liquid form into suitable geological reservoirs eg/ underground aquifers.Theoretically, CCS could cut global CO2 emissions by up to 19%. However, its not currently financially viable.

2)Hydrogen Fuel cells: Hydrogen is the most abundant element on Earth, but its usually combined with other elements such as Carbon. Once separated, it provides an alternative to oil. Fuel cells convert chemical energy in hydrogen to electricity, with pure water as a by product. Hydrogen fuel cells are far more efficient than petrol engines in vehicles. Separating hydrogen from other elements can initially req. energy, but this can be provided from renewable sources.

Growing demands

Global demands for fuel, food and other resources have led to land-use changes, which are threatening both the carbon and water cycles.

Deforestation in Madagascar

CASE STUDY

Since the 50s, Madagascar’s tropical forests have been cleared at a rapid rate. Small-scale clearance by farmers had long been common in the country, but a growing international demand for tropical hardwood, an expanding pop. and debt repayments meant that the Madagascan Gov. began to encourage farmers to clear more land in order to grow cash crops to earn foreign currency to help repay the country’s debts. B4 1950, had 11.6 mill hectares of tropical forest, 1984 3.8 million hectares.

Impacts of Madagascan deforestation:

WATER CYCLE

SOIL HEALTH

ATMOSPHERE

BIOSPHERE

-water cycle= Infiltration is decreased + runoff and erosion are increased. flood peaks are higher and the lag time is shorter and increased discharge leads to flooding.

-soil health= Raindrop impact washes finer particles of clay and hummus away, coarser and heavier sands left behind, C02 is released from decaying wooded material, biomass is lost due to reduced plant growth or photosynthesis, Increased leaching ( loss of nutrients from the soil by rainfall).

-atmosphere= Turbulence is inc. as the heated ground makes convectional air currents, oxygen content reduced and transpiration rates lower, reduced evapotranspiration makes it less humid+ the air is dryer.

- biosphere= Evap. from vegetation dec., species diversity decreased, less absorption of CO2 means a reduced carbon store, biomass is lost.

Converting grasslands into farming

CASE STUDY: The American Midwest

‘07 - ‘15, a biofuel ‘rush’ swept across American Midwest (Prairies). Farmers were encouraged to grow corn, soy, canola and sugar cane as part of the US Environmental Protection Agency’s Renewable Fuel Standard Policy. This policy aimed to:

-Increase amnt of ethanol used in petrol, boost economies of US rural states, reduce US depend. on overseas oil imports, reduce CO2 emissions from transport.

Growth in production reflected growing global demand. By ‘13 the price of corn has trebled, and a no. of US States (eg/ N Dakota)cashed in: Grasslands, trad. used for cattle ranching, were ploughed up = over5.5 million hectares of natural grassland disappeared across US M west, matching rate of rainforest deforestation in Brazil, Malaysia and Indonesia.

The impacts of converting grasslands

Benefits of natural grasslands:

• Grasslands trap moisture and floodwater, absorb toxins from the soil, provide cover for dry soils, maintain natural habitats, acts as a carbon sink ( absorbing C02 + releasing 02 all year round in a ‘lung effect’), acts as a terrestrial carbon store.

Disadvantages of converting grasslands to grow biofuel crops:

• Initial removal releases Co2 from soils into atmosphere, annual ploughing enables soil bacteria to release CO2. Biofuel crops are heavy consumer of water so need irrigation which has a significant impact on aquifers. Cultivated soils are liable to erosion by runoff and wind + all benefits reduced

Afforestation

Trees provide a vital carbon store- sequestering carbon during photosynthesis. Afforestation thus effectively counters all of the negative impacts of deforestation. The EU’s Afforestation Grant Scheme encourages the planting of forests for their value as terrestrial carbon stores and for the ecosystems they provide.

Ocean acidification

The World’s oceans are a major carbon sink- They have absorbed around 30% of the C02 produced as a result of human activities since 1800, and about 50% of that produced by burning fossil fuels. As CO2 in the ocean increases, the Ocean pH decreases (become more acidic). This is known as Ocean acidification.

As the ocean become more acidic, corals cannot absorb the alkaline Calcium Carbonate that they need to maintain their skeletons, and reefs begin to dissolve. Ocean acidification has lowered the pH of the ocean by about 0.1, meaning that it’s now about 30% more acidic than it was in 1750 (the early days of the Industrial Revolution).

‘Corals matter’

Corals- which are marine invertebrates- get their vibrant colour from algae that live in their tissues. The most important role of the algae is to provide food to the coral through the carbohydrates produced during photosynthesis. Coral has a narrow temp range within which it can live; never below 18°C and ideally in the range 23-29°C. If water become too warm, the algae are ejected and the coral turns white - coral bleaching.

The biggest cause of coral bleaching is climate change, which raises ocean temps. If CO2 emissions continue at their current rate, the pH of the ocean surface could be lowered to 7.8 by 2100, which would dissolve ocean skeletons and cause reefs to disintegrate. Increased acidification risks crossing the critical threshold for the health of coral reefs and other marine ecosystems. If coral reefs are destroyed, we will lose the vital ecosystem services they provide. They:

• Shelter 25% of marine species, protect shorelines, support fishing industries, provide income from tourism.

Increasing drought

-The repercussions of climate change.

-Patterns of evapotranspiration and ocean currents

-Expansion of arid and semi arid areas.

Climate change causes:

-Increase in the frequency and intensity of storms and hurricanes, rising sea levels+ more freq. floods , droughts and heatwaves.

Any change in ocean currents and atmospheric circulation could also affect patterns of precip., evapotranspiration and temp., as climate belts move in response to climate change.

Certain regions, such as North America, Europe &other mid and high latitude regions. + the coldest zones of the planet are decreasing in extent+dry areas are increasing.

It’s likely that today’s arid and semi-arid areas will expand into continental areas of Asia, as well as parts of Northern and Sub-Saharan Africa.

Drought in the Amazon

CASE STUDY

The Amazon Basin suffered extreme droughts in 05 and 10, and the drought of ‘14 was the worst to hit Brazil for 80 years.

The Amazon basin plays a key role in the Earth’s carbon cycle, holding 17% of the terrestrial vegetation carbon store. A study of the 2010 Amazon drought showed that trees died and growth rates declined. The drought effectively shut down the Amazon’s function as a carbon sink. There are further concerns that, as climate change increases temps and alters rainfall patterns across S America, the Amazon rainforest will change from a carbon sink to a carbon source. This would accelerate global warming.

Forest loss:

• Impacts on well-being

• protecting forest stores

• forest recovery

-WELLBEING: Palm oil industry meets demand for a much-desired raw material, but local communities come off badly as a result ( many depend on the rainforest / have inhabited the forest for generations and are driven away by the actions of palm oil producers)+ loss of biodiversity and habitat which endangers species such as the orang-utan.

-PROTECTING FOREST STORES: May ‘11. Indonesia’s president declared a ‘forest moratorium’, aimed at reducing deforestation (W/ funding from UN & Norwegian gov. the moratorium has stopped issuing permits for the clearance of primary forests / peatland for timber, wood pulp or palm oil and by ‘13 emissions had fallen 1-2.5%). Permits issued before ‘11 went ahead.

-FOREST RECOVERY:Although global forested area fell by 3% between 1990 and ‘15, this trend may be beginning to change. Between 10 and ‘15, an avg 7.6 mill hectares of forest were lost every year, but 4.3 mill hectares were also gained leaving a net annual loss of 3.3 million hectares - half that of the 90s.

Climate change and Yukon

CASE STUDY

Yukon is a territory in the far NW of Canada, and a significant part of it lies within the Arctic Circle. Like most Arctic and Sub-Arctic areas, it has seen temp. rise sharply+ forecasts are for continued warming. The increasing temp. has implications for precip. patterns, river regimes and water stores:

• Increasing temps lead to increased evap. and atmospheric water vapour.

• Snowmelt now begins earlier in Yukon, and snow cover is decreasing. This alters river regimes, bringing earlier peak flows to most river basins.

• Between ‘58 and 08, the total ice area in Yukon shrank by 22%, and, as glaciers recede, streamflow is decreasing despite an initial increase in meltwater.

• Thawing permafrost = increased groundwater and deeper water penetration into soil instead of surface runoff.

Changing precipitation patterns: Predictions of changes (2)

Climate models predict that, as temps rise, precip. patterns will change in two ways:

1) Existing patterns will strengthen- wet get wetter, dry get dryer.

2) As atmospheric circulation changes, a shift in storm tracks will move storms further from the equator towards the poles.

Food insecurity

520 mill of the poorest people on Earth depend on fisheries for their food and income. Climate change is altering the distribution and productivity of species, food webs and biological processes. It’s not just tropical waters that are affected : warming waters in the North Atlantic are killing the cold-water plankton that North American cod eat.

+ coral bleaching affects food sources and incomes for people living in coastal communities.

1)Future emissions

2) Atmospheric concentration levels

3) Surface temperatures

1) As energy consumption rises, global greenhouse gas emissions are expected to continue to rise- uncertainty as to how much /where the greatest increases will be.

2)Greenhouse gas conc. likely to inc. as emerging economies such as India industrialise further. GG remain in the atmos. for long periods of time so even if emissions stabilised/ decreased, surface air temps would continue to warm bc greenhouse gases would still be added to the atmos. faster than carbon sinks could remove them.

3)Climate models predict that surface temps will continue to rise, with increases between 2000 and 2100 in the range of 2-6°. Temps are expected to warm more rapidly over the Northen hemisphere (more land than ocean)and some regions (eg/ the Arctic) will see larger increases than the global avg.

Why is future climate change so uncertain?

One of the uncertainties about climate change is feedback mechanisms, such as carbon release from peatlands and permafrost- and tipping points

Tipping points

• Forest die back and changes to thermohaline circulation.

2 particular phenomena are capable of creating tipping points:

FOREST DIE BACK: A tipping point could be reached where the lvl of die back actually stops the recycling of moisture within the rainforest (rainfall caused by moisture within the forest) = more die back.

CHANGES TO THERMOHALINE CIRCULATION: Cold, deep water in the North Atlantic forms part of the thermohaline circulation. To keep the ‘conveyor belt’ of warm water heading from the tropics towards Britain, heavy, salty water must sink in the north. Melting of Northern ice sheets releases significant quantities of freshwater into the ocean, which is lighter and less salty- thus blocking and slowing the conveyor belt. As ice sheets melt, thermohaline circulation is susceptible to a critical tipping point.

Facing the future:

-Adaptation strategies

(adopting new ways of doing things in order to live with the likely outcome of climate change):

1) Water conservation + management .

2) Land Use planning and flood risk management

3)Resilient Agricultural Systems

Facing the future:

-Mitigation Strategies

(re-balancing the carbon cycle and reducing any impacts of climate change):

1) Carbon taxation (fee for users of fossil fuels)

2)Energy Efficiency

3)Afforestation

4)Carbon capture storage

5) Renewable switching

2015 Paris Agreement

Climate conference (COP21) dec 15, 195 countries adopted the 1st universally legally binding global climate deal. It set out a plan to:

-Limit the global temp increase to 1.5°C above pre-Industrial levels.

-Report on the implementation of individual national plans to reduce emissions.

-Provide adaptation and initiative support for developing countries to reduce emissions.

Came into force Nov 2016 + 96 states , accounting jointly for 66% of global emissions, ratified the treaty.