The Carbon Cycle

How much carbon is stored in the atmosphere?

750 Pg (petagrams)

From 1751 to 1990, surface ocean pH dropped from 8.25 to what globally?

8.14 (30% increase in H ion concentration)

Every year fires release how many tonnes of carbon into the atmosphere as carbon dioxide?

more than a billion

Decomposition involves physical, chemical and biological mechanisms that transform organic matter into increasingly stable forms. What processes are involved in chemical transformation?

oxidation and condensation

What is a biogeochemical pathway?

pathway by which a chemical element moves between abiotic (atmosphere, lithosphere, hydrosphere and cryosphere) and biotic (biosphere - the areas of the earth that contain life) components of the earth.

Gigatonnes are the same as the measurement

petagram

According to the Intergovernmental Panel on Climate Change (IPCC), how much anthropogenic (human causes) carbon release comes from the combustion of fossil fuels?

90% - primarily coal - also oil and natural gas.

Why is the recycling of carbon essential for life on earth?

A balanced carbon cycle is important for maintaining a stable climate on earth.

What type of process is the carbon cycle?

A biogeochemical process

What are the impacts of glacial periods on water flow, and the subsequent impact on the carbon cycle.

A reduction in the build-up of sediment on the ocean floor (rivers freeze). Carbon store here is reduced.

When would 'the anthropocene' be a good point to mention in Carbon essays?

In the INTRO

(In relation to Carbon) Life on earth is described as...

carbon based

96% of living matter consists of which 4 elements?

carbon, hydrogen, oxygen and nitrogen

Partial decomposed organic matter from past geological eras is converted into what?

coal, oil and gas

Decomposition involves physical, chemical and biological mechanisms that transform organic matter into increasingly stable forms. What are these biological mechanisms?

feeding and digestion aided by catalytic effect of enzymes

What are the processes (transfers) which control the movement of carbon between stores on land, in oceans and the atmosphere called?

fluxes

Terrestrial Store Plants absorb CO2 through... and release some back to the atmosphere through...

photosynthesis respiration

Globally, how many Gt of Carbon does permafrost hold?

1,600 Giga tonnes of Carbon (twice atmosphere)

Atmospheric concentrations of carbon dioxide are currently what?

In excess of 400ppmv

What is the estimated amount of CO2 within the atmosphere in GtC and %.

- 720GtC - 800 GtC - Makes up about 0.04% (400 ppm) of atmosphere: Low concentration belies its importance to planet and all life on it

1986 Lake Nyos disaster, Cameroon. How does CO2 build up?

- 1986 - 1,746 people and over 3,500 livestock from surrounding farms died. - Water in Lake Nyos was extremely enriched in dissolved CO2. - Lake overlies a volcanic source, which appears to release CO2 and other gases. - CO2 dissolves into bottom waters of lake. At depth of over 200m, sheer weight of upper lake levels exerts considerable pressures on bottom waters. - Confining pressure allows CO2 to dissolve into the bottom waters without escaping to the surface, and resulted in build-up of 1 billion cubic yards of gas on the the southern floor of Lake Nyos.

Impact on the land: Climate change affects frequency of Wildfires

- Causes vegetation to dry out - Droughts are lengthened - These factors combined mean climate change has made bushfires 30% more likely - Globally, the number of days where wildfires are likely to burn has risen as a result of climate change - Influence of climate change on fire seasonality is especially pronounced in regions that have seasonal snow cover, such as Canada. With warming temperatures, snow melts earlier in year and later in year before we see return of snow cover meaning there is a longer fire season. - When temperatures are warmer than average, rates of evaporation increases causing moisture to be drawn out from plants on the land. This drying can create 'tinderbox conditions' meaning that is a fire is sparked, it can spread rapidly over large areas.

What are human causes of changes in the carbon cycle?

- Combustion of fossil fuels - Land use changes (agricultural) - Deforestation - Urbanisation

Describe what has been caused by carbon concentrations in the atmosphere having altered due to human activities generally.

- Due to human activities, present concentration of CO2 is higher than it has been for 800,000 years - Potent greenhouse gas and plays vital role in regulating Earth's surface temperature. - Global warming has been attributed primarily to increasing industrial CO2 emissions into atmosphere.

Natural Cause of Change: Volcanic Eruptions.

- Eruptions return carbon that has been trapped for millions of years in rocks deep within the earth's crust, to the atmosphere. - At present, volcanoes emit between 130 and 380 million metric tons of CO2 per year. For comparison, humans emit about 30 billion tons CO2 per year by burning fossil fuels (100-300x more volcanoes)

1986 Lake Nyos disaster, Cameroon. How did CO2 get released?

- Expelled rapidly - Caused by overturning of the bottom waters by some unknown mechanisms (largely believed to be dense rainwater or a rockslide) - As a CO2-rich cloud, rising at the speed of around 100 km per hour. CO2 is about 1.5x density of air, meaning the gaseous mass (50m thick) hugged the ground surface on its descent down valleys along the north side of the crater at a rate of 20 to 50 km per hour.

Arctic sea ice positive feedback loop which destabilise earth's climate: Insulation

- Forming a layer on ocean surface, ice acts as buffer between frigid arctic air and relatively warmer water underneath. - However, when it thins or melts heat escapes from ocean which warms atmosphere and causes more ice to melt in turn.

How much of the earth does permafrost cover?

- Globally permafrost covers 23m square km. - Makes up nearly ¼ of all land in Northern Hemisphere, 8.82 miles. Siberia: frozen 1000 ft deep.

Carbon Store: Terrestrial

- In the form of plants, animals, soils and microorganisms (bacteria and fungi). - Of these plants and soils are by far the largest stores. - Unlike the other stores most of the carbon in this store is 'organic' carbon (compounds produced by living things) such as leaves, roots, dead plant material and soil humus.

Carbon resides in stores. What are these stores?

- Living organisms in biosphere (plants and trees, animals, marine organisms) - Atmosphere (gases: CO2 and methane) - Oceans (dissolved CO2) - Fossil fuels (coal, oil or gas) - Ocean sediments - Sedimentary rock - limestone - Soils and peat

Carbon Store: Earth's Crust

- Made up of sedimentary rocks produced either by the hardening of mud (containing organic matter) into shale over geological time periods, or by the collection of calcium carbonate particles, from the shells and skeletons of marine organisms, into limestone and others. - The other source of carbon in the Earth's crust are fossil fuels, formed over millions of years from ancient living organisms through intense pressure and temperature. LARGEST STORE

Carbon Store: Atmosphere

- Mainly CO2 but also methane. - Much less carbon than that contained in the oceans or crust - Carbon in the atmosphere is of vital importance due to its impact on the greenhouse effect and climate.

Human Cause of Change: Land Use Change (Farming Practices)

- Many farming processes that release carbon e.g. ploughing, rearing livestock, using machinery and using fertiliser that is based on fossil fuels. - Some farming practices result in high levels of methane emissions (methane being a potent greenhouse gas) - Livestock, especially cattle, emit large quantities of methane. In the USA cattle emit around 5.5 million tonnes of methane per year into the atmosphere (20% of total methane emissions). - Methane produced by cultivation of rice. Rice is the primary food source for 50% of the worlds population, mostly in developing regions. Studies show that rice may contribute to 20% of global methane production.

The NOOA measure atmospheric carbon. How do they do this and what have they found?

- NOOA measure atmospheric carbon with the MLO (since 1958) - Carbon concentration has increased since Industrial Revolution from 280ppm to 317.7 ppm in 1958 to 400.3 ppm as of February 2015 (deforestation, fossil fuels)

What are physical causes of changes in the carbon cycle?

- Natural climate change - Volcanic activity - Wildfires

Carbon Store: Oceans

- Oceans contain dissolved inorganic carbon stored at depths. - This store has a long residence time. - Smaller amount is located near the ocean surface and this is exchanged rapidly with the atmosphere through growth, death and decay of plankton.

Negative impacts of ocean acidification

- Phytoplankton producers (cocolithophores) in oceanic ecosystems are severely affected by changes in pH. Plankton is crucial to ecosystems, meaning having larger affects. - Bad for marine organisms as the carbonic acid reacts with carbonate ions that shell building creatures use to create calcium carbonate shells. This is bad for shell-based creatures making their shells thinner and more fragile, and damaging coral. - An effect called coral bleaching can be seen on the Great Barrier Reef in Australia. Unicellular organisms that help make up the coral begin to die off and leave the coral giving it a white appearance. This could reduce biological sequestration of CO2 in the oceans i.e. the biological pump might become less effective.

How is the emission of carbon dioxide into the atmosphere from a volcanic eruption an example of a small scale negative feedback loop?

- Release of CO2 into the atmosphere from volcanic eruption causes temperatures to increase. - With the rise in temperature, warm moist air will rise and condensation will occur. This causes precipitation. - Chemical weathering will then increase, weathering rocks on the ground and dissolving of Carbon. - This Carbon in water will then travel to rivers and then into seas. - Carbon will end up as sedimentation and will be stored within the earth's crusts, where it started before the eruption (a return to dynamic equilibrium).

Researchers suspect that for every 1ºC rise in the earth's temperature on average, permafrost may release the equivalent of how many years worth of coal, il and natural gas emissions?

4-6 years worth

Impact on the land: Permafrost thawing (explain positive feedback)

- Releases large amounts CO2 and methane. - As global temperatures have increased this melts the permafrost which releases large amounts of methane and CO2. - This will result in a positive feedback loop causing atmosphere to warm even more.

Secondary effects of permafrost melting

- Tiggers landslides: on Banks Island in Canada, scientists documented a 60-fold increase in massive ground slumps from 1984 to 2013. - Localized thawing of permafrost, especially in villages where development disturbs the surface and allows heat to penetrate, has eroded shorelines, undermined roads and schools, cracked pipelines, and collapsed ice cellars where Arctic hunters store walrus meat and bowhead whale blubber. Warm summers are already warping life for Arctic residents, and this challenge to the development built on permafrost has caused entire communities to relocate.

Flux of Carbon: Chemical weathering

- Water is key medium for chemical weathering. - When carbon dioxide is absorbed by rainwater it forms a mild carbonic acid. - This reacts with calcium carbonate in chalk and limestone, forming calcium bicarbonate which is soluble and removed by percolating water.

Human Cause of Change: Combustion of Fossil Fuels

- When burnt to generate energy and power, the stored carbon is released as CO2 into atmosphere. - Since the Industrial revolution fossil fuels have been burnt in increasing quantities, pumping CO2 into the atmosphere. - Since the 1960's the global concentrations of carbon dioxide in the atmosphere have increased dramatically from about 320ppm to over 400ppm. - The result is the 'enhanced greenhouse effect', increasing global temperatures (global warming).

What are impacts on the land?

- carbon fertilisation - permafrost thawing - agriculture - climate change affects frequency of wildfires

What are impacts on the ocean?

- ocean acidification - ocean warming - sea level rise - melting sea ice - ocean salinity and the thermohaline conveyor

1986 Lake Nyos disaster, Cameroon. What were the effects of mist on living things within the area?

- sudden death to the villages of Nyos, Kam, Cha, and Subum - lost consciousness or dying in a few breaths from CO2 asphyxiation

What are the summarised (bullet points) results of putting more carbon into the atmosphere? These are all linked.

- warmer climate - melting Arctic - higher sea levels - increase in evaporation and precipitation - new ocean chemistry

Atmospheric carbon dioxide levels have reached very high values in the deep past, possibly topping over..(1)...in the Cambrian period around 500 million years ago. Its lowest concentration has probably been over the last 2 million years during the ....(2)....glaciation when it sank to about...(3)...

1) 7,000 ppm 2) Quaternary 3) 180 ppm

How much carbon is stored in the soils?

1,500 Pg (petagrams)

How much of global carbon release is land use change responsible for?

10%

How much carbon is stored in the Earth's crust (sedimentary rock)?

100,000,000 Pg (petagrams)

On Alaska's North slope, permafrost temperatures have spiked how much in 30 years?

11 degrees F

Predictions that if global warming continues, how much of permafrost could be gone by 2200?

2/3

Dead plants trapped in permafrost amount for huge amounts Carbon trapped in the soil, roughly how many times the anthropogenic sources into atmosphere per year?

200x

How much has the sea level risen since 1901?

20cm

How much stronger is methane than CO2 as a greenhouse gas, withheld in permafrost?

25x stronger

Permafrost has warmed up by how much in last 20 years?

2ºC

How much CO2 released into atmosphere has diffused into the ocean through direct chemical exchange?

30%

How much carbon is stored in the oceans?

38,000 Pg (petagrams)

How much carbon is stored in plants?

560 Pg (petagrams)

Flux of Carbon: Consumption

Animals feed on plants and other animals. Carbon is passed along the food chain. Phytoplankton in the ocean is consumed by other marine organisms and carbon is passed long the food chain by fish and larger sea animals as they consume one another.

Negative feedback loop of Arctic ice melting

Arctic is warming more than twice as fast as the rest of the planet, as it loses sea ice which helps to chill the environment.

Impact on ocean: Melting sea ice

Arctic sea ice has reduced by 40% in the last 35 years. This causes positive feedback loop as the highly reflective ice is replaced by more heat absorbent water so, with melting, the ocean is able to absorb more sunlight, increasing the warming that caused the melting.

Which areas can expect to have the largest net absorption of carbon?

Areas of highest productivity, such as rainforests as the year round rainfall and warm temperatures encourage rapid growth in biomass - high Net Primary Productivity (gain by producers in energy or biomass)

Impact on the ocean: Ocean acidification

As CO2 dissolves into the ocean it creates carbonic acid, and this increases the acidity of the water. Surface ocean waters have become 30% more acidic since pre-industrial era.

What are the impacts of glacial periods on soil, and the subsequent impact on the carbon cycle.

As the soil freezes and is overlain with ice (up to 1km), the store of Carbon is held in soil therefore this will stop transfers (fluxes) of Carbon. The gas carbon withheld in the soil will be frozen in the soil (permafrost).

Why is the extra growth caused by 'carbon fertilisation' not boundless?

Because plants also need water, sunlight, and nutrients, especially nitrogen. This means the amount of extra carbon taken in from place to place on earth varies according not just to how much extra carbon there is but also factors such as water and nitrogen availability.

Why does our burning of fossil fuels have a major effects on the earth's carbon cycle if natural fluxes of carbon dioxide into and out of the atmosphere are still more than 10 times larger than the amount humans put in every year?

Because the human addition matters disproportionately because it unbalances natural flows.

How does climactic conditions (and therefore carbon cycling) differ spatially?

Broad regional differences in climatic affect carbon cycle flows in the earth's different biomes e.g. tropical rainforest (Brazil) versus deciduous forest (UK) versus tundra (Northern Russia).

How is the carbon flux decomposition carried out?

By decomposers whose special role is to break down the cells and tissues in dead organisms into large biomolecules and then break those biomolecules down into smaller molecules and individual atoms.

At a global scale, is the carbon cycle open or closed?

CLOSED: supply of carbon remains within the Earth system. As with all systems the global carbon cycle is made up of inputs, stores, flows and outputs.

Flux of Carbon: Carbon sequestration (HUMAN)

CO2 captured at source e.g. power plants and then injected in liquid form into underground stores such as coal beds or depleted gas and oil reserves.

Flux of Carbon: Diffusion. Where does CO2 diffuse to and from?

CO2 diffuses: - from the atmosphere or water into plants - from atmosphere to ocean

How is calcium bicarbonate transferred, and how much carbon is transferred from rocks to atmosphere and oceans globally?

Calcium bicarbonate can be transferred by overland flow, throughflow or groundwater flow into river where it becomes part of the solute load. Globally, some 0.3 billion tonnes of carbon are transferred from rocks to the atmosphere and oceans each year by chemical weathering.

Impact on the land: Agriculture

Changes in location of crop growing areas can be expected, with movements north and south from the equator. Increased desertification could occur in some areas. If large areas of grassland are damaged by desertification, carbon storage will be lost.

Flux of Carbon: Respiration

Chemical process that happens in all cells. Respiration takes oxygen from atmosphere and replaces it with carbon dioxide.

1986 Lake Nyos disaster, Cameroon. How far did mist travel?

Deadly mist persisted in a concentrated form over a distance of 23 km, quickly enveloping houses within the crater that were 120m above shoreline of the lake.

What are carbon system flows which vary spatially and temporally related to?

Different climatic conditions (precipitation, insolation and temperature)

DIFFUSION: Oceans take up CO2 by 2 carbon cycle 'pump' mechanisms. Describe the biological pump.

Driven by photosynthesis

Suggest why trees are important carbon sinks.

During photosynthesis, trees and plants "sequester" (absorb) carbon from the atmosphere in the form of CO2. The carbon from the CO2 becomes part of the plant and is stored as wood. Eventually, when the plant or tree dies, the carbon it has been storing is released into the atmosphere.

Natural Cause of Change: Natural Climate Change. Describe how this has worked over the Quaternary period.

During the Quaternary geological period (from 2.6 million years ago to the present) global climate has fluctuated considerably between interglacial and glacial periods.

Impact on the atmosphere

Enhanced greenhouse effect leads to global warming and changes in weather patterns and rainfall (in both quantity and distribution). An increase in more extreme weather conditions e.g. tropical storms can be expected as atmospheric patterns are disturbed.

What does decomposition ensure?

Ensures that Carbon is continually recycled into soil and made available for life.

Why are natural carbon sinks taking up more carbon?

In response to the 'extra' carbon in the atmosphere. Every year from 2005-2014, the land has taken up 3Gt and the oceans 2.6Gt of the Carbon.

What are the rates of sea level rise over the last 2 years?

Global-average rise over the last 2 decades centred on 3.2 mm per year.

What are flows within the carbon cycle measured in?

Gt, according to the IPCC

Flux of Carbon: Volcanic Activity

Huge volumes of stored carbon in sedimentary rocks are on move constantly (albeit at extremely slow rates) through the geological process of tectonic plate movement. This is shown in slow geologic carbon cycle. Carbon is released into atmosphere by volcanic eruptions, as CO2 is released from melted rocks when subduction occurs at plate boundaries.

Flux of Carbon: Shell and coral formation

In oceans some carbon gets incorporated into marine organisms as structural calcium carbonate shells and coral skeletons. When oceanic organism die shells and sinks to the bottom, where it forms a layer of carbon rich sediment. They are eventually lithified (turned into rock). This can lock up carbon for millions of years.

Where is the largest amount of carbon on Earth is stored?

In sedimentary rocks within the earth's crust.

Describe how oceans become less effective at sequestration.

In the past 2 centuries, atmospheric carbon dioxide levels have risen by over 30% - More 80% earth's added heat is stored in the ocean. - BUT as the water warms, warm water can hold less Carbon than cold water - Carbon won't be able to be transported to the deep sea due to weaker circulation = becomes less effective at absorbing CO2

How does carbon fertilisation cause a negative feedback loop?

Increased plant growth would reduce CO2 levels in the atmosphere.

Impact on ocean: Sea Level Rise

Increased temperatures in the atmosphere and ocean is causing the massive ice sheets that cover Greenland and Antarctica to melt at an accelerated pace. Scientists also believe meltwater from above and seawater from below is seeping beneath Greenland's and West Antarctica's ice sheets, effectively lubricating ice streams and causing them to move more quickly into the sea. Higher sea temperatures are causing the massive ice shelves that extend out from Antarctica to melt from below, weaken, and break off.

DIFFUSION: Oceans take up CO2 by 2 carbon cycle 'pump' mechanisms. Describe the physical pump.

Involves movement of CO2 from atmosphere to ocean by diffusion. CO2 dissolved in surface of ocean can be transferred to deep ocean in areas where cold dense surface waters sink. = 'downwelling'' Carries carbon molecules to great depths where they may remain for centuries. When cold water returns to the surface and warms up again it loses carbon dioxide to atmosphere.

90% of anthropogenic carbon release comes from the combustion of fossil fuels. What does the remaining 10% come from?

Land use change, such as deforestation, land drainage and agricultural practises.

Negative feedback that leads to positive from melting ice which releases moisture.

Melting ice releases moisture into atmosphere which increases amount and thickness of clouds present which cools atmosphere by reflecting sunlight. This is short lived though, because of brief Arctic summers. Throughout the rest of the year, the increased moisture and clouds warm the surface by trapping earth's heat.

Impact on the land: Carbon fertilisation

More CO2 available in the atmosphere results in more photosynthesis and plant growth. This is called 'carbon fertilisation'.

Overall, wildfires are magnifying the greenhouse effect which in turn is creating global warming. The relationship between forest fires and carbon is that of a positive feedback loop as each one increases the other. Explain this.

More wildfires cause more CO2 in atmosphere and fires also mean there are less trees to act as stores of carbon, both increasing greenhouse effect by releasing more CO2 in the atmosphere which will cause more fires to spawn due to hotter temperatures.

What is the Keeling curve?

Named after David Keeling, who discovered in 1958 to show that atmospheric concentration of carbon dioxide at Mauna Loa Observatory in Hawaii were increasing. The Keeling Curve shows the monthly average atmospheric carbon dioxide concentration over time at Observatory from 1958 - present year.

At the local scale, is the carbon cycle open or closed?

OPEN: inputs and outputs into and from the system.

Terrestrial Store What is the most prevalent form of carbon in soil?

Organic carbon derived from dead plant material and microorganisms. Most of the carbon enters soil in the form of dead plant matter that is broken down by microorganisms during decay. The decay process also releases carbon back to the atmosphere.

Flux of Carbon: Methane formation

Organic matter held under water is metabolised by methane producing bacteria. Methane accumulates in ground in porous rocks or underwater, but may diffuse into the atmosphere In air and light methane is oxidised to CO2 and water.

Flux of Carbon: Fossilisation

Over millions of years chemical and physical processes may turn the carbon rich sediment at the bottom of the ocean into sedimentary rocks (chalk and limestone) This is known as lithification. This can lock up carbon for millions of years.

Within a few years, if we don't slow fossil fuel use, what could be as big a source of greenhouse gases as china, the world's largest emitter?

Permafrost

What is permafrost?

Permafrost is any earth material underground surface which is at or below 0ºC for 2 or more consecutive years.

Flux of Carbon: Photosynthesis (Biological Pump)

Plants use energy from sunlight to combine CO2 from atmosphere with water from the soil to create carbohydrates. MARINE PLANTS (phytoplankton): In sunlit waters of ocean (euphotic zone - surface layer). Process of phytoplankton absorbing CO2 through photosynthesis is known as the 'biological pump'. Phytoplankton form the bottom of the marine food web. They are consumed by other organisims and carbon is transferred along food chains. Organic carbon may eventually be transferred to the deep ocean when dead organisms sink to the ocean floor.

Human Cause of Change: Urbanisation

Replacing open countryside with concrete and tarmac: important stores are either replaced (vegetation) or covered up (soils) with impermeable surfaces. - Globally urban areas occupy about 2% of total land area but account for 97% of all anthropogenic carbon dioxide emissions - Major sources of these emissions are transport and industry. Cement production for the building sector contributes 2.5% of global carbon emissions.

How is anthropogenic carbon absorbed proportionately?

Roughly half the anthropogenic carbon is absorbed equally by oceans and vegetation and the rest is absorbed by the atmosphere.

How are glacial periods triggered?

Scientists believe that the trigger for these long term trends in temperature (and associated CO2) is orbital change - the Milankovitch cycles.

How does climate varies temporally?

Seasonal changes in climate bring marked differences in carbon cycling during different months of the year.

How long does diffusion take?

Seconds

Looking at the structure of permafrost, what is the active layer

Soil thaws each summer and refreezes in winter, protecting the permafrost from rising heat above. However in Spring of 2018 found the dirt near the surface around Cherisky has not iced up at all overnight.

What is the season cycle which reflects the way CO2 is taken up by the terrestrial biosphere?

Spring: plants grow and take up atmospheric CO2 for photosynthesis Autumn and Winter: leaves fall from trees and release carbon back to atmosphere through autotrophic respiration

Oceanic stores can be divided into 3 zones:

Surface layer (euphotic zone) where sunlight penetrates so that photosynthesis can take place contains approximately 900 GtC Intermediate (twilight zone) and the deep layer of water contain approximately 37,100 GtC Living organic matter (fish, plankton, bacteria etc.) amount to approximately 30 GtC and dissolved organic matter 700 GtC.

Impact on ocean: Ocean salinity and the thermohaline conveyor

The Earth has ocean currents and wind systems that move heat from the equator northwards towards the poles then transport the cold water back towards equator. The oceanic part of this is known as the thermohaline circulation. 1. As ocean water moves northwards towards the higher latitudes it both cools and increases in salt content at the surface as some water evaporates and/or salt is ejected in the forming of sea ice. 2. The saltier colder water is denser and thus heavier, it drops into ocean. 3. Water moves along the depths until it can rise to the surface near the equator, often in the Indian or Pacific Ocean. 4. Heat from the sun then warms the cold water at the surface, and evaporation leaves the water saltier. 5. The warm salty water is then carried northwards; it joins the Gulf Stream, a large powerful ocean current that is also driven by winds. 6. The warm salty water travels up the U.S. east coast, then crosses into the North Atlantic region where it releases heat and warms Western Europe. With Global warming, it is a concern that large amounts of melting ice in Greenland could dilute the salty water and weaken or even shut down this circulation. This would cool large parts of Western Europe.

Who are the IPCC?

The IPCC (Intergovernmental Panel on Climate Change) is a body made up of hundreds of scientists from around the world.

Positive feedback of melting permafrost

The added warmth allows bacteria to digest organic material in the soil and emit CO2 or methane year-round, instead of for just a few short months each summer. And the winter warmth spreads down into the permafrost itself, thawing it faster.

What are the impacts of glacial periods on vegetation growth, and the subsequent impact on the carbon cycle.

The amount of vegetation growth and coverage significantly drop, which affects processes of photosynthesis and respiration.

What have been the greatest anthropogenic carbon sources between 2005 and 2014?

The burning of fossil fuels and cement production, releasing around 9Gt of carbon into the atmosphere each year from the period 2005-2014. Land-use change released a further 1Gt.

What is a more optimistic viewpoint of ocean acidification?

The more acidic seawater is, the better it dissolves calcium carbonate rocks (chalk and limestone). Over time this reaction will allow the ocean to soak op excess CO2, because the more acidic water will dissolve more rock, release more carbonate ions and increase the oceans capacity to absorb CO2.

In deciduous woodland seasonal variations in sunlight, rainfall and temperature limits what?

The overall net primary productivity and we see seasonal changes in carbon cycling.

Flux of Carbon: Combustion

When organic material is burned in the presence of oxygen it gives off CO2, energy and water. Since the start of the industrial revolution carbon dioxide has been released at an increasing rate by burning of fossil fuels and biomass (naturally occurring wildfires as well as human induced burning).

What is a negative feedback loop?

Where a disruption will be neutralised promoting a state of dynamic equilibrium.

How are glacial periods an example of a positive feedback loop?

These regular cycles of orbital eccentricity cause slight variations in the amount of the sun's radiation that warms up the earth. So, as temperatures start to rise at the end of a glacial period (triggered by orbital change), there is a surge of CO2 released into the atmosphere by the warming of the oceans and the 'unlocking' of the land surface that had previously been frozen. This surge of CO2 enhances the greenhouse effect, amplifying the warming trend.

What does the IPCC say is our carbon budget and why? How long have we got left at current emission rates until we reach this?

They have estimated a carbon budget that would hold the global average temperature at 2ºC, which amounts to around 800 billion tonnes of carbon. At current emission rates (released 550 billion tonnes at around 10 billion tonnes a year), we only have 25 years, probably fewer, until what remains of the carbon budget is spent and the global average temperature rises by 2º.

Human Cause of Change: Deforestation

This is the removal of trees by burning or felling, for building, ranching, mining or growing of commercial crops, such as soya or palm oil. Deforestation is widespread but concentrated in the tropical regions. - When deforestation by burning occurs, carbon is immediately released. - If the land is used for another purpose (cattle ranching) then future absorption of carbon will be reduced. - As a result the system becomes a source of carbon, rather than a sink.

How is natural carbon sequestration enhanced?

Through land management practices that maximise amount of carbon that remains stored in soil and in plants for the long term.

Impact on ocean: Ocean warming

Warmer oceans decreases abundance of phytoplankton , which grow better in cool, nutrient rich waters. This could limit the oceans ability to take carbon from the atmosphere through the biological carbon pump and reduce effect of oceans as a carbon sink. A study on phytoplankton changes in the Indian Ocean shows a decline of up to 20% in marine phytoplankton during the past 60 years. - Ocean warming also kills off algae that corals need to grow resulting in coral bleaching and the death of coral reefs.

What does weathering involve generally?

Weathering involves the breakdown of rocks in situ (their original place).

Arctic sea ice positive feedback loop which destabilise earth's climate: Reflectivity

Whiter surfaces (snow) are effective at reflecting the sun's energy into space, whereas darker surfaces such as water and land absorb more incoming sunlight. Arctic warms causing melting, increased heat caused by absorption of light causes further melting.

Natural Cause of Change: Wildfires

Wild fires can turn forests from being a carbon sink to being a carbon source, as combustion returns huge quantities of carbon back into atmosphere.

When describing the anthropocene, in their study of physical systems over millions of years many scientists have said that they believe we have reached what point?

a 'tipping point', moving out of the Holocene into a new epoch called the Anthropocene. They believe this represents a permanent shift from the Holocene and is dominated by human activities.

Left undisturbed, the fast and slow carbon cycles maintain a relatively steady concentration of carbon in the atmosphere, land, plants, and ocean. What is this called.

a dynamic equilibrium.

If more carbon enters a store more than leaves it that store is considered as what?

a net carbon sink

If more carbon leaves a store than enters it, that store is considered as what?

a net carbon source

Today, Carbon Dioxide is what kind of gas in Earth's atmosphere?

a trace gas

It's estimated that if 10% of the world's permafrost were to thaw it could release enough CO2 to atmosphere to raise temperatures by...

an extra 0.7ºC by 2100.

Photosynthesis in global forests cycles what proportion of atmospheric carbon dioxide every year? And what % does this make up of terrestrial photosynthesis?

approximately one-twelfth, accounting for about 50% of terrestrial (land based) photosynthesis.

In colder ecosystems like the tundra, water is locked up as ice and is not available to plants, meaning what is reduced?

productivity and carbon fluxes

The geological component of the carbon cycle is where it interacts with...

the rock cycle in the processes of weathering, burial, subduction and volcanic eruptions.