School chemistry revision 14-16 GCSE and A level chemistry notes:

Causes and consequences of global warming and climate change

Scroll down and take time to study the content and/or follow links or [Use the website search box] 23/07/2022

non-renewable fossil fuel coal oil gas diagram electricity power generation turbine generator transformer power lines

4. FOSSIL FUEL COMBUSTION, Air Pollution & Climate Change

4C Levels of CO2 in atmospheres, global warming - climate change, reducing our carbon footprint from fossil fuel burning

It is estimated that without the 'insulating' effect of carbon dioxide gas and water vapour, the surface temperature of the Earth would be ~30oC lower!, but we may be overdoing the warming effect!

Doc Brown's chemistry revision notes: GCSE chemistry, IGCSE chemistry, O level & ~US grades 9-10 school science courses or equivalent for ~14-16 year old chemistry students

Over the recent past years the Arctic region has experienced the greatest melting of sea ice and record temperature highs and the greatest recorded melting of Greenland's glaciers.  The carbon dioxide level is steadily increasing year by year. Whatever is causing climate change, global warming is happening.

Anthropogenic means any environmental change or pollution due to human activity.

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Sub-index for this page

(a) Some of the latest evidence of global warming

(b) Introduction to global warming - impacts, climate change, carbon footprint from fossil fuel burning

(c) The EVIDENCE for global warming and rising CO2 levels in the atmosphere and ocean

(d) What do scientists and politicians believe?!

(e) What exactly is the 'Greenhouse Effect' and what contributes to it?

(f) What is our 'carbon footprint'? and ways of reducing it to minimise global warming

(g) Playing around with graphs and consequences of climate change - posing a few questions?

(h) Further environmental, social and economic discussion points -   a brainstorm bullet points of global warming consequences! (follows on from (g)

doc b oil notesSee also

4A Fossil fuel air pollution: incomplete combustion, carbon monoxide & soot particulates

4B Pollution, Accidents and Economic Aspects of the Petrochemical Industry

4D Fossil fuel air pollution - effects of sulfur oxides and nitrogen oxides

and A local acid rain project!!!

 4C (a) Some of the latest evidence of global warming

The current global picture

The global temperature change diagram from 1966 to 2019 shows the greatest warming is in the northern region of the Arctic Circle (from NASA-GISS data June 2020).

The average global temperature has risen by ~1oC, but in the Arctic it has risen by 4oC.

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4C (b) Introduction to global warming - impacts climate change, carbon footprint from fossil fuel burning

A big contributor to our 'carbon footprint', a conventional fossil fuel power station in Yorkshire, where the last deep coal mine in the UK closed in December 2015.

A good way of reducing our 'carbon footprint', windfarm of wind turbines in Co. Durham, a county once permeated by dozens of coal mines !

We know that an increase in average global temperature is a major cause of climate change, and, whatever the cause, we are not sure about is the consequences! Most scientists think the current pattern of global warming is due to increasing carbon dioxide levels in the atmosphere from burning fossil fuels. Possible consequences are ...

  1. The potential effects of global climate change include eg sea level rise from melting polar ice, which may cause flooding of low lying land and increased coastal erosion.

  2. More frequent and severe storm destruction leading to infra-structure disruption e.g. electrical power-lines affected, road and rail travel disrupted. There is some statistical evidence for this in crease in more violent weather activity.

  3. Changes in the amount, timing and distribution of rainfall - increase in deserts - regions becoming more hotter and drier - more arid - drought or just the opposite with flooding from much heavier rainfall than expected- some countries are experience unusually hot and dry periods.

  4. The local climate temperature (too low/high) and water (too little/much) stress for humans and wildlife.

  5. 3. and 4. result in changes in the food producing capacity of some regions by disruption/reduction of agriculture.

  6. Changes to the distribution of wildlife species - there is evidence that species of various animals are moving north in north-west Europe (e.g. the UK) as the overall climate gets milder.

  7. BUT, its very difficult to predict if and when these extreme weather events happen, therefore its difficult to predict their effects and where and how many people might be affected.

  8. Historically we have limited data for long-term trends - see section about past atmospheres.

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4C (c) The EVIDENCE for global warming and rising CO2 levels in the atmosphere and ocean

RISING CARBON DIOXIDE LEVELS - greenhouse gases - climate change - global warming

  • Some of the evidence for connecting fossil fuel burning with global warming.

  • doc b oil notes GRAPH A (see extra data below)

    • The graph shows the steady rise in the concentration of carbon dioxide in the atmosphere from 1959-2010 as measured at the Mauna Loa mountain top observatory on the Pacific island of Hawaii.

      • The rise in carbon dioxide level correlates well with the increasing amounts of carbon dioxide produced from fossil fuel combustion as more countries become more industrialised and consumers demand more electricity etc.!!!

      • This represents the highest carbon dioxide levels in the atmosphere for at least 250,000 years. This is known because trapped air bubbles in ice cores from the arctic regions can be analysed to obtain their % composition. Every year snow falls form a new layer that become compacted into thin layers of ice which become buried beneath successive yearly precipitations so a long geological record of the earth's atmosphere is preserved.

    • It is a good base-line for our planet because it is well away from any industry involving fossil fuel burning.

    • The concentration of CO2 is in ppm (parts per million).

    • 1ppm means 1 in 106 of air molecules is CO2. In % volume terms, 1 ppm = 100 x 1 / 106 = 0.0001%.
    • The graph shows that the CO2 has risen from 0.0316% (316 ppm) in 1959 to 0.0378% (378 ppm) in 2004.

      • I haven't updated the graph for 2005-2015 data yet, but the carbon dioxide concentration continues to rise at about 2 ppm per year.

      • The latest data I've got from the Mauna Loa website is a s follows: Year and ppm CO2 concentration
        • 2005  379.8,  2006  381.9,  2007  383.8,  2008  385.6,  2009  387.4
        • 2010  389.9  2011  391.7,  2012  393.9,  2013  396.5,  2014  398.7
        • 2015 400.8,  2016  404.3  2017  406.6,  2018 408.6,  2019  411.9
        • 2020 414.2,  2021 416.3 (forecast)
        • In the last hundred years the carbon dioxide level has grown from ~300 ppm to >400 ppm.
        • There has been a 50% increase in CO2 levels since 1750-1800.
          • I will update all the graphs eventually !
    • This doesn't seem much of an increase, BUT on a global scale, the extra 'Greenhouse CO2 Gas' could have drastic consequences (see next paragraph), but the computer model predictions have a high degree of uncertainty.

  • Based on peer-reviewed evidence, most, but not all, scientists believe that human activities will cause the temperature of the Earth’s atmosphere to increase at the surface and that this will result in global climate change.

    • There is good evidence for human activity causing climate change when you consider the correlation between the ever increasing atmospheric level of carbon dioxide, the ever increasing consumption of fossil fuels and an overall small rise temperature over the past few decades in particular. Note also the rise in world population.

    • Graph B1

    • GRAPH B1 The steady rise in carbon dioxide concentration in the atmosphere, particularly through and after the industrial revolution in the 19th century and into the 20th and 21st century.

    • Data Source - NOAA/ESRL Global Monitoring Division: https://www.esrl.noaa.gov/gmd/

    • Prior to any growth in industries using fossil fuels the baseline carbon dioxide concentration was about 277 ppm 1000 years ago (277  parts per million means 277 CO2 molecules in a mixture a million air molecules).

    • Rose steadily through industrial revolution but as the world economy gets going after the 2nd World War the rise in CO2 concentration starts to become much more significant.

    • Except in recent times, the CO2 concentration had reached a maximum of 300 ppm over the last 400 000 years.

    • -

  • Graph 2: The rise in use of fossil fuel use in terms of CO2 emission 1850-2003
Graph B2

    •  Graph B2: The rise in use of fossil fuel use in terms of CO2 emission 1850-2003

      • Data source - Oak Ridge National Laboratory USA:

    • This graph parallels the rise in atmospheric CO2 concentration in general but seems to be far more significant after the 2nd World War.

    • The dips usually (all cases?) coincide with periods of world economic recession e.g. the 1930's and the early 1980's when less fuel is burned by the power and manufacturing industries.

    • The steady rise in 'extra' carbon dioxide, presumably from increased fossil fuel burning, is cited as evidence for its contribution to global warming irrespective.

    • -

    • GRAPH C The unfortunate steady rise of coal, oil and natural gas use, though its good to see the rise in hydroelectric power and biofuels.

    • GRAPH D The steady rise in population, steady rise in energy demand!

    • GRAPH E1

    • GRAPH E2

    •  Graphs E1 and E2 (E2 is the latest, and the most worrying graph of global warming) show the small, but significant global temperature rise through the 20th century and continuing into the 21st century.

    • However, it is difficult to accurately computer model such complex systems as global climate change.

    • This is partly due to uncertainties caused by the location where carbon dioxide and temperature (in particular) measurements are taken and extra problems of historical accuracy.

    • Inevitably this leads to simplified models with large margins of uncertainty, allowing speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased to suite an individual's point of view!

    • Graph F

    •  GRAPH F From analysis of atmospheric gases trapped in ice core samples drilled out of the Greenland ice-cap you can estimate the concentration of carbon dioxide over the past 400,000 years. From this NASA graph you can see there has been considerable oscillation between 'highs and lows' in the concentration of carbon dioxide in the air. BUT, there has been quite an acceleration in the rise of carbon dioxide in the atmosphere in recent times, which is higher than its ever been in the past 400,000 years.

    • Graph G

    •  GRAPH G Paralleling the oscillation of carbon dioxide you see the temperature over hundreds of thousands of years shows a similar oscillation and the two are believed to be connected. The temperature anomaly is based on the difference between the average temperature around 1950.

    • Graph H

    •  GRAPH H The temperature anomaly looks even more dramatic if you focus on the last 1500 years and look what has happened over the past decade.

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4C (d) What do scientists and politicians believe!?

You should appreciate that based on peer-reviewed evidence, most scientists believe that human activities are causing a small rise in the temperature of the Earth’s atmosphere and surface and that this will result in global climate change.

  • BUT, it is difficult to model such complex systems as global climate change. This leads to simplified models allowing speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased - political and economic interests may not always present the whole and balanced evidence story!

  • Generally speaking politicians world-wide agree on the central theory that global warming is linked to fossil fuel burning, but action may be slow!


2nd BUT: Some things seem reasonable to accept based on the evidence presented by scientists, and, politicians adopt policies to deal with climate change and its consequences ...

  • An increase in average global temperature is a major cause of climate change.

  • The potential effects of global climate change which be small or large, include:

    • a rise in sea level, which may cause flooding of low lying land and increased coastal erosion,

    • more frequent and severe storms causing more erosion and destruction of coastal communities,

    • uncertain changes in the amount, timing and distribution of rainfall,

    • more temperature and water stress for humans, agricultural systems and wildlife habitats,

    • changes in the food producing capacity of some regions - temperature and water supply affected,

    • changes to the distribution of wildlife species as ecosystems are affected the ambient temperature and water supply.

  • So, make sure you are able to discuss the scale, risk and environmental implications of global climate change and long after you leave school, college or university!.

  • Some human activities increase the amounts of greenhouse gases in the atmosphere eg

    • carbon dioxide from combustion of fossil fuels,

    • deforestation - less photosynthesis, less CO2 absorbed by plants,

    • methane from animal farming (digestion, waste decomposition),

    • decomposition of rubbish in landfill sites produces methane, a much more 'greenhouse' gas than carbon dioxide.

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4C (e) What exactly is the 'Greenhouse Effect' and what contributes to it?

It should be clearly stated at the start of this section that the greenhouse effect is a completely natural process that warms the Earth’s surface. When the Sun’s energy enters the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated. Much of this re-radiation that is eventually absorbed by the atmosphere as infrared heat radiation.

Having presented some of the evidence for global warming, we now need to know and understand the technicalities of the 'Greenhouse Effect'.

  • The burning of oil and other fossil fuels is believed to be contributing to the 'Greenhouse Effect' or global warming.

    • The Earth's average temperature depends on the net input of energy from the Sun and the energy re-radiated from the Earth's surface.

    • Water vapour and carbon dioxide are the principal greenhouse gases that absorb radiation from the Sun and maintain an Earth temperature suitable to maintain life.

      • This does not mean global warming takes place - its all about balance.

      • See last section on the Earth and EM radiation in the GCSE physics notes

    • This greenhouse effect is vital for life on Earth !!! It is neither too hot or too cold and the ambient temperatures of planet Earth allows a huge variety of life-forms to co-exist at this distance from the sun and with the particular composition of the Earth's atmosphere..

      • The mechanism of the greenhouse effect.

          • When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space.

          •  (This solar radiation is electromagnetic radiation, mainly ultraviolet light, visible light and short wave infrared radiation, the latter being heat/thermal radiation)

        1. The rest of the Sun's energy is absorbed by the land and oceans, warming the Earth. So most of this radiation is NOT initially absorbed by greenhouse gases.

        2. All surfaces on the Earth are constantly emitting infra-red radiation outwards.

        3. In this 'greenhouse' context, the infrared light re-emitted (re-radiated IR) from the warmed earth's surface is of longer wavelength than the incoming IR and is now re-radiated in all directions from the Earth's surface, scattered and absorbed by 'greenhouse gases' like water, carbon dioxide and methane,

        4. Therefore this absorbed infrared radiation becomes heat energy in the atmosphere and transferred to the Earth's water or land surfaces too, and all contributing to global warming.

          • The thermal energy store of the Earth's atmosphere is increased.

          • This also means the weather systems are being powered by more energy.

        5. It is this 'greenhouse' effect that maintains the relatively warm average global temperature. The Earth's atmosphere containing the 'greenhouse gases' acts exactly like the glass window panes of a greenhouse trapping sunlight with a sort of insulating heat retaining effect.

    • HOWEVER, it is believed by most scientists that the increasing levels of carbon dioxide are causing more of the Sun's radiated energy to be retained in the Earth's atmosphere than previously by the mechanism described above.

      • This is referred to as an anthropogenic effect -  an environmental impact or pollution due to human activity!

      • Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs).

      • So, it isn't just carbon dioxide gas that is causing global warming, water vapour also absorbs IR and gases like methane too, in fact lots of chemicals in the atmosphere from human activity can absorb IR radiation.

      • With more energy in the atmospheric weather systems, we may get more storms, wetter weather, more climate extremes e.g. more severe drought in places.

      • The effects are complex and its VERY difficult to predict what might happen!

      • There is also concern about rising temperatures of the oceans and the increase in acidity due to more carbon dioxide dissolving in the oceans.

        • Carbon dioxide is a weakly acidic gas and delicate ecosystems can be affected by a lowering of the pH e.g. the complex biodiversity of a coral reef.

        • A change in temperature can also have a negative effect and there is evidence of species migrating and spreading as sea temperatures change, even slightly.

  • Apart from burning fossil fuels, there are also other factors which may indirectly increase global warming by NOT reducing carbon dioxide levels.

    • Greenhouse gas Relative measure of the infrared  absorption % contribution to greenhouse warming
      water vapour  H2O 1 36-72
      methane  CH4 7 9-26
      carbon dioxide  CO2 24 4-9
      ozone  O3 ? 3-7
    • Although carbon dioxide is the main contributor to global warming 9apart from water vapour), other gases can significantly contribute to global warming.
    • Methane (CH4) is a powerful greenhouse gas is produced from animal farming in the digestion system of farm animals like cows, and from animal waste decomposition with anaerobic bacteria.

      • Methods animal husbandry in livestock farming should be developed to reduce methane emissions.

    • Methane is also produced by decomposition of organic matter (e.g. waste food) in landfill sites.

      • Again, methods of managing landfill sites to reduce the release of methane into the atmosphere.

      • In some cases, the methane formed is collected and burnt to power a small electricity generating system.

    • Sources of carbon dioxide other than burning fossil fuels.

    • Deforestation for farming and timber, cutting down large tracts of forest is removing plants that are absorbing carbon dioxide in photosynthesis.

    • Not only that, clearing forests by burning is adding carbon dioxide to the atmosphere.

    • Microorganisms are also producing carbon dioxide when they decompose dead wood, though this is recycled via plant and algae photosynthesis.

    • However, burning fossil fuels at the current rate, is still the biggest contributor to rising carbon dioxide levels, but scientists are doing their best to try to fix the problem and restore the balance of the carbon cycle!

See also Biodiversity, land management, waste management, maintaining ecosystems - conservation gcse biology revision notes

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4C (f) What is our 'carbon footprint' and ways of reducing it to minimise global warming

  • Carbon dioxide from fossil fuel burning, and other gases including methane, water vapour and CFC's absorb the re-radiated lower frequency infrared energy from the Earth's surface and so warming the atmosphere, rather like a greenhouse allows the sunlight in but not out. The effects are predicted to be dramatic e.g. rising sea levels as polar ice melts causing flooding in low lying land, more energy in the global weather system leads to more frequent violent weather patterns etc. etc.

    • There is considerable uncertainty as to what might actually happen, but the consensus amongst scientists is that fossil fuel burning is raising the global temperature by a small, but not insignificant amount.

    • Important definition: The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

    • This isn't just about fossil fuel power stations, we are talking about the energy involved in producing and using consumer goods, road vehicles, methods of farming, fertiliser production etc. etc. i.e. anything involving the use of energy!

  • Some of the many sources of our carbon footprint

    • Businesses or factories are consuming energy, particularly electricity, much of which is still being generated using fossil fuels as the initial energy resource - hence the need for greener renewable bulk energy resources.

    • The same can be said for our domestic use of energy where insulation and more careful use of electricity can help reduce are personal carbon footprint including more walking, cycling and less use of car if possible!

    • How is a product manufactured? What resources are used? Transport costs? and many other factors ...

    • for a deeper discussion on these last points see the notes on ...

    • Chemical & Pharmaceutical Industry Economics & Sustainability - Life Cycle Assessment

    • Products of the Chemical & Pharmaceutical Industries & impact on us

  • Reminder - the carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.

    • The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane by switching to 'greener' energies supplies e.g. solar panels, wind turbine, hydroelectric etc.

    • Other actions to reduce the carbon footprint include reducing energy conservation, carbon capture and storage, carbon taxes and licences, carbon off-setting, including through tree planting - trying to achieve carbon neutrality – zero net release.

    • BUT, problems of reducing the carbon footprint include eg

      • scientific disagreement over causes and consequences of global climate change,

      • lack of public information and education,

      • lack of government support e.g. aiding developing green technologies with subsidies,

      • 'us' not making less energy consuming lifestyle changes,

      • economic considerations:

        • greener economies are initially more expensive.

        • poorer countries lack the finance to invest in greener energy resources - richer countries can take the lead, but other countries need help!

      • incomplete international cooperation and agreement on carbon emission limits..

    • Any increased efficiency in any process to use less energy produces less waste will help.

    • Governments can tax (i) companies or (ii) you as an individual for activity producing greenhouse gases like carbon dioxide e.g.

      • (i) subsiding green energy resources until the unit cost comes down

      • (ii) increased car tax on heavy fuel vehicles, less flying, saving energy in the home - insulation, turn the heating down a bit!

    • Carbon off-setting involves buying carbon credits by companies or individuals to reduce carbon dioxide in the atmosphere e.g. planting trees to remove carbon dioxide by photosynthesis.

      • If a company can off-set all of its greenhouse emissions its said to be carbon neutral.

    • Some of these points are discussed in more detail below.

  • What more can we do about it?

  • i.e. how can we reduce even more our 'carbon footprint' to reduce global warming?

    1. Reduce the amount of fossil fuels we burn in power stations, but the international community struggles to come to an agreement over this issue and the huge, and fast growing economies of India and China are demanding the building of large numbers of fossil fuel power stations (in 2006 China was starting to build one every week!).

    2. 'Green' alternative renewable energy resources can be more exploited, but not without problems e.g.

      • wind turbines - weather dependant

      • wave power - subject to storm damage

      • hydroelectric power, a large scale alternative energy supply -

        • damming the exit from a valley or canyon, but who wants their valley flooded!

        • a large tidal barrage across a river estuary, but what about environmental-ecological effects, and possible silting up.

      • photovoltaic cells - depends on intensity of sunlight and varies from country to country, through the day and the seasons

      • solar power panels in roofs etc. - comments as above!

        • all reduce acid rain pollution and CO2 production by using less fossil fuels.

        • Many are good for domestic and small communities but only nuclear power and large scale hydroelectric power schemes are suitable for large scale energy production for the highly populated countries with large industrial economies.

      • There is much work still to be done to improve the efficiency of these schemes. Alternative technologies do not come cheaply at first including the above, but the more they are commercially developed, the lower the unit cost becomes to the consumer.

    3. Like 2., nuclear power is another option that does not produce carbon dioxide and is suitable for large scale power generation, but there are real public fears about the safety of nuclear power generation 'fuelled' by the consequences of the nuclear power plant accident at Chernobyl, in the Ukraine in 1986. It is extremely costly to build nuclear power stations and there are added extra long term costs in decommissioning nuclear power stations, safely processing the waste and safely storing the residual radioactive waste for hundreds to thousands of years.

    4. Recent ideas include 'carbon capture and storage', that is storing the CO2 from fossil fuel power stations underground in rocks under pressure e.g. in exhausted oil and gas wells or some other form of deep underground storage.

      • Ideally reducing carbon dioxide release into the atmosphere while still using fossil fuels, but I don't know any details or how feasible it is?

      • Personally I'm quite sceptical about this method, quite large amounts of energy will be needed to 'capture' the carbon dioxide and compress it into some storage area, but we shall see !.

    5. Use less electricity and heat energy from fuel combustion by being careful of its use e.g. increase home insulation and more efficient electrical appliances like 'low energy' light bulbs.

    6. Burning wood is sustainable and an example of carbon neutrality (a net zero carbon footprint) and the CO2 formed on its combustion is recycled via photosynthesis, BUT ...

      • (i) it does not burn cleanly - the smoke is quite polluting,

      • (ii) its energy density is low (heat energy released per mass of fuel),

      • (iii) no good for large scale power generation.

    7. Using alternative fuels like hydrogen (no CO2 formed) and carbon neutral fuels based on biomass like ethanol, biodiesel etc. See 9b. Biofuels & alternative fuels, hydrogen, biogas, biodiesel

    8. Scientists do come up with some other interesting ideas e.g.

      • Much of the photosynthesis in oceans is done by phytoplankton in the upper layers of the ocean. One of the essential minerals these plants need to photosynthesis is an iron. It has been suggested that seeding parts of the ocean with a soluble iron compound will promote the growth of plankton and absorb more carbon dioxide via photosynthesis. However, although in principle a good idea, you can't control which plankton grow and some of them are toxic. These blooms of phytoplankton may become so 'thick' so that in lower layers of the oceans, microorganisms decompose them, using up oxygen and killing most aquatic life in the vicinity!

    9. Developing 'greener' less polluting public transport systems to reduce the number of private cars on the roads, particularly in cities and other busy urban areas.

    10. Economic policies like carbon taxes and licences to encourage using green energy, putting a premium on using fossil fuel energy,

  • Unfortunately although there is lots of good science and technology available to reduce our carbon footprint, in reality its never that simple !

    • Problems in trying to reduce the carbon footprint include:

      • scientific disagreement over causes and consequences of global climate change, scepticism of the need to change energy policies over such unpredictable science as climate change,

      • a lack of public information and education,

      • our reluctance  to change our lifestyles,

      • economic considerations, coal and oil are cheap, green alternative energy sources are less economic at the moment, but maybe needed whether we like it or not !

      • difficulty to get complete international cooperation, every major country needs to be working in the same direction to reduce carbon dioxide from fossil fuel emissions,

        • its not easy for politicians - have some sympathy for them, economic and electoral pressures can make life quite difficult for them even if the agree with most scientists about global warming and climate change! Incidentally,

        • I also feel there is a distinct lack of scientists in the UK parliaments, even though there are many scientific advisors to the UK government, we the public tend to hear much more from politicians than scientists!.

  • Global dimming.

    • This makes the predictions about global warming even more uncertain.

    • As the earth warms up, more water vapour can exist in the atmosphere.

    • The more cloud that is formed in the upper atmosphere the more sunlight is reflected, so less radiated energy reaches the Earth's surface, leading to the opposite of global warming.

    • It has been suggested that cloud formation could be encouraged by seeding the atmosphere with crystals to promote cloud formation.

    • It is ironic that the vapour trails of aircraft, with their heavy use of fossil fuels, actually contribute to global dimming as well as to global warming at the same time!

    • The effect of global dimming was noticed in the aftermath of the 9/11 terrorist attacks on New York's World Trade Center Twin Towers in 2001.

    • All aircraft were grounded in the USA and many parts of the world for several days after the attacks and sunlight gauges showed a small but abnormal increase in sunlight levels reaching the Earth's surface.

      • There was also other evidence from monitoring stations which measure rates of water evaporation from large tanks, when a small but abnormal increase in evaporation rate from extra sunlight was noted.

    • It is believed that small (fine) solid particles like soot/carbon or ash in the atmosphere can cause global dimming because they form the nuclei of water condensation producing the fine water drops of clouds and this reduces the
      amount of sunlight that reaches the Earth’s surface. I'm not sure if the particulates disperse a small amount of the sunlight directly?

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rising sea levels!?rising temperatures - more risk of forest fires and drought

4C (g) More on data graphs, global warming & consequences of climate change?

Just playing around' with graphs and posing myself some questions !

Data Graphs, Global Warming and Carbon Dioxide Emissions

 Greenhouse Effect and Climate Change

Notes and possible class discussion points

The carbon dioxide level in the atmosphere is slowly rising due to the burning of fossil fuels. Theoretically this leads to global warming and inevitable climate changes. BUT, are the current climate changes due to 'man's activity'? i.e. the so-called anthropogenic effect, or, is burning fossil fuels just adding to climate changes that would have happened anyway?

The consensus of the scientific community is that burning fossil fuels at the current rate is contributing directly to global warming and the subsequent climate changes have important consequences, particularly economic and other effects on communities around the world. However, there is debate as to how much of the current climate change is due fossil fuel burning and the climate change.

Effects are extremely variable, and frankly, not very predictable e.g. some areas of the world are suffering heat waves, others have extra torrential rain and catastrophic flooding, in some areas of the Andes in South America, the average climate temperature has gone up 5o leading to rapid melting of glaciers that years later reduce the amount of fresh water available in the summer but other places show little change. Unfortunately, you can selectively pick the data to fit your belief! Not good science!

Over the past 150 years the global temperature has increased by about 1o, which doesn't seem very much, but it isn't wholly understood what the consequence of this might be? Also, is the rise accelerating? All I can do is present some of the evidence and many points for discussion.

I've done my best to sift data and ideas but not all websites are to be trusted, and I'm no expert in this field, so there are lots of ? marks on this page! There is a list at the end of good general resources of more ideas, facts, theories etc. but some are quite technical in places. So I hope these revision notes on climate change and global warming should prove useful for the NEW AQA GCSE chemistry, Edexcel GCSE chemistry & OCR GCSE chemistry (Gateway & 21st Century) GCSE (9–1), (9-5) & (5-1) science courses.

EXTRA Graphs 3 and 4: Mean Global Temperature variation from 1850-2005

Graph 3: The Mean Global Temperature variation from 1850-2005

  • Data source - East Anglia University, Climate Research Unit:

  • The data is based on both atmospheric and oceanic temperatures.

  • The purple line is the average global temperature of 14oC for the period 1961-1990 and is used by some research groups as the baseline for calculating the so-called temperature anomalies plotted below. Essentially the temperature anomaly here = mean global temperature(1961-1990) - 14o. Other research groups use different baselines and different calculation methods, but they all agree that the Earth is warming up.

  • My thanks to Mike Salmon of the Climate Research Unit of East Anglia University, England, for taking the trouble to explain temperature anomaly data to me.

  • 1998, 2002 to 2006 were the 6 warmest years on record, at least from 1850 anyway, and 11 of the warmest years have occurred in the last 12. This definitely indicates we are in a warm period, though on a short timescale compared to 'geological time'.

  • Although the atmospheric CO2 concentration is rising steadily, as is the quantity of fossil fuels burned, in cannot be said that the average global temperature has been steadily rising. In fact it shows considerable fluctuation. The temperature tended to fall from the 1940's to the mid 60's, so a new ice age was being predicted in the early 1970's.

  • However the consequent trend in rising temperature is now leading to predictions of 'excessive' global warming and its potentially dire consequences.

  • However, it should be also noted that Earth has cooled a little since 1999.

  • I've explained the theory of the 'Greenhouse Effect' or 'Global Warming' on the Section 4. Oil Notes page!

Graphs 4: The Mean Global Temperature anomaly from 1850-2005

  • Data source East Anglia University, Climate Research Unit:

  • The temperature anomaly graph is a good statistical way of showing the trends i.e. a positive (+) value means warmer than a negative (-) value.

  • The purple trend line is based on the polynomial function in Excel, it might not be the real statistical truth BUT its independent of human prejudice!

  • There was a significant rise from 1900 (or earlier?) until the early 1940's, then there was a small decrease until 1964, but after that the temperature is steadily rising, which is the worrying feature.

  • You can see that from 1950 there is on average a steady rise in temperature despite the regular fluctuations and it is this later temperature pattern that leads most scientist to believe that global warming is a significant threat

Further graphs (5-7), which I haven't see elsewhere, but they seem to me to reinforce the case for global warming due to fossil fuel combustion. The graphs may seem to do strange things at times i.e. the graph lines loop round, but this is because the absolute vales are plotted against each other and not necessarily in strict chronological order. However, roughly speaking, you go from 1850 on the left to 2003 on the right.

EXTRA Graph 5 The temperature anomaly variation with carbon dioxide from fossil fuel combustion

Graph 5 shows on average, that, as more fossil fuel is burned producing more carbon dioxide, the average global temperature is rising, albeit somewhat erratically!

This is a statistical correlation graph for 'sceptics', NOT the usual chronological graph that you find on the internet.

It shows a clear statistical correlation between global warming and the CO2 released from burning fossil fuels

EXTRA Graph 6 The temperature anomaly variation and carbon dioxide concentration in the atmosphere

Graph 6 shows on average, that, as the concentration of carbon dioxide in the atmosphere rises, the average global temperature is rising.

This is a statistical correlation graph for 'sceptics', NOT the usual chronological graph that you find on the internet.

It shows a clear statistical correlation between global warming and the concentration of atmospheric CO2.

EXTRA Graph 7  The variation of air carbon dioxide concentration with carbon dioxide from fossil fuel burning

Graph 7 shows on average, that, as the amount of fossil fuel burned increases, so does the concentration of carbon dioxide in the atmosphere - a very unambiguous graph!

This is a statistical correlation graph for 'sceptics', NOT the usual chronological graph that you find on the internet.

It shows a clear statistical correlation between CO2 from burning fossil fuels and the concentration of atmospheric CO2.

EXTRA Graph 8 The growth of the total population of the world

GRAPH 8: Growth of world population

Graph 8 Shows the growth of world population (in millions) from 1.26 billion in 1850 to 6.71 billion in 2008. Graph 8 is similar shape to the graphs for the increase in carbon dioxide in the atmosphere (Graph 1) and the increasing amounts of fossil fuels being burned (Graph 2).

I'm not suggesting that the two are automatically related, but its worth bearing in mind that oil based fertilisers have helped increase food production dramatically and of course 'fuel' 'consumer society'. Increases in standards of living and better medical healthcare worldwide mean that more people are surviving so the population is steadily growing.

So what happens when oil production begins to decrease?! Can the rise in population be sustained? Must the population then decrease by choice, war, plague, global catastrophe etc.???? or do we all grow more food in our garden using organic methodology? (My wife's solution! who is generally far more sensible and practical than I am, and I'm not being patronising!).

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4C rising sea levels!?rising temperatures - more risk of forest fires and drought(h) Further environmental, social and economic discussion points -   a brainstorm bullet points of global warming consequences!

The Inter-governmental Panel on Climate Change (IPCC) states:

'Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.'

'Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations12. This is an advance since the IPCC's conclusion that "most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations". Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes and wind patterns'

  • Some of the first points made are NOT on the GCSE syllabus, but unfortunately, they are very relevant to the current 'heated' debate on what causes the current global warming. Incidentally, there is no dispute (as far as I know?) in the opinion that the Earth is currently warming up.

  • Over the past 2 million years the Earth has passed in and out of ice ages. In terms of the paleoclimatological record we are currently in an inter-glacial period. So, will fossil fuel CO2 induce global warming to override the historical pattern?

  • Two of the major obstacles to good predictions to climatology are accuracy of data (improving) and the fact that changes in climate can be due to changes from what happened several or hundreds of years ago, the great 'systems' of the Earth can only change very slowly (we hope?).

  • You can miss out the next two bullet points if you want BUT ... ???? The three Milankovitch Cycles are to do with the input variation of solar radiation onto the Earth's surface and are considered to be major factors affecting the increase/decrease of glaciations of the Earth's surface.

    1. The eccentricity of the Earth's orbit changes over a 100,000 year cycle. The Earth's orbit around the Sun is not perfectly circular, but is slightly elliptical and changes over a 5% range from a narrower to a wider ellipse. This means that the Earth - Sun distance is smaller/greater leading to an increase/decrease in the intensity of solar radiation reaching the Earth.

    2. Currently the Earth's spin axis is 23.5o with respect to a vertical line to the plane of its path of its elliptical orbit around the Sun and this causes the change in the angle the sunlight hits the Earth's surface, causing changes in the sunlight intensity and length of day which produces the seasons. However this angle changes over a 41,000 year cycle from 21.5o to 24.5o so changing the way the solar radiation is distributed over the Earth's surface and so changing weather patterns and their consequences.

    3. The 3rd Milankovitch factor is the precession of the Earth's spin axis. The spin axis 'wobbles' and precesses around from one side to another over a period of about 23,000 years.

  • As consequence of the interaction of the three Milankovitch cycles, it is believed, and backed up by certain data, that the glacial cycles last about 100000 years and the current interglacial ('warmer period') started about 18000 years ago, but within the 'big cycle' there are cycles and sometimes the effects will combine or cancel each other out producing a very complicated pattern of events which can be plotted to some extent from analysis of ancient ice core data. However, the question till begs, 'will increase in fossil fuel burning override the Milankovitch factors'?

  • Despite the mention of Sun spot cycles affecting our climate, and despite the fact that it does affect the total solar radiation reaching the Earth, there is no credible scientific evidence yet that sun spots affects our climate significantly if at all.

  • On a short term basis, huge volcanic eruptions of ash clouds can produce mini-ice-age effects which last for several years after the event. The distribution of fine ash clouds can directly block out sunlight or cause more cloud formation which reflects sunlight. Either way, global temperatures will fall due to this 'dimming effect' and long term effects may be more than we recognise, but there is no recognisable pattern in the geological record.

  • The Earth is about 5o cooler than it was 20000 years ago, but it was coming out of the last ice age, and warming up in the 'great climate cycle', so this in not unexpected in principle.

  • The current prediction from the IPCC report (Inter-Governmental Panel on Climate Change) based on the work of thousands of 'credible' scientists, is for a one degree rise in average global temperature over the next century. It doesn't sound much BUT it involves  an enormous amount of energy which drives the ocean and atmospheric systems. See the IPCC quotes at the start of this section.

  • One consequence is rising sea levels due to thermal expansion of the oceans and the melting of the polar ice-caps, but which is the more significant effect?

  • How much of the extra CO2 will be absorbed by the ocean or used in plant photosynthesis? Is there a significant time lag? Will it have any significant effect at all?

  • Do the dips in fossil fuel usage e.g. in the 1930's and 1980's correspond with a temperature fall?

  • Will small countries such as the UK make any impact on the situation if their 'carbon footprint' is decreased? especially as China is bringing on-stream a large fossil fuelled power station each week?

  • Do we have the right in the developed western economy (e.g. in Europe/USA) to expect less developed countries in the East to show restraint in burning fossil fuels as they try to develop

  • Wouldn't it be a good idea if the UK reduces fossil fuels for (a) setting an example or (b) other very different reasons e.g. (i) less dependent on gas/oil supplying countries who may be politically unstable and over control the price, (ii) less need for the very controversial nuclear power, (iii) conservation of a valuable chemical resource for non-fuel use e.g. drugs, plastics and other materials. (a) is a moral-philosophical altruistic attitude, (b) is about self-interest, so why not combine the two?

  • Business opportunities due to climate change e.g. if the UK becomes warmer there will be more vineyards in southern England. However the 'warming up' is reducing the skiing tourist industry in Scotland and the Northern Pennines as less snow falls and sticks around, though manufacturers of artificial snow equipment are doing well.

  • Ecological changes and their consequences e.g. as the temperature warms up, species tend to move and occupy more northern regions. If the winters are not as severe e.g. less frosts, insect species harmful to plants may not be killed in the same numbers increasing their risk of harming crops. South East may become warmer and drier, so water supplies will be affected and it is an area which is predicted to have the largest number of new houses built in the next decade.

  • A selection of actions that can be taken to reduce our 'carbon footprint' is listed on the Section 4C Oil Notes - Carbon Footprints and I'm sure many more ideas can be added.

Multiple Choice Quizzes and Worksheets

KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products (easier-foundation-level)

KS4 Science GCSE/IGCSE m/c QUIZ on Oil Products (harder-higher-level)

KS4 Science GCSE/IGCSE m/c QUIZ on other aspects of Organic Chemistry

and (c) doc b 3 linked easy Oil Products gap-fill quiz worksheets

ALSO gap-fill ('word-fill') exercises originally written for ...

... AQA GCSE Science (c) doc b Useful products from crude oil AND (c) doc b Oil, Hydrocarbons & Cracking etc.

... OCR 21st C GCSE Science (c) doc b Worksheet gap-fill C1.1c Air pollutants etc ...

... Edexcel GCSE Science Crude Oil and its Fractional distillation etc ...

... each set are interlinked, so clicking on one of the above leads to a sequence of several quizzes

KS3 BIOLOGY QUIZZES ~US grades 6-8 KS3 CHEMISTRY QUIZZES ~US grades 6-8 KS3 PHYSICS QUIZZES ~US grades 6-8 HOMEPAGE of Doc Brown's Science Website EMAIL Doc Brown's Science Website
GCSE 9-1 BIOLOGY NOTES GCSE 9-1 CHEMISTRY NOTES and QUIZZES GCSE 9-1 PHYSICS NOTES GCSE 9-1 SCIENCES syllabus-specification help links for biology chemistry physics courses IGCSE & O Level SCIENCES syllabus-specification help links for biology chemistry physics courses
Advanced A/AS Level ORGANIC Chemistry Revision Notes US K12 ~grades 11-12 Advanced A/AS Level INORGANIC Chemistry Revision Notes US K12 ~grades 11-12 Advanced A/AS Level PHYSICAL-THEORETICAL Chemistry Revision Notes US K12 ~grades 11-12 Advanced A/AS Level CHEMISTRY syllabus-specificatio HELP LINKS of my site Doc Brown's Travel Pictures
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revision study notes for 14-16 school chemistry AQA Edexcel OCR IGCSE/GCSE 9-1 chemistry science topics modules for studying the graphs of CO2 ppm concentration versus year showing the rise of carbon dioxide in the atmosphere,  graphs of temperature versus time, what is the greenhouse effect causing climate like global warming, what is a carbon footprint?, how can we reduce our carbon footprint, what is global dimming? what causes global dimming? gcse chemistry revision notes igcse revising KS4 science online fashion brands global warming climate change,

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