Carbon Literacy

A 1.5°C World

The United Nations International Panel on Climate Change used to say that we should limit the rise of global temperature to two degrees above the pre-industrial average for us to remain safe.

If temperatures rose by 2°C, what would it be like?

This video from Sky News explains a two degree world.

The IPCC have now revised that to 1.5 degrees centigrade. In October 2018, The International Panel on Climate Change warned that;

“Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate.”

(high confidence)
In other words, in 2018, we had twelve years left in which to limit the rise…

Test Yourself

If you’re feeling confident about what you’ve learned you can test yourself with the quiz at the end of this lesson.

If you’re still unsure about some of the science, please get in touch with your tutor and they will be able to support you. There will also be general reviews of the information during the facilitated session.

Revisit any of the videos or articles that you missed or do your own reading around the subject in the ‘Discover More’ sections.

Discover More

If you would like to continue to explore and learn about the science of climate change, these are some useful websites:

British Antarctic Survey | Ice cores and Climate Change.

A Smithsonian Article on Charles Keeling | The enduring legacy of Mauna Loa.

Sceptical Science | A website dismantling climate change denial and mis-information.

Grist have created a well-sourced guide on how to disarm climate sceptics with common arguments from climate change deniers. This is also good reading for your own knowledge and will help make the links between the science and the arguments you may hear. 

A 1.5°C World Read More »

Can we Blame the Sun?

Not surprisingly, the Sun, that great ball of fire in the sky – plays a major role in the Earth’s temperature and climate.

The Earth’s orbit around the Sun is not constant, it’s is elliptical. The Sun itself does not burn with a constant heat – sometimes it enters periods of dormancy when less energy reaches the Earth from the Sun.

Some people say that the recent measured warming of the Earth is caused by an increased output from the Sun.

This is not true. The Sun has in fact been in a rather sleepy phase recently and has produced less heat energy than in the past.

Credit: NASA/JPL-Caltech

The graph compares global surface temperature changes (red line) and the Sun’s energy that Earth receives (yellow line) in watts (units of energy) per square meter since 1880. The lighter/thinner lines show the yearly levels while the heavier/thicker lines show the 11-year average trends. Eleven-year averages are used to reduce the year-to-year natural noise in the data, making the underlying trends more obvious.

The amount of solar energy that Earth receives has followed the Sun’s natural 11- year cycle of small ups and downs with no net increase since the 1950s. Over the same period, global temperature has risen markedly. It is therefore extremely unlikely that the Sun has caused the observed global temperature warming trend over the past half-century.

Discover More

Visit the Treehugger website to explore the Earth’s orbit around the Sun in more detail and understand how this relates to climate change.

Visit the NASA global climate change website where you can find out more about the Sun’s Role in Climate Change.

Can we Blame the Sun? Read More »

So is it any Warmer?

NASA's Climate Time Machine


Let’s take a trip on NASA’s Climate Time Machine.

  1. Select the ‘global temperature’ topic.
  2. Press play to watch the visualisation showing how the temperature of the earth has changed in the last 150 years or so.

Did you see the colours change?

How did that make you feel?

The sequence is not a depiction of the actual temperature of earth, it is the change (hotter or colder) from the average temperature between 1951 and 1981.

The period of 1951-1980 was chosen largely because the U.S. National Weather Service uses a three-decade period to define ‘normal’ or average temperature. The GISS temperature analysis effort began around 1980, so the most recent 30 years was 1951-1980. It is also a period when many of today’s adults grew up, so it is a common reference that many people can remember.

Global temperature records start around 1880 because observations did not sufficiently cover enough of the planet prior to that time.

17 of the 18 warmest years in the 136 year record have all have occurred since 2001, with the exception of 1998. The year 2016 ranks as the warmest on record. 2019 was the 2nd warmest. The last ten years have been confirmed as the warmest decade on record. (Source: BBC Science news).

This research is broadly consistent with similar constructions prepared by the Climatic Research Unit and the National Oceanic and Atmospheric Administration.


2017 – CO2 and CH4 (Methane) levels reached new highs

2018: rise continues, 2019 higher still – 411ppm

illustration depicting sea level around Italy during the pliocene

The last time carbon dioxide levels were as high as today was during the geological epoch known as The Pliocene (around 4 million years ago). Temperatures were 2-3 degrees higher than today and sea level 10 -20 metres higher. While we cannot see the same right now, the carbon dioxide levels indicate that there is a significant risk that sea levels might rise to levels not seen since the Pliocene.

Discover More

You can read more about this link to the Pliocene in this BBC story: Climate change: Warning from ‘Antarctica’s last forests’.

So is it any Warmer? Read More »

Carbon Dioxide Levels

So, the Keeling Curve tells us that in our lifetimes, CO2 levels are rising…is it a worrying rise? To answer that we need to compare the recent rise to the data of centuries. Remember the ice cores? This is where they come in.
Graph: Global Monitoring Laboratory, questions about greenhouse gases
Law Dome Ice Core data source: D.M. Etheridge, L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola and V.I. Morgan. 1998. Historical CO2 records from the Law Dome DE08, DE08-2, and DSS ice cores. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A

This graph puts the Keeling curve into historical context. The data here starts at the time of the Norman invasion of Britain. The Keeling Curve is shown here in red.

What happens around 1600? Would you expect the Earth to have got warmer or colder at that point?

Notice what happens after 1850. What else was going on in history at that time?

Here’s an interesting theory from geological and environmental science researchers from Stanford University.

The Frozen Thames 1677

The Frozen Thames 1677

Abraham Hondius, Public domain, via Wikimedia Commons

Carbon Dioxide Levels Read More »

The Keeling Curve

Since the development of scientific instruments like the thermometer, we have been able to make direct observations of the climate and of carbon dioxide levels – we don’t need proxy indicators.

One of the most important places for measuring the atmosphere is Mauna Loa Observatory on the island of Hawaii. Since the 1950s, scientists have been measuring the components of the atmosphere in this remote spot. It’s an ideal location for doing this because it is far from human settlements, the air is undisturbed, it’s very high and there is very little vegetation – all of which could influence the concentration of carbon dioxide and other gasses.

David Keeling was the pioneering scientist who first started measuring the concentration of carbon dioxide in the atmosphere at Manua Loa. The “Keeling Curve” is a graph that shows us that Carbon Dioxide levels have been steadily rising since the 1950s. 


Credit: Graph courtesy of the Scripps Institution of Oceanography SIO.

Study this graph. Why do you think there is an annual cycle (indicated by the saw tooth pattern of the black line)?

What do you think causes the saw tooth pattern on the Keeling Curve?

Notice the timescale of this graph.

This is within our lifetimes.

It shows a steady rise in CO2 which is worrying, but how much of a rise is this when looked at from a timescale of centuries not just our lifetimes?

We will be finding out more in the next topic.

Discover More

You can read more about the observatory and the work of David Keeling, on the Smithsonian online magazine.

Find out what causes the saw tooth pattern in the Keeling Curve on the Scripps Institution of Oceanography website.

The Keeling Curve Read More »

Geological Climate Detective Work

The Importance of Cores

Without a time machine we cannot directly experience the climate of the past.

So, we have to deduce what past climates were like from information that scientists call ‘proxy indicators’.

Ice Cores

At the North and South Poles, ice has been accumulating for hundreds of thousands of years. Drilling down into the ice is effectively a journey back in time. The Vostok station in Antarctica sits above three kilometres of ice that has been accumulating for 400,000 years. This is one of many sampling sites at the poles, where scientists can drill down and extract long tubular ‘cores’ of ice.
Ice core extracted at Talos Dome showing an ash layer corresponding to the Toba eruption.
Ice core extracted at Talos Dome showing an ash layer corresponding to the Toba eruption.
Image: Dargaud, CC BY-SA 4.0, via Wikimedia Commons

Each layer of ice is a slice in time and contains bubbles of air trapped when snow fell to the ground and ice formed. These bubbles are little pockets of ancient atmosphere. Scientists can analyse these air fossils to see how much carbon dioxide, methane and other gases were in the atmosphere at that specific point in time.

As snow deposits onto a growing glacier, the temperature of the air affects the structure of the water molecules. So, the cores also tell us something about the temperature of the Earth in past times.

The icy layers also hold particles—aerosols such as dust, ash, pollen, trace elements and sea salts—that were in the atmosphere at that time. These particles remain in the ice thousands of years later, providing physical evidence of past global events, such as major volcanic eruptions.

Sediment Cores

Just like ice cores, drilling down into deep layers of ocean sediment is like a journey into the past. Sediment at the bottom of the oceans accumulates over hundreds of millions of years. Analysing these sediments tells us how the temperature and chemistry of the oceans varied over millions of years.
Pollen washed from the land and the shells of plankton are key indicators. Small life forms (plankton) that spend their lives floating in the ocean before sinking down to the ocean floor when they die, are sensitive to ocean temperature and the acidity of the water. The more that carbon dioxide dissolves in water, the more acid that water becomes. So, when you see the abundance of certain species of plankton change between layers of sediment core, then you know that temperature and/or acidity has changed. And if that has changed, then the climate has changed.

Imagine if scientists found lots of polar bear fossils buried under what is now a tropical beach: that would tell them that at a specific time in the past that beach was a cold and icy place. It’s the same with the plankton but their relative abundance tells the story of much more subtle changes in temperature.

On land, plants and animals are sensitive to the humidity and temperature of the climate. Certain species like cold and dry, warm and dry, warm and wet, cold and wet etc.

Pollen, seeds, shells, and insect exoskeletons get washed from the land into sea sediments.

Marine sediments are therefore a treasure trove of information, telling us what the climate was like a very long time ago. Over decades, thousands of scientists have analysed both ice and marine cores to piece together, like detectives, the story of the Earth’s climate changes.

Geological Climate Detective Work Read More »

Recommendations: Reducing your Carbon Footprint

Companies and public bodies all over the world are now reporting on how their activities are contributing to global warming. Investors are diverting money towards organisations that can show they are reducing emissions of greenhouse gases.

Calculating Your Carbon Emissions

When your company calculates and reports its emissions of greenhouse gases, it should do so using the ‘Carbon Dioxide Equivalent’ unit. All companies that report on their emissions do this.

It is possible to reduce many emissions that organisations are responsible for but some things are harder to reduce.

In order to achieve an overall ‘net zero emissions’ standard, it may be necessary to offset emissions.

The Benefits and Dangers of Offsetting

‘Offsetting’ means taking measures to compensate for emissions that you cannot reduce. For example; international flights have a disproportionately large contribution to greenhouse gases and hence climate change but sometimes they are unavoidable.

It is possible to calculate the emissions associated with your flight and offset these by making a financial contribution to a certified scheme that will store the equivalent amount of carbon dioxide that your journey has emitted.

This is not an exact science and open to abuse, but it is a legitimate way to try and minimise the damage caused by certain activities such as flying.

There are several certification schemes to ensure that you are contributing in the most sustainable way. The most famous of these is Gold Standard.

You should seek impartial advice before embarking on a carbon offsetting strategy.

It is very important that you shop around and scrutinise carefully any off-setting scheme before signing up.

Keep it Local

Where possible we suggest that you work with local companies and charities to start your offsetting e.g. Size of Wales, and United Purpose. You could also consider The World Land Trust.

Test Yourself

If you’re feeling confident about what you’ve learned you can test yourself with the quiz at the end of this lesson.

If you’re still unsure about some of the science, please get in touch with your tutor and they will be able to support you. There will also be general reviews of the information during the online session.

Revisit any of the videos or articles that you missed or do your own reading around the subject in the ‘Discover More’ sections.

Put your feet up! You now know about the carbon cycle, fossil fuels and greenhouse gases and are ready to look deeper into climate change!

Discover More

If you want to delve deeper, this article from the Guardian explains the options and how to navigate them: Carbon Offsetting; carbon emissions: ‘It has proved a minefield’

The Carbon Offset Guide from the Stockholm Environment Institute (SEI) and Greenhouse Gas Management Institute is an excellent resource for businesses and organisations seeking to understand carbon offsets and how to use carbon offsets in voluntary greenhouse gas (GHG) reduction strategies.

Meanwhile, Friends of the Earth asks Does carbon offsetting work?

If you are responsible for reporting within your team or organisation you can download emission conversion factor spreadsheets from the UK Government website.

Recommendations: Reducing your Carbon Footprint Read More »

The Greenhouse Effect

The Earth’s distance from the sun predicts that it should have an average surface temperature of minus 18 Degrees Centigrade or zero Fahrenheit:

Most water on earth would be ice and complex life would not be possible.

The average temperature however is plus 15 degrees centigrade and life thrives. Why?

Gases in Earth’s atmosphere – steam, carbon dioxide, methane and others – absorb heat energy and trap it.

Just like a greenhouse (or any glass structure like a conservatory), heat energy from the sun can enter the air inside the earth’s atmosphere and warm things up but some of that heat gets trapped making the atmosphere of the earth warmer.
Credit: Nasa

The way that greenhouse gases trap heat is relatively simple. It is all about how energy of different wavelengths interacts with the structure and behaviour of molecules. Greenhouse gases trap wavelengths of energy mostly in the infra-red part of the spectrum.

Energy of various wavelengths comes from the sun and passes through the atmosphere to reach the surface of the Earth. Some of it is absorbed by the earth while some bounces back off the earth.

Some wavelengths pass through the atmosphere back into space, but enough energy gets trapped by the molecules of greenhouse gasses to keep the earth warm.

Adding more of these gases however will of course trap more energy and make the earth warmer.

Discover More

So who first discovered Greenhouse gases?

Most people attribute the discovery of greenhouse gases to the Irish scientist John Tyndall (in 1859-60) which is why the The UK’s Tyndall Centre for Climate Change Research bears his name, as does Ireland’s Tyndall National Institute.

But more recently, papers have been discovered by climate science pioneer Eunice Newton Foote that first suggested that changes in carbon dioxide in the atmosphere could affect the Earth’s temperature in 1856.

You can read more about Eunice Newton Foote and John Tyndall’s discoveries in the Royal Society Journal.

The Greenhouse Effect Read More »

Fossil Fuels

Oil, natural gas and coal are referred to as the ‘fossil fuels’. Like fossils, they were buried underground millions of years ago…but where did they come from?

Coal Formation | Credit Siyavula Education

Oil, gas and coal are all formed from living things that lived on earth millions of years ago. The image above explains how coal was formed from swamps rich in plant and animal life.

Because plants get the energy they need to capture and store carbon from sunlight, we can say that fossil fuels are FOSSILISED SUNLIGHT! Ultimately, the sun is our only readily available energy source…. It has powered planet Earth for billions of years.

photo of roman baths
Roman Baths Photo Credit: Mario Klassen (Unsplash)

The Roman Empire was one of many ancient civilisations that achieved remarkable things. Stop for a minute and think where they got their energy from…

Our modern global civilisation is unique. It is the only human civilisation in history that has built itself using the energy provided by fossilised sunlight

Take a closer look at the graph showing CO2 emissions by fuel type. What do you notice?

Graph showing global co2 emissions by fuel type
Source: Our World in Data—CO2 emissions b fuel type

When you burn fossil fuels to release energy, you are adding oxygen to carbon that has been stored for millions of years. The carbon dioxide produced would not normally be there. Under natural conditions it would stay locked away – as it has been for all human history until the Industrial Revolution. So since about 1845 we have released massive amounts of carbon dioxide into the atmosphere.

Fossil Fuels Read More »

The Carbon Cycle

Watch this simple video on YouTube which explains the carbon cycle. 

Credit: Doctor David Faulkes

Plants have a very important role to play in keeping the planet at a stable temperature. They moderate the levels of carbon dioxide in the atmosphere, locking away carbon in their structure.  

As the video explained, when we burn something that contains carbon, we add oxygen to it to create carbon dioxide. Wood contains carbon because it was once a living tree. So, each time you burn a log, you are combining the carbon in that log with oxygen to produce…. Carbon Dioxide. 

In recent years the problem of global warming and the changes to the climate caused by this have been made worse by deforestation. Not only are we losing the lungs of the world through deliberate felling but forest fires release tonnes of carbon dioxide into the atmosphere. 

An Area the Size of Wales

Journalists often use the phrase ‘An area the size of Wales’ to measure the rate of forest destruction. A charity called “The Size of Wales” has been established to turn this phrase on its head. The actual size of Wales measures about 2 million hectares.
Photo credit: Size of Wales, A tree nursey in Mbale, Uganda
The charity achieved the goal of planting forest across the world that added up to this size in 2013 and is now in the process of doubling it. Size of Wales encourages people to help tackle climate change by protecting and restoring forests. Other organisations such as The World Land Trust and Ecosia also do this.

Discover More

This article on the Live Science website explains the causes and effects of deforestation clearly.

Find out how the Size of Wales project is tackling Climate Change.

The Carbon Cycle Read More »

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