Greenhouse effect

On dew, greenhouses & IR thermometers: Coffee & Science at Amoret

starting with a coffee
Always good to start with a coffee. The evening started with two coffees (from Ethiopia and El Salvador). What will be the effects of climate change on the coffee industry?

January 2020 was the 6th warmest on record in the UK, with a mean temperature 2C higher than the 1981-2010 average. Early in February it was announced that Antartica had recorded the highest temperature ever recorded there of 18.3C, beating the previous record of 17.5C in March 2015. The atmospheric concentration of CO2 in January 2020 was measured to be 413 ppm following the trend that has seen the atmospheric CO2 concentration increase more than 10% from just the year 2000. That the polar regions would warm faster than other parts of the planet had long been a prediction of global warming based on increased CO2 emissions. Nonetheless, to see the figures reported quite so starkly was startling.

Each month brings new headlines and more concerns about whether we are responding fast enough to limit global warming to 1.5 or 2C. And yet, the greenhouse effect was proposed back in 1824; the idea that carbon dioxide (and water vapour) were greenhouse gases suggested during the 1850s (1,2) and it was back in 1895 that Arrhenius predicted that doubling the atmospheric levels of CO2 (relative to 1890s levels) would result in a global temperature increase of 5-8C.

So given that it is such an established theory, why are we still arguing about it? And, more importantly perhaps, what has this to do with coffee?

It is, in many ways, an ideal connection for the theme for one of the Coffee & Science evenings that we’ve been holding at Amoret Coffee in Notting Hill. And so it was that a group of us got together over coffee to discuss the greenhouse effect and its links to coffee.

coffee bowl pour over
The first connections can be seen with the condensation. How does dew form, and why does it suggest that space is cold?

The first coffee-greenhouse connection is in the condensation. When you make a pour over, or even if you pour your coffee into a cold mug, you will notice the condensation forming on the colder glass (or ceramic) surfaces as the steam evaporates. We know that the droplets form because the temperature of the surface is below that at which water vapour will re-condense into liquid. Technically, this temperature is known as the dew point. And it is partly to dew that we owe our understanding of the greenhouse effect.

Back in 1814, William Charles Wells made a series of detailed observations about how, where and when dew formed. He was able to show that more dew formed on clear (or not terribly cloudy) nights and on surfaces that were exposed to the sky; they were space facing. Which brings us to a second coffee connection: just as your coffee cup warms you by radiating its heat (in the infra red) to your hands, so all objects with heat radiate their energy out. Wells realised that this meant that space was cold because, just as a coffee cup if it is not being heated and not surrounded by reflecting material (think about the inside of a thermos flask) will radiate its heat and get cold* so the surfaces of the earth, if there is no energy coming in from space and no surfaces above them to reflect their heat back at them, will also get cold.

If space is cold, you can calculate what the temperature of the Earth should be if the energy it is losing is balanced by the energy it gains from the Sun and when you do this, it turns out that the mean temperature of the Earth should be -18C or about 30C lower than that observed**.

Earth from space, South America, coffee
One common home.
The Blue Marble, Credit, NASA: Image created by Reto Stockli with the help of Alan Nelson, under the leadership of Fritz Hasler

This leads to the idea that there is a natural greenhouse effect whereby gases in the Earth’s atmosphere form a layer which lets through a large amount of the energy from the Sun but lets a lot less energy escape back through it from the Earth (owing to the lower frequency of the radiation being emitted by the Earth compared with that coming in from the Sun). This ‘natural’ greenhouse effect results in a warming of the Earth to a delicate balance and to the temperatures that we experience on Earth***. Fairly clearly, if this delicate balance is disturbed by adding extra greenhouse gases to the atmosphere it will lead to a warming effect (as Arrhenius predicted back in 1895), the question is how much and how fast?

We were very fortunate to be joined for the evening by Dr Robin Lamboll of the Grantham Institute of Imperial College London. Robin explained the latest science and understanding of the effects of climate change and of adding increased CO2 into the atmosphere. Particularly highlighting how an increase in CO2 leads to an increase in water vapour (owing to the initial temperature increase produced by the CO2) which is itself a greenhouse gas, and so the warming effects of a small amount of CO2 can be amplified by this mechanism.

At this point the conversation diverged away from coffee, not just because Robin is a tea drinker (!) but we moved onto the effects of sulphur dioxide in the atmosphere, local vs global temperature effects and the science of Eunice Newton Foote. We discussed what we know, and what we are just starting to understand, such as how what happens in one part of the world may lead to consequences in other parts of the world (weather wise). We also got to a discussion of albedo and the reflection of heat by ice via playing with a couple of infra red thermometers that we had to hand and the different ways that human eyes and shrimp eyes detect colour. How is this connected to climate change and coffee? I’m afraid that there is a connection but the path to it is a little circuitous for a write up. It’s the sort of thing that pops up when you have a number of people of different backgrounds all contributing to the discussion. This is what, from my point of view, makes these evenings so interesting (and on a personal level induces such pre-event nerves): the fact that the conversation can go in so many directions, with such different contributions from the attendees, that each evening takes on a different character, with a different set of connections and a new set of things to think about. I hope that others feel the same way!

“An Essay on Dew”, Wells book of 1815 summarising his observations on dew. An excellent piece of observational science.

Our next Coffee & Science evening is scheduled for March 2020. Please do sign up to the events list or keep an eye on the Facebook events page to learn details as they are announced. Thanks again to Dr Robin Lamboll for coming along in January. I look forward to seeing both familiar faces and some new people in March.

Bean Thinking’s Evenings of Coffee & Science @ Amoret Coffee are held approximately every 2 months from 5.30 until about 8pm at Amoret Coffee in Notting Hill. More details can be found here.

*Two caveats here: firstly the coffee will also get cold through convection and conduction, the connection is illustrative rather than precise – though were you to put your coffee into a vacuum it would cool via radiative cooling only. Secondly, Wells himself never made the coffee connection but instead considered the latest physics theories about heat.

**In “Introduction to Atmospheric Physics”, David Andrews, (2000)

***For details about how we can know what the temperatures have been over such a time period and the effects of other cyclical temperature variations on the climate, it’s worth reading “The Ice Chronicles” P Mayewski & F White, (2002)

Plastic, coffee and ethical consumerism

“[W]hile 30% of UK consumers claimed to espouse ethical standards only 3% of purchases examined reflected those standards”∗.

Earth from space, South America, coffee

The Blue Marble, Credit, NASA: Image created by Reto Stockli with the help of Alan Nelson, under the leadership of Fritz Hasler

Most of us are aware of the growing number of environmental problems facing our planet and many of us want to do something. The question is what? Take the packaging that we use for freshly-roasted coffee. It often comes in metallised plastic bags with aroma valves on the front. Is this packaging good for the environment, or for our coffee?

Many factors will influence our decisions as consumers. Even our ‘ethical’ decisions can be based on different arguments. One factor though is, hopefully, the insights gained from scientific studies on the environmental effects of different types of packaging. Today’s Daily Grind examines some of this science.

Types of coffee packaging available

When you order coffee from a roaster, or buy it at a supermarket, mostly it will arrive in a metallised plastic bag. Some companies will supply coffee in compostable ‘plastic’ packaging, or paper, but most bags are still made from ordinary plastic. Some, larger, coffee roasters supply their coffee in cans. Although these are 100% recyclable, the increased weight compared to plastic packaging and the limited re-usability of the cans mean that plastic packaging can be more environmentally friendly than canned coffee. This article is therefore only going to consider smaller roasters and the plastic vs paper debate.

The problems of packaging

It is helpful to clarify the environmental concerns with respect to packaging. For the case of paper vs plastic, three major areas of concern are:

  • Depletion of a limited resource, recycling and re-usability.
  • Carbon dioxide emissions – in the manufacture and transportation of packaging.
  • Degradability – in both landfill and as litter.

Recycling and the Limited Resource problem

air valve, plastic, environmental coffee packaging

Disposable products make up about 37% of plastics produced‡. Are we wasting limited supplies by wanting our coffee as fresh as possible?

Paper comes from wood but plastics are generally a by-product of the petroleum industry (5% of petroleum in the US is used to produce plastics). Perhaps you will say that not all plastics are made from petroleum by-products. It is true. “Compostable” plastics are typically manufactured from starch based products (corn etc). However other bio-degradable plastics are petroleum based. “Oxo-biodegradable” plastic is ‘ordinary’ plastic with a small amount of catalyst added to it during manufacture. The catalyst causes the plastic to break down more quickly than the conventional plastic without the additive. Typically oxo-biodegradable plastic will be manufactured to degrade after 18 months compared with many years for ‘ordinary’ plastic.

Both compostable and oxo-biodegradable plastic are sometimes called ‘biodegradable’, but there are crucial differences between the two. For the sake of this article, I’ll be comparing ‘ordinary’ plastic with ‘compostable’ plastic (conforming to EN 13432) and oxo-biodegradable plastic (regulation ASTM D6954).

So the first part of the question would be to ask if the coffee packaging is made from recycled material. Paper can clearly be made from recycled material as can ordinary plastic and oxo-biodegradable plastic. Compostable plastic cannot be recycled and so cannot have been made from recycled material.

The second part of the question is whether you can recycle the packaging after using it. Again, paper packaging can obviously be recycled (provided it is not lined with plastic). Although both ordinary and oxo-biodegradable plastic can, in principle, be recycled, the multilayered and metallised design of the coffee bag means that it is not normally recyclable. Some coffee roasters however have started using specially designed plastic packaging that can be recycled in normal recycling centers. It would be great if more followed suit.

Two questions for your coffee supplier: Are the bags used to package the coffee made from recycled material and are they recyclable?

Greenhouse Gas emissions and energy costs

paper bag roasted coffee

Is a paper bag necessarily better for the environment?

Perhaps it is greenhouse gas emissions that concern you and so want to choose an environmentally sound packaging in terms of its CO2 emissions? Paper or plastic? You may be surprised. The environmental cost of a packaging type as measured by its CO2 emissions depends mostly on the energy that is required to manufacture it and the energy that is required to transport the packaging material to the point at which it is used (ie. the delivery of the bags to the roaster).

A few years ago, the Environment Agency performed a lifecycle analysis of different types of shopping bags (plastic, paper, cloth). Plastic bags are typically significantly lighter than the heavier paper bags. So, in addition to the cost of making the bags, it is going to require more energy to transport paper bags to the point of use. The report calculated that the manufacture and transportation of paper bags consumed so much more energy than plastic bags, that paper bags had to be re-used 4 times in order to have the same CO2 emissions as an ordinary supermarket plastic bag, re-used as a bin liner. The situation for a cloth bag was even worse.

Although the plastic used for coffee packaging is much heavier than a standard supermarket shopping bag, the analysis suggests that if your concern is CO2, paper is not necessarily better than plastic. It depends on how you are going to re-use the bags before you eventually recycle them.

Litter and Degradability

I hope that no one is deliberately discarding their used coffee packets onto the street or onto the beach! But litter and bio-degradability are big issues for plastic based packaging materials, particularly at sea. There are horrific stories about marine animals being starved due to consuming plastic or being drowned because they are entangled in it. Paper will degrade very quickly and so clearly does not suffer from the same problems as the plastic packaging in this topic. However, as mentioned above, not all plastic is the same. As well as ordinary plastic, your coffee could come roasted and packaged in a degradable plastic, either compostable or oxo-biodegradable.

sea no litter

There is a big problem with plastic litter ending up in the oceans

The name ‘compostable plastic’ (EN13432) is, to me, a bit disingenuous. It suggests that it breaks down in a composting facility such as my worm bin. But the standard EN13432 does not refer to such home-composting at all. For a plastic to be deemed compostable it has to break down under industrial composting conditions (ie. it is held at 58 C for the period of its degradation). Not all countries/councils offer such facilities for their waste disposal and so a compostable plastic sent to landfill offers little advantage over ‘ordinary’ plastic. However, in the marine environment it has been shown that the compostable plastic bag did degrade quickly relative to ordinary plastic bags‡.

Oxo-biodegradable plastic on the other hand works very differently. At the time of its manufacture, metal-salt catalysts are added to the plastic that determine how long the plastic survives before it breaks down. As long as it is exposed to light and oxygen, the oxo-biodegradable plastic will break down after, typically, 18 months (though the usable time can be made longer than this). Recent studies have shown that it is safe to recycle oxo-biodegradable plastic together with conventional plastic recycling†. Provided that the bag does not get covered in algae, an oxo-biodegradable plastic will break down after 18 months (if that was the time specified at manufacture) whether it is on land or on sea.

Therefore if litter is what you are worried about, you have to ask where you think that the plastics are going to end up and whether you want to be able to recycle them or just re-use them.

So what should you do?

There’s no point me answering this question for you. Ultimately I do not know your individual circumstances and concerns, nor how you are buying and consuming your coffee. Moreover, these considerations have been solely based on some of the environmental problems associated with different packaging. Coffee consumption has other factors, such as the major issue of how the coffee tastes. Earlier this year, Roasting House conducted an experiment to blind-taste the coffee after it had been stored in different types of packaging. You can find the results of that interesting study here.

a take away cup

The next problem. What should we do about take-away cups?

Personally, my concerns are principally the greenhouse gas emissions and the litter/degradability problem. I also buy coffee that is delivered to me very soon after it has been roasted. So I tend to favour packaging that uses unbleached, recycled paper. There is a caveat though. The CO2 emissions caused by paper manufacture and transportation means that I need to find a way to re-use the bags as often as possible before recycling/composting. Fortunately, I think there is a great use for old paper coffee bags: They are the perfect size for carrying loose vegetables or uncooked fish/meat products in supermarkets (rather than use the plastic bags that can be supplied for these products). Each paper coffee bag can be reused multiple times before it finally becomes unusable.

If I were drinking coffee that wasn’t quite so freshly roasted, I would be in favour of using oxo-biodegradable plastic (preferably from recycled material). I do not currently have an opinion on compostable (EN13432) plastic. The results of the degradation of compostable plastic in a marine environment were encouraging and if it starts to become genuinely compostable (as I understand the word in terms of home composting) it would definitely be a type of packaging to consider.

You may come to different conclusions, if you do so, please do let me know what you think in the comments section below. In the meantime, a map of coffee roasters who are trying to improve the environmental footprint of their packaging in a variety of ways can be found here.

 

I am grateful for discussions with Oh Ying Ying of Miracle Spectrum Sdn Bhd who helped me to navigate the minefield of environmental plastics. There is much more to write about plastics, the environment, litter & the Paris meeting, the whole issue of take-away cups for example!

∗ Yeow et al., “Bags for life: the embedding of ethical consumerism” J. Business Ethics, 125, 87 (2014)

‡ O’Brine et al., “Degradation of plastic carrier bags in the marine environment”, Marine Pollution Bulletin, 60, 2279 (2010)

† A report by the Transfer Centre für Kunststofftecknik GmbH (“TCKT”) dated 12 November 2013 on behalf of European Plastic Converters (EuPC), Roediger Agencies.

ª Plastics and the Environment, Ed. AL Andrady, Wiley-Interscience Publications, 2003

In the Greenhouse at CoffeeGeek

Coffee Geek and Friends, Coffee Victoria

Coffee Geek and Friends

Earlier this year, a new café opened up in Victoria. Coffee Geek and Friends is located at the far end of Cardinal Place as you enter from Victoria Street. Cardinal Place is an odd sort of shopping centre, a small collection of shops with a glass roof. The building site near Coffee Geek as well as the constant stream of people rushing to and fro make Coffee Geek an ideal place to spend some time watching the world go by. Coffee is by Allpress espresso and is served in very individual mugs. Apparently there is a range of geek-ery in the cafe including a ‘centre piece’ water filter but I admit I missed that as I was too focussed on my coffee. Coffee Geek and Friends is definitely a cafe to keep in mind (along with Irish & June’s) if you need a good place to meet near Victoria Station.

It was a very humid day when I enjoyed my coffee at Coffee Geek and, because the mug had not been pre-warmed before my Americano/long black (my notes don’t specify which) was poured into it, condensation quickly formed around the rim of the mug. The condensation forms for the same reason that dew forms after a cool night: the vapour pressure of the water above the coffee (or the ground) has reached the dew point at the temperature of the mug. The lower the temperature, the lower the vapour pressure has to be for the water in the atmosphere to start condensing into liquid droplets. Hence you will often find that your coffee is more ‘steamy’ on a winter’s, rather than a summer’s day.

Condensation on mug in CGaF

Look carefully at the rim of the mug. Do you see the condensation?

Just over two hundred years ago, William Charles Wells made a study of dew. He observed the weather conditions under which dew formed. He observed on which surfaces dew collected. He noted whether the dew formed on space facing surfaces or ground facing surfaces. After several years of careful study he published his “Essay on Dew” in 1814. His work, showed that the earth radiated heat at night (when it was not being kept warm by the Sun) and therefore that space was cold. Cloud cover reduced the amount by which the ground cooled which implied that cloud cover was acting as a type of blanket for the Earth, keeping the heat trapped inside. Later calculations of the balance between the heat radiated by the Earth and the heat received by the Sun confirmed that, without some heat getting trapped by clouds and ‘greenhouse’ gases in the atmosphere, the earth would be a good 30 C cooler than it is observed to be. Although these calculations are just rough, “back of the envelope” figures, detailed calculations confirm that the Earth is in a delicate balance, heated by the Sun, cooled by radiation and kept warm (and live-able) by a layer of natural greenhouse gases. This “natural greenhouse effect” has been necessary for our development, the problem is that now we are adding yet more greenhouse gases to the atmosphere which threatens to tip the established delicate balance by a few degrees.

Cardinal Place roof, greenhouse

The roof of Cardinal Place shopping centre. A very appropriate place for a meditation on the greenhouse effect

What we now call the greenhouse effect are these extra gases, which are more efficient at trapping heat within our atmosphere. If you can imagine what has been happening over the past three hundred years or so as we have been pumping yet more of these gases into the atmosphere at an accelerated rate, we are in danger of tipping this delicate balance towards further heating of the earth. The 2015 Paris Climate Conference is being held with the aim of requiring all nations to agree to a legally binding commitment to reduce the amount of extra greenhouse gases that we emit to a level that will only result in a temperature increase of 2C. To achieve this requires all of us to work together to reduce our own ‘carbon footprint’. Each of us will have to find our own, individual ways to reduce our emissions but perhaps when we look at the condensation on the rim of our coffee cup, we could remember William Charles Wells and his essay on dew and just think, what can I do, at this moment, to reduce my carbon footprint? Maybe it could be something as simple as turning off that phone (to conserve the battery) and watching what is going on in a café instead. A small gesture but one that would be good for us as well as the earth.

Coffee Geek and Friends is at the northern end of Cardinal Place shopping centre (opposite Westminster Cathedral).

As a Coffee Geek note, I would like to just comment that my notes on Coffee Geek and Friends were written using a “linux-sure” ball point pen. Not particularly environmentally friendly but definitely quite geeky.

The Corner One, Camden

20 Oval Road, Corner One

The Corner One in Camden

While browsing London’s Best Coffee, I came across a recommendation for The Corner One in Camden. The Corner One is tucked away on a side street near Camden Lock. What a great recommendation. The café itself is quite small and could be described as ‘cosy’. As the name suggests, it is on a corner, meaning that there are plenty of window seats on which to perch while enjoying your coffee. We ordered an Americano and a Flat White (Nude roastery) and couldn’t resist trying their muffins (which were very good). The atmosphere in the café was relaxed and, in a nice touch, dotted around the room were a variety of potted plants.

The strangely leaf-less plant at the Corner One

The strangely leaf-less plant at the Corner One

After a while, our attention was drawn to one plant in particular that had no leaves on it, although the flowers themselves seemed very healthy. This observation reminded us of the importance of plant life (and leaves) in the global environment and the fact that this week, diplomats from 200 countries are meeting in Geneva to edit the text agreed at the Peru climate summit. Their aim is to get the text into a form that could become a legally binding agreement at the climate talks to be held in Paris in December.

Plants are an essential part of the ecosystem of our planet. They absorb carbon dioxide and produce oxygen during photosynthesis. Another important contributor to the world’s oxygen supply are algae, as I became aware when I went to a recent Café Scientifique at the Royal Society (free and open to all). Dr Sinead Collins of Edinburgh University was describing her work on algae and what may happen to them as the oceans become more acidic. (The audio recording of the evening is available here). Ocean acidification is a consequence of increasing CO2 in the atmosphere. As CO2 dissolves in the sea water, it forms carbonic acid thereby increasing the acidity of the oceans (for more information click here). This increased acidity affects the ocean’s plant and animal life in ways that we are only just starting to understand. The evening emphasised how important it is to address the issue of climate change before it is too late.

latte art, flat white art

What the plant lacked, the coffee made up for

During the meeting, Collins mentioned that she preferred the term “global weirding” to “global warming”. The term does indeed convey the fact that a large greenhouse effect would make the weather system highly unpredictable rather than merely ‘warmer’. We should expect odd weather if we continue to pump CO2 and other greenhouse gases into the atmosphere. It is critical that the draft text currently being discussed in Geneva is agreed in Paris this year. We need a legally binding agreement to reduce our greenhouse gas emissions. Already our aim is very low; to reduce global greenhouse gas emissions to a quantity that would limit the global temperature increase to not more than 2°C higher than pre-industrial levels. Even so, this modest aim occasionally seems too high.

Let’s hope that the diplomats in Geneva this week and then the world leaders in Paris from 30 Nov – 11 Dec, agree to limit our CO2 emissions to that we can continue to enjoy our coffee.

The Corner One can be found at 20 Oval Road, NW1 7DJ.

Brunswick House

Brunswick House, coffee, cortado

Coffee at the Brunswick House cafe

Last Thursday, I had the opportunity to try the coffee at Brunswick House. The old building which houses this cafe/restaurant sits on the corner of a major junction two minutes walk from Vauxhall tube station and feels somewhat out of place with the buildings around it. Inside, the incongruity continues with quirky decor and bookcases stacked with all manner of titles. Coffee beans are supplied by the roasters Coleman Coffee. As it was a lunchtime, I had a very enjoyable cortado (an espresso “cut” with steamed milk in a ratio of 1:1 – 1:2) which was full of flavour but not too bitter. With friendly staff and a spacious interior, this is definitely a place to return to whenever I am next in the Vauxhall area.

However, The Daily Grind is not so much interested purely in the coffee as in the connections between what we can observe in the coffee cup and the physics of the wider world. At Brunswick House, this came in the form of the link between one way in which we know that space is cold and a seemingly mundane observation, the condensation of water onto cold surfaces. Lifting my glass to appreciate the cortado, I noticed a number of water droplets on the (cold) saucer underneath the (hot) cup. As I kept the cup on the saucer, the saucer became warmer and the water droplets evaporated. By the time I finished my coffee, the saucer was dry. We can observe a similar phenomenon on the inside rim of a cup of steaming hot coffee. As we watch, water droplets form around the cold rim of the cup before starting to evaporate off again as the cup gets warmer. How is this related to the coldness of space? For that, we have to digress to an essay written two hundred years ago about dew.

cortado, Brunswick House, everyday physics, coffee cup science

The cortado on the saucer. 

William Charles Wells published his “Essay on Dew” in 1814 after two years of patient observation of the circumstances under which dew formed in the mornings. By carefully noting the weather conditions of the night preceding the dew fall and the surfaces onto which the dew formed, Wells came to some important conclusions. Firstly, the surfaces onto which dew formed suggested that the earth must be radiating heat into space; space must be cold. Secondly, the earth lost more heat on some nights than on others, it appeared that certain clouds kept the surface of the earth warm. If Wells was right it suggests that there is a natural greenhouse effect which is helpful for life on earth. This in turn suggests that the surface temperature of the earth is the result of a delicate balance between heat transfer to and away from our planet. Upsetting this balance (by introducing more greenhouse gases for example), could have serious consequences. Was Wells right? Perhaps we should start noticing when and where dew forms. So, over the next few weeks, make a note of dew laden mornings. Where did the dew form and under what circumstances? Do you agree with Wells? Let me know in the comments section (below). In a few weeks we will revisit Wells and his essay, in the meanwhile, enjoy your coffee!