What’s the carbon wedges approach?

Climate change is a complicated issue. Its reasons are to be found across different disciplines and become clear only when approaching them with a wide knowledge of multiple topics. This could discourage many of us but is there a way to make this approach simpler? Let’s find out, as always, together.

Photo by Marcin Jozwiak on Pexels.com


In case you didn’t notice, the Earth is getting warmer. In 2014, the International Panel on Climate Change published a report claiming that “each of the last three decades has been successively warmer at the Earth’s surface than any preceding decades before 1850”.

The two main factors that influence the temperature of any planet of the solar system are their distance from the Sun and the composition of their atmosphere. The reason why our Planet is getting warmer is that, as a consequence of human activity, we increased the level of Greenhouse Gases (GHG) in the atmosphere, resulting in less sunlight that is reflected back in the space. The increasing sunlight is “trapped” in our atmosphere because GHG make the atmosphere layer’s thicker and so the Earth’s temperature increases.

So far everything seems easy to comprehend. The problem starts when we try to assess which human activities are contributing to increased levels of GHG. 

To summarize some of them here is a list of the ones you might be more familiar with:

  • CO2 emissions (from cars, manufacturers and everything you can think of that requires burning of fossil fuels).
  • Food waste.
  • Agriculture and livestock.
  • Deforestation.

The list is much wider, that was just to give you a general idea of what we are talking about. So, considering that each one of these human activities has several implications, how do we deal with them all at once, in order to tackle the main issue?

A solution was provided in 2004 by two American academics Steve Pacala and Robert Socolow. Their idea, named “the carbon wedges approach”, aims to break down a complex subject such as climate change into smaller wedges, all part of the big problem, to deal with them separately. Apparently, the name came up because when representing the idea on a chart, they seem to take down the temperature increase by wedges.

They recognised that each solution would take time and effort, both from institutions and private citizens (which, in my opinion, will always play the bigger part: complaining does not get you anywhere, acting does. I’m trying with this blog, what about you?)

Some math

They took as a target the main goal of trying to reduce the Earth’s temperature increase to 2℃ by 2100. They also calculated that each wedge would bring a reduction of CO2 emissions of 1 Gt in 50 years (assuming that emissions rate do not sharply increase in different sectors. For example, if we stop flying but we increase the number of cars in the street without finding an affordable replacement for diesel and petrol, it is not going to be a smart solution).

Example of carbon wedges approach. The flat path is the equivalent of applying 7 wedges, more are needed to further decrease CO2 emissions in order to meet our targets.

At a current rate of growth of GHG emissions, if we don’t intervene, by 2100 the Earth’s temperature is expected to increase by ≃4℃. If we apply 7 wedges, reducing in 50 years time GHG emissions by 350 Gt, we would have by the end of the century a situation of +2.7℃, which is the same we would face if GHG emissions wouldn’t increase at all and would stay stable at the current rate.

The approach shows that if we really want to meet our target and limit the Earth’s temperature increase, 7 more wedges are needed, to bring down the emissions to 700 Gt in the next 50 years: in that scenario, the Earth’s temperature would still increase but only by 1-2℃, which according to the scientific community should not lead to catastrophic scenarios.

The mathematic is basic, the resources seem to be available, so what is the problem?

Why do we avoid the problem?

The problem is that we have a lifespan of 60-90 years and we are not able to see or imagine further than that. Why would a middle-aged man care about the next century? Even having children seems not to work on them. The pleas of many young environmentalists of last year did not bring any change, if not in the popularity of a few of them: they got meetings with the UN, a widespread media coverage, they probably made many of their age aware of these issues, but concretely nothing has happened, besides of some more promises or plans that from time to time we hear from national governments. 

If we wait that our generation grows old enough to be in the position of making decisions, it would probably take us 20 more years or so, and this will all be precious time that we are wasting.

Also, WE need to make some decisions: enough with videos of polar bears and ice sheets, we all know they are starving because of us, but I would not swap anyone of my species to save a bear if I had to choose: not because I dislike them, simply because my primordial instinct makes me care more for my fellow relatives than other species.

Think about trees: they care about them, fungi, bees and a few insects. They do not fight for our rights, they simply get along with life, and if you would know how much struggle a tree has to go through to fully develop you would stop complaining about not having money to buy a new iPhone.


Coming back to the main point, each one of the wedges represents a problem and must be matched with a solution. I named 4, so here are my proposals for them.

  1. CO2 emissions. Easy but hard. It is probably the easiest of them: we need to leave the fossil fuels in the ground and replace them with renewable sources of energy. And I talk about energy production: an electric car won’t be enough as long as we produce electricity by burning coal. The hard part is that probably the richest and wealthiest corporations of the Planet won’t be really happy to end their business just like that. Should we compensate them by handing them over the monopoly of renewable energy? (In my opinion, no, but that is up to each one of you).
  2. Food waste. This is where you are the only one who can do something. Grocery is a serious thing if you think about the implications. In a sustainable world, you eat only seasonal and locally produced food, with a few exceptions of fruits and vegetables that are not energy-intensive to produce and can be shipped by boat (bananas, pineapple etc). Most importantly, do not throw away food: the World Health Organization provides an extensive list of how to spot food not safe to eat so next time you see a black spot on your carrot, for example, peal it, don’t bin it.
  3. Agriculture and livestock. Another easy but hard task. First of all, we need to reduce the ruminants livestock: check this post in case you missed it. We should abandon monoculture in favour of crop rotation: it could provide less food but also less spread of crop-diseases. Besides, we don’t need to produce more food, we just need to distribute it more evenly and waste less, there’s plenty out there.
  4. Deforestation. Carbon release. Widespread fires. Avalanches in mountain areas. Biodiversity loss. Is there anything else to mention? (There is, the real question would be “Are you that stupid that these are not enough to get it?”).

There is plenty to do and apparently also plenty of time. Let’s be clear: if we don’t do anything, the rivers won’t dry out (at least not by 2100), the ice sheets could disappear to reveal new continents to explore, we will certainly have more severe weather condition. The problem is at the current time we are still on time to fix it: it will come the time when it will be too late and we will be long gone but our kids will be out there. In case you are concerned but still not willing to take actions in your everyday life, I would suggest you not to have children, spare them that sorrow.

Do you have any more suggestions to reduce our GHG emissions? Let us in the comments and don’t forget to Stay Green!

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