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Carbon Efficiency


Emit the least amount of carbon possible.


Understanding the impact of greenhouse gases on our environment is key to understanding software's own carbon footprint. You will learn about the different kinds of greenhouse gases present in the environment, how they are emitted and measured, and what is being done by different organizations around the world to control and reduce these emissions.

You will find out about the GHG protocol and what it means for green software practitioners.

Key concepts

Global warming vs climate change

Global warming is the long-term heating of Earth's climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning. Climate change is long-term shifts in temperatures and weather patterns. These shifts may be natural, but since the 1800s, human activities have been the main driver of climate change.

Climate vs weather

Weather refers to the conditions of the atmosphere in a short period of time. Climate refers to the conditions of the atmosphere over long periods of time. Any changes to the long-term condition of the atmosphere will also cause changes to the short-term conditions. An obvious comparison is that if the average temperature of the atmosphere increases, the average temperature of the weather in any given season will also increase. Some examples of measurable changes to weather conditions due to climate change are:

  • Changes to the water cycle, including rainfall
  • Melting of ice
  • Heating of the land, air, and ocean
  • Changes in ocean currents, acidity, and salinity

These changes can lead to flooding - both in coastal areas and due to increased rainfall - drought, wildfires and more frequent extreme weather conditions.

Greenhouse gases and the greenhouse effect

Greenhouse gases are a group of gases that trap heat from solar radiation in the Earth's atmosphere. These gases act as a blanket, increasing the temperature on the surface of the Earth. This is a natural phenomenon which has been accelerated due to man-made carbon emissions. Now the global climate is changing at a faster rate than that at which animals and plants can adapt.

Greenhouse gases and the greenhouse effect are crucial to all life on Earth and often come from natural sources like animals, volcanoes, and other geological activity. The greenhouse effect allows the Earth to maintain a higher temperature than it would without them by capturing more heat from solar radiation. Like many other natural processes of the Earth, the greenhouse effect is a finely tuned balance that can be upset by multiple factors.

Carbon and CO2eq

Carbon is often used as a broad term to refer to the impact of all types of emissions and activities on global warming. CO2eq/CO2-eq/ CO2e, which stands for carbon equivalence, is a measurement term used to measure this impact. For example, 1 ton of methane has the same warming effect as about 84 tons of CO2 over 20 years, so we normalize it to 84 tons CO2eq. We may shorten even further to just carbon, which is a term often used to refer to all GHGs.

Monitoring climate change

As a result of the effects of climate change and an ever-increasing number of destructive weather events, efforts have been made by the global community to address these issues and take steps to control and limit global warming in order to mitigate and reverse the effects of climate change.

The Paris Climate Agreement is an international treaty agreed in 2015 by 196 parties and the UN to reduce the Earth's temperature increase. The agreement is to keep the rise in global mean temperature to 2°C compared to pre-industrial levels, with a preferable lower limit of 1.5°C. The agreement is reviewed every five years and mobilizes finance to developing nations to mitigate the impacts of climate change and prepare for and adapt to the environmental effects caused by climate change. In addition, each party is expected to update its progress through a Nationally Determined Contribution (NDC). The agreement is currently signed by 193 parties.

The United Nations Framework Convention on Climate Change (UNFCCC) is a group created to achieve the stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous interference with the climate system.

The COP (Conference of the Parties) is an annual event involving all parties in the United Nations Framework Convention on Climate Change. At the conference, each party member's progress on tackling global warming, as agreed as part of the Paris Climate Agreement, is reviewed and assessed. The COP is also a chance for parties to come together and make decisions that will reduce the effects of global warming. Common topics include strategies to reduce carbon, financing low carbon strategies and preservation of natural habitats.

The IPCC (Intergovernmental Panel on Climate Change), created by the UN in 1988, aims to provide governments at all levels with scientific information that they can use to develop climate policies. IPCC reports are also a key input into international climate change negotiations. The IPCC is an organization of governments that are members of the United Nations or the World Meteorological Organization (WMO). The IPCC currently has 195 members.

We will always emit carbon through our activities but being carbon efficient means minimizing the amount of carbon emitted per unit of work. We aim to ensure that for each gram of carbon we emit into the atmosphere, we extract the most value possible.


In the software space, the part we play in the climate solution is building carbon-efficient applications. Being carbon efficient is about building applications that add the same value for you or your users but which emit less carbon.


  • Greenhouse gases are a group of gases contributing to global warming. Carbon is often used as a broad term to refer to the impact of all types of emissions and activities on global warming. CO2eq is a measurement term used to measure this impact.
  • The international community, in groups such as the UNFCCC, has come together to limit the impact of global warming by reducing emissions, aiming for a 'preferable' lower limit of 1.5°C. This was agreed through the UN IPCC in 2015 in the Paris Climate Agreement and is monitored at the regular COP event.
  • Everything we do emits carbon into the atmosphere, and our goal is to emit the least amount of carbon possible. This constitutes the first principle of green software: carbon efficiency, emitting the least amount of carbon possible per unit of work.


What are GHGs?

How can we abbreviate carbon equivalent?

What is the IPCC?

What is COP?

What was the agreed preferred limit to the temperature rise in the Paris Climate Agreement?

Which of the following statements is true?

What has been the key driver of climate change in recent years?

What do we need greenhouse gases for?