Category: The ABC of climate change

Educate yourself on climate science and sustainability with these short articles explaining important concepts and terms.

The ABC of climate change: Deforestation

Deforestation is the process whereby natural forests are cleared through logging and/or burning, either to use the timber or to replace the area for alternative uses such as agriculture or urbanisation. The FAO estimates 12-15 million hectares of forest are lost each year, the equivalent of 36 football fields per minute.

TIP: if you’re in a hurry, you find a summarizing infographic at the end of this post



The ABC of climate change: Carbon Capture Storage

Carbon Capture Storage (CCS) is an integrated set of technologies that prevent carbon dioxide from being released into the atmosphere during the combustion of fossil fuels. It is mainly mentioned in the context of large power plants running on coal, gas or biomass.

There are three main steps to avoid CO2 escaping into the air:

  1. Seperate the carbon dioxide from the other exhaust gases
  2. Compress and transport the CO2 via pipelines to a suitable site for geological storage, typically salt caves, old mines etc
  3. Inject the CO2 deep underground, often at depths of more than one kilometer
Graphical representation of the Carbon Capture and Storage process (graph: University of Nottingham)

Graphical representation of the Carbon Capture and Storage process (graph: University of Nottingham)

CCS is not a new technology and has been applied since the mid nineties, although the amount of CO2 captured and stored remains marginal.

Carbon Capture and Storage got renewed attention when the IPCC’s latest progress report (fall of 2014) announced that the technology was crucial if we want to limit Earth’s temperature rise below 2°C by 2100. They estimated that big emissions cuts would cost more than double when not applying CCS technologies.

Although some say that CCS will allow us to keep consuming fossil fuels at an increasing rate, that is not really true. The processes itself are energy intensive so the overall efficiency of the energy generation process including the carbon capture goes down significantly. In addition, there are concerns regarding the long-term storability and possible leakage of the CO2 out of the caves and rock formations.


The ABC of climate change: Brundtland report

The Brundtland report is probably the most famous document regarding sustainable development. The report, officially titled “Our Common Future”, was published in 1987 by the World Commission on Environment and Development (WCED) under the lead of former Prime Minister of Norway Gro Harlem Brundtland.

The 300-pages long report coined and defined the term sustainable development for the first time as a broad economical and ecological concept. Although it had been used before with regard to sustainable forestry and fisheries, it was not until the release of this document that economic and ecological policies were linked in an integrated framework.

By now, the document’s definition has become famous, quoted in countless studies, reports and policy documents around the world. Chances are high you have come across it yourself already.

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Personally I don’t think it’s the best definition to quote from the report, but it might have to do with the fact that it is the very first sentence of the chapter that introduces the concept of sustainable development. Less abstract is article 15 of that same chapter 2:

In essence, sustainable development is a process of change in which the exploitation of resources, the direction of investments, the orientation of technological development; and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspirations.

The famous Brundtland report was published in 1987 and meant a turning point in global ecological policy-making

The famous Brundtland report was published in 1987 and meant a turning point in global ecological policy-making

By using the first definition, all too often the focus shifts to the now-future relation; we have to live and consume now such that the future generations are not compromised. It is essential though that the document also stresses that sustainability demands equity among all within one generation.

A world in which poverty and inequity are endemic will always be prone to ecological and other crises.

This is strikingly similar to what Pope Francis wrote in his encyclical Laudate Si last year. Ecological crises can simply not be seen decoupled from social and humanitarian wrongs. Everything is interconnected.

The Brundtland report laid the foundations for the famous Earth Summit in Rio de Janeiro five years later. It became an environmental conference of unseen scale, with more than hundred heads of state present.  The conference was a major step forward, with the Convention on Biological Diversity, the Framework Convention on Climate Change (UNFCCC), Agenda 21 and so on.

Since then, countries have been meeting yearly during climate conferences, also known as “COPs”, Conferences of the Parties. Soon those conferences turned into a diplomatic arena for developed versus developing countries. Finally, in December 2015 they reached an internationally binding agreement on how to tackle climate change.


The ABC of climate change: Atmospheric lifetime

The atmospheric lifetime of a greenhouse gas refers to the approximate amount of time it would take for the anthropogenic increase (i.e. increase due to human behavior) to an atmospheric pollutant concentration to return to its natural level. That can happen as a result of either being converted to another chemical compound or being taken out of the atmosphere via a so-called sink. The lifetime depends on the pollutant’s sources and sinks as well as its reactivity.

The lifetime of a pollutant is often considered together with the mixing of pollutants in the atmosphere –a long lifetime will allow the pollutant to mix throughout the atmosphere. Average lifetimes can vary from about a week ( e.g. sulfate aerosols, small particles in a gas) to more than a century (e.g. carbon dioxide). The chart below shows the atmospheric lifetime of four common greenhouse gases.

In the graph you see that carbon dioxide is hanging around in the atmosphere for quite a long time after we emit it, longer than other greenhouse gases like methane. But you may have heard people talking about methane being 20 times or even 50 times stronger than carbon dioxide. Such statements are quite misleading without further clarification. In fact, that’s the reason why scientist have come up with something called the Global Warming Potential, which looks at the overall effect of a greenhouse gas over the timespan of 100 years after it has been emitted. Even though methane has disappeared after 12-15 years, the net effect is still 23 times stronger than carbon dioxide!