Welcome back to the blog. This is the second part of our interview with Professor Andreas Ibrom from DTU. If you have not read the first one you can do so here LINK.
Measuring Greenhouse Gases
What gases do you measure and how do you measure them?
At the ICOS sites, we measure fluxes (or flows) and concentrations of CO2 and water vapour (evaporation). In a new project set in a rural landscape, we are also measuring other greenhouse gasses such as CH4, N2O and CO.
We use the eddy covariance method to do these measurements. Its working principle is simple. We can determine if there is a certain gas flux by pairing very frequent measurements (every tenth of a second) of two main parameters: the gas concentration and wind vertical speed. You may wonder why we measure the vertical wind speed. Well, imagine you can divide the air surrounding the station into blocks. We call them air parcels. When wind passes, it moves these air parcels, forming vertical eddies in a process known as turbulent transport. If there is a flux, the concentration of air parcels moving in the direction of the flux is significantly higher compared to those going against the flux direction. This method measures the turbulent transport of the air parcels (the vertical wind speed and concentration in the vertical eddies) from a few to up to 10 meters above the ecosystem. To obtain the net flux we need to calculate the product of the vertical wind speed and the gas concentration for each measurement and take the average, say, over 30 minutes. Such an average product is called covariance in statistics. Thus the name of the method, where “eddy” refers to rotating air parcels in a turbulent flow and “covariance” alludes to the calculations performed.
Key Observations and Findings
What have been the most interesting results that you have observed?
The novelty in observation arises from confronting results with expectations. The differences between them guide us towards relevant new hypotheses and research. Among our studies, we have observed a long-term trend of increasing net CO2 uptake by the forest as one key result. It is especially pronounced in the first 10-20 years, driven by increased photosynthetic capacity. While similar trends have been observed in some other forests, we still do not have an explanation as to why the observed forest was almost carbon neutral in the first two to three years of observations. We have also found that the change in CO2 uptake is not primarily driven by trends in the physical climate. We hypothesise that nitrogen availability and the fertilising effect of increasing CO2 concentration result in an increase in photosynthesis. The initial carbon neutral behaviour might rather be a consequence of a disturbance before the beginning of measurements. We are changing climate and every year that we do not use to observe the impacts on our natural systems is a lost opportunity.
Another very noteworthy result of our measurements is the recording of the effects of the extreme drought and heat waves that hit Denmark and Central Europe in 2018. The only way to assess ecosystem responses to extreme events is continuous observation. We detected reduced photosynthesis in the second half of the vegetation period, both in the beech forest and the willow plantation, where willow trees even shed some of their leaves when the drought stress was highest. Ecosystems develop slowly but respond fast. A 28-year data set is therefore very appealing to be used for multiple purposes. That is why the data from the beech forest site Sorø has been used in numerous studies. We have led some of them, some have been in collaboration with others, and the majority have been carried out by third parties, who have used our data.
Applications and Future of ICOS Data
How can we use the data obtained?
The scientific objectives for data use comprise fundamental ecological research, and climate change impact research, from local to global scales as the international networks allow global scale analysis. Due to the high value of ecosystem services, e.g. CO2 sequestration, the research results are extremely useful for understanding nature-based solutions and predicting climate change impacts.
The most prominent role of the ICOS data is to provide empirical data for model development and testing, such as the models used by the IPCC. These models help us project the possible consequences of our current actions on climate, nature and humanity. This is not to say that the data is perfect. There are also challenges to the data collection and the resulting models. For example, responses to climate change effects, such as extreme weather are difficult to collect. There are rare but strong responses to rare but extreme events. Such data is naturally scarce but exists due to the long-term ecosystem observation efforts here in Denmark (like the ICOS network) and elsewhere. The data is also being used to inform Danish ministries about what is happening in Denmark’s nature.
The data can be freely downloaded (data.icos-cp.eu) at the ICOS carbon portal for fair data use. Every data set has its own Digital Object Identifier (DOI) and can be cited as such. The portal enables users to trace the origin, methodology and uncertainty parameters for every variable in the data set. The measurement protocols are openly available. Everything is open and transparent.
What would you like to happen in the future with the ICOS project?
From the beginning, ICOS stakeholders agreed on a time perspective of 20 years (almost 7 times as long as a usual research project). With our Sorø station, we have extended the ICOS station with 20 years more of legacy data. However, the need for long-term observation does not stop in 2035. Unfortunately, in our experience, the relevant ministries and administrations often simply do not know this infrastructure exists. Thus, they are not aware of how the data and the science behind it can help to understand the effects of policies and economic activities. I expect that by then, the European and national societies will have learned to appreciate the value generated by the ICOS project and find, like me, that a developed country like Denmark must be able to fund this work as a national effort.
So, can we measure the effectiveness of our efforts to combat climate change?
I believe that when you mention effectiveness you mean “Are we doing well enough?”. However, effectiveness can also relate to the practical question “Do our investments pay back?” or in other words, “Are the results worth the money?”. I will position myself with respect to both perspectives to answer your question.
The first, “Are we doing well enough?” is easy: Not yet. But maybe this perspective is not as relevant as one thinks. This perspective of distant reflection, typically taken from a scientist, starts with looking into the scientific evidence.
Do CO2 emissions fall? Do CO2 concentrations stabilise? Despite being used as evidence, global emissions (what we put into the atmosphere) are not easily measurable. We estimate emissions using several uncertain assumptions and information supplied by the emitters. By using the same standardised approaches every year, we can be “quite sure” (see how uncertain this sounds) that the trend for reducing emissions isn’t yet any good.
On the other hand, we can measure the resulting CO2 concentrations in the atmosphere with high accuracy, and they are rising. This evidence is, however, soberingly, nothing that we can do anything about, because of the inertia of the climate system. The climate system has stored huge amounts of CO2 emitted by humans in our recent history and this storage is reversible, i.e. CO2 stored in the biosphere and the oceans will be released into the atmosphere at some point when the emissions sink. That’s why it is so important to stop the emissions now, to trigger the slow process of recovery.
From the second perspective (are our actions “worth the effort”?), we need to understand that our efforts are significant, yes, but require more understanding and collective action. We, as a global society, are new to joint reasonable action. Societies are constantly developing, and different ideas come up and leave their traces. We come from a time when the mindset was that limitations were just a matter of investment - e.g., if you lack energy, drill deeper. Now, we are aware that we have always been in a limited situation. It is no longer just a matter of money but about our agency as actors with limited global impact. It has become clear that we are the main players of the era, as the term Anthropocene highlights. This awareness of our role has now become the common view. However, to take collective action we need a better understanding of the nature and the potential of globalised societies and how they can transform themselves. A huge effort is required to convince ourselves to change our lives and be part of an unprecedented experiment with only one try. Given this challenge, I have become less radical, and respect the ones, who try to get the train moving towards the right direction, where there is a goal but no established method or blueprint.
Why is it important to have a systemic perspective of the different existing ecosystems?
This question is easy to answer. Imagine you are part of a system and ignore this fact. You will have a very narrow and selective view of reality, and your conclusions and decisions will likely be imperfect. A systemic perspective is a paradigm for understanding systems as a whole; to become aware of the relationships between the parts and how these create the properties of that system.
I’d like to use this opportunity and the brevity of the above answer to explore the term “the different ecosystems” which I think is a brilliant apt formulation. At a second glance, we can see that, in practical terms, we only live in one ecosystem. It is a hierarchical system that consists of “the different ecosystems” we hear about in the media. Traditionally, biology looks at natural ecosystems that form relatively homogeneous entities, such as forests or deserts, but also there, we know that these ecosystems form biomes and then, the continental, marine and global biosphere. “The different ecosystems” are interlinked with the same global environment, each with its local and temporal differentiations. Furthermore, these links feed into their own “boundary” conditions, into how they function as a sub-system. We find that the concept of ecosystems is universal and includes nature, societies and man. Everything and everyone are related to one another through matter, energy and information flows, and inevitably forms an ecosystem, irrespective of any conscious or hidden intention. This insight fills me with admiration and mental connectedness with the environment and with a more realistic sense of responsibility for the bigger picture.
Conclusion
The journey towards a greener world is undoubtedly complex and requires collective effort. Projects like ICOS not only improve our understanding of the complex dynamics of our environment and the impact of our emissions on them but also highlight the importance of scientific collaboration and remind us of the critical need for continuous, long-term investment in environmental research. The actions we take when striving for sustainability must be informed by robust scientific evidence. However, it is important to consider this evidence through a systemic perspective to make better and more conscious decisions.
Many thanks to Professor Andreas for sharing his insights into the challenges we face in transitioning to a more sustainable society. It was a pleasure having this conversation and learning from a different area of environmental engineering.