every activity. If the benefits are higher than the costs, we should do it – it’ s worth it. But what are the costs and benefits of, say, traveling to a scientific conference? On the cost side, the most obvious points are the time and money that could have been spent otherwise as well as the carbon emissions for travel, accommodation and the conference venue. Benefits include an effect on the outreach of the research presented – if the science has some value and more people are confronted with it, the value will be multiplied – as well as positive influences due to interactions between scholars that can increase the value of the research itself: the concentration of relevant science as well as interesting conversations can help generate good ideas. It might be relatively straightforward to write down an equation capturing all these factors. However, bringing the equation to life can prove extremely difficult. How much more impact does a result make when it is presented at a conference compared to when it’ s not? This is not an easy question, but it should be possible to find an empirical answer. What difference does the input of the academic community at a conference make? This one is already quite a lot harder to answer, but it may still be possible to get a good estimate. However, what is the value of a scientific project? Should we use data from the past to assess what average impact each study ever conducted has made? Should we just use the funds a project received as an approximation, because if society is willing to spend a certain amount on it, it must be expected to be worth at least that?
Box 1: Estimating the costs and benefits of a scientific conference
C = C t + C m
+ C CO2 = t conference
t project
= V · + V · + C CO2
B = r · i · V
If we assume that the benefits B of a conference are determined by a reach effect r, an interaction effect i and the value of the scientific project V, and the costs C are determined by the time investment t conference
, the monetary investment m conference and the climate costs C CO2
, the benefits of a conference can be estimated as:
t conference
t project m conference
m project
m conference
m project
B- C = V ·( r · i--)- C CO2
If B-C > 0, the conference provides an additional value. But what are the values of all the individual variables?
This makes it very difficult to use considerations like this one to make actual decisions about whether a given activity is overall beneficial or not. While it might be helpful to try to estimate costs and benefits in this way to get a general feeling for the important factors, we should probably not spend too much time on it or rely on the results blindly.
We cannot immediately stop emitting excess CO 2
, and we are unable to determine good cost-benefit estimates for most of our decisions. Are we doomed? Do we have to hope for miracles or is there anything else we can do? I believe there is a third way that will ultimately effectively tackle climate impacts while not being too demanding on anyone along the way. All it requires is that more researches gain awareness about the climate costs of their work and are willing to act on this awareness – even if it is only in very little steps, as long as these steps are bigger than the ones that everyone else is taking. The first step in becoming aware is to gain an idea of science’ s climate impact. Is it even significant? And are any of the emissions avoidable? In a recent case study, the carbon impact of a 4-year PhD in Environmental Sciences was estimated at 21.5 tons of CO 2
, which was equivalent to 2.7 tons per paper or 5.4 tons per year, 75 % of which was due to travel [ 4 ]. As values might be very different for different scientific fields, I tried to crudely estimate the carbon impact of research more similar to my own.
I use Magnetoencephalography( MEG) to measure magnetic fields in the human brain. To function, the MEG has to be continuously cooled using liquid Helium, and 14.5 liters of liquid Helium evaporate in a single day. It is not easy to find information on the carbon footprint of helium production, but helium is mostly obtained as a byproduct from natural gas purification and might therefore have a similar footprint. Under this assumption the 657 kg of Helium required every year lead to the gigantic emission of 241 tons of carbon equivalent [ 5 ]. Luckily, the MEG Center installed a recovery system which enables the recycling of about 95 percent of the helium used which – taking into account the energy needed for liquefaction – reduces yearly emissions to about 16 tons of CO 2 equivalent. In 2015, groups at the MEG center published 10 papers, leading to an amount of 1.6 tons of CO 2 per paper due to the use of MEG. To process the high-dimensional data the MEG gives us, we need a lot of computing power. For this purpose, my group has a high-performance cluster, whose energy consumption I estimate at 7700 kWh per year – leading to emissions of about 3 tons of CO 2
, or 0.6 tons of CO 2 per paper published in 2015.
Finally, I will make the assumption of traveling to one international conference per published paper, by airplane, using the distance Stuttgart-Chicago as an example. This leads to another 3 tons of CO 2 per paper.
Only a few neuroscientists use MEG. But most of us depend on big, expensive machines, laboratory animal facilities or extensive computing power, all of which have considerable environmental footprints. Most of us like to travel and take opportunities to give talks, attend conferences or courses whenever we can. Therefore, most of us probably emit greenhouse gasses in a similar order of magnitude, even if the individual contributors vary.
So what can be done? For those of us who are near the bottom of the scientific hierarchy, there is only so much we can do; the most significant factor everyone can influence is probably travel. While there might be a not-toodistant future in which physical travel is not necessary anymore due to virtual conferences [ 7 ], this will not be achieved by personal decisions of single scientists – but if you are not entirely sure whether it is worth going to an international conference, you can let the climate be the decisive factor and give it a miss – or try out a more local meeting that can be reached by train, bus or car.
May 2017 | NEUROMAG | 11