Hans Nielsen was a long-standing, highly skilled and committed employee of the Ecological Council - currently the Green Transition Denmark. He worked full-time for us from 1997-2012 and then continued part-time for another number of years. He made a huge difference to the protection of nature and the environment, both by authoring a number of informative booklets - especially in relation to agricultural pollution. He was always matter-of-fact and thorough, both in his coverage and in his communication. He threw himself i.a. into appealing hundreds of municipalities' approvals for livestock farming in the years 2007-14. When we started, the approvals were far too lenient, i.a. against the discharge of ammonia, to the detriment of both biodiversity and health. We, and especially Hans, received many angry comments as a result of this work. But thanks to Hans' thorough work, we were successful in the vast majority of cases, and the result was that the municipalities gradually adjusted, so that we made our work in this field redundant. In this process, agricultural emissions of ammonia were halved.

At the same time, Hans threw himself into a fight against the invasive species that threaten our nature. Hans was in many ways a loner, but he could also be sociable and was always willing to share his knowledge of nature, even outside of strictly work-related matters. I remember a forest trip where he showed around the nature around Lyngby. He brought fishing nets and showed us various small animals and water plants. I asked him if he could find a salamander. He went off a bit and then came back with a salamander – to my great surprise!

I am grateful for Hans' contribution to our work over many years – and sad that he had to pass away too soon – at the age of 70.