Climate change and species loss are two sides of the same coin, as both are the result of increasing human influence on our planet. But are they also linked, i.e., does climate change affect biodiversity and vice-versa? The lecture will discuss the existing evidence for the interrelationship between the two crises and then focus on the relative importance of climate change for species extinction. Using our own research results, we will illustrate how we can experimentally study the effects of climate change on biodiversity and how we could control the effects of climate on ecosystems. Climate change will affect natural and man-made ecosystems, but probably much less severely if they contain more species. Vice-versa, smart land use designed for protecting biodiversity can also mitigate climate change.