| A bunch of tree-huggers|
|Save the rainforests!|
|Watch that carbon footprint!|
“”Anyone who believes in indefinite growth in anything physical, on a physically finite planet, is either mad or an economist.
|—Kenneth E. Boulding|
Degrowth is an economic and social movement based on anti-consumerism and anti-productivism. It consists mostly of a rejection of capitalism and infinite growth, and support of degrowth of many productions to reach a sustainable level of production. 
History of the concept
The ideology finds its roots in malthusian philosophy: Thomas Malthus believed that if population grew too fast, there wouldn't be enough food for everyone, and that therefore population growth had to be restricted by war, disease and starvation (such a nice fellow). The modern degrowth ideology is, of course, very different and does not preach that wars must regulate population, but is influenced by Malthus on the idea of limited resources.
The modern concept of degrowth was founded on the book Limits to Growth, a report produced by the Club of Rome, which concluded that growth in a finite world was limited and that if society kept increasing production and population, it would face the limits of growth, which would lead to a sudden decline in both population and industrial capacity. Its core predictions seem to have held true.   The report suggested that growth trends could be altered to achieve sustainable ecological and economic stability.
Policies in agreement with degrowth
Degrowth apologists tend to support renewable energies and recycling, but consider that it still consumes natural resources or energy, and that a degrowth of consumption of energy and production is also necessary. They believe in reducing conspicuous consumption and useless consumption in general. Believers in degrowth oppose planned obsolescence and advertising, they also believe in ending the car-based system, promoting biking or walking instead. The degrowth movement is generally supporting a reform of agriculture, for example supporting permaculture.
Degrowth activists support housing (through requisition of empty houses for example), education and healthcare for all, and the reducing of working hours.
Basic income is also supported by some degrowth economists.
Earth Overshoot Day is the date on which humanity’s resource consumption for the year exceeds Earth’s capacity to regenerate those resources that year. In 2016, Earth Overshoot Day was in August 03. 
The degrowth movement argues that resource depletion will end up in peak minerals. For example, nickel and zinc could face production peaks in a few decades.
Arguments against degrowth
The main argument against degrowth is that its proposals cannot be applied, that an economic model based on degrowth would be unable to supply enough food and other commodities, and that it would end with everyone being poor (or worse).
An argument used against degrowth is that technological innovation will lead to ways to produce more while using less ressources.
- Graham Turner. A Comparison of the Limits to Growth with Thirty Years of Reality. CSIRO Working Paper Series 2008-2009.