Key climate impacts and indirect impacts

In this lecture, we cover the main impacts of climate change. On a given territory, climate change can have basically two types of impacts:

• Direct impacts, such as floods, heat waves etc. These impact directly affect the territory
• Indirect impacts, i.e. impacts which indirectly affect a territory via trade, the movements of population etc. They include population migrations, the risk of war, the destabilization of food markets etc.

Both direct and indirect impacts can affect cities, but the adaptation strategies are completely different.

Required reading

• The Uninhabitable Earth (2017) a famous newspaper article describing in great details potential impacts of climate change on earth in unabated GHG emission scenarios. NB: If you are interested, it was later developed into a book.
• [optional] For French speaking students, it is worth having a look at this 2025 article in Le Monde which describes what France would look like with a +4° warming at the country level (i.e. about +3 °C globally, at the world level).

Foreword

Key Impacts

If you want to know more

• The impacts with different levels of global warming
• How we can model the climate on MIT website.

Ecosystems and biodiversity

The reference document on this question

• The Biodiversity And Climate Change report by IPBES and IPCC

Agriculture and food security

Some reference documents on these questions

• The impacts of climate change on food production by Our World in Data
• Food Security and Food Production Systems in the 6th IPCC report (2021)
• The special report on climate change and land (2019) of the IPCC
• If you’re interested by the adaptation of coffee farmers in Uganda, here are a few documents:
  • WRI report
  • article in the National Geographic
  • The original agronomic study

War and migrations

References cited in the video

• Xu, C., Kohler, T.A., Lenton, T.M., Svenning, J.-C., Scheffer, M., 2020. Future of the human climate niche. PNAS 117, 11350–11355. https://doi.org/10.1073/pnas.1910114117
  • FYI, there is a vidi academic debate around this article. See for instance here and here.
• Mach, K.J., Kraan, C.M., Adger, W.N., Buhaug, H., Burke, M., Fearon, J.D., Field, C.B., Hendrix, C.S., Maystadt, J.-F., O’Loughlin, J., Roessler, P., Scheffran, J., Schultz, K.A., Uexkull, N. von, 2019. Climate as a risk factor for armed conflict. Nature 571, 193–197. https://doi.org/10.1038/s41586-019-1300-6

General references

• Climate Change and Conflict Risks by the International Crisis Group
• A nice interactive article by the Guardian
• (in French)A nice interactive article by AFP
• Collapse: How Societies Choose to Fail or Succeed (2005) by Jared Diamond. He reviews the causes of historical and pre-historical instances of societal collapse, particularly those involving significant influences from environmental changes.