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The big picture

This article discusses global trends and uses examples to demonstrate they are interconnected and why they are so challenging to solve.
photo of logs on the forest floor
© University of Reading

A planetary polycrisis

It seems bad news about the environment is everywhere. On news websites, Twitter, even TikTok, it’s almost inevitable you’ll find stories about the decline of the world’s environment. If we’re not careful we can see these stories as presenting disconnected pieces of information: facts about air pollution, facts about extreme flooding, facts about rainforests being bulldozed. We become desensitised by their frequency. The information washes over us with limited emotional impact. Yet, the many pieces of bad news are connected and are symptoms of a deeper change in core planetary systems.

Here are a few important global trends.

  • Around 25% of animal and plant species that have been assessed are threatened with extinction and the average biomass of wild mammals has fallen by 82% from prehistoric levels1. This rapid loss of biodiversity threatens us through the loss of many benefits including pollination of food crops, soil health, regulation of climate and protection from extreme weather.
  • Carbon dioxide levels in the atmosphere are now 420 parts per million (ppm), compared with 280 ppm before the industrial revolution2, which is projected to lead to increasingly frequent and severe extreme weather events, and ultimately mass human displacement.
  • There are over 100,000 chemicals used in world markets, but over 70,000 have ‘very poor’ characterisation3 in terms of the potential hazards they present to human and ecosystem health (only 500 are well characterised).

It’s simplistic to talk about the ‘climate crisis’, a ‘chemical pollution crisis’, a ‘biodiversity crisis’ as if they are all separate phenomena. They are all part of one interlinked planetary crisis, which we will refer to as a ‘polycrisis’. The term was used in 2020 by previous president of the European Commission, Jean-Claude Juncker, to describe the multifaceted crises that Europe faces from security threats, the refugee crisis and the UK referendum on EU membership. A comparable term is ‘cascading crises’, as used by US President Biden in his 2021 inaugural address. Both refer to unavoidably interlinked social and environmental issues, like climate change, pollution, war, financial instability and inequality, that threaten the health and prosperity of citizens.

Why are they interlinked?

The living Earth is made up of a number of systems on which its continued functioning depends.

  • The lithosphere – the Earth’s rock surface and upper mantle
  • The hydrosphere – water, making up 70% of the Earth’s surface
  • The atmosphere – the air up to 100 kilometres above the Earth’s surface
  • The biosphere – comprising all the living organisms on the Earth.
How the lithosphere, hydrosphere and atmosphere interact with each other and with the biosphere

These systems interact with each other all the time and in ways we are just beginning to understand. For example, human-driven changes to the atmosphere mean that many regions are now becoming uninhabitable for particular species (ie, irreversibly altering the biosphere). If species cannot adapt to the new climate or disperse to new places (a process which is hampered by our intensive agricultural land use), they become extinct.

Impacts on society

Our human activities, including the food we eat (obtained from globalised food supply chains), the way we live (our built environment and material consumption patterns), and how we travel (our transport systems), impact all four of the Earth’s linked environmental systems – the lithosphere, hydrosphere, atmosphere and biosphere. However, the polycrisis doesn’t just comprise environmental issues. The impacts on environmental systems cascade to cause social and economic problems that put our health and prosperity under threat. A recent study predicted between one and three billion people – 12.5% to 37.5% of the world’s population – will be living outside the climate niche in which humans have existed for the last 6000 years. Their only choice is to adapt (which is unlikely given regional poverty levels) or migrate to cooler regions4. The world is on track for human displacement on an unprecedented scale, which will make the current flow of refugees look like a trickle.

The stability of our food and fresh water supplies is also under increasing pressure. Malnutrition has direct effects on people’s health, and history shows how food and water scarcity can quickly become a major cause of civil unrest and geopolitical conflict.

The UN Sustainable Development Goals outline a set of basic essentials for human wellbeing and prosperity. All 17 are severely impacted by the effects of climate change and biodiversity loss, which in turn influences our capacity to tackle these environmental problems. Click to expand.

Understanding and responding to the polycrisis

Complex environmental problems such as climate change and biodiversity loss and their consequent social and economic impacts span many different sectors, such as food, energy, transport and healthcare. Understanding them requires insights from multiple academic disciplines from ecology and economics, to psychology and politics. Addressing them therefore needs holistic ways of thinking that can ‘join the dots’ between disciplines and uncover the real root causes of problems. Systems thinking is a way of approaching complex problems by using different lenses: one might start with an economic perspective, focusing on material flows of resources, then shift to a political perspective, focusing on the distribution of power. Ultimately, one might shift to analysing the mindsets and cultures that underpin these aspects as illustrated in the ‘iceberg model’ below.

The ‘iceberg model’ captures an important aspect of systems thinking: events and underlying patterns we see in the world are ultimately strongly influenced by the ‘hidden’ aspects of mindsets and culture.

You’ll unpack these concepts in this course, learning about what systems thinking is and how to achieve it. This will help arm you with the right skills to tackle the planetary polycrisis.


  1. Summary for policymakers of the global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. S. Díaz, et al. (eds.). IPBES (2019).
  2. Carbon dioxide now more than 50% higher than pre-industrial levels. News & Features, National Oceanic and Atmospheric Administration (NOAA) June 3, 2022.
  3. Chemical Pollution Chapter 10, The European Environment State and Outlook 2020.
  4. Future of the human climate niche. Xu, C., et al. PNAS 117:11350-11355, 2020.
© University of Reading
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Using Systems Thinking to Tackle the Climate and Biodiversity Crisis

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