Confused about the climate crisis? Not sure where to start? Don’t worry! Below is a full list of key environmental terms that you should know in 2025. The climate crisis and other environmental issues can be very overwhelming at times, so this list is here to provide you with some simple definitions of key terms to help you navigate key environmental developments, issues, and strategies. (Definitions are credited to Charity Digital and Pittsburgh Earth Day).  

Anthropocene: A proposed term to describe the period of time during which human activities have impacted the environment enough to constitute a distinct geological change.

Biodiversity: The variety of all life on Earth: animals, plants, fungi, microorganisms, etc. These all work together to support the functioning of the ecosystem and one another.

Carbon footprint: Measures the total greenhouse gas emissions (mainly carbon dioxide and methane) produced by an individual, organization, product, or practice.

Carbon neutral: The ideal balance between carbon dioxide emissions caused by human activities and carbon removal (eg. through reforestation or carbon capture). 

Circular economy: A system designed to keep products in circulation to the fullest extent possible by streamlining production processes, reusing, repairing and recycling materials to reduce waste. 

Clean tech: Innovations and processes that reduce negative environmental impacts, such as solar power, wind power, biofuels, and energy-efficient lighting.

Climate mitigation: Human effort and intervention to reduce or prevent greenhouse gas emissions, enhance carbon sinks or engage in other mitigating climate action.

Climate risk: The potential for climate change to create negative effects on human or ecological systems such as businesses, communities, or ecosystems.  

Conference of the Parties (COP): The annual UN Climate Change Conference. The goal of the conferences is to review progress made by members of the United Nations Framework Convention on Climate Change (UNFCCC) to mitigate climate change.

Corporate social responsibility (CSR): A company’s efforts to consider the impact they have on all aspects of society, including economic, social, and environmental impacts.

Desertification: The process by which land becomes arid, semi-arid, or dry due to factors relating to climatic variations, often caused by human activity. 

Drawdown: The point at which atmospheric greenhouse gas levels stop climbing and begin to decline. 

Environmental justice: The principle that all people, regardless of race, color, national origin or income, are treated equally regarding environmental laws, regulations, and polices. Holds that no group should bear a disproportionate share of negative environmental consequences.

ESG framework: This stands for Environmental, Social, and Governance Framework. It is a set of criteria that screens company policies and encourages companies to act ethically. ESG examines how companies manage relationships with employees, suppliers, customers, communities, and so on. This framework is also becoming increasingly important to investors.   

Fossil fuels: Carbon-based energy sources formed from decaying plants and animals that have been compressed over thousands of years. They can be converted into usable forms through human activity into crude oil, coal, natural gas, or heavy oils. 

Geoengineering: Deliberate, large-scale interventions in the Earth’s natural systems in an attempt to counteract climate change, including carbon capture and storage (CCS) and solar radiation modification.  

  • CCS: Technologies that capture and store CO2 emissions from industrial processes or the atmosphere.
  • Solar radiation modification: A controversial geoengineering strategy that aims to decrease global average surface temperatures by reflecting sunlight away from the Earth.

Global warming: The long-term increase in Earth’s average temperature due to trapped heat caused by the increase in greenhouse gases, released by the burning of fossil fuels for human activity.

Greenhouse effect: The natural process by which certain gases trap heat in the Earth’s atmosphere. The greenhouse effect regulates our atmospheric temperature to a temperature habitable for life, but as humans increase the amount of greenhouse gases in the atmosphere, the temperature is becoming less and less habitable for humans and other organisms. This is known as the enhanced greenhouse effect.  

  • Greenhouse gases: Gases that absorb infrared radiation in the atmosphere, trapping heat and keeping Earth a suitable climate to support life. Examples of greenhouse gases include CO2, methane, nitrous oxide, and ozone.  

Greenwashing: When a company, organization, community, or even individual makes it seem as if they are participating in and profiting from activities that are environmentally friendly without taking any meaningful action on climate change.  

Intergovernmental Panel on Climate Change (IPCC): The IPCC is a scientific body established by the UN Environmental Programme and the World Meteorological Organization, which works to review and assess scientific, technical, and socio-economic work relevant to climate change. A great resource for tracking and measuring the current rate of climate change (Check out the Summary for Policymakers as an accessible format!)

Kyoto Protocol: The Kyoto Protocol is an international treaty adopted in December 1997 in Kyoto, Japan which committed nations involved to reduce greenhouse gas emissions by at least 5% below 1990 levels between 2008-2012. Many of these goals have not been realised, and the protocol has in effect been replaced by the Paris Agreement.

Negative emissions: The removal of greenhouse gases from the atmosphere by human activities such as reforestation or CCS.

Net zero: Achieved when a system removes as much greenhouse gas as it emits, either by limiting anthropogenic emissions or by removing carbon from the atmosphere. 

Ocean acidification: The decreasing pH of ocean water due to increased absorption of CO2, which can cause damage to marine ecosystems.

Paris Agreement: Adopted in December 2015 at the UN Climate Change Conference, the Paris Agreement is a legally binding international treaty on climate change that aims to limit global warming to a 1.5°C increase above pre-industrial levels by the end of the century.

Recycling: The process of collecting and repurposing a resource so it can be reused, or the conversion of waste materials into new objects.

Reforestation: The restoration of forests on lands that have previously contained forests but that have been converted to some other use.  

Renewable Energy: Energy from naturally replenishing sources such as biomass, geothermal, solar, wind, and wave action.

Social costs: The broader costs of an action in terms of social welfare losses, including external costs associated with the impact on the environment, economy, and society in general. 

I hope these 30 terms have helped clarify some key aspects of the environmental and climate crisis, especially to help combat any misinformation. As Oxford students, there is often a pressure to know everything about everything and, from my experience, this can be overwhelming and puts a lot of pressure on students. So don’t worry if you are still unsure or confused; these are complicated concepts in a complex world that can produce feelings of dread or anxiety. So by providing these 30 terms, I hope this provides a small, yet accessible step you can take to learn a little bit more!