An A-Z of sustainability terms for investors

Sustainability, once a fringe consideration, has become core for many investors.

Impacts on the planet – such as climate change and biodiversity loss – and on people – for example through the treatment of workers – are in the news every day. 

We've put together an A-Z of key terms for investors to dip into. It will be updated over time.

1.5°C: This is the global temperature rise above pre-industrial levels targeted by the 2015 Paris Agreement. The hope is that limiting global warming to 1.5°C could stave off catastrophic impacts from droughts, storms and flooding.

Abatement: The curbing of emissions to reduce the concentration of greenhouse gases such as carbon dioxide and methane in the environment.

Anthropogenic: Resulting from human beings.

Adaptation: Adjusting to current or expected effects of climate change, such as building defences to protect against rising sea-levels, to reduce risk or benefit from opportunities where possible.

AR6: The Sixth Assessment Report of the United Nations Intergovernmental Panel on Climate Change. The latest in a series of reports to assess scientific knowledge on climate change.

Article 6: Article 6 of the Paris Agreement sets out how countries can “pursue voluntary cooperation” to reach their climate targets. Following years of delays, at COP21 last year countries agreed on rules for the implementation of international carbon market mechanisms.

Active ownership: Actively influencing corporate behaviour to ensure the companies we invest in are managed in a sustainable way. This helps to both protect and enhance the value of investments. 

Avoided emissions: Avoided emissions quantify the emissions saved by products and services which can substitute high carbon activities with low carbon alternatives, for example replacing fossil fuel power generation with wind power reduces economy-wide emissions. Conventional carbon footprint analysis (such as Scope 1, 2 and 3) attributes relatively high emissions to the companies that manufacture wind turbines, without recognising their contribution to the savings created when they are deployed to displace fossil fuel based generating capacity.

Best-in-class: A company or country that leads its peers in terms of sustainability practices and performance.

Biodiversity:Sometimes the terms natural capital and biodiversity are used in ways that suggest they are interchangeable. But biodiversity applies to the diversity of living organisms. Natural capital includes living organisms but also includes the flow of ecosystem services from this biodiversity.

Black carbon: Commonly known as soot, it is formed from wildfires and fossil fuel consumption and contributes to climate change.

Carbon capture and storage: Carbon Capture and Storage (CCS) is the process of capturing CO2, transporting it and permanently depositing it in an underground geological formation. This is carried out to reduce the emissions of CO2 by the heavy industry (Utilities, Oil & Gas, Cement, Steel, Chemicals, Other Manufacturers, Heating).

Carbon footprint: A measure of a group, individual, company or country’s greenhouse gas emissions. Common metrics include total carbon emissions or carbon intensity.

Carbon intensity: A group, individual, company or country’s carbon emissions per $million of sales.

Carbon market (including carbon offsets): A trading system in which countries or companies can trade carbon credits or offsets in order to comply with national limits. Those markets can be either regulated (reflecting laws requiring companies to secure credits in proportion to their emissions) or voluntary (where buyers choose to acquire credits generated by carbon-reducing activities). 

Carbon negative: An entity whose activity removes more carbon emissions from the atmosphere than it adds.

Carbon neutral: Achieving net zero carbon emissions by balancing existing emissions with carbon offsets. Unlike “net zero”, carbon neutrality is often (but not always) validated or certified by a third party. Use of these terms varies by region.

Carbon offsetting: Compensating your total carbon emissions by funding carbon negative activities elsewhere. Companies often offset their existing emissions by investing in projects such as tree-planting.

Carbon pricing: Assigning a cost to emitting CO2 into the atmosphere, usually in the form of a fee per tonne of CO2  emitted, or limiting the total emissions firms can produce and issuing emissions permits. Putting an economic cost on emissions is widely considered to be the most efficient way to encourage polluters to reduce what they release into the atmosphere.

Carbon sequestration: The process of capturing and storing carbon dioxide, for example through forest regrowth.

Carbon Disclosure Project (CDP): CDP runs a global disclosure system for investors, companies, cities, states and regions to manage their environmental impacts. As a signatory of CDP, we have access to its extensive research and database on climate change, water and forestry. We also submit to their climate change questionnaire annually. 

Circular economy: Creating a circular economy that limits pollution and waste, such as plastic pollution, and promotes re-use and recycling is critical in reducing the intensity of natural resource consumption and alleviating environmental pressures.

Clean technology: A range of products, services and processes that reduce the use of natural resources, cut or eliminate emissions and waste, and improve environmental sustainability. Wind turbines and electric vehicles are two examples.

Climate Action 100+: We were a founding signatory to the CA100+, a five-year collaborative engagement project to engage over 100 of the world’s largest corporate greenhouse gas emitters to improve governance on climate change, curb emissions consistent with a 2°C scenario and strengthen climaterelated financial disclosures in line with TCFD recommendations.

Climate change: The changing nature of our global climate, such as warming temperatures and rising sea levels, as a result of both natural weather patterns and human activity. Not to be mistaken for global warming, which focuses solely on rising temperatures due to human activity.

Climate finance: Finance that is used to tackle climate change. It can either be used to reduce carbon emissions or promote ways in which to adapt, mitigate and build resilience to the effects of climate change.

In 2015, developed countries committed to coming up with $100 billion per year by 2020 to tackle climate change in developing countries.

Climate neutral: Achieving zero total emissions of all greenhouse gases such as methane and nitrous oxide, not just carbon dioxide. Once carbon neutrality commitments become commonplace, we expect commitments to become more stringent by progressing towards climate neutrality.

Collective or collaborative engagement: Working together with other institutional shareholders to influence company management and effect positive change. Collective engagement may involve meeting companies jointly with other shareholders, via membership organisations or other more informal groupings. Climate Action 100+ is one example.

Conference of the Parties (COP): The highest decision-making body of the United Nations Framework Convention on Climate Change (UNFCCC) which meets annually to implement the Convention. The Convention’s ultimate aim is to stabilise greenhouse gases at an acceptable level. The Paris Agreement was born at COP21.

COP15: COP15 is the United Nations’ two-week biodiversity summit taking place from December 7-19 in Montreal, Canada, this year. It is the 15th meeting of the Conference of the Parties to the UN Convention on Biological Diversity. The biggest biodiversity conference in a decade, it was originally planned to take place in October 2020 but was delayed because of the Covid-19 pandemic. A Post-2020 Global Biodiversity Framework is expected to be agreed.

Corporate controversies: When a company or representative behaves in an improper, unethical or negligent way which negatively impacts stakeholders (e.g. causing a major accident or human rights breach), resulting in reputational damage to, and in some cases the complete collapse of the firm.

Corporate governance: An oversight framework that was initially designed to ensure company management acted in the best interests of shareholders. In more recent years there has been a broader recognition of the value in considering all stakeholders.

Corporate responsibility: A company’s responsibility to operate its business in a way that positively impacts, or at least does not negatively impact the environment or society.

Corruption: Dishonest and sometimes illegal activities including bribery and fraud that can have a devastating impact on a company and its stakeholders.

Decarbonisation: The process of reducing a company, industry or country’s carbon emissions. Decarbonisation is a critical component of the world’s transition to a low-carbon economy.

Deforestation: Forests are an important carbon sink and they also play a critical role in the earth’s water cycle and sustaining biodiversity. Deforestation is a major contributor to greenhouse gas emissions and biodiversity loss.

Dialogue: Communication with investees to find out more about their sustainability practices and how prepared they are for the changing world.

Diversity and inclusion: Diversity refers to the differences people have in terms of their gender, age, ethnicity, sexual orientation, disability, religion, beliefs or other characteristics. Inclusion is about embracing and promoting diversity, addressing inequality and ensuring people feel valued and respected irrespective of their background or beliefs.

Divestment: The sale of an investment. Divestment may occur when the investee company consistently fails to meet investor expectations, often after attempts to engage with the company. Divestment may also be used to achieve social or political goals. For example, investors divested from South African assets during the apartheid era in protest against the regime.

Ecosystem services: Nature’s important benefits are called ecosystem services. They include food and water, pollination and carbon capture.

Engagement: Engagement is more than just meeting with company management, it’s an opportunity to gain insight into a company’s approach to sustainability. It also gives us the opportunity to share our expectations on corporate behaviour and to influence company interactions with their stakeholders; ensuring that the companies we invest in are treating their employees, customers and communities in a responsible way.

Energy transition: This refers to the global energy sector’s shift from energy consumption and production based on fossil fuels to low carbon sources.

Environmental factors: This is the “E” of the term “ESG” (environmental, social and governance) and concerns issues related to pollution, climate change, energy use, natural resource use, waste management, biodiversity and other environmental challenges and opportunities.

Ethical investing: Also known as “values-based investing”.

ESG: Environmental, social and governance.

ESG integration: An investment approach that incorporates ESG considerations into the investment decision alongside traditional financial analysis. ESG integration is about understanding the most significant ESG factors that an investment is exposed to, and making sure that you’re compensated for any associated risk.

ESG fund ratings: A rating, most commonly provided by third-party commercial providers like MSCI and Morningstar, that looks at a fund’s underlying holdings and scores its overall ESG risk based on specific metrics. The choice of metrics and the resulting rating vary amongst different providers.

ESG indices: Indices traditionally track the performance of a basket of bonds or shares, such as the FTSE 100. A growing number of indices track investments by screening out certain industries or, more recently, by evaluating which companies qualify based on ESG measures. FTSE4Good indices, for example, exclude companies that do not meet specific ESG criteria.

EU Green Deal: A policy framework and package of measures that aim to make Europe climate neutral by 2050, boosting the economy through green technology, creating sustainable industry and transport and cutting pollution.

Fossil fuels: A natural, non-renewable energy source, such as coal, oil and gas. These are naturally high in carbon  and the gases released from burning these fuels (such as carbon dioxide) are widely believed to be the leading cause of climate change.

Glasgow Climate Pact: The name for the agreement reached at the 2021 UN climate conference in Glasgow, COP26. It is the first to explicitly reference reduction of unabated coal usage.

Gender pay gap: A gender equality measure that shows the difference in average or median earnings between men and women.

Governance factors: See “corporate governance”. This is the “G” in “ESG” and is about assessing how well a company is run. Governance factors include remuneration, board structure and corporate strategy.

Green bond: A bond in which the proceeds are used by the issuing company or government specifically to fund new and existing projects with environmental benefits such as renewable energy and energy efficiency projects.

Greenhouse gases (GHG): Carbon dioxide, methane, nitrous oxide and fluorinated gases. These gases trap heat close to the surface of the earth and are a key cause of climate change.

Greenwashing: Falsely communicating the environmental credentials of a product, service or organisation in order to make a company seem more environmentally-friendly than it really is.

Hydroflourocarbons (HFCs): Industrial chemicals, mainly used for cooling and refrigeration, which are potent greenhouse gases and contributing to climate change.

Human capital management: Human capital management refers to people working within the direct operations of a company and includes the practices to recruit, retain and develop human capital. 

Human rights: Basic rights that belong to all human beings. They include the right to life, liberty, freedom from slavery and torture, and freedom of opinion and expression. The UN Declaration on Human Rights is widely recognised as a benchmark of these basic standards.

Impact investing: Investments that are made with the primary goal of achieving specific, positive social and environmental benefits while also delivering a financial return. Impact investments create a direct link between portfolio investment and socially beneficial activities, and historically most of the activity has occurred in unlisted assets. Not to be confused with impact measurement (see below).

ImpactIQ: ImpactIQ, our set of award-winning tools, measure the impact that companies have on society and the environment. We developed these tools based on over 20 years of ESG investing experience. Used as part of our investment process, impactIQ examines the externalities of

companies, the risks that unsustainable practices pose to their business,

as well as their overall alignment with the UN SDGs (Sustainable

Development Goals).

Impact measurement: The measurement of how companies’ activities affect the world both positively and negatively.

Integrated reporting: Company reporting that articulates the relationship between a company’s strategy, governance and performance, and how this creates value for a range of stakeholders. The framework set by the International Integrated Reporting Council is widely recognised as the core standard in this area.

Intergovernmental Panel on Climate Change (IPCC): The Intergovernmental Panel on Climate Change is the United Nations body for assessing the science related to climate change.

Just transition: A transition to a low carbon global economy that does not unduly disadvantage weaker economies or parts of societies.

Just Transition Finance Challenge: The Just Transition Finance Challenge is an initiative to mobilise more public and private capital into investments that support a just transition to net zero in the UK and other developed and emerging markets. It was launched by the Impact Investing Institute in May 2022.

Kyoto Protocol: An international agreement adopted in 1997 to implement the objective of the UNFCCC to reduce emissions. It is named after the Japanese city in which it was adopted.

Low-carbon economy: An economy that emits minimal carbon into the atmosphere. Typically this means using low-carbon power sources rather than fossil fuels. 

‘Make it Mandatory’: The Make it Mandatory campaign from Business for Nature, a global coalition of more than 75 organisations, is calling for mandatory requirements for all large businesses and financial institutions to disclose their impacts and dependencies on biodiversity by 2030.

Methane: A greenhouse gas which is impacting climate change. Composed of carbon and hydrogen, it enters the environment through livestock, leaks from natural gas systems, landfills and waste from homes and businesses.

Microfinance: Financial services typically offered to those traditionally excluded from the formal banking sector such as entrepreneurs, small business owners, the unemployed or low-income groups or individuals.

Mitigation: Efforts to reduce or prevent greenhouse gas emissions.

Modern slavery: Although no standard definition exists, modern slavery can broadly be thought of as the exploitation of people who are coerced into an activity by someone who controls them. It can take many forms including forced or bonded labour, human trafficking or child labour.

Nature-based solutions: Actions that protect, sustainably manage and restore the natural environment, such as reversing deforestation and accelerating the transition to sustainable agriculture.

Natural capital: Natural capital refers to the stock of renewable and non-renewable natural assets, such as soil, forests, air, water, geology, and all living organisms. They provide vital ecosystem services, for example carbon capture, pollination or protection from soil erosion and flooding. More than 50% of global GDP, $44 trillion of economic value, depends on natural resources.

Natural Capital Investment Alliance (NCIA): The Natural Capital Investment Alliance aims to accelerate the development of natural capital as a mainstream investment theme.

Nationally Determined Contributions (NDC): Individual countries’ emissions reduction targets and plans to adapt to climate impacts. They’re updated every five years to ensure they’re in line with global temperature targets.

Natural climate solutions: Natural climate solutions are efforts to conserve, restore or improve ecosystem services in order to absorb and store carbon from the atmosphere.

Nature positive: Nature positive is a term being used to describe an approach that enriches biodiversity, stores carbon, purifies water and reduces pandemic risk. In short, a nature positive future will enhance the resilience of our planet and our societies. Civil society organisations such as the Global Commons Alliance are calling for a global nature positive goal to halt and reverse the destruction of nature by 2030 with a full recovery of a resilient biosphere by 2050. Increasingly, businesses are also adopting the term, with Science Based Targets for Nature being developed as a parallel initiative to science-based target setting on climate.

Nature-based solutions: Nature-based solutions are actions to protect, sustainably manage or restore natural ecosystems that address societal challenges such as climate change, human health, food and water security, and disaster risk reduction while providing human wellbeing and biodiversity benefits.

Nature-related risks: Nature-related risks include disruption of activities or supply chain; raw material price volatility; adjustment or relocation of activities; stranded assets; liquidity risk and legal, regulatory or reputational costs.

Nature-related risk management: The degradation of natural capital, including the loss of biodiversity and depletion of renewable stocks, poses a risk for businesses, their earnings and their value.

Net zero: See “carbon neutral”. Unlike “carbon neutral”, companies or countries that call themselves “net zero” usually have not had this validated or certified by a third party. Use of “carbon neutral” and “net zero” may vary by region. Not to be confused with “zero carbon”.

Net zero emissions: When the amount of carbon emitted equals the amount of carbon being removed from the atmosphere (either through the purchase of carbon credits or carbon offsets). In this way the overall position is one of “net zero carbon emissions”.

Net Zero Asset Managers (NZAM): We were a founding member of NZAM, an international group of asset managers committed to supporting the goal of net zero greenhouse gas emissions by 2050 or sooner, in line with global efforts to limit warming to 1.5ºC; and to supporting investing aligned with net zero emissions by 2050 or sooner.

Non-renewable natural capital: Examples of non-renewable natural capital include fossil fuels, soil and minerals that exist in finite amounts.

Over-boarding: When a board member takes on too many board roles, hindering their ability to appropriately distribute their time, and discharge their responsibilities to each board effectively.

Paris Agreement: A global commitment, agreed at COP 21 in Paris in 2015, to limit increase in the global average temperature to below 2°C above pre-industrial levels. See also “2 degrees”.

Physical risks of climate change: The risk posed by climate events on a company's physical assets such as supplies and equiptment, its supply chain, operations, markets and customs.

Post-2020 Global Biodiversity Framework: This draft global biodiversity framework from the UN Convention on Biological Diversity (CBD) is designed to guide actions worldwide through 2030 to preserve and protect nature and its essential services to people. It will be presented for consideration at the COP15 summit in Canada. It comprises 21 targets and 10 “milestones” for “living in harmony with nature” by 2050. Targets include ensuring at least 30% of land and sea areas, especially areas of importance for biodiversity, are conserved through equitably managed and protected. Another proposed target is reducing nutrients lost to the environment by at least half, pesticides by at least two thirds, and eliminating discharge of plastic waste.

Proxy voting: When a shareholder delegates their vote to another who votes on their behalf at company meetings. This allows the shareholder to exercise their right to vote without being physically present. Most institutional investors vote by proxy online, via phone or via e-mail, often with the help of a third party to process voting instructions.

Renewable energy: Energy collected from resources that are naturally replenished such as sunlight, wind, water and geothermal heat.

Renewable natural capital: Professor Dieter Helm, who is a director at natcap research, points to the North Sea’s fishing stocks as an example.

“If you eat kippers or herring, you’re enjoying the benefits of a renewable bit of natural capital. Provided we don’t overexploit this renewable natural capital, people in 100 years’ time will also be able to have kippers,” he says.

As long as natural stock is not driven below critical thresholds, the assets can regenerate.

Responsible investing: An investment approach that considers ESG risks and opportunities as part of the investment process and uses engagement and voting in order to generate sustainable, long-term financial returns. See also sustainable investing.

Science-Based Targets initiative: The Science Based Targets initiative defines and promotes best practice in science-based target setting. Offering a range of targetsetting resources and guidance, the SBTi independently assesses and approves companies’ targets in line with its criteria.

Science-Based Targets for Nature (SBTN): Science-based targets for nature are in the early stages of development by the Science-Based Targets Network. These targets are a way in which businesses can align their individual sustainability action with globally agreed environmental goals.

Science-based targets: Carbon emissions reduction targets that are consistent with what the latest climate science says is necessary to keep global warming well below 2oC from pre-industrial levels.

Scope 1 emissions: Direct emissions that come from sources owned or controlled by the emitter, such as emissions from company vehicles.

Scope 2 emissions: Indirect emissions from sources owned or controlled by the emitter, such as emissions from the electricity used in a company’s office.

Scope 3 emissions: Indirect emissions from sources not owned or controlled by the emitter, but which indirectly impact the emitter’s supply chain, such as emissions from a company’s employees commuting to work.

Screening: An investment approach that filters companies based on pre-defined criteria before investment. Negative screening deliberately excludes certain companies because of their involvement in undesirable activities or sectors. Positive screening deliberately includes companies that lead their peer groups in terms of sustainability practices and performance). Positive screening is also known as a “best-in-class investment”.

Shareholder activism: A form of engagement where investors use their shareholder rights to promote change at a company, typically at a transformational level.

Shareholder resolution: A proposal submitted by a shareholder for consideration at a company’s general meeting, requesting that the company takes particular action.

Share blocking: When restrictions are placed on the trading of shares which are to be voted on prior to an annual general meeting.

Short-lived Climate Pollutants (SLCPs): SLCPs include black carbon, methane, and hydroflourocarbons (HFCs).

Sin stocks: Investments associated with activities considered to be “unethical” or “immoral” according to an investor’s personal values or beliefs. Activities may include tobacco, alcohol, gambling and adult entertainment.

Social bonds: A bond in which the proceeds are used by the issuing company or government specifically to fund new and existing projects with social benefits such as affordable healthcare and housing.

Social factors: This is the “S” of “ESG”. Social issues relate to how a company interacts with the communities it operates in, its suppliers, employees, customers, communities, governments and regulators. These include, for example, labour standards, health and safety, supply chain management and nutrition and obesity.

Stakeholder: A group, entity or individual impacted by a company or country’s activity. Shareholders have historically been the priority stakeholder. More recently, however, companies and investors are realising the importance of their relationships with employees, suppliers, customers, the environment, communities and the governments and regulators with which it deals.

Stewardship: Actively influencing the responsible allocation, management and oversight of an investee’s capital in a way that creates long-term, sustainable value. See also “active ownership".

Stewardship codes: a set of standards that help set stewardship expectations and best practice for asset managers and asset owners. These codes are established on a country-by-country basis.

Stranded assets: assets that already exist but risk being “stranded” or unable to deliver a return in the longer term. Fossil fuels are the most commonly-known stranded assets.

Sustainability: The ability to adapt to changing pressures and responsibilities in order to survive and add value in the long-term. This ability is strongly linked to a company or country maintaining strong relationships with its stakeholders.

Sustainability factors: Any factor that can affect the value of an investment in the long-term. This includes ESG factors.

Sustainable food and water: The food and water system is both at risk from climate change and is a significant contributor to greenhouse gas emissions and other environmental pressures; for example, through the use of fertiliser and pesticides.

Sustainability risk: A change or event in any factor that can have a negative impact on the long-term value of an investment. This includes ESG factors.

Sustainability Accounting Standards Boards (SASB): A non-profit organisation started in 2011 to establish sustainability standards that are used worldwide. SASB is well-known for its materiality map.

Sustainable Development Goals (SDGs): A collection of 17 interlinked UN goals intended to be achieved by 2030. They were set up in 2015, and developed from the UN Millennium Development Goals. Goal 13 is Climate Action.

Sustainable investing: Although sustainable investing involves ESG integration, it takes things further by focusing on the most sustainable companies that lead their sector when it comes to ESG practices. Both the ESG integration and sustainable investing approaches are about engaging with company management to make sure the firm is being run in the best possible way.

Task Force on Climate-related Financial Disclosures (TCFD): A voluntary standard for climate-focused disclosures that aims to create consistent and comparable reporting of climate-related risks. TCFD is widely used by companies, banks, and investors.

Taskforce for Nature-related Financial Disclosures (TNFD): Work has begun on a Taskforce for Nature-related Financial Disclosures with a plan to create a framework, similar to the Taskforce for Climate-related Financial Disclosures, for firms to disclose their exposure to nature-related financial risks by the end of 2023.

ThemEx: ThemEx (in development) aims to measure, for very company, how their product/product mix is positively or negatively aligned to each

Sustainable Development Goal. This enables our investment teams to

understand and track alignment of their portfolios to one or multiple

SDG themes, whilst also enabling reporting to clients. This will facilitate

adherence to our reporting obligations under Article 9 of SFDR.

Thematic investing: Investing in companies that align to a particular investment theme such as renewable energy, waste and water management, education or healthcare innovation.

Transition risk: The financial risks that could result from significant policy, legal, technology and market changes as we transition to a lower-carbon global economy and climate resilient future.  

Triple bottom line accounting: An accounting approach that considers a company’s social (people) and environment (planet) impacts in addition its bottom line (profits) to understand the full cost of doing business.

UN Global Compact: A voluntary pact of the United Nations to promote responsible business through its ten universally accepted principles and encourage action to advance broader societal goals, such as the UN Sustainable Development Goals (SDGs).

United Nations Framework Convention on Climate Change (UNFCCC): The UNFCCC was signed by around 150 countries in Rio de Janeiro in 1992 at the UN Conference on Environment and Development. It is the initial agreement that acknowledged the threat of climate change and has formed the basis of further agreements such as the Kyoto Protocol and Paris Agreement.

UN Principles for Responsible Investing (PRI): A set of six principles under which asset owners and asset managers voluntarily commit to incorporating ESG issues into their investment processes, active ownership and reporting, and promote responsible investment across the industry.

UN Sustainable Development Goals (SDG): A collection of 17 goals reflecting the biggest challenges facing global societies, environments and economies today. The United Nations describes the SDGs as a “blueprint to achieve a better and more sustainable future for all”.

Voting: Public equity investors typically have the right to vote on company and shareholder resolutions at annual and extraordinary general meetings (AGMs and EGMs) on issues such as electing directors, authorising remuneration or requests for the company to set emissions targets.

Vote against management: Shareholders may vote “for” or “against” proposals. Shareholders whose votes do not align with the outcome preferred by management would be classified as a vote against management.

Zero carbon: A company whose emissions are zero, not achieved through carbon offsetting, but simply because they do not generate any carbon emissions. Not to be confused with net zero.

Zero-emission: This means emitting no greenhouse gases to the atmosphere.