Concepts of climate change

Social Cost of Carbon

  • The net present value of aggregate climate damages (with overall harmful damages expressed as a number with positive sign) from one more tonne of carbon in the form of carbon dioxide, conditional on a global emissions trajectory over time.

Tipping Point

  • A level of change in system properties beyond which a system reorganises, often abruptly, and does not return to the initial state even if the drivers of change are abated.
  • For the climate system, it refers to a critical threshold when global or regional climate changes from one stable state to another stable state.

Net Zero Emissions

  • Net zero emissions are achieved when anthropogenic emissions of greenhouse gases to the atmosphere are balanced by anthropogenic removals over a specified period.
  • Where multiple greenhouse gases are involved, the quantification of net zero emissions depends on the climate metric chosen to compare emissions of different gases (such as global warming potential, global temperature change potential, and others, as well as the chosen time horizon).


  • It refers to temporal evolution of natural and/or human systems towards a future state. Pathway concepts range from sets of quantitative and qualitative scenarios or narratives of potential futures to solution-oriented decision-making processes to achieve desirable societal goals. 1.5oC pathway:
    • A pathway of greenhouse gas emissions that provides an approximately 1/2 or 2/3rd chance of global warming either remaining below 1.5oC or returning to 1.5oC by around 2100 following an overshoot.

Biophilic urbanism

  • Designing cities with green roofs, green walls and green balconies to bring nature into the densest parts of cities to provide green infrastructure and human health benefits.

Coping Capacity

  • The ability of people, institutions, organizations, and systems, using available skills, values, beliefs, resources, and opportunities, to address, manage, and overcome adverse conditions in the short to medium term.


  • The process by which countries, individuals or other entities aim to achieve zero fossil carbon existence.
  • Typically refers to a reduction of the carbon emissions associated with electricity, industry and transport.


  • Decoupling (for climate change) is where economic growth is no longer strongly associated with consumption of fossil fuels.
  • Relative decoupling is where both grow but at different rates. Absolute decoupling is where economic growth happens but fossil fuels decline.


  • The positive effects that a policy or measure aimed at one objective might have on other objectives, thereby increasing the total benefits for society or the environment.
  • Co-benefits are often subject to uncertainty and depend on local circumstances and implementation practices, among other factors.
  • Co-benefits are also referred to as ancillary benefits.

Blue Carbon

  • Biologically driven carbon fluxes and storage in marine systems that are amenable to management. Coastal blue carbon focuses on rooted vegetation in coastal zone, such as tidal marshes, mangroves and seagrasses. These ecosystems have high carbon burial rates on a per unit area basis and accumulate carbon in their soils and sediments.
  • They provide many non-climatic benefits and can contribute to ecosystem-based adaptation. If degraded or lost, coastal blue carbon ecosystems are likely to release most of their carbon back into atmosphere.

Total Carbon Budget

  • Maximum amount of cumulative net global anthropogenic CO2 emissions that would result in limiting global warming to a given level with a given probability, considering the effect of other anthropogenic climate forcers.
  • This is referred to as the Total Carbon Budget when expressed starting from pre-industrial period, and as the Remaining Carbon Budget when expressed from a recent specified date.

Carbon footprint

  • Measure of the exclusive total amount of emissions of CO2 that is directly and indirectly caused by an activity or is accumulated over the lifecycle stages of a product.
  • Household Carbon Footprint: Carbon footprint of an individual household, inclusive of the direct and indirect CO2 emissions associated with home energy use, transportation, food provision and consumption of other goods and services associated with household expenditures.

Carbon neutrality

  • It is a condition in which anthropogenic CO2 emissions associated with a subject are balanced by anthropogenic CO2 removals.
  • The subject can be an entity such as a country, an organisation, a district or a commodity, or an activity such as a service and an event.
  • Carbon neutrality is often assessed over life cycle including indirect emissions but can also be limited to the emissions and removals, over a specified period.

Fugitive emissions

  • The release of greenhouse gases that occur during the exploration, processing and delivery of fossil fuels to the point of final use.
  • This excludes greenhouse gas emissions from fuel combustion to produce useful heat or power. It encompasses venting, flaring and leaks


  • The reduction, avoidance or removal of a unit of greenhouse gases emissions by one entity, purchased by another entity to counterbalance a unit of GHG emissions by that other entity.
  • Offsets are commonly subject to rules and environmental integrity criteria intended to ensure that offsets achieve their stated mitigation outcome.
  • Criteria include avoidance of double counting and leakage, use of appropriate baselines, additionality and permanence or measures to address impermanence

Carbon Leakage & Carbon Border Adjustment Mechanism

  • Carbon leakage refers to the situation that may occur if, for reasons of costs related to climate policies, businesses were to transfer production to other countries with laxer emission constraints.
  • This could lead to an increase in their total emissions. The risk of carbon leakage may be higher in certain energy-intensive industries. (Trade and Climate Change).
  • To deal with this risk of carbon leakage, EU as part of European Green Deal is implementing Carbon Border Adjustment Mechanism, which would prevent the risk of carbon leakage and support EU’s increased ambition on climate mitigation, while ensuring WTO compatibility.
  • Functioning of CBAM: EU importers will buy carbon certificates corresponding to the carbon price that would have been paid, had the goods been produced under the EU’s carbon pricing rules.
  • Conversely, once a non-EU producer can show that they have already paid a price for the carbon used in the production of the imported goods in a third country, the corresponding cost can be fully deducted from the EU importer.
  • The CBAM will help reduce the risk of carbon leakage by encouraging producers in non-EU countries to green their production processes.
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