The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations responsible for advancing knowledge on human-induced climate change. It was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), and later endorsed by the United Nations General Assembly. It is based in Geneva, Switzerland, and is composed of 195 member states. The IPCC is governed by its member states, which elect a bureau of scientists to serve for the duration of an assessment cycle ; the bureau selects experts nominated by governments and observer organisations to prepare IPCC reports. The IPCC is supported by a secretariat and various "Technical Support Units" from specialised working groups and task forces.
An emission intensity is the emission rate of a given pollutant relative to the intensity of a specific activity, or an industrial production process; for example grams of carbon dioxide released per megajoule of energy produced, or the ratio of greenhouse gas emissions produced to gross domestic product (GDP). Emission intensities are used to derive estimates of air pollutant or greenhouse gas emissions based on the amount of fuel combusted, the number of animals in animal husbandry, on industrial production levels, distances traveled or similar activity data. Emission intensities may also be used to compare the environmental impact of different fuels or activities. In some case the related terms emission factor and carbon intensity are used interchangeably. The jargon used can be different, for different fields/industrial sectors; normally the term "carbon" excludes other pollutants, such as particulate emissions. One commonly used figure is carbon intensity per kilowatt-hour (CIPK), which is used to compare emissions from different sources of electrical power.
The Special Report on Emissions Scenarios (SRES) is a report by the Intergovernmental Panel on Climate Change (IPCC) that was published in 2000. The greenhouse gas emissions scenarios described in the Report have been used to make projections of possible future climate change. The SRES scenarios, as they are often called, were used in the IPCC Third Assessment Report (TAR), published in 2001, and in the IPCC Fourth Assessment Report (AR4), published in 2007. The SRES scenarios were designed to improve upon some aspects of the IS92 scenarios, which had been used in the earlier IPCC Second Assessment Report of 1995. The SRES scenarios are "baseline" scenarios, which means that they do not take into account any current or future measures to limit greenhouse gas (GHG) emissions.
Climate change mitigation consists of human actions to reduce greenhouse gas emissions or to enhance carbon sinks that absorb greenhouse gases from the atmosphere. As such, mitigation limits the amount of global warming. The combustion of fossil fuels can be reduced by switching to clean energy and through energy conservation. Examples of climate change mitigation policies include carbon pricing by carbon taxes and carbon emission trading, easing regulations for renewable energy deployment, reductions of fossil fuel subsidies and divestment from fossil fuel finance and subsidies for clean energy.
The economics of climate change concerns the economic aspects of climate change; this can inform policies that governments might consider in response. A number of factors make this and the politics of climate change a difficult problem: it is a long-term, intergenerational problem; benefits and costs are distributed unequally both within and across countries; and both the scientific consensus and public opinion on climate change need to be taken into account.
Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and large oil and gas companies, many state-owned by OPEC and Russia. Human-caused emissions have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but it was consistent among all greenhouse gases (GHG). Emissions in the 2010s averaged 56 billion tons a year, higher than ever before.
Carbon leakage occurs when there is an increase in greenhouse gas emissions in one country as a result of an emissions reduction by a second country with a strict climate policy.
Climate risk refers to risk assessments based on formal analysis of the consequences, likelihoods and responses to the impacts of climate change and how societal constraints shape adaptation options. Common approaches to risk assessment and risk management strategies based on natural hazards have been applied to climate change impacts although there are distinct differences. Based on a climate system that is no longer staying within a stationary range of extremes, climate change impacts are anticipated to increase for the coming decades despite mitigation efforts. Ongoing changes in the climate system complicates assessing risks. Applying current knowledge to understand climate risk is further complicated due to substantial differences in regional climate projections, expanding numbers of climate model results, and the need to select a useful set of future climate scenarios in their assessments.
Low-carbon power is electricity produced with substantially lower greenhouse gas emissions than conventional fossil fuel power generation. The energy transition to low-carbon power is one of the most important actions required to limit climate change. Power sector emissions may have peaked in 2018. During the first six months of 2020, scientists observed an 8.8% decrease in global CO2 emissions relative to 2019 due to COVID-19 lockdown measures. The two main sources of the decrease in emissions included ground transportation (40%) and the power sector (22%). This event is the largest absolute decrease in CO2 emissions in history, but emphasizes that low-carbon power "must be based on structural and transformational changes in energy-production systems".
The Fifth Assessment Report (AR5) of the United Nations Intergovernmental Panel on Climate Change (IPCC) is the fifth in a series of such reports and was completed in 2014. As had been the case in the past, the outline of the AR5 was developed through a scoping process which involved climate change experts from all relevant disciplines and users of IPCC reports, in particular representatives from governments. Governments and organizations involved in the Fourth Report were asked to submit comments and observations in writing with the submissions analysed by the panel. Projections in AR5 are based on "Representative Concentration Pathways" (RCPs). The RCPs are consistent with a wide range of possible changes in future anthropogenic greenhouse gas emissions. Projected changes in global mean surface temperature and sea level are given in the main RCP article.
The economics of climate change mitigation is the part of the economics of climate change related to climate change mitigation, that is actions that are designed to limit the amount of long-term climate change. Mitigation may be achieved through the reduction of greenhouse gas (GHG) emissions and the enhancement of sinks that absorb GHGs, for example forests.
Climate change scenarios or socioeconomic scenarios are projections of future greenhouse gas (GHG) emissions used by analysts to assess future vulnerability to climate change. Scenarios and pathways are created by scientists to survey any long term routes and explore the effectiveness of mitigation and helps us understand what the future may hold this will allow us to envision the future of human environment system. Producing scenarios requires estimates of future population levels, economic activity, the structure of governance, social values, and patterns of technological change. Economic and energy modelling can be used to analyze and quantify the effects of such drivers.
Climate change and poverty are deeply intertwined because climate change disproportionally affects poor people in low-income communities and developing countries around the world. Those in poverty have a higher chance of experiencing the ill-effects of climate change due to the increased exposure and vulnerability. Vulnerability represents the degree to which a system is susceptible to, or unable to cope with, adverse effects of climate change including climate variability and extremes.
The energy transition is the ongoing process of replacing fossil fuels with low carbon energy sources. More generally, an energy transition is a significant structural change in an energy system regarding supply and consumption.
Co-benefits of climate change mitigation are the positive benefits related to mitigation measures which reduce greenhouse gas emissions or enhance carbon sinks. The beneficial or adverse impacts of deploying climate-change mitigation measures are highly context-specific and also depend on the scale. With regards to the transport sector, possible co-benefits of mitigation strategies include: air quality improvements, health benefits, equitable access to transportation services, reduced traffic congestion, and reduced material demand. For example, measures promoting walkable urban areas can create health co-benefits from cleaner air and benefits from enhanced mobility. The increased use of green and blue infrastructure can reduce the urban heat island effect and heat stress on people, which will improve the mental and physical health of urban dwellers. Country-specific co-benefits can include biodiversity conservation, ecosystem services, and livelihoods.
Fatima Denton is the Officer-in-Charge of the Special Initiatives Division and the Co-ordinator for the African Climate Policy Centre (ACPC) of the United Nations Economic Commission for Africa (UNECA), based in Addis Ababa, Ethiopia. She focuses on innovation, science, technology and natural resource management. She partners with countries such as Benin and Liberia to develop and implement country needs assessment missions.
The Sixth Assessment Report (AR6) of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC) is the sixth in a series of reports which assess scientific, technical, and socio-economic information concerning climate change. Three Working Groups have been working on the following topics: The Physical Science Basis (WGI); Impacts, Adaptation and Vulnerability (WGII); Mitigation of Climate Change (WGIII). Of these, the first study was published in 2021, the second report February 2022, and the third in April 2022. The final synthesis report is due to be finished by early 2023.
Climate change vulnerability is defined as the "propensity or predisposition to be adversely affected" by climate change. It can apply to humans but also to natural systems (ecosystems). Human and ecosystem vulnerability are interdependent. Climate change vulnerability encompasses "a variety of concepts and elements, including sensitivity or susceptibility to harm and lack of capacity to cope and adapt". Vulnerability is a component of climate risk. Vulnerability differs within communities and across societies, regions and countries, and can change over time. Approximately 3.3 to 3.6 billion people live in contexts that are highly vulnerable to climate change in 2021.
