The scientific community has been investigating the causes of climate change for decades. After thousands of studies, it came to a consensus, where it is "unequivocal that human influence has warmed the atmosphere, ocean and land since pre-industrial times." This consensus is supported by around 200 scientific organizations worldwide, The dominant role in this climate change has been played by the direct emissions of carbon dioxide from the burning of fossil fuels. Indirect CO2 emissions from land use change, and the emissions of methane, nitrous oxide and other greenhouse gases play major supporting roles.
Global warming potential (GWP) is an index to measure how much infrared thermal radiation a greenhouse gas would absorb over a given time frame after it has been added to the atmosphere. The GWP makes different greenhouse gases comparable with regard to their "effectiveness in causing radiative forcing". It is expressed as a multiple of the radiation that would be absorbed by the same mass of added carbon dioxide, which is taken as a reference gas. Therefore, the GWP has a value of 1 for CO2. For other gases it depends on how strongly the gas absorbs infrared thermal radiation, how quickly the gas leaves the atmosphere, and the time frame being considered.
The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) set up the IPCC in 1988. The United Nations endorsed the creation of the IPCC later that year. It has a secretariat in Geneva, Switzerland, hosted by the WMO. It has 195 member states who govern the IPCC. The member states elect a bureau of scientists to serve through an assessment cycle. A cycle is usually six to seven years. The bureau selects experts in their fields to prepare IPCC reports. There is a formal nomination process by governments and observer organizations to find these experts. The IPCC has three working groups and a task force, which carry out its scientific work.
The United Nations Framework Convention on Climate Change (UNFCCC) is the UN process for negotiating an agreement to limit dangerous climate change. It is an international treaty among countries to combat "dangerous human interference with the climate system". The main way to do this is limiting the increase in greenhouse gases in the atmosphere. It was signed in 1992 by 154 states at the United Nations Conference on Environment and Development (UNCED), informally known as the Earth Summit, held in Rio de Janeiro. The treaty entered into force on 21 March 1994. "UNFCCC" is also the name of the Secretariat charged with supporting the operation of the convention, with offices on the UN Campus in Bonn, Germany.
There is a nearly unanimous scientific consensus that the Earth has been consistently warming since the start of the Industrial Revolution, that the rate of recent warming is largely unprecedented, and that this warming is mainly the result of a rapid increase in atmospheric carbon dioxide (CO2) caused by human activities. The human activities causing this warming include fossil fuel combustion, cement production, and land use changes such as deforestation, with a significant supporting role from the other greenhouse gases such as methane and nitrous oxide. This human role in climate change is considered "unequivocal" and "incontrovertible".
The IPCC Third Assessment Report (TAR), Climate Change 2001, is an assessment of available scientific and socio-economic information on climate change by the IPCC. Statements of the IPCC or information from the TAR were often used as a reference showing a scientific consensus on the subject of global warming. The Third Assessment Report (TAR) was completed in 2001 and consists of four reports, three of them from its Working Groups: Working Group I: The Scientific Basis; Working Group II: Impacts, Adaptation and Vulnerability; Working Group III: Mitigation; Synthesis Report. A number of the TAR's conclusions are given quantitative estimates of how probable it is that they are correct, e.g., greater than 66% probability of being correct. These are "Bayesian" probabilities, which are based on an expert assessment of all the available evidence.
The Second Assessment Report (SAR) of the Intergovernmental Panel on Climate Change (IPCC), published in 1995, is an assessment of the then available scientific and socio-economic information on climate change. The report was split into four parts: a synthesis to help interpret UNFCCC article 2, The Science of Climate Change, Impacts, Adaptations and Mitigation of Climate Change, Economic and Social Dimensions of Climate Change. Each of the last three parts was completed by a separate Working Group (WG), and each has a Summary for Policymakers (SPM) that represents a consensus of national representatives.
Climate Change 2007, the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC), was published in 2007 and is the fourth in a series of reports intended to assess scientific, technical and socio-economic information concerning climate change, its potential effects, and options for adaptation and mitigation. The report is the largest and most detailed summary of the climate change situation ever undertaken, produced by thousands of authors, editors, and reviewers from dozens of countries, citing over 6,000 peer-reviewed scientific studies. People from over 130 countries contributed to the IPCC Fourth Assessment Report, which took six years to produce. Contributors to AR4 included more than 2,500 scientific expert reviewers, more than 800 contributing authors, and more than 450 lead authors.
The First Assessment Report (FAR) of the Intergovernmental Panel on Climate Change (IPCC) was completed in 1990. It served as the basis of the United Nations Framework Convention on Climate Change (UNFCCC). This report had effects not only on the establishment of the UNFCCC, but also on the first session of the Conference of the Parties (COP), held in Berlin in 1995. The executive summary of the WG I Summary for Policymakers report that said they were certain that emissions resulting from human activities are substantially increasing the atmospheric concentrations of the greenhouse gases, resulting on average in an additional warming of the Earth's surface. They calculated with confidence that CO2 had been responsible for over half the enhanced greenhouse effect.
In 2005, an international conference titled Avoiding Dangerous Climate Change: A Scientific Symposium on Stabilisation of Greenhouse Gases examined the link between atmospheric greenhouse gas concentration and global warming and its effects. The conference name was derived from Article 2 of the charter for the United Nations Framework Convention on Climate Change The conference explored the possible impacts at different levels of greenhouse gas emissions and how the climate might be stabilized at a desired level. The conference took place under the United Kingdom's presidency of the G8, with the participation of around 200 "internationally renowned" scientists from 30 countries. It was chaired by Dennis Tirpak and hosted by the Hadley Centre for Climate Prediction and Research in Exeter, from 1 February to 3 February. The conference was one of many meetings leading up to the 2015 Paris Agreement, at which the international community agreed to limit global warming to no more than 2 °C in order to have a 50-50 chance of avoiding dangerous climate change. However, a 2018 published study points at a threshold at which temperatures could rise to 4 or 5 degrees through self-reinforcing feedbacks in the climate system, suggesting the threshold is below the 2 degree temperature target.
Yuri Antonievich Izrael was a Soviet and Russian meteorologist. He served as the vice-chairman of the Intergovernmental Panel on Climate Change (IPCC) until September 2008, when the new bureau was elected. He was the "most influential scientific adviser" for Vladimir Putin, the president of Russia, according to CNN.
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 Lindau Nobel Laureate Meetings are annual scientific conferences held in Lindau, Bavaria, Germany, since 1951. Their aim is to bring together Nobel laureates and young scientists to foster scientific exchange between different generations, cultures and disciplines. The meetings assume a unique position amongst international scientific conferences, as from 30 to 65 Nobel laureates attending each edition they are the largest regular congregation of Nobel laureates in the world, apart from the Nobel Prize award ceremony in Stockholm.
Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits, resulting in the greenhouse effect. The Earth is warmed by sunlight, causing its surface to radiate heat, which is then mostly absorbed by greenhouse gases. Without greenhouse gases in the atmosphere, the average temperature of Earth's surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F).
The 2007 Bali Declaration by Climate Scientists was a statement signed by over 200 climate scientists advocating specific targets for greenhouse gas emissions for the 21st century. The statement was based on the United Nations Framework Convention on Climate Change Article 2 that committed signatories to the "...stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system" and on the science available in the Intergovernmental Panel on Climate Change Fourth Assessment report. The Bali Declaration was released to coincide with the 2007 United Nations Climate Change Conference which took place in Bali 3–15 December 2007.
The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change Earth's energy balance and climate. The existence of the greenhouse effect, while not named as such, was proposed as early as 1824 by Joseph Fourier. The argument and the evidence were further strengthened by Claude Pouillet in 1827 and 1838. In 1856 Eunice Newton Foote demonstrated that the warming effect of the sun is greater for air with water vapour than for dry air, and the effect is even greater with carbon dioxide.
The 2012 United Nations Climate Change Conference was the 18th yearly session of the Conference of the Parties (COP) to the 1992 United Nations Framework Convention on Climate Change (UNFCCC) and the 8th session of the Meeting of the Parties (CMP) to the 1997 Kyoto Protocol. The conference took place from Monday 26 November to Saturday 8 December 2012, at the Qatar National Convention Centre in Doha.
Ozone depletion and climate change, or Ozone hole global warming in more popular terms, are environmental challenges whose connections have been explored and which have been compared and contrasted, for example in terms of global regulation, in various studies and books.
The Special Report on Global Warming of 1.5 °C (SR15) was published by the Intergovernmental Panel on Climate Change (IPCC) on 8 October 2018. The report, approved in Incheon, South Korea, includes over 6,000 scientific references, and was prepared by 91 authors from 40 countries. In December 2015, the 2015 United Nations Climate Change Conference called for the report. The report was delivered at the United Nations' 48th session of the IPCC to "deliver the authoritative, scientific guide for governments" to deal with climate change. Its key finding is that meeting a 1.5 °C (2.7 °F) target is possible but would require "deep emissions reductions" and "rapid, far-reaching and unprecedented changes in all aspects of society". Furthermore, the report finds that "limiting global warming to 1.5 °C compared with 2 °C would reduce challenging impacts on ecosystems, human health and well-being" and that a 2 °C temperature increase would exacerbate extreme weather, rising sea levels and diminishing Arctic sea ice, coral bleaching, and loss of ecosystems, among other impacts.
