1.5-degree target

At the 21st UN Climate Change Conference in 2015 (COP 21), almost all countries in the world signed a treaty in the Paris Agreement, according to which they intend to make efforts to achieve the 1.5-degree target.{{cite web|access-date=2020-01-27 |date=2019-11-05 |title=Der internationale Klimavertrag - ohne die USA |url=https://www.br.de/klimawandel/klimaabkommen-paris-protokoll-klimapolitik-klimawandel-102.html |website=br.de}} According to a special report by the Intergovernmental Panel on Climate Change (IPCC), meeting the 1.5-degree target would be significantly more favorable than if only the two-degree target could be achieved.{{cite web|access-date=2020-01-27 |date=2019-07-30 |publisher=Schweizerischer Bundesrat |title=Klimaübereinkommen von Paris |url=https://www.admin.ch/opc/de/classified-compilation/20162916/index.html#a2}}{{cite web|access-date=2020-01-27 |date=2016-06-14 |publisher=Deutsches Umweltbundesamt |title=Übereinkommen von Paris |url=https://www.bmu.de/fileadmin/Daten_BMU/Download_PDF/Klimaschutz/paris_abkommen_bf.pdf}} However, according to the IPCC, the efforts made before 2023 to reduce greenhouse gas emissions are far from sufficient. Without an immediate increase in measures, the world could warm by around 3.2 °C over the next 70 years, with catastrophic consequences for people and the environment.{{cite web |url=https://www.umweltbundesamt.de/themen/ipcc-synthesebericht-macht-aktionsdruck-fuer-15degc |title=IPCC-Synthesebericht macht Aktionsdruck für 1,5°C noch deutlicher |language=de |publisher=Umweltbundesamt |date=2023-03-21 |access-date=2023-08-31}}

The World Meteorological Organization (WMO) predicted that the 1.5-degree temperature threshold would have been probably be exceeded in at least one year between 2023 and 2027.{{cite web |date=May 2023 |editor=World Meteorological Organization |title=Global Annual to Decadal Climate Update |url=https://hadleyserver.metoffice.gov.uk/wmolc/WMO_GADCU_2023-2027.pdf}} Accordingly, 2024 was the first single calendar year above 1.5 °C relative to pre-industrial levels. A study published in 2025 shows that such a first year above 1.5 °C indicates that most probably Earth has already entered the 20-year period that will reach the Paris Agreement limit — that is, a 20-year period with average warming of 1.5 °C.{{cite journal |last1=Bevacqua |first1=Emanuele |last2=Carl-Friedrich|first2=Schleussner|last3=Zscheischler|first3=Jakob|title=A year above 1.5 °C signals that Earth is most probably within the 20-year period that will reach the Paris Agreement limit |journal=Nature Climate Change |date=Feb 2025 |doi=10.1038/s41558-025-02246-9 |url=https://www.nature.com/articles/s41558-025-02246-9|doi-access=free }} According to the United Nations Environment Programme (UNEP), the international community is heading towards dangerous global warming of up to 2.9 °C if it fully implements its current climate protection commitments, which are not dependent on preconditions.{{citation|date=2023 |doi=10.59117/20.500.11822/43922 |editor=United Nations Environment Programme |section=Conditional nationally determined contribution |isbn=978-92-807-4098-1 |pages=X, 12 |title=Broken Record – Temperatures hit new highs, yet world fails to cut emissions (again)}}

In a 2017 study, the chances of achieving the 1.5-degree target were rated as low. At that time, it was assumed that even without further greenhouse gas emissions, the global average temperature would still rise to at least 1.1 °C compared to pre-industrial times, and with a probability of 13% even to 1.5 °C or more. A second study from the same year considers it unlikely that global warming will even be limited to 2 °C by 2100, let alone 1.5 °C. According to models at the time, which relied on predictions about gross domestic product per capita and population development, among other things, the probability of achieving this target was estimated at just one percent.{{cite web|access-date=2019-12-31 |author=Marlene Weiß |date=2017-08-01 |title=Das 1,5-Grad-Ziel kann man vergessen |url=https://www.sueddeutsche.de/wissen/klimawandel-das-1-5-grad-ziel-kann-man-vergessen-1.3611756#redirectedFromLandingpage |website=sueddeutsche.de}}{{cite journal|date=2017-07-31 |title=Less than 2 °C warming by 2100 unlikely |journal=Nature Climate Change|doi=10.1038/nclimate3352 |last1=Raftery |first1=Adrian E. |last2=Zimmer |first2=Alec |last3=Frierson |first3=Dargan M. W. |last4=Startz |first4=Richard |last5=Liu |first5=Peiran |volume=7 |issue=9 |pages=637–641 |pmid=30079118 |pmc=6070153 |bibcode=2017NatCC...7..637R}}

However, the IPCC's 1.5-degree global warming special report published in October 2018 concludes that the 1.5-degree target is still achievable. To achieve this, human {{CO2}} emissions would have to start falling significantly long before 2030 and reach net zero emissions from around 2050.{{cite web|access-date=2019-12-31 |publisher=Deutsche IPCC-Koordinierungssstelle |title=1,5 °C globale Erwärmung - Zusammenfassung für politische Entscheidungsträger |url=https://www.de-ipcc.de/media/content/SR1.5-SPM_de_barrierefrei.pdf |website=de-ipcc.de}} In order to reduce greenhouse gas emissions in this relatively short period of time, a shift away from fossil fuels towards renewable energy sources and a predominantly plant-based diet is needed.{{cite web|access-date=2019-12-31 |author=Joachim Müller-Jung |date=2019-08-08 |title=Bericht des Weltklimarats: Der Klimastachel im Fleisch |url=https://www.faz.net/aktuell/wissen/bericht-des-weltklimarats-der-klimastachel-im-fleisch-16324587.html |website=faz.net}}{{cite web|access-date=2020-01-09 |author=Annika Flatley |date=2016-04-01 |title=Studie: Vegane Ernährung könnte Klima und Menschenleben retten |url=https://utopia.de/studie-vegane-ernaehrung-klimaschutz-15078/ |website=utopia.de}} Simultaneously, carbon dioxide removal of up to 100 to 1000 billion tons {{CO2}} are required until the end of the century, equaling 2.5 to 25 times of the yearly {{CO2}} emissions of c. 40 gigatons.Kati Mattern, Eric Fee, Thomas Voigt, Juliane Berger, Guido Knoche, Achim Daschkeit, Claudia Kabel, Mathias Bornschein: [https://www.umweltbundesamt.de/sites/default/files/medien/1410/publikationen/2019-10-02_climate-change_34-2019_kernbotschaften-ipcc.pdf "Kernbotschaften des IPCC-Sonderberichts über 1,5 °C globale Erwärmung zur Verbreitung in der Öffentlichkeit."] (PDF) Deutsches Umweltbundesamt, 2019-10-02. Retrieved 2020-11-09. One option to achieve this through natural means would be through carbon dioxide removal measures (CDR) in context of agriculture, forestry and other land use (AFOLU) like afforestation and moorland restoration,[https://science.orf.at/v2/stories/2899249/ "Wie sich das 1,5-Grad-Ziel erreichen lässt."] orf.at. 2018-03-05, Retrieved 2019-12-31. however in most modeled emission pathways of the IPCC this is considered insufficient. Additionally, carbon capture and storage would have to be used to cool down the earth after exceeding the 1.5-degree target.{{cite web|access-date=2019-12-31 |publisher=Deutsche IPCC-Koordinierungssstelle |title=1,5 °C globale Erwärmung - Zusammenfassung für politische Entscheidungsträger |url=https://www.de-ipcc.de/media/content/SR1.5-SPM_de_barrierefrei.pdf |website=de-ipcc.de}} The world climate council itself mentions that it isn't confirmed that such measurements would work in large scale application.[https://www.de-ipcc.de/media/content/SR1.5-FAQs_de_barrierefrei.pdf "1,5 °C globale Erwärmung - Häufig gestellte Fragen und Antworten."] (PDF) de-ipcc.de. Deutsche IPCC-Koordinierungsstelle, Retrieved 2019-12-31.

One prognosis published in 2023 certified that the 1.5-degree target would collapse between 2033 and 2035 even in positive scenarios.{{cite journal | doi=10.1073/pnas.2207183120 | title=Data-driven predictions of the time remaining until critical global warming thresholds are reached | date=2023 | last1=Diffenbaugh | first1=Noah S. | last2=Barnes | first2=Elizabeth A. | journal=Proceedings of the National Academy of Sciences | volume=120 | issue=6 | pages=e2207183120 | doi-access=free | pmid=36716375 | pmc=9963891 | bibcode=2023PNAS..12007183D}} One report from the same year considers the compliance of the 1,5-degree goal and the decarbonization to 2050 as "no plausible".{{Cite web |url=https://www.fdr.uni-hamburg.de/record/11230 |doi=10.25592/uhhfdm.11230 |date=2023 |last1=Engels |first1=Anita |last2=Marotzke |first2=Jochem |last3=Gresse |first3=Eduardo |last4=López-Rivera |first4=Andrés |last5=Pagnone |first5=Anna |last6=Wilkens |first6=Jan |title=Hamburg Climate Futures Outlook: The plausibility of a 1.5°C limit to global warming - social drivers and physical processes |publisher=Universität Hamburg}}

One case study on London published in 2023 suggests that the biggest contribution to reaching the 1.5-degree target in major cities consists of a drastic reduction in private transport.Lalon Sander: "Verkehrswende in London: Drastisch weniger Auto fahren." Die Tageszeitung: taz. 2023-06-03, ISSN [https://zdb-katalog.de/list.xhtml?t=iss%3D%220931-9085%22&key=cql&asc=false 0931-9085] Retrieved 2023-06-04. The scientists recommend a mix of measurements in form of neighborly carsharing, the restructuring of the street layout after a superblock model, comprehensive local supply based on a compact city model, the stop of big road construction projects as well as a dynamic toll for roads with considerably higher traffic jam or areas of high hazardous effect on health.{{cite journal | pmc=10125996 | date=2023 | last1=Winkler | first1=L. | last2=Pearce | first2=D. | last3=Nelson | first3=J. | last4=Babacan | first4=O. | title=The effect of sustainable mobility transition policies on cumulative urban transport emissions and energy demand | journal=Nature Communications | volume=14 | issue=1 | page=2357 | doi=10.1038/s41467-023-37728-x | pmid=37095105 | bibcode=2023NatCo..14.2357W}}

The worldwide planned production volume of coal, oil and gas continuously exceeds the permissible dimensions needed for mitigation of the climate change.ORF at/Agenturen red: [https://orf.at/stories/3339105/ "UNO: Förderpläne für Öl, Gas und Kohle gegen 1,5-Grad-Ziel.] 2023-11-08, retrieved 2023-11-09. On basis of the undisputed correlation between {{CO2}} emissions and the economic growth, growth-critical measurements in order to reduce the rate of economical growth are considered central to the adherence to the 1.5-degree and 2-degree targets. According to research by Jason Hickel for example, the growth targets of the International Monetary Fund (IMF) would be opposing to these goals.{{cite journal | url=https://linkinghub.elsevier.com/retrieve/pii/S2590332223005079 | doi=10.1016/j.oneear.2023.11.004 | title=Post-growth: A viable path to limiting global warming to 1.5°C | date=2024 | last1=Slameršak | first1=Aljoša | last2=Kallis | first2=Giorgos | last3=o'Neill | first3=Daniel W. | last4=Hickel | first4=Jason | journal=One Earth | volume=7 | pages=44–58}}[https://phys.org/news/2023-12-economic-growth-climate-15c-threshold.html "Low economic growth can help keep climate change within the 1.5°C threshold, says study."] Phys.org. Autonomous University of Barcelona, retrieved 2023-12-21.

Recent works indicate that the achievability of the 1.5-degree target through the retroactive withdrawal of {{CO2}} emissions from the earth's atmosphere (overshoot scenario) had been overestimated within climate research because of irreversible effects.{{cite journal | doi=10.1038/s41586-024-08020-9 | title=Overconfidence in climate overshoot | date=2024 | last1=Schleussner | first1=Carl-Friedrich | last2=Ganti | first2=Gaurav | last3=Lejeune | first3=Quentin | last4=Zhu | first4=Biqing | last5=Pfleiderer | first5=Peter | last6=Prütz | first6=Ruben | last7=Ciais | first7=Philippe | last8=Frölicher | first8=Thomas L. | last9=Fuss | first9=Sabine | last10=Gasser | first10=Thomas | last11=Gidden | first11=Matthew J. | last12=Kropf | first12=Chahan M. | last13=Lacroix | first13=Fabrice | last14=Lamboll | first14=Robin | last15=Martyr | first15=Rosanne | last16=Maussion | first16=Fabien | last17=McCaughey | first17=Jamie W. | last18=Meinshausen | first18=Malte | last19=Mengel | first19=Matthias | last20=Nicholls | first20=Zebedee | last21=Quilcaille | first21=Yann | last22=Sanderson | first22=Benjamin | last23=Seneviratne | first23=Sonia I. | last24=Sillmann | first24=Jana | last25=Smith | first25=Christopher J. | last26=Steinert | first26=Norman J. | last27=Theokritoff | first27=Emily | last28=Warren | first28=Rachel | last29=Price | first29=Jeff | last30=Rogelj | first30=Joeri | journal=Nature | volume=634 | issue=8033 | pages=366–373 | pmid=39385053 | pmc=11464373 | bibcode=2024Natur.634..366S}} According to a survey by The Guardian only 5 percent of the surveyed climate scientists at the beginning of 2024 expected the achievability of the 1.5-degree target.Damian Carrington, Damian Carrington Environment editor: "World's top climate scientists expect global heating to blast past 1.5C target." The Guardian. 2024-05-08, ISSN [https://zdb-katalog.de/list.xhtml?t=iss%3D%220261-3077%22&key=cql 0261-3077] [https://www.theguardian.com/environment/article/2024/may/08/world-scientists-climate-failure-survey-global-temperature theguardian.com] retrieved 2024-06-02.

A special report issued by the IPCC to as global warming of 1.5 °C makes among other things the following central statements to the consequences of a global warming of 1.5 °C in comparison to one of 2 °C:

1. A reduced increase to average temperatures, heat waves, droughts, heavy precipitation and precipitation deficits.
2. The rise of the sea level would be reduced by 0.1 more meters by adhering to the 1.5-degree target instead of the 2-degree target. Based on the population counts of 2010 and without any adjustment measures 10 million fewer people would be affected by the rise of the sea level than by 2 °C of warming. The oceans will rise regardless, even when adhering to the 1.5-degree target, although with less speed than with a warming of 2 °C.
3. There would be less extinction of species, less damage on ecosystems on land, in fresh water and coasts so that more of the services of the ecosystems are retained longer.
4. A lower increase in ocean warming and acidification, along with a smaller decline in ocean oxygen levels, and a reduced loss of biodiversity and fishery yields. A summer without sea ice in the Arctic would statistically occur only once per century instead of once per decade.
5. There would be lower risks to human health and safety, livelihoods, food and water supplies, and economic growth.
6. Fewer adjustments to the new climate would be necessary. The limits of the adaptation capacity of some human and natural systems are reached with 1.5 degrees of global warming, but the losses due to exceeding the limits of climate change adaptation would be smaller than with 2 degrees of global warming.1,5 °C globale Erwärmung - Zusammenfassung für politische Entscheidungsträger. (PDF) In: de-ipcc.de. Deutsche IPCC-Koordinierungssstelle, retrieved 31 December 2019.

The risk of triggering tipping points in the Earth's climate system and uncontrollable chain reactions is significantly lower at 1.5 °C of warming. Tipping points in the cryosphere, according to a group of researchers in a 2019 commentary, could already be dangerously close. With warming of 1.5 °C to 2 °C, the Greenland ice sheet or Arctic sea ice could melt. The tipping point for the West Antarctic ice sheet may already have been surpassed, but warming of 1.5 °C would slow the melting process by a factor of ten compared to 2 °C of global warming, making it easier to adapt to a sharply rising sea level. However, the carbon budget of 500 billion tons for a 50 percent chance of reaching the 1.5-degree target may already have been used up.Timothy M. Lenton, Johan Rockström, Owen Gaffney, Stefan Rahmstorf, Katherine Richardson, Will Steffen, Hans Joachim Schellnhuber: Climate tipping points – too risky to bet against. In: Nature. 27 November 2019, {{doi|10.1038/d41586-019-03595-0}} (Open Access).

Compared to the current global warming projections by the Intergovernmental Panel on Climate Change (IPCC), achieving the 1.5-degree target could force 80 percent fewer people to migrate due to climate change, as fewer areas of the Earth would become uninhabitable. According to CAN Europe, aligning Europe with the 1.5-degree target could save one trillion euros by 2030.Olivier Vardakoulias, Giulia Nardi: Paris Pact Payoff. Speeding Up the Green Transition for Socio-Economic Co-Benefits. CAN Europe, Brüssel 2024 (caneurope.org [PDF]).Paris einhalten heißt 1 Billion Euro sparen. In: Plattform Transformative Finanzpolitik. 23 January 2024, retrieved 31 January 2024 {{in lang |de}}.

Due to the low confidence of the IPCCThe world is going to miss the totemic 1.5°C climate target. In: The Economist. 5 November 2022, ISSN 0013-0613 (economist.com [retrieved 6 November 2022]). and climate researchersJeff Tollefson: Top climate scientists are sceptical that nations will rein in global warming. In: Nature. Band 599, Nr. 7883, 4 November 2021, ISSN 0028-0836, pg. 22–24, {{doi|10.1038/d41586-021-02990-w}}. regarding the achievability of the target, various groups, such as Scientist Rebellion, argue that the 1.5-degree target should be declared politically unfeasible.Open Letter. A united academia can fight climate failure. In: Scientist Rebellion. 2022, retrieved 6 November 2022 . Direct democratic initiatives, such as Climate Restart, the initiator of the 2023 Berlin climate neutrality referendum, emphasize that decarbonization in industrialized nations must still be implemented in line with the 1.5-degree target to mitigate risks.Klimaneustart Berlin: Volksentscheid Berlin 2030 Klimaneutral. Retrieved 6 November 2022 {{in lang |de}}.

File:Kurz vor der Räumung Rebellinnen von Extinction Rebellion blockieren die Marschallbrücke, um auf den IPCC-Report hinzuweisen. (51928536535).jpg point to the imminent failure to meet the target. ("1,5 ° R.I.P.") (2022)]]

Political scientists Wim Carton and Andreas Malm (both from Lund University) criticize representatives of climate science for having based their simulations on the achievability of the 1.5-degree target for too long, while relying on implausible assumptions that distracted from real-world scenarios.Andreas Malm, Wim Carton: How mainstream climate science endorsed the fantasy of a global warming time machine. In: The Conversation. 9 October 2024, retrieved 10 October 2024 (amerikanisches Englisch).

The words "1.5 degrees" or "1.5°C" are often used as slogans by activists, such as by Fridays for Future since July 2022, with the inscription "We all for 1.5°C" on the asphalt of Hamburg's Mönckebergstraße,Hamburger Abendblatt: Hamburger Innenstadt: 1,5-Grad-Schriftzug bleibt auf Mönckebergstraße. 15 July 2022, retrieved 25 November 2022 {{in lang |de}}.

or during the occupation of Lützerath starting in 2022 ("1.5°C means: Lützerath stays!").tagesschau.de: Proteste in Lützerath: Aktivisten verschanzen sich in Tunneln. Retrieved 13 January 2023.

{{Reflist}}

{{subject bar|auto=y|d=y|Environment|Climate change}}

Category:Climate change policy

Category:Climate change