Synthesis report of the IPCC Sixth Assessment Report (AR6), Longer report. IPCC.

This Synthesis Report (SYR) of the IPCC Sixth Assessment Report (AR6) summarises the state of knowledge of climate change, its widespread impacts and risks, and climate change mitigation and adaptation, based on the peer-reviewed scientific, technical and socio-economic literature since the publication of the IPCC’s Fifth Assessment Report (AR5) in 2014. The assessment is undertaken within the context of the evolving international landscape, in particular, developments in the UN Framework Convention on Climate Change (UNFCCC) process, including the outcomes of the Kyoto Protocol and the adoption of the Paris Agreement. It reflects the increasing diversity of those involved in climate action. This report integrates the main findings of the AR6 Working Group reports1 and the three AR6 Special Reports. It recognizes the interdependence of climate, ecosystems and biodiversity, and human societies; the value of diverse forms of knowledge; and the close linkages between climate change adaptation, mitigation, ecosystem health, human well-being and sustainable development. Building on multiple analytical frameworks, including those from the physical and social sciences, this report identifies opportunities for transformative action which are effective, feasible, just and equitable using concepts of systems transitions and resilient development pathways. Different regional classification schemes are used for physical, social and economic aspects, reflecting the underlying literature. After this introduction, Section 2, ‘Current Status and Trends’, opens with the assessment of observational evidence for our changing climate, historical and current drivers of human-induced climate change, and its impacts. It assesses the current implementation of adaptation and mitigation response options. Section 3, ‘Long-Term Climate and Development Futures’, provides a long-term assessment of climate change to 2100 and beyond in a broad range of socio-economic futures. It considers long-term characteristics, impacts, risks and costs in adaptation and mitigation pathways in the context of sustainable development. Section 4, ‘Near-Term Responses in a Changing Climate’, assesses opportunities for scaling up effective action in the period up to 2040, in the context of climate pledges, and commitments, and the pursuit of sustainable development. Based on scientific understanding, key findings can be formulated as statements of fact or associated with an assessed level of confidence using the IPCC calibrated language5 . The scientific findings are drawn from the underlying reports and arise from their Summary for Policymakers (hereafter SPM), Technical Summary (hereafter TS), and underlying chapters and are indicated by {} brackets. Figure 1.1 shows the Synthesis Report Figures Key, a guide to visual icons that are used across multiple figures within this report

IPCC, 2023: Climate Change 2023: Synthesis Report, Summary for Policymakers. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, H. Lee and J. Romero (eds.)]. IPCC, Geneva, Switzerland.

This Synthesis Report (SYR) of the IPCC Sixth Assessment Report (AR6) summarises the state of knowledge of climate change, its widespread impacts and risks, and climate change mitigation and adaptation. It integrates the main findings of the Sixth Assessment Report (AR6) based on contributions from the three Working Groups1 , and the three Special Reports. The summary for Policymakers (SPM) is structured in three parts: SPM.A Current Status and Trends, SPM.B Future Climate Change, Risks, and Long-Term Responses, and SPM.C Responses in the Near Term.This report recognizes the interdependence of climate, ecosystems and biodiversity, and human societies; the value of diverse forms of knowledge; and the close linkages between climate change adaptation, mitigation, ecosystem health, human well-being and sustainable development, and reflects the increasing diversity of actors involved in climate action. Based on scientific understanding, key findings can be formulated as statements of fact or associated with an assessed level of confidence using the IPCC calibrated language

Changements climatiques et ressources en eau Bassin versant de I'Ouergha (Maroc)

Les changements climatiques, prévus avec l'augmentation des gaz à effet de serre, pourraient avoir un impact certain sur les ressources en eau, en particulier dans les régions arides à semi-arides, comme celle du Maghreb. Tenant compte des connaissances actuelles concernant le réchauffement probable de la région, et en vue d'évaluer l'impact possible sur la ressource en eau de tels événements, la recherche dont les résultats sont présentés ici, a consisté à : $\ast$ Simuler à l'aide d'un modèle, le comportement hydrique d'un bassin versant pilote au Maroc (bassin de I'Ouergha) $\ast$ Utiliser ce modèle pour estimer le déficit hydrique probable en cas de changement climatique dans ce bassin Les premiers résultats indiquent une diminution des ruissellements annuels à l'exutoire de ce bassin atteignant les 8% d'ici à 2050 : déficit important dans un pays où la ressource est particulièrement rare

Spatio- temporal variability of vegetation cover over Morocco (1982-2008) : linkages with large scale climate and predictability

The dominant patterns of vegetation cover interannual variability over Morocco are isolated using rotated extended empirical orthogonal functions applied to AVHRR NDVI data (1982-2008). The three leading modes capture the NDVI signal at the vegetation peak for three distinct locations: mode 1 (18.7% of total variance) is located along the Atlantic coastline, mode 2 (13.1%) is southwest of the Riff Mountain whilst mode 3 (11.2%) is along the Mediterranean coastline. Correlations between the NDVI time coefficients for the modes Atlantic' and Mediterranean' dominated by annuals and precipitation amount during the early stage of the vegetation cycle (NDJ) are found. Significant fluctuations of NDVI time coefficients are isolated: a quasi-biennial signal is present in the three modes and an additional quasi-quadriennial (approximate to 4.4 years) signal is identified for the Atlantic' mode only. Connection between vegetation activity and atmospheric and oceanic climate signals are sought using time-lag correlation analyses. The NAO during fall-beginning of winter (NDJ) is found to impact vegetation peak for the Atlantic' mode while the Scandinavian Pattern is related to NDVI peak over the Atlantic' and Riff' latter in the season (DJF). A significant connection is also found between vegetation over the Atlantic' mode and the Riff' and the Atlantic Nino' mode leading the SST variability in the equatorial Atlantic with a 6-months lag. Finally, linkages between NDVI and climate information are used to build a seasonal prediction model for NDVI using multiple linear regression. The NDVI anomalies during March-April may be predicted with a reasonable accuracy from January with 79% of explained variance, 60% and 72% for the Atlantic', the Riff' and the Mediterranean' regions, respectively. Results have (1) direct impacts for a better understanding of the role of large-scale climate signals on vegetation cover over Morocco and (2) contribute to the implementation of an agricultural early warning system

Detecting inhomogeneities in Caribbean and adjacent Caribbean temperature data using sea-surface temperatures

This study presents a systematic evaluation of the homogeneity of daily surface temperature observations for the Caribbean and neighboring regions on a monthly timescale. The reference series are developed using adjacent sea-surface temperatures (SSTs). This novel approach is undertaken instead of the conventional use of highly correlated nearby stations, given the sparse station network for the Caribbean and adjacent Caribbean. The temperature data are from the regional climate change workshops held for the Caribbean, and Central and Northern South America in 2001 and 2004, respectively, complemented with data from the National Climatic Data Center (NCDC), the Caribbean Institute for Meteorology and Hydrology (CIMH), and the Caribbean meteorological stations. Correlations are used to explore the degree of association between the maximum and minimum temperatures and SSTs, and homogeneity tests are performed on their individual and difference series (e.g., maximum temperature minus SSTs). The results suggest SSTs as a viable option for use in evaluating homogeneity in the data sparse region of the Caribbean. Common statistically significant change points identified across at least three stations are investigated using composite analysis to determine links to large-scale atmospheric circulation patterns. The study identifies two homogeneous periods from the analyses, i.e., 1970-1992 and 1984-1998, with the former used to reanalyze some extreme temperature trends for the Caribbean and adjacent Caribbean. The results are found to be consistent with those obtained from the 2001 Caribbean data workshop

Global observed changes in daily climate extremes of temperature and precipitation

A suite of climate change indices derived from daily temperature and precipitation data, with a primary focus on extreme events, were computed and analyzed. By setting an exact formula for each index and using specially designed software, analyses done in different countries have been combined seamlessly. This has enabled the presentation of the most up-to-date and comprehensive global picture of trends in extreme temperature and precipitation indices using results from a number of workshops held in data-sparse regions and high-quality station data supplied by numerous scientists world wide. Seasonal and annual indices for the period 1951-2003 were gridded. Trends in the gridded fields were computed and tested for statistical significance. Results showed widespread significant changes in temperature extremes associated with warming, especially for those indices derived from daily minimum temperature. Over 70% of the global land area sampled showed a significant decrease in the annual occurrence of cold nights and a significant increase in the annual occurrence of warm nights. Some regions experienced a more than doubling of these indices. This implies a positive shift in the distribution of daily minimum temperature throughout the globe. Daily maximum temperature indices showed similar changes but with smaller magnitudes. Precipitation changes showed a widespread and significant increase, but the changes are much less spatially coherent compared with temperature change. Probability distributions of indices derived from approximately 200 temperature and 600 precipitation stations, with near-complete data for 1901-2003 and covering a very large region of the Northern Hemisphere midlatitudes (and parts of Australia for precipitation) were analyzed for the periods 1901-1950, 1951-1978 and 1979-2003. Results indicate a significant warming throughout the 20th century. Differences in temperature indices distributions are particularly pronounced between the most recent two periods and for those indices related to minimum temperature. An analysis of those indices for which seasonal time series are available shows that these changes occur for all seasons although they are generally least pronounced for September to November. Precipitation indices show a tendency toward wetter conditions throughout the 20th century