"(SRM) involves large-scale methods... is untested and is not included in any of the mitigation scenarios. If it were deployed, SRM would entail numerous uncertainties, side effects, risks and shortcomings... If it were terminated [after and if once begun], there is high confidence that surface temperatures would rise very rapidly impacting ecosystems..."

"Adaptation and mitigation responses are underpinned by common enabling factors. These include effective institutions and governance, innovation and investments in environmentally sound technologies and infrastructure, sustainable livelihoods and behavioural and lifestyle choices."

"In the absence or under limited availability of mitigation technologies (such as , CCS and their combination BECCS, nuclear, wind/solar), mitigation costs can increase substantially..."

"Many adaptation and mitigation options can help address climate change, but no single option is sufficient by itself."

"Cooperative responses, including international cooperation, are... required to effectively mitigate... and address other climate change..."

"Improving institutions as well as coordination and cooperation in governance can help overcome regional constraints associated with mitigation, adaptation and disaster risk reduction..."

"Climate change has the characteristics of a collective action problem at the global scale, because most GHGs accumulate over time and mix globally, and emissions by any agent (e.g., individual, community, company, country) affect other agents."

"A reduction in extent is virtually certain with continued rise in global temperatures."

"Mitigation can be more cost-effective if using an integrated approach that combines measures to reduce energy use and the green-house gas intensity of end-use sectors, decarbonize energy supply, reduce net emissions and enhance carbon sinks..."

"International cooperation is critical for effective mitigation..."

"Effective mitigation will not be achieved if individual agents advance their own interests independently."

"[[w:Ocean acidification|[O]cean acidification]] will increase for centuries if CO2 emissions continue, and will strongly affect s."

"The most cost-effective mitigation options in forestry are , sustainable forest management and reducing ... and in agriculture, cropland management, grazing land management and restoration of organic soils..."

"Delaying global mitigation actions may reduce options..."

"By 2100... the combination of high temperature and humidity in some areas for parts of the year is expected to compromise common human activities, including growing food and working outdoors..."

"Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks."

"It is very likely that human influence has contributed to the observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-20th century."

"Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond."

"It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale."

"[C]limate change will impact human health mainly by exacerbating health problems that already exist... Throughout the 21st century, climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income..."

"In urban areas climate change is projected to increase risks for people, assets, economies and ecosystems, including risks from heat stress, storms and extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, water scar-city, sea level rise and storm surges... These risks are amplified for those lacking essential infrastructure and services or living in exposed areas."

"The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen."

"Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century."

"Rural areas are expected to experience major impacts on water availability and supply, food security, infrastructure and agricultural incomes..."

"In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans."

"Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia."

"Global temperature increases of ~4°C or more above late 20th century levels, combined with increasing food demand, would pose large risks to food security globally..."

"Multiple lines of evidence indicate a strong, consistent, almost linear relationship between cumulative CO2 emissions and projected global temperature change to the year 2100..."

"Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history."

"Changes in many extreme weather and climate events have been observed since about 1950. Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions."

"[N]egative impacts of climate change on crop yields have been more common than positive impacts..."

"Climate change is projected to reduce renewable surface water and groundwater resources in most dry subtropical regions... intensifying competition for water..."

"Recent climate changes have had widespread impacts on human and natural systems."

"Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems."

"Impacts from recent climate-related extremes, such as heat waves, droughts, floods, cyclones and wildfires, reveal significant vulnerability and exposure of some ecosystems and many human systems to current climate variability..."

"Many terrestrial, freshwater and marine species have shifted their geographic ranges, seasonal activities, migration patterns, abundances and species interactions in response to ongoing climate change..."

"Due to projected climate change by the mid-21st century and beyond, global marine species redistribution and marine biodiversity reduction in sensitive regions will challenge the sustained provision of fisheries productivity and other ecosystem services..."

"Stabilization of global average surface temperature does not imply stabilization for all aspects of the climate system. Shifting , , s, ocean temperatures and associated all have their own intrinsic long timescales which will result in changes lasting hundreds to thousands of years after global surface temperature is stabilized."

"Surface temperatures will remain approximately constant at elevated levels for many centuries after a complete cessation of net anthropogenic CO2 emissions. A large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible on a multi-century to millennial timescale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period."

"The IPCC is now 95 percent certain that humans are the main cause of current global warming."

"[G]lobal mean sea level rise will continue for many centuries beyond 2100..."

"Many of those most vulnerable to climate change have contributed and contribute little to GHG emissions."

"Adaptation and mitigation are complementary strategies for reducing and managing the risks of climate change. Substantial emissions reductions over the next few decades can reduce climate risks in the 21st century and beyond, increase prospects for effective adaptation, reduce the costs and challenges of mitigation in the longer term and contribute to climate-resilient pathways for sustainable development."

"[T]he more human activities disrupt the climate, the greater the risks of severe, pervasive and irreversible impacts for people and ecosystems, and long-lasting changes in all components of the climate system."

"Arctic sea ice extent has decreased in every season and in every successive decade since 1979..."

"Delaying additional mitigation to 2030 will substantially increase the challenges associated with limiting warming over the 21st century to below 2°C..."

"There are multiple mitigation pathways that are likely to limit warming to below 2°C relative to pre-industrial levels. These pathways would require substantial emissions reductions over the next few decades and near zero emissions of CO2 and other long-lived greenhouse gases by the end of the century."

"[This report] calls for the urgent attention of both policymakers and citizens of the world to tackle this challenge."

"Many of the observed changes since the 1950s are unprecedented over decades to millennia."