Source: The Intergovernmental Panel on Climate Change (IPCC) 9 August 2°21

Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions, limiting warming to close to 1.5°C or even 2°C will be beyond reach.

Climate change is already affecting every region on Earth, in multiple ways. The changes we experience will increase with additional warming. The report projects that in the coming decades climate changes will increase in all regions. For 1.5°C of global warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons. At 2°C of global warming, heat extremes would more often reach critical tolerance thresholds for agriculture and health, the report shows.

But it is not just about temperature. Climate change is bringing multiple different changes in different regions – which will all increase with further warming. These include changes to wetness and dryness, to winds, snow and ice, coastal areas and oceans.

  • Climate change is intensifying the water cycle. This brings more intense rainfall and associated flooding, as well as more intense drought in many regions.
  • Climate change is affecting rainfall patterns. In high latitudes, precipitation is likely to increase, while it is projected to decrease over large parts of the subtropics. Changes to monsoon precipitation are expected, which will vary by region.
  • Coastal areas will see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion. Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century.
  • Further warming will amplify permafrost thawing, and the loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of summer Arctic sea ice.
  • Changes to the ocean, including warming, more frequent marine heatwaves, ocean acidification, and reduced oxygen levels have been clearly linked to human influence. These changes affect both ocean ecosystems and the people that rely on them, and they will continue throughout at least the rest of this century.
  • For cities, some aspects of climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea level rise in coastal cities.

For the first time, the Sixth Assessment Report provides a more detailed regional assessment of climate change, including a focus on useful information that can inform risk assessment, adaptation, and other decision-making, and a new framework that helps translate physical changes in the climate – heat, cold, rain, drought, snow, wind, coastal flooding and more – into what they mean for society and ecosystems This regional information can be explored in detail in the newly developed Interactive Atlas interactive-atlas.ipcc.ch as well as regional fact sheets, the technical summary, and underlying report.

The report also shows that human actions still have the potential to determine the future course of climate. The evidence is clear that carbon dioxide (CO2) is the main driver of climate change, even as other greenhouse gases and air pollutants also affect the climate. Stabilizing the climate will require strong, rapid, and sustained reductions in greenhouse gas emissions, and reaching net zero CO2 emissions. Limiting other greenhouse gases and air pollutants, especially methane, could have benefits both for health and the climate.

Summary of 5 Key Messages

  1. We are set to pass 1.5C warming by 2040: Under all emissions scenarios outlined in the IPCC report, the earth’s surface warming is projected to reach 1.5C or 1.6C in the next two decades. Drastic reductions in CO2 would be needed this decade and net zero emissions by 2050.
  2. Human activity is driving extreme weather: There is “high confidence” that human activities are the main drivers of more frequent or intense heatwaves, glaciers melting, ocean warming and acidification
  3. We know more about regional climate impacts: Climate models have improved since the last IPCC report, enabling scientists to analyse current and projected temperatures and hydrological extremes at a regional level and understand what global climate impacts will look like in different parts of the world. Modelling shows that the Arctic is warming faster than other regions and that high latitudes in the Northern Hemisphere are projected to warm by two to four times the level of global warming. While warming in the tropics is slower, it is noticeable because temperatures over land near the equator do not vary much year on year in the absence of human influence. The Gulf Stream is very likely to weaken over the century, according to the report. A complete collapse of the Atlantic Ocean current would disrupt regional weather patterns, weakening African and Asian monsoons and strengthening dry spells in Europe, scientists warn.
  4. We are closer to irreversible tipping points: The report sounds the alarm about the possibility of irreversible changes to the climate, often called tipping points. For example, forests could start to die as temperatures rise, becoming less able to absorb carbon dioxide, leading to further warming. Or Antarctic ice sheets could become destabilised, leading to rapid sea level rise. The probability of low-likelihood, high impact outcomes increases with higher global warming levels the report notes. Abrupt responses and tipping points of the climate system, such as strongly increased Antarctic ice sheet melt and forest dieback, cannot be ruled out. The melting of Antarctic ice sheets could cause sea levels to rise more than a metre by 2100 and 15 metres by 2500. Many temperature extremes are outside the bounds of natural variability and triggering extreme events, such as wildfires. Parts of the Amazon are now emitting more carbon than they absorb.
  5. Methane emissions are an important lever: Methane levels are now higher than at any point in the past 800,000 years and are well above the safe limits . Methane, which is released into the atmosphere from abandoned coal mines, farming and oil and gas operations, has a global warming impact 84 times higher than CO2 over a 20-year period. It is responsible for almost a quarter of global warming. Ecosystem responses to global warming, such as thawing permafrost and wildfires, are highly likely to further increase concentrations of methane in the atmosphere. A strong and rapid reduction in methane emissions would not only curb global warming but also improve air quality. Despite its global warming impact, methane has received far less attention than CO2 and is not included in most countries’ climate pledges. A sharp reduction in methane would give us a short-term win, but it has largely been ignored by governments to date, all the focus has been on CO2 net zero targets.

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