Rapid and Intensifying Climate Change

Geneva: In its latest report, the Intergovernmental Panel on Climate Change (IPCC) highlights that climate changes are being observed across the entire Earth’s climate system and in every region. Many of these climate shifts are unprecedented in thousands, if not hundreds of thousands, of years, and some, like ongoing sea level rise, are irreversible over extended periods of hundreds to thousands of years.

Nevertheless, significant and sustained reductions in carbon dioxide (CO2) and other greenhouse gas emissions could mitigate the extent of climate change. While immediate improvements in air quality would result, it may take 20-30 years for global temperatures to stabilize, as outlined in the IPCC Working Group I report titled ‘Climate Change 2021: the Physical Science Basis.’ This report gained approval from 195 member governments of the IPCC during a virtual session held over two weeks, commencing on July 26.

The Working Group I report marks the initial segment of the IPCC’s Sixth Assessment Report (AR6), slated for full completion in 2022.

Hoesung Lee, Chair of the IPCC, commented on the report, stating, ‘This report represents remarkable endeavors undertaken during exceptional circumstances. The breakthroughs presented in this report, along with the progress in climate science it signifies, offer invaluable contributions to climate discussions and the decision-making process.

The report presents fresh estimations regarding the likelihood of surpassing the 1.5°C global warming threshold in the coming decades. It underscores that without immediate, substantial, and extensive reductions in greenhouse gas emissions, the goal of limiting warming to approximately 1.5°C or even 2°C will become increasingly unattainable.

Additionally, the report highlights that human activities have been responsible for around 1.1°C of warming since 1850-1900 through greenhouse gas emissions. Over the next two decades, it is anticipated, on average, that global temperatures will reach or surpass the 1.5°C warming mark. This assessment is founded on improved observational datasets for evaluating historical warming and advancements in comprehending how the climate system responds to human-induced greenhouse gas emissions.

IPCC Working Group I Co-Chair Valérie Masson-Delmotte remarked, ‘This report serves as a reality check. It provides us with a far more distinct understanding of past, present, and future climate trends, which is crucial for ascertaining our trajectory, feasible actions, and the measures necessary for preparedness.

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Climate change’s impacts are closely linked to the level of global warming, but the effects experienced by people can vary significantly from the global average. For instance, warming over land surpasses the global average, with the Arctic experiencing over twice the global warming rate.

IPCC Working Group I Co-Chair Panmao Zhai noted, ‘Climate change is already affecting every region on Earth, in multiple ways. The changes we experience will increase with additional warming.’

The report predicts that climate changes will intensify across all regions in the coming decades. With 1.5°C of global warming, there will be an increase in heatwaves, longer warm seasons, and shorter cold seasons. At 2°C of global warming, heat extremes are more likely to reach critical thresholds that impact agriculture and public health.

However, it’s not solely about temperature. Climate change induces various changes in different regions, all of which magnify with further warming. These encompass alterations in wetness and dryness, wind patterns, snow and ice coverage, coastal areas, and oceans. Some examples include:

• Climate change intensifies the water cycle, leading to more intense rainfall, flooding, and drought in numerous regions.
• Rainfall patterns are affected, with increased precipitation expected in high latitudes and decreased rainfall projected in many subtropical areas. Monsoon precipitation patterns will also change by region.
• Coastal areas will witness ongoing sea level rise, contributing to more frequent and severe coastal flooding and erosion.
• Further warming exacerbates permafrost thawing, loss of seasonal snow cover, glacier and ice sheet melting, and summer Arctic sea ice reduction.
• Changes in the ocean, including warming, more frequent marine heatwaves, ocean acidification, and decreased oxygen levels, are attributed to human influence. These changes impact ocean ecosystems and the people who depend on them and will persist throughout at least the remainder of this century.
• Urban areas may experience amplified effects of climate change, including heightened heat due to urban heat island effects, increased flooding from heavy precipitation, and coastal cities grappling with sea level rise.

In a significant development, the Sixth Assessment Report offers a more detailed regional assessment of climate change. It provides valuable information for risk assessment, adaptation, decision-making, and a new framework that translates physical climate changes—such as heat, cold, rainfall, drought, snow, wind, coastal flooding, and more—into their societal and ecological implications.

This regional data is available for exploration in the newly developed Interactive Atlas, regional fact sheets, the technical summary, and the underlying report.

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For decades, it has been evident that the Earth’s climate is undergoing change, with human influence on the climate system being beyond dispute,” noted Masson-Delmotte. However, the new report also signifies significant advancements in the field of attribution science, enhancing our understanding of how climate change contributes to the intensification of specific weather and climate events, such as extreme heatwaves and heavy rainfall.

Furthermore, the report emphasizes that human actions still possess the capacity to shape the future trajectory of the climate. The evidence is unequivocal that carbon dioxide (CO2) serves as the primary driver of climate change, although other greenhouse gases and air pollutants also exert an influence on the climate.

“To stabilize the climate, we must commit to robust, swift, and continuous reductions in greenhouse gas emissions, ultimately achieving net-zero CO2 emissions. Additionally, mitigating the impact of other greenhouse gases and air pollutants, particularly methane, could yield health and climate-related benefits,” stated Zhai.