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Understanding the IPCC Sixth Assessment Report Key Findings

The Intergovernmental Panel on Climate Change (IPCC) has begun releasing its Sixth Assessment Report (AR6) 气候变化的驱动因素和潜在影响,以及人类社会可能采取的应对方式. 报告概述了我们在减少温室气体排放和减轻气候变化对人类和地球的最坏影响方面面临的巨大挑战.

Craig Clifton和Global Technology Leader Resilience and Climate Change汇总了这份报告的主要发现.

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Climate Change 2021: the physical science basis

《首页》是IPCC第一工作组(WGI)的关键成果。. 它提供了对当前气候状态的当代理解, how it is changing, how it may continue to change over shorter and longer timescales, and the influence of human activity in driving that change. 这是AR6周期的第一份主要报告,在2021年和2022年期间,第二工作组将提交关于影响的报告, 与气候变化有关的适应性和脆弱性以及关于减缓温室气体排放和气候变化备选方案的第三工作组.

Human influence on the climate system

该报告基于政府间气候变化工作组对IPCC第五次评估报告(AR5)的贡献。, published in 2013 and several IPCC Special Reports published in 2018-19. Its findings are broadly consistent with AR5. Notably, it affirms that the increase of carbon dioxide, methane, 而工业时代大气中的一氧化二氮是人类活动的结果. 报告的结论是,人类的影响是全球平均地表温度上升近1的主要驱动因素.自工业时代开始以来的1摄氏度,以及许多其他观察到的大气变化, ocean, cryosphere, and biosphere.

The future

气候建模基于5种共享社会经济路径(SSP)情景,这些情景描述了未来温室气体排放的5种替代轨迹. Two of these scenarios - SSP1-1.9 and SSP1-2.6 - anticipate rapid decarbonization, 导致大气中温室气体的净清除在21年的后半期st Century. These contrast with SSP3-7.0 and SSP5-8.预计排放将持续增长至少到本世纪下半叶.

IPCC chart

报告中明确的一点是,我们将全球平均气温上升限制在1的几率是多少.比工业化前水平高出5°C(《正规博彩十大网站排名》缔约方《正规博彩十大网站排名》更雄心勃勃的目标)现在看来很小. Under all SSP scenarios, the best estimate is that the 1.5°C threshold will be breached some time during the next 20 years. 只有在两种最激进的脱碳情景下,全球变暖可能将保持在2°C以下,从而造成人类对全球气候系统的危险干预. Under the two high emissions growth scenarios, 到本世纪末,全球气温可能比工业化前的水平上升4摄氏度以上.

预计全球气候变暖的影响是深远的:

  • Frequency and intensity of hot extremes and marine heatwaves will increase.
  • Heavy precipitation events will intensify, 随着北半球高纬度地区和大多数季风地区降水的进一步增加.
  • Agricultural and ecological droughts will be more severe.
  • Proportion of intense tropical cyclones will continue to increase.
  • Reductions in Arctic sea ice, snow cover and permafrost will accelerate.

这些气候变化将与全球变暖和温室气体排放的程度成正比. The warming itself will be much more rapid in some regions, particularly at high latitudes in the northern hemisphere.

然而,如果全球范围内大规模减少温室气体排放,气候系统的某些变化可以逆转, other changes to oceans, ice sheets, and sea level are effectively locked in. Mountain and polar glaciers will continue melting for decades or centuries. Permafrost thaw appears to be irreversible at centennial timescales. 格陵兰岛和南极冰盖的冰流失将继续,至少在本世纪.

These combined with continued warming of oceans, mean sea levels will continue to rise for centuries to millennia. 到2100年,海平面可能上升1米,但不能排除2100年海平面上升接近2米、2150年海平面上升接近5米的可能性(尽管不太可能)。.

The implication of these changes for human society, food production, water resources, 和自然系统将在IPCC即将发布的WGII报告中讨论.

So what now?

Limiting human-induced warming to the 1.《正规博彩十大网站排名》的5°C目标要求迅速限制二氧化碳的累积排放量,并将二氧化碳排放至少减少到零净排放量. Large reductions in emissions of other greenhouse gases are also required.

全球气候变化全球指标的报告包括两项关于大气碳排放的重要说明. 第一,二氧化碳排放在提高气温方面比从大气中去除碳在降低气温方面更有效. 第二,去除二氧化碳的方法可能会对生物地球化学循环和气候产生广泛和潜在的意想不到的不利影响. The implications of both findings are that urgent emissions reductions, 与各国在《正规博彩十大网站排名》下的承诺一致,甚至可能更有雄心, 为提高效率和减少人类对全球气候系统的干扰所需要的.

How can Jacobs help?

IPCC《正规博彩十大网站排名》的全球气候变化工作组报告强调了在两个方面采取紧急行动的必要性:第一, the need for human society and economies to decarbonize rapidly, and second, 需要增强各种人类和自然系统的抵御能力. As a global team of specialists, we can help cities, infrastructure providers, utilities, 社区在这两个方面应对温室气体排放和气候变化带来的挑战.

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