全球气候变暖1.5°C：它的含义和影响

The science is clear: to avert the worst impacts of climate change and preserve a liveable planet, global warming needs to be limited as much as possible and as a matter of urgency. (IPCC) Under the Paris Agreement, countries agreed to substantially reduce global greenhouse gas emissions to enable the long-term global average surface temperature increase to be kept well below 2°C above pre-industrial levels and pursue efforts to limit it to 1.5°C.(Paris Agreement) At COPs 26, 27, and 28, countries emphasized that the impacts of climate change would be much lower at a temperature increase of 1.5°C, compared with 2°C, and expressed their firm resolve to pursue efforts to limit global warming to 1.5°C.(COP outcomes; IPCC)

科学明确表示：为了避免气候变化的最严重影响并保护宜居星球，需要尽可能地限制全球变暖，并将其作为紧急事项。 (IPCC) 根据《巴黎协定》，各国同意大幅减少全球温室气体排放，使全球平均地表温度上升长期远低于工业化前水平2°C，并努力将其限制在1.5°C.（《巴黎协定》）各国在COP第26、27、28次会议上强调，气温升高1.5°C，气候变化的影响将远低于2°C，并表达了继续努力的坚定决心将全球变暖限制在 1.5°C。（COP 结果；IPCC）

Monthly and annual breaches of 1.5°C do not mean that the world has failed to achieve the Paris Agreement’s temperature goal, which refers to a long-term temperature increase over decades, not individual months or years. Temperatures for any single month or year fluctuate due to natural variability, including El Niño/La Niña and volcanic eruptions. Consequently, long-term temperature changes are typically considered on decadal timescales. (WMO) Nevertheless, breaches of 1.5°C for a month or a year are early signs of getting perilously close to exceeding the long-term limit, and serve as clarion calls for increasing ambition and accelerating action in this critical decade. (UNEP). Global temperature changes are typically measured against the average temperature over a historical, pre-industrial baseline of 1850–1900. This baseline is the earliest period for which high-quality observations of surface temperatures over the land and ocean are available. (IPCC).

每月和每年超过1.5°C并不意味着世界未能实现《巴黎协定》的气温目标，该目标指的是数十年的长期气温上升，而不是个别月份或年份。由于自然变化，包括厄尔尼诺/拉尼娜和火山喷发，任何一个月或一年的气温都会波动。因此，通常在十年时间尺度上考虑长期温度变化。 (WMO) 尽管如此，一个月或一年气温突破 1.5°C 是危险地接近超过长期限制的早期迹象，也是在这个关键十年中增强雄心和加速行动的号角。 （全球温度变化通常是根据 1850 年至 1900 年工业化前历史基线的平均温度来衡量的。该基线是可获得陆地和海洋表面温度高质量观测的最早时期。(IPCC）。

The first months with an average temperature that was more than 1.5°C above the pre-industrial average occurred during 2015-16, driven by both human-caused climate change and a strong, naturally occurring El Niño. The latter part of 2023 and early 2024 also experienced monthly average global temperature anomalies above 1.5°C. (WMO) The first 12-month period to exceed 1.5°C as an average was February 2023 – January 2024, boosted by El Niño, when the average temperature worldwide was estimated to be 1.52°C higher than 1850–1900, according to one scientific dataset (Copernicus Climate Change Service). The likelihood of the annual average global temperature exceeding 1.5°C above pre-industrial levels for at least one year over the coming five years has increased significantly since 2015, when it was close to zero (WMO). The global average temperature for the most recent 10-year period, from 2014 to 2023, is estimated to be the warmest 10-year period on record, at around 1.2°C above the 1850-1900 average (WMO). The 20-year average warming for 2001–2020 relative to 1850–1900 is 0.99°C (IPCC).

2015-16 年，在人为气候变化和强烈的自然发生的厄尔尼诺现象的推动下，平均气温首次比工业化前平均气温高出 1.5°C 以上。 2023年下半年和2024年初，全球月平均气温异常也超过1.5°C。 (WMO) 据一项研究称，在厄尔尼诺现象的推动下，第一个平均气温超过 1.5°C 的 12 个月是 2023 年 2 月至 2024 年 1 月，当时全球平均气温估计比 1850 年至 1900 年高出 1.52°C科学数据集（哥白尼气候变化服务）。自 2015 年以来，全球年平均气温在未来五年内至少有一年比工业化前水平高出 1.5°C 的可能性已显着增加，当时的气温接近于零 (WMO)。最近 10 年（2014 年至 2023 年）的全球平均气温估计将是有记录以来最热的 10 年，比 1850-1900 年平均气温（WMO）高出约 1.2°C。 2001-2020 年相对于 1850-1900 年的 20 年平均升温为 0.99°C (IPCC)。

Every fraction of a degree of warming matters. With every additional increment of global warming, changes in extremes and risks become larger. For example, every additional 0.1°C of global warming causes clearly discernible increases in the intensity and frequency of temperature and precipitation extremes, as well as agricultural and ecological droughts in some regions. (IPCC) Limiting global warming to below 1.5°C will significantly reduce the risks, adverse impacts, and related losses and damages from climate change. Failing to do so will lead to increasingly frequent and dangerous extreme weather events including heatwaves, droughts, wildfires, and heavy precipitation and flooding (IPCC). Extreme heat causes the greatest mortality of all extreme weather, with an estimated 489,000 heat-related deaths per year between 2000 and 2019 (WMO). Exceeding 1.5°C could also trigger multiple climate tipping points — such as breakdowns of major ocean circulation systems, abrupt thawing of boreal permafrost, and collapse of tropical coral reef systems — with abrupt, irreversible, and dangerous impacts for humanity.

每一度的变暖都很重要。随着全球变暖每进一步加剧，极端情况和风险的变化就会变得更大。例如，全球变暖每增加0.1°C，就会导致极端温度和降水的强度和频率明显增加，以及某些地区的农业和生态干旱。 (IPCC) 将全球变暖限制在 1.5°C 以下将显着减少气候变化带来的风险、不利影响以及相关损失和损害。如果不这样做，将导致越来越频繁和危险的极端天气事件，包括热浪、干旱、野火、强降水和洪水（IPCC）。在所有极端天气中，极端高温造成的死亡率最高，估计 2000 年至 2019 年间，每年有 489,000 人因高温而死亡（WMO）。超过 1.5°C 还可能引发多个气候临界点，例如主要海洋环流系统的崩溃、北方永久冻土突然融化以及热带珊瑚礁系统崩溃，对人类造成突然、不可逆转和危险的影响。

Even at current levels of global warming, we are already seeing devastating climate impacts, including intensifying extreme weather events, alarming reductions in ice sheets, sea ice, and glaciers, and several mass coral bleaching events, with widespread harms to people, economies, and nature (IPCC). In the last two decades, the 55 most climate-vulnerable economies alone have already experienced climate damages exceeding US$ 500 billion (UNEP). In 2022, disasters triggered a record 32.6 million internal displacements, of which 98% were caused by weather-related hazards such as floods, storms, wildfires and droughts (UNHCR). Human health impacts from climate change have been apparent for at least 20 years, but the climate crisis is still not treated like other global public health emergencies. The cumulative death toll from climate change since 2000 will pass 4 million in 2024. This number is likely a substantial underestimate since it only focuses on climate-related malnutrition, diarrheal disease, malaria, floods, and cardiovascular diseases, whereas climate change is a threat multiplier of many other extreme weather events and public health risks. (Nature; PLOS)

即使在目前的全球变暖水平下，我们也已经看到了毁灭性的气候影响，包括极端天气事件加剧，冰盖、海冰和冰川惊人减少，以及几次大规模珊瑚白化事件，对人类、经济和社会造成广泛危害。自然（政府间气候变化专门委员会）。在过去二十年中，仅 55 个最容易受到气候影响的经济体就遭受了超过 5000 亿美元的气候损失（联合国环境规划署）。 2022 年，灾害引发了创纪录的 3260 万人境内流离失所，其中 98% 是由洪水、风暴、野火和干旱等天气相关灾害造成的（联合国难民署）。气候变化对人类健康的影响已经显现了至少 20 年，但气候危机仍未像其他全球突发公共卫生事件一样得到处理。自 2000 年以来气候变化造成的累计死亡人数到 2024 年将超过 400 万人。这个数字可能被严重低估，因为它只关注与气候相关的营养不良、腹泻病、疟疾、洪水和心血管疾病，而气候变化是一种威胁许多其他极端天气事件和公共卫生风险的倍数。（《自然》）

Many climate impacts, especially sea-level rise from ice sheets, disappearance of mountain glaciers, and ocean acidification, are essentially permanent for many generations to come and will take centuries to thousands of years to restore to even today’s conditions. To minimize losses and damages, it is crucial to minimize the magnitude and duration of temporarily exceeding 1.5°C by urgently and significantly reducing greenhouse gas emissions and phasing out fossil fuels. (New insights; IPCC)

许多气候影响，特别是冰盖导致的海平面上升、山地冰川消失和海洋酸化，对后代来说基本上是永久性的，甚至需要几个世纪到几千年的时间才能恢复到今天的状况。为了最大限度地减少损失和损害，至关重要的是通过紧急大幅减少温室气体排放和逐步淘汰化石燃料来最大限度地减少暂时超过 1.5°C 的幅度和持续时间。（IPCC）