For decades, Arctic sea ice has been melting earlier in spring and freezing later in fall, extending the melt season and contributing to widespread ice loss. A new NASA-led study has found that while the Arctic melt season has lengthened dramatically since satellite records began, that trend unexpectedly stabilized around 2010.
几十年来，北极海冰在春季融化较早，秋季结冰较晚，从而延长了融化季节并导致广泛的冰损失。美国宇航局领导的一项新研究发现，虽然自卫星记录开始以来，北极融化季节已大幅延长，但这一趋势在 2010 年左右出乎意料地稳定下来。
The Arctic sea ice melt season is now about 40 days longer than it was in 1979, according to the study. Most of the increase occurred before 2010. Since then, the average melt season length has remained relatively unchanged, despite large year-to-year fluctuations.
研究显示，现在北极海冰融化季节比 1979 年延长了约 40 天。大部分增加发生在 2010 年之前。此后，尽管逐年波动较大，但平均融化季节长度保持相对不变。
Researchers analyzed satellite observations between 1979 and 2023 to track when sea ice begins to melt each spring and refreezes each autumn. They found that the change was driven primarily by sea ice freezing later in the year rather than melting earlier in the spring.
研究人员分析了 1979 年至 2023 年间的卫星观测数据，以追踪每年春季海冰开始融化和每年秋季重新结冰的时间。他们发现，这种变化主要是由于海冰在今年晚些时候结冰而不是在春季早些时候融化造成的。
“Previously, there was more of this multiyear ice that didn’t melt away each summer,” said Linette Boisvert, a co-author on the study and ice scientist at NASA’s Goddard Space Flight Center. “Now that the ice is thinner and there’s less of it, there’s a lot more variability.” On average, though, the decline in sea ice thickness and extent that occurred during the 2000s appears to have stopped for the time being.
“以前，每年夏天都有更多的多年冰不会融化，”该研究的合著者、美国宇航局戈达德太空飞行中心的冰科学家利内特·布瓦维特说。 “现在冰越来越薄，数量也越来越少，变化也更大。”不过，平均而言，2000 年代发生的海冰厚度和范围的下降似乎暂时停止了。
To understand why, the team examined changes in the Arctic’s energy balance—the net difference between incoming heat from the Sun, atmosphere, and ocean and the outgoing infrared radiation emitted back to space.
为了理解其中的原因，研究小组研究了北极能量平衡的变化——来自太阳、大气和海洋的传入热量与发射回太空的红外辐射之间的净差异。
During the period of rapid ice loss in the 2000s, reduced ice cover exposed darker ocean water, which absorbed more sunlight. The additional solar energy delayed freezing and helped extend the melt season. In the left map above, the reddest areas mark where the melt season grew fastest that decade, by up to 5 days per year. Much of the Arctic ice today is younger and thinner than the multiyear ice that was once more widespread in the Arctic Ocean, leaving it more vulnerable to variations in cloud cover, storms, and winds.
在2000年代冰层快速流失期间，冰盖减少暴露出颜色较深的海水，从而吸收了更多的阳光。额外的太阳能推迟了结冰并有助于延长融化季节。在上面的左侧地图中，最红的区域标志着该十年融化季节增长最快的区域，每年最多增加 5 天。如今，北冰洋的大部分冰比曾经在北冰洋广泛分布的多年冰更年轻、更薄，因此更容易受到云层、风暴和风变化的影响。
Since 2010, changing cloud patterns have reduced the amount of sunlight reaching parts of the Arctic Ocean. The result has been a melt season that fluctuates from one year to the next but remains relatively stable over longer periods. The right map above reflects this shift, with the lighter blues and reds showing the more modest rates of change during that decade.
自 2010 年以来，变化的云层模式减少了到达北冰洋部分地区的阳光量。结果是融化季节每年都会波动，但在较长时期内保持相对稳定。上面的右图反映了这种转变，浅蓝色和红色显示了这十年间较为温和的变化率。
These findings don’t suggest that shifts in Earth’s climate have stopped affecting the Arctic. The region continues to warm nearly four times faster than the global average, and the remaining sea ice is substantially thinner than it was several decades ago. Instead, the study suggests that the Arctic may have entered a new phase, in which annual weather patterns exert a stronger influence on melt season than they once did.
这些发现并不表明地球气候的变化已经停止影响北极。该地区的变暖速度持续快于全球平均水平的四倍，而剩余的海冰比几十年前要薄得多。相反，该研究表明北极可能已经进入一个新阶段，年度天气模式对融化季节的影响比以前更大。
“Melt season length is much more dependent on atmospheric effects,” Boisvert said. “They seem to be playing a bigger role because the ice is generally thinner and more vulnerable to begin with.”
“融化季节的长度更多地取决于大气的影响，”博瓦维特说。 “它们似乎发挥着更大的作用，因为冰通常更薄且更脆弱。”
The researchers caution that the apparent stabilization may prove temporary. Thick Arctic ice still exists throughout the year to the north of Greenland and the Canadian Arctic Archipelago. Continued thinning of ice in those regions could trigger another period of rapid sea ice loss, with the potential to further extend the melt season.
研究人员警告说，表面上的稳定可能是暂时的。格陵兰岛北部和加拿大北极群岛全年仍然存在厚厚的北极冰。这些地区的冰层持续变薄可能会引发又一个海冰快速流失的时期，并有可能进一步延长融化季节。
For now, the study highlights the importance of continued satellite observations of Arctic sea ice and the energy balance that controls its growth and melting. Whether the recent stabilization represents a lasting change in the melt season or a pause before another period of rapid change remains an open question.
目前，该研究强调了持续卫星观测北极海冰以及控制其生长和融化的能量平衡的重要性。最近的稳定是否代表融化季节的持久变化，还是另一个快速变化时期之前的暂停，仍然是一个悬而未决的问题。
NASA Earth Observatory images by Michala Garrison, using data from Boisvert, L., et al. (2026). Story by James Riordon/NASA’s Earth Science News Team.
NASA 地球观测站图像，由 Michala Garrison 拍摄，使用 Boisvert, L. 等人的数据。 （2026）。故事由 James Riordon/NASA 地球科学新闻团队撰写。