EK小课堂是10位培元生态编辑部的小编辑们定期给大家呈现生态小知识的栏目。我们肉眼可见的极端天气越来越多，由此更多的人意识到了气候变化带来的严重问题，但如何解决呢？首先要了解这个问题是什么，其次才会有解决方案。EK小课堂就是小编辑们让大家更多了解问题是什么，让大家一起来探寻解决办法。希望大家喜欢并点赞，更希望大家可以传播给更多的人。

本期由胡胜凯、吴潇、严思瀚三位小编辑，为读者们带来关于墨西哥湾流、永久冻土层、气溶胶的知识分享。

（胡胜凯）

“大家好，我是胡胜凯，今年14岁，现在在35中的初三。我性格开朗，乐于助人，乐观向上。兴趣爱好有钢琴，足球，摄影，旅行等等（原神，启动！）参与生态知识编辑项目，我希望能提升自身英语水平，更希望传播生态知识，和同学们一起进步。”

什么是墨西哥湾流系统？What is the Gulf Stream System?

墨西哥湾流系统是全球海洋环流模式的一部分。它始于热带地区，那里的高温不仅使海水变暖，而且通过蒸发增加了海水盐度。这些温暖的咸水从美国海岸线向东北方向流向欧洲，形成了墨西哥湾流, 并从赤道向北流向格陵兰岛，在那里它冷却，密度降低，下沉，使北大西洋洋流将水送回南方。墨西哥湾流系统就像一个巨大的传送带。墨西哥湾流每秒移动超过2000万立方米的水，几乎是亚马逊河流量的100倍。

The Gulf Stream System is a part of the network of global ocean circulations patterns. It starts in the tropics, where high temperatures not only warm up the seawater but also increase its proportion of salt by boosting evaporation. This warm, salty water flows northeast from the US coastline toward Europe — creating the Gulf Stream, and carries warm surface water from the equator up north to Greenland, where it cools, becomes less dense, and sinks, allowing the North Atlantic Current to send the water back down south. The Gulf Stream System works like a giant conveyor belt. The Gulf Stream System moves over 20 million cubic meter of water per second, almost a hundred times the Amazon flow.

墨西哥湾暖流系统是否即将崩溃，并且如果崩溃将会发生什么?Is the Gulf Stream System close to collapse, and what will happen if it does?

只要存在必要的温度和盐度梯度，墨西哥湾流系统就能自我维持。但气候变化改变了这种平衡。更高的温度使海水更温暖、更轻。如果这些海水不够沉，整个墨西哥湾流就会停止。最新研究发现，AMOC极有可能在本世纪内萎缩。突然的崩塌很可能会导致气候模式和区域水循环的急剧变化。

The Gulf Stream System is self-sustaining as long as the necessary temperature and salinity gradients exist. But climate change has shifted the balance. Higher temperatures make ocean waters warmer and lighter. If these waters aren’t heavy enough to sink, the entire Gulf Stream will shut down. The latest research finds it is very likely that AMOC will decline over this century. A sudden collapse would very likely cause sharp shifts in weather patterns and the regional water cycle. 

全球变暖与墨西哥湾流系统的变化有何联系?How is global warming linked to changes in the Gulf Stream System? 

北极海冰以及南极洲和格陵兰岛冰川的融化导致海平面上升，对全球天气的形成起关键作用。墨西哥湾暖流系统的变化是冰川融化问题加剧的一个例子。全球变暖导致水文循环的变化，导致北大西洋次极地降水增加，海洋淡水增加。这减少了北大西洋水从表面下沉的趋势。

The melting of Arctic sea ice as well as glaciers in Antarctica and Greenland pose a series of threats. These changes contribute to sea level rise, play critical roles in global weather formation. Changes to the Gulf Stream System is one example of the compounding risks of ice melt. Global warming causes changes to the hydrological cycle leading to increased precipitation over the subpolar North Atlantic, adding more freshwater to the ocean. 

（吴潇）

“我叫吴潇，今年14岁，来自北京三十五中，初三。兴趣爱好：围棋，足球，画画。不擅长的事：语文，体育，英语。希望大家以后能互相认识，和谐相处。”

1. 定义

永久冻土是一层冻土，覆盖了北半球25%的面积。它就像一个巨大的冰柜，将微生物、碳和土壤锁在原地。

Definition: Permafrost is a layer of frozen soil that covers 25 percent of the Northern Hemisphere. It acts like a giant freezer, keeping microbes, carbon, and soil locked in place. 

2. 现在及未来状况

北极理事会最近的一份报告称，到2040年，地表附近20%的永久冻土可能会融化。科学家们已经注意到永久冻土的温度正在缓慢攀升。美国地质调查局在2015年解释说:“在20世纪80年代，阿拉斯加、俄罗斯和其他北极地区的永久冻土温度平均接近18华氏度。”

“现在的平均温度刚刚超过28华氏度。”2010年俄罗斯的一项研究发现，在过去的30年里，冻土变暖了0.5℃到2℃，使一些地区危险地接近融化，并将永久冻土区的边界向北推进。

在欧洲北部的北极地区，“活跃层”(夏季融化的永久冻土顶层)的深度越来越深，这是不稳定的迹象。永久冻土最简单的定义是冻结了至少两年的土地。但它远不止于此。在北极的大部分地区，地面已经冻结了数万年。其中很大一部分是冻结的——永久冻土占北半球所有陆地面积的25%。永久冻土就像北极的基岩(你真的需要手提钻才能把它敲开)。但是北极地区不断上升的气温正在侵蚀这片地区的基岩。 

Current and future situation: 

Permafrost is a layer of frozen soil that covers 25 percent of the Northern Hemisphere. It acts like a giant freezer, keeping microbes, carbon, and soil locked in place. A recent Arctic Council report says that 20 percent of the permafrost near the surface may melt by 2040. Already scientists have noticed permafrost temperatures slowly climbing.

“In the 1980s, the temperature of permafrost in Alaska, Russia and other Arctic regions averaged to be almost 18°F,” the U.S. Geological Survey explained in 2015. “Now the average is just over 28°F.”A 2010 study in Russia found 0.5°C to 2°C permafrost warming in the past three decades, bringing some locations dangerously close to thawing and pushing the boundary of permafrost regions ever northward. 

And the depth of the “active layer” — the top layer of permafrost that thaws in the summertime — is growing deeper in the Arctic regions north of Europe, a sign of instability. 

The simplest definition of permafrost is ground that has been frozen for at least two years. But it’s so much more than that. In much of the Arctic, that ground has been frozen for tens of thousands of years. And a huge amount of it is frozen — permafrost rests in 25 percent of all the land area in the Northern Hemisphere. Permafrost is like the bedrock of the Arctic (you literally need jackhammers to break it apart). But rising air temperatures in the region are chipping away at this bedrock.

3. 当永久冻土层融化时，会发生什么？ 

霍姆斯说:“永久冻土层的一半可能是冻结的水。”“当它融化时，水就会流失。水可能会往下坡，或者水的体积比冰小，所以地面就会塌陷，有点分崩离析。”你可以把北极永久冻土想象成一个巨大的厨房冰箱。如果你把有机(碳基) 物质放在冰箱里，食物就会完好无损。但如果冰箱的压缩机坏了，它就会慢慢升温。随着温度的升高，细菌开始吃掉你细菌开始吃掉你的食物。细菌使食物腐烂。当细菌消耗食物时，它们会产生二氧化碳、甲烷和其他气味难闻的气体和化学物质。

数万年来，永久冻土就像一个冰柜，将1.4亿吨(10亿吨)的植物碳封存在土壤中。(这是目前大气中碳含量的两倍多。)有些植物物质是最近的，有些来自冰河时期，从根本上把郁郁葱葱的景观变成了苔原。 

霍姆斯说:“植物生长在永久冻土区，当这些植物因为寒冷的温度而死亡时，它们没有完全分解，所以一些有机碳被留下了。”当永久冻土解冻时，“它开始腐烂，开始分解，这就是释放的东西。 

What happens if the permafrost melts?

“Half the volume of permafrost may be frozen water,” Holmes says. “When that thaws, the water just runs off. The water may head downhill or the water has a lower volume than is ice, so the ground just slumps and kind of falls apart.” You can think of the Arctic permafrost as a giant kitchen freezer.If you put organic (carbon-based) matter in your freezer, the food will stay intact. But if the freezer compressor breaks, it will slowly heat up. As it heats up, bacteria begin to eat your food. The bacteria make the food go rotten. And as the bacteria consume the food, they produce carbon dioxide, methane, and other gases and chemicals that smell terrible. 

For tens of thousands of years, permafrost has acted like a freezer, keeping 1,400 gigatons (billion tons) of plant matter carbon trapped in the soil. (That’s more than double the amount of carbon currently in the atmosphere.) Some of the plant matter is more recent, and some is from glacial ice ages that radically transformed a lush landscape into tundra. “Plants are growing in permafrost regions, and when those plants die, because of the cold temperature, they don't fully decompose, so some of that organic carbon is left behind,” Holmes says. When the permafrost thaws, “it starts to rot, it starts to decompose, and that's what's releasing.

“它开始腐烂，开始分解，这就是释放的东西—二氧化碳和甲烷，”他说。这就是科学家们如此担心北极融化的一个原因:当细菌将北极的碳转化为二氧化碳和甲烷时，它会加速一个反馈循环。释放的甲烷和碳越多，气候变暖就越严重。越严重就越变暖……你懂的。永久冻土的深度冻结不仅阻止了碳的逃逸，还保持了微生物的完整……细菌只需要解冻就能苏醒过来。他说:“如果你把酸奶放在永久冻土中(保持冷冻状态)，我敢肯定，从现在起一万年后，它还是可以吃的。”这些微生物就像时间旅行者——在一个人类失去了对它们的免疫防御的时代，它们可能会在醒来时茁壮成长。

“It starts to rot, it starts to decompose, and that's what's releasing carbon dioxide and methane,” he says. This is one reason scientists are so worried about a melting Arctic: When the bacteria turn the carbon in the Arctic into C02 and methane, it accelerates a feedback loop. The more methane and carbon released, the more warming. The more warming ... you get it. The deep freeze of the permafrost doesn’t just keep carbon from escaping — it keeps microbes intact as well...All the bacteria need is a thaw to wake back up. “If you take a yogurt and put it in permafrost [that remains frozen], I’m sure in 10,000 years from now it still will be good to eat,” he said... These microbes are like time travelers — and they could thrive waking up in an age when humans have lost an immune defense against them.

（严思瀚）

“我叫严思瀚，今年13岁了，来自东直门中学。我爱好广泛，其中非常喜欢数学和物理。我长大希望成为一个科学家，为世界环保事业做出贡献。”

什么是气溶胶？（Aerosol）

是指悬浮在气体介质中的固态或液态颗粒所组成的气态分散系统。

It refers to a gaseous dispersion system composed of solid or liquid particles suspended in a gas medium.

🌍气溶胶颗粒的大小和形状

这些固态或液态颗粒的密度与气体介质的密度可以相差微小，也可以悬殊很大。气溶胶颗粒大小通常在0.01~10μm之间，但因为来源和形成原因范围很大，例如：花粉等植物气溶胶的粒径在5~100μm之间、木材及烟草燃烧产生的气溶胶，其粒径通常为0.01~1000μm，所以颗粒的形状多种多样，可以是近乎球形，诸如液态雾珠，也可以是片状、针状及其它不规则形状。

The density of these solid or liquid particles can differ from that of the gaseous medium by a small or large amount. Aerosol particle size is usually between 0.01~10μm, but the source and formation of a wide range of reasons, for example: pollen and other plant aerosol particle size between 5~100μm, wood and tobacco combustion aerosol, its particle size is usually 0.01~1000μm,and the shape of the particles are varied, it can be nearly spherical, such as liquid fog beads, flakes, needles, and other irregular shapes. and other irregular shapes.

🍁气溶胶对大气和人类有何影响？

气溶胶可以直接影响人类健康和气候，与二氧化碳排放无关。气溶胶与负面的健康影响密切相关，它可以通过影响温度、降水模式和阳光到达地球表面的程度来影响气候。研究人员指出，气溶胶排放对排放者和整个地球都是有害的。气溶胶会对呼吸系统造成影响。气溶胶的直径一般小于5微米。当存在呼吸道传染病的患者咳嗽，吐痰时，就会产生气溶胶。

Aerosols can directly affect human health and climate, and are not related to carbon dioxide emissions. Aerosols are closely related to negative health effects, as they can affect climate by affecting temperature, precipitation patterns, and the extent to which sunlight reaches the Earth's surface. Researchers point out that aerosol emissions are harmful to emitters and the entire Earth. Aerosols can have an impact on the respiratory system. The diameter of aerosols is generally less than 5 microns. When patients with respiratory infectious diseases cough and spit, aerosols are produced.