https://www.earth.com/climate/earth-may-not-bounce-back-after-temporarily-crossing-climate-limits/
Hitting a climate target on paper does not mean the planet actually bounces back. New research shows that crossing warming targets for a time can leave lasting scars on the oceans and permafrost（永冻土）, even after temperatures fall again. The study, led by Concordia University and Simon Fraser University, feels timely: current policies put the world on track to blow past 2°C this century.
To test what an overshoot（超调）really costs, the researchers ran 42 pairs of climate scenarios（情景）. In each pair, one of them went beyond its warming target for a time before returning to it, while the other stayed under the threshold（阈值） throughout. Both ended with the same cumulative（累积的） CO2 emissions. That design let the team compare two roads to the same destination: the only difference was the shape of the journey, not the final total.
To measure the damage, the team came up with a metric they call degree-years. It combines two things: how far temperatures exceeded a target, and how long they stayed there. Across all the scenarios, degree-years of overshoot showed a near-linear（线性的） relationship with how much certain climate variables failed to recover. For several highly irreversible（不可逆的）ocean and permafrost variables, the metric explained roughly 90% or more of the variation - and it held true no matter how high the peak temperature got.
Some parts of the climate system snap back quickly once temperatures ease off; others barely move. Permafrost sits at the stubborn end. Once carbon stored in frozen ground is released during an overshoot, there is almost no recovery, and rebuilding those stores can take thousands of years. Sea level rise, ocean warming and falling ocean oxygen levels largely stuck around too. The reason is that extra heat soaked up at the surface is carried down into deeper water, where it exchanges with the atmosphere far more slowly.
A major Atlantic circulation（环流） pattern showed the same refusal to recover, driven by its own slow feedback loops（回路）. Not everything behaved this way. Atmospheric CO2 levels and surface ocean carbon chemistry returned to normal faster than average global temperature did, because the ocean keeps soaking up CO2 even as temperatures come down.
These findings push back on a common way of talking about climate goals. Warming targets are usually expressed in terms of peak temperature alone, yet how long temperatures spend above a target helps determine how much lasting damage remains. Two scenarios could reach the same peak and still leave the climate system in clearly different states. For policymakers, the message is direct: the path matters as much as the destination.
(1) What does "That design" in paragraph 2 refer to?
A. Setting up two routes that finish with identical overall emissions
B. Measuring how long temperatures stay above a target
C. Running 42 pairs of scenarios that end with different final totals
D. Letting temperatures fall back to the level they started from
(2) Which of the following is true about the climate variables that fail to recover?
A. They are limited to the frozen ground of the far north.
B. They return to their original state once the warming has ended.
C. They respond mainly to how far temperatures rise above a target.
D. They cover both carbon locked in frozen soil and several ocean measures.
(3) How does the author develop the argument?
A. By tracing how climate policy has changed since the 1990s.
B. By contrasting two routes to the same goal and measuring the damage each leaves behind.
C. By comparing the views of two research teams and supporting one of them.
D. By listing the causes of global warming in order of importance.
(4) What can be inferred from the last paragraph?
A. Climate targets are easier to meet when temperatures fall quickly.
B. Staying above a target briefly is as acceptable as never crossing it.
C. Coming back to a target does not undo the damage done above it.
D. Policymakers have so far ignored the dangers of rising sea levels.
(5) What is the passage mainly about?
A. Why frozen ground takes thousands of years to rebuild.
B. That climate targets should be dropped because they cannot be met.
C. How ocean circulation shapes the climate of the North Atlantic.
D. That how long temperatures stay above a target matters more than how high they climb.
词汇短语精讲
1. bounce back/ snap back 恢复原状；迅速复原
例句：Hitting a climate target on paper does not mean the planet actually bounces back.
提示：bounce 本义「弹跳」，bounce back 引申为「（从打击、下跌中）恢复过来」，属熟词生义；本文第 4 段以近义词组 snap back 表达同一含义，snap back 更突出「猛地弹回、动作之快」：Some parts of the climate system snap back quickly once temperatures ease off; others barely move. 两者常用于经济、健康、生态等语境。写作可迁移：The economy bounced back quickly after the crisis.
2. blow past 冲过、突破（目标、限额等）
例句：The study, led by Concordia University and Simon Fraser University, feels timely: current policies put the world on track to blow past 2°C this century.
提示：blow 本义「吹」，blow past sth. 引申为「带着冲力越过某个界限」，常接目标、纪录、限额；属熟词生义，比 exceed 更口语化。
3. come up with 想出、提出（办法、指标、主意等）
例句：To measure the damage, the team came up with a metric they call degree-years.
提示：come up with sth. 后接被提出的事物，不可接人；常用于研究提出方法、团队提出方案等语境。写作可迁移：They came up with a cheaper way to store the data.
4. stick around （不良影响、状况）持续存在、不消失
例句：Sea level rise, ocean warming and falling ocean oxygen levels largely stuck around too.
提示：stick 本义「粘住」，stick around 字面为「留在附近、待着不走」，本文引申为「（变化）长期留存、迟迟不消退」，属熟词生义；该表达多用于口语，此处用于描述长期效应。
5. push back on 对……提出质疑、反驳
例句：These findings push back on a common way of talking about climate goals.
提示：push back 本义「推回」，push back on sth. 引申为「对某个说法、主张表示反对或质疑」，常见于学术与公共讨论语境；同义于 challenge。
句子精讲
1. Warming targets are usually expressed in terms of peak temperature alone, yet how long temperatures spend above a target helps determine how much lasting damage remains.
翻译：升温目标通常只以峰值温度来表达，然而温度高于目标的持续时间，同样决定着会留下多少持久损害。
结构：并列句，由 yet 连接两个分句。前一分句 Warming targets are usually expressed in terms of peak temperature alone 为被动语态，in terms of 引出衡量标准；后一分句的主语是 how long temperatures spend above a target 这一主语从句，谓语为 helps determine，宾语为 how much lasting damage remains 这一宾语从句。两句构成「通行做法——被忽略的维度」的转折关系。
语法：yet 连接的转折并列句 + how long 引导的主语从句作主语 + how much 引导的宾语从句
仿写：可用句式：___ ___ are ___ ___ in ___ of ___ ___ ___ , but how ___ ___ ___ ___ a ___ ___ ___ how much ___ ___ ___ .（例：A team's ranking is judged by its win number only, but how many seasons a young player stays there shapes how big a future contract becomes.）
2. The reason is that extra heat soaked up at the surface is carried down into deeper water, where it exchanges with the atmosphere far more slowly.
翻译：原因在于，地表吸收的多余热量会被带入更深的水层，而在那里它与大气交换的速度要慢得多。
结构：主句为 The reason is that ...，that 引导表语从句；表语从句的主语是 extra heat soaked up at the surface，其中 soaked up at the surface 为过去分词短语作后置定语修饰 extra heat，从句谓语 is carried down into deeper water 为被动语态；逗号后 where it exchanges with the atmosphere far more slowly 为非限制性定语从句，关系副词 where 指代 into deeper water，说明深层水体中热量与大气交换缓慢。
语法：that 引导的表语从句（The reason is that...）+ 过去分词短语作后置定语 + 被动语态 + where 引导的非限制性定语从句
仿写：可用句式：The ___ is that ___ ___ ___ at the ___ is ___ ___ into ___ ___ , where it ___ ___ the ___ ___ ___ ___ .（例：The point is that waste gas trapped inside the engine is piped away to a cooling tower, where it mixes with the outside air at a much gentler pace.）
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