Is the weather actually becoming more extreme? - R. Saravanan

翻译人员: Qian Xu 校对人员: Wanting Zhong

From 2016 to 2019,

在 2016 到 2019 年间，

meteorologists saw record-breaking heat waves around the globe,

气象学家在全球观测到了 前所未有的热浪，

rampant wildfires in California and Australia,

加利福尼亚州与 澳大利亚山火肆虐，

and the longest run of category 5 tropical cyclones on record.

五级热带飓风的持续时间 也创下了纪录。

The number of extreme weather events has been increasing for the last 40 years,

过去 40 年来， 极端天气事件发生的次数在持续增加，

and current predictions suggest that trend will continue.

而当前的预测表明， 这一趋势还会继续下去。

But are these natural disasters simply bad weather?

但这些自然灾害 仅仅是 “天气不好” 吗？

Or are they due to our changing climate?

还是源自我们的气候变化？

To answer this question

要回答这个问题，

we need to understand the differences between weather and climate—

我们首先要理解 天气与气候之间的区别——

what they are, how we predict them, and what those predictions can tell us.

它们是什么？如何进行预测？ 预测结果又代表了什么？

Meteorologists define weather as the conditions of the atmosphere

气象学家将 “天气” 定义为

在某个特定时间及地点的大气状况。

at a particular time and place.

Currently, researchers can predict a region’s weather for the next week

目前，研究人员能够以 大约 80% 的准确率

with roughly 80% accuracy.

预测出某个地区 接下来一周的天气。

Climate describes a region’s average atmospheric conditions

“气候” 描述的则是某个地区 在一个月或以上的时间段内的

over periods of a month or more.

平均大气状况。

Climate predictions can forecast average temperatures for decades to come,

气候预测能够预估 未来数十年的平均气温，

but they can’t tell us what specific weather events to expect.

但无法预测可能发生的 具体天气事件。

These two types of predictions give us such different information

这两种预测之所以能提供 如此不同的信息，

because they’re based on different data.

是因为它们分别基于不同的数据。

To forecast weather,

在预测天气时，

meteorologists need to measure the atmosphere’s initial conditions.

气候学家要测量大气的初始状况：

These are the current levels of precipitation, air pressure, humidity,

当前的降水量、气压、湿度、

wind speed and wind direction that determine a region’s weather.

风速及风向，决定了 该地区的天气状况。

Twice every day, meteorologists from over 800 stations around the globe

来自全球 800 多个气象站的 气候学家

每天会向大气中 释放两次探空气球。

release balloons into the atmosphere.

These balloons carry instruments called radiosondes,

这些气球搭载的仪器 叫做“无线电探空仪”，

which measure initial conditions

它会测量大气的初始状况，

and transmit their findings to international weather centers.

然后将结果传送给国际气象中心。

Meteorologists then run the data through predictive physics models

气象学家将数据输进 物理预测模型，

that generate the final weather forecast.

生成最终的天气预报。

Unfortunately, there’s something stopping this global web of data

遗憾的是，某件事情 妨碍了这张全球数据网

from producing a perfect prediction:

做出完美的预测：

weather is a fundamentally chaotic system.

天气本质上是一个混沌系统。

This means it’s incredibly sensitive and impossible to perfectly forecast

这意味着它极度敏感， 若没有对系统中所有因素了如指掌，

without absolute knowledge of all the system’s elements.

就不可能做出完美的预测。

In a period of just ten days,

在短短的十天内， 即便是极度微小的干扰，

even incredibly small disturbances can massively impact atmospheric conditions—

也能对大气状况造成巨大的影响——

making it impossible to reliably predict weather beyond two weeks.

因此，要准确预测 两周以后的天气是不可能的。

Climate prediction, on the other hand, is far less turbulent.

相对而言，气候预测 则远没有这么大的不确定性。

This is partly because a region’s climate is, by definition,

部分原因在于，气候的定义本身

the average of all its weather data.

就是一个地区 所有天气数据的平均值。

But also because climate forecasts ignore

除此以外，

气候预测会忽略 大气当前的状况，

what’s currently happening in the atmosphere,

and focus on the range of what could happen.

而注重可能出现的 大气状况的范围。

These parameters are known as boundary conditions,

这些参数被称为“边界条件”，

and as their name suggests, they act as constraints on climate and weather.

顾名思义，它们代表了 气候及天气状况的边界限制。

One example of a boundary condition is solar radiation.

边界条件的一个例子是太阳辐射。

By analyzing the precise distance and angle between a location and the sun,

通过分析某个地区 与太阳间的精确距离和角度，

we can determine the amount of heat that area will receive.

我们就能判断该地区所接收的热量。

And since we know how the sun behaves throughout the year,

既然我们知道 一年中太阳的运行模式，

we can accurately predict its effects on temperature.

就能够准确地预测 它对气温的影响。

Averaged across years of data,

对多年的数据取平均值后，

this reveals periodic patterns, including seasons.

就能发现周期性规律，例如季节。

Most boundary conditions have well-defined values that change slowly, if at all.

边界条件的数值大多定义明确、 变动很慢，甚至完全不变。

This allows researchers to reliably predict climate years into the future.

因此，研究者能对未来数年的气候 做出可靠的预测。

But here’s where it gets tricky.

但问题来了。

Even the slightest change in these boundary conditions

这些边界条件 即使发生极其微小的变化，

represents a much larger shift for the chaotic weather system.

也对混沌的天气系统 产生巨大的扰动。

For example, Earth’s surface temperature has warmed by almost 1 degree Celsius

例如，过去 150 年以来，

地球的表面温度 上升了将近 1 摄氏度。

over the last 150 years.

This might seem like a minor shift,

这变化看似微小，

but this 1-degree change has added the energy equivalent

但这 1 摄氏度的变化 向大气层中释放的能量

of roughly one million nuclear warheads into the atmosphere.

相当于约 100 万颗核弹。

This massive surge of energy has already led to a dramatic increase

这一波巨大的能量

已导致了热浪、干旱及 风暴潮的数量急剧增加。

in the number of heatwaves, droughts, and storm surges.

So, is the increase in extreme weather due to random chance, or changing climate?

那么，极端天气的增长 究竟是出于偶然还是气候变化？

The answer is that—

答案是——

while weather will always be a chaotic system—

虽然天气系统永远是混沌的，

shifts in our climate do increase the likelihood of extreme weather events.

但气候变化确实会增加 极端天气事件的概率。

Scientists are in near universal agreement that our climate is changing

科学家们几乎一致同意， 我们的气候在产生变化，

and that human activity is accelerating those changes.

且人类活动正在加剧这些变化。

But fortunately,

所幸，

we can identify what human behaviors are impacting the climate most

我们能通过追踪 哪些边界条件发生了变动，

来判断哪些人类行为 对气候造成的影响最大。

by tracking which boundary conditions are shifting.

So even though next month’s weather might always be a mystery,

所以，虽然下个月的天气 可能始终是个谜，

we can work together to protect the climate for centuries to come.

但我们仍然可以为共同保护未来 数百年的气候而努力。