How Aerosols Brighten Clouds — and Cool the Planet | Sarah J. Doherty | TED

Translator: Lucía Campillo Rey

So I'm a climate scientist,

Son climatóloga.

and based on that,

Sabendo iso, seguro que pensades que veño falarvos

I bet you think I'm here to tell you about all the ways

de como causamos o aumento de temperaturas.

that we're making the climate warmer.

But I'm not actually going to do that today

Pero hoxe non farei iso,

because I think you already know that part of the story.

porque creo que esa parte do conto xa a coñecedes.

I want to tell you instead a story about unintended consequences.

En lugar diso, quero relatarvos un conto sobre consecuencias imprevistas.

For many of us, it's really easy to forget

Para moitos de nós, é fácil esquecer

that in addition to emitting a lot of greenhouse gases,

que, ademais de emitir gases de efecto invernadoiro,

humans have been adding a lot of particulate pollution

os humanos engaden contaminación por partículas á atmosfera.

to the atmosphere.

These small particles, which we scientists call aerosols,

Estas pequenas partículas, que os científicos chamamos aerosois,

are responsible for the death of between four and 10 million people a year

son as causantes da morte de entre catro e dez millóns de persoas

cada ano no mundo.

around the globe.

For much of the world, this remains a major public health crisis.

Para gran parte do planeta, isto supón unha crise de saúde pública.

And because of that, there are significant efforts underway

Por ese motivo, lévanse a cabo importantes traballos

to clean up the source of these emissions,

para limpar a fonte destas emisións,

which is fantastic.

e iso é fantástico.

But here's the thing.

Pero hai un problema.

The unintended consequence of doing that

A consecuencia imprevista de facer iso

is that we might actually be accelerating climate warming.

é que, en realidade, poderiamos estar acelerando o quentamento global.

And that's because most of these aerosols actually cool climate.

E débese a que a maior parte dos aerosois, en realidade, baixan as temperaturas.

I spent my career as a climate scientist

Dediquei a miña carreira na climatoloxía

studying how aerosols in the atmosphere around the globe

a estudar como os aerosois da atmosfera de todo o planeta

absorb sunlight in the atmosphere

absorben a luz solar na atmosfera

and increase the reflection of sunlight away from our planet.

e aumentan o reflexo da luz en dirección contraria ó planeta.

Aerosols directly scatter sunlight back to space,

Os aerosois envían a luz do sol directamente de volta ó espazo

and when they mix into clouds,

e, cando se mezclan coas nubes,

they can make clouds brighter or more reflective.

poden facelas máis brillantes e reflectoras.

And both of these effects act to cool the climate

Estes dous efectos axudan a arrefriar as temperaturas

by reducing the amount of sunlight that's available to heat the surface.

ó reducir a cantidade de luz solar que chega a quentar a superficie.

We estimate that right now,

Os nosos cálculos indican que, neste momento,

aerosols from human activities are cooling climate

os aerosois das actividades humanas causan un descenso da temperatura

by about half a degree Celsius.

de aproximadamente medio grao Celsius.

In other words, if it weren't for these climate effects,

É dicir, se non fose por este efecto climático,

estariamos experimentando impactos climáticos

we would already be experiencing significantly worse climate impacts

moito peores dos que xa temos.

than we already are.

So here's a conundrum.

E velaquí un enigma.

As we clean up the air for human health,

Ó limpar o aire para facelo máis san,

we're reducing the concentration of these aerosols in the atmosphere,

reducimos a concentración de aerosois na atmosfera

and we're removing the source of climate cooling.

e eliminamos a fonte de redución da temperatura.

And because these aerosols only last in the atmosphere for about a week,

E, como os aerosois só permanecen na atmosfera unha semana,

o efecto de arrefriamento desaparece case inmediatamente

their cooling effect goes away almost immediately

after we stop emitting them.

cando deixamos de emitilos. Os gases invernadoiro, en cambio,

Unlike greenhouse gases,

which continue to warm for decades to centuries.

seguen quentando durante décadas ou séculos.

Here's a second conundrum.

E velaquí un segundo enigma.

While our best estimate is that aerosols are cooling climate

Os cálculos indican que os aerosois baixan as temperaturas medio grao Celsius,

by about half a degree Celsius,

this effect could be quite a bit smaller,

pero este efecto podería ser algo menor

or it could be a lot bigger.

ou podería ser moito maior.

It's possible that aerosols right now are cooling climate

É posible que os aerosois estean baixando as temperaturas

by up to almost a full degree Celsius.

ata un grao Celsius completo.

And because we don't know

Ó non saber cal é o efecto de arrefriamento

how much of a cooling effect these aerosols are currently providing,

que proporcionan os aerosois actualmente,

we don't know how much of a climate warming they're going to unmask

non sabemos canto quentamento global deixarán ó descuberto

as we clean up the air.

cando limpemos o aire.

So let's step back and talk a little bit more

Imos facer un inciso para falar un pouco

about how it is that aerosols cool climate

de como os aerosois arrefrían o planeta

and why these effects are so uncertain.

e de por que os efectos son tan incertos.

So aerosols mostly cool climate

A principal forma na que arrefrían o planeta

by increasing the reflection of sunlight from clouds.

é aumentando o reflexo da luz solar nas nubes.

This increase in cloud brightness from aerosols

En xeral, o aumento de brillo nas nubes polos aerosois

is not generally very visibly apparent

non se percebe a simple vista,

because clouds are just so naturally variable in their brightness.

porque as nubes teñen por natureza un brillo moi variable.

But a case where it is really visually obvious

Un caso onde si que é moi perceptible

is in what we call ship tracks.

é no que chamamos ronsel dos barcos.

So what you're looking at here is a satellite image

Isto que vedes é unha imaxe por satélite da costa oeste de América do Norte.

off the west coast of North America.

And you can see that there are these lines of clouds

Veredes que hai unhas liñas de nubes

that are brighter or more reflective than the clouds around them.

que son máis brillantes ou reflectoras que as que as rodean.

So to understand what's going on here,

Para entender que pasa aquí,

you first have to know that cloud droplets always form on an aerosol.

tedes que saber que as gotículas das nubes sempre se forman sobre un aerosol.

Out over the ocean, there's just not generally that many aerosols

En mar aberto non adoita haber moitos aerosois na atmosfera.

in the atmosphere.

So what you end up with

O que atoparemos será unha nube

is a cloud with a small number of larger droplets.

formada por un número reducido de gotículas de maior tamaño.

Well, along comes your ship,

E por aí vén o noso barco,

and it's adding aerosols to the atmosphere

engadindo aerosois á atmosfera e ás nubes.

and to the clouds.

The water gets distributed over those aerosols,

A auga distribúese sobre eses aerosois

and you now have a cloud with a large number of smaller droplets.

e obtemos unha nube cun gran número de gotículas de menor tamaño.

This change in droplet size increases the reflectivity of the cloud.

O cambio no tamaño das gotículas aumenta a reflectancia da nube.

Now this is not just happening where ship emissions are mixing into clouds.

E isto non só pasa

onde as emisións dos barcos se mesturan coas nubes.

This is actually mostly happening over broad regions of the planet

En realidade, ocorre principalmente sobre grandes rexións do planeta

where pollution aerosols mix into clouds.

onde hai aerosois da contaminación que se mesturan coas nubes.

So I've shown you here a very striking example

Mostreivos un exemplo moi evidente

of where pollution aerosols are clearly making clouds more reflective.

de onde os aerosois claramente fan as nubes máis reflectoras.

But this actually doesn't always happen.

Pero isto non sempre ocorre.

And why is that?

E por que?

Well, I'm going to give you scientists' two very favorite answers.

Contestareivos con dúas das respostas preferidas dos científicos.

It’s complicated. And it depends.

É complicado. E depende.

(Risas)

(Laughter)

If you have ever looked at clouds for very long,

Se algunha vez mirastes nubes durante un tempo

you could see that they’re incredibly complex,

veriades que son incriblemente complexas

and they are constantly evolving.

e que están en constante evolución.

When you add aerosols to clouds,

Ó engadir aerosois ás nubes,

it doesn't just change their droplet size,

non só cambia o tamaño das gotículas,

it actually can then change how they evolve

senón que tamén pode cambiar como evolucionan

in ways that also affect cloud brightness.

en formas que afectan ó brillo das nubes.

Depending on the details of the atmospheric conditions,

Dependendo dos detalles das condicións atmosféricas,

clouds can be made either more or less reflective with the addition of aerosols,

as nubes serán máis ou menos reflectoras a causa dos aerosois,

or not really changed at all.

ou pode que non cambien en absoluto.

But what we do know is that under the right conditions,

O que si que sabemos é que, baixo as condicións axeitadas,

aerosol additions to clouds can make them quite a bit brighter.

a adición de aerosois pode facer as nubes bastante máis brillantes.

So this poses an interesting question.

E isto presenta unha pregunta interesante.

Might it be possible to rapidly reduce climate warming

Sería posible reducir rapidamente o quentamento global

by mimicking this effect

imitando o efecto dos aerosois da contaminación nas nubes

that pollution aerosols are already having on clouds,

but do so by adding natural aerosols rather than pollution to clouds?

pero con aerosois naturais

en lugar de contaminar as nubes?

Specifically by adding sea salt aerosol to clouds over the ocean,

En concreto, engadindo aerosois de sal mariño

a nubes sobre o océano

where sea salt aerosols already act as seeds for cloud droplet formation.

onde estes aerosois xa actúan como xermes de formación de gotículas.

Well we start with studying this problem using computer models.

Comezamos estudando o problema con modelos de computación.

And when we add tiny sea salt aerosols to the clouds over the ocean

Se engadimos aerosois de sal mariño ás nubes sobre o océano nestes modelos,

in global climate models,

we find that brightening just a fraction of the clouds over the ocean

vemos que aumentar o brillo dunha pequena parte das nubes do océano

does, in fact, rapidly and significantly reduce climate warming

efectivamente reduce as temperaturas de forma rápida e significativa

from greenhouse gases.

fronte ós gases invernadoiro.

So these models indicate it is possible.

Os modelos indican que é posible.

But here's the problem.

Pero hai un problema.

These global-scale models

Os modelos globais que usamos para estudar o impacto no clima

used to study the climate impacts of marine cloud brightening,

do brillo das nubes mariñas

lack the ability to resolve all of these detailed interactions

non son quen de resolver tódolos detalles das interaccións

between aerosols and clouds.

entre os aerosois e as nubes.

So they can't tell us how much cloud brightening is possible or where.

Non poden dicirnos canto se pode aumentar o brillo nin onde.

For that problem,

Para ese problema, temos que acudir a modelos

we have to turn to models that cover much more localized areas of the globe

que cobren áreas do planeta moito más localizadas

but that include many, many more details about aerosols, clouds

pero que inclúen moitos máis detalles

sobre aerosois, nubes e como interactúan.

and how they interact.

So what we really need is better real-world data

E o que nos fai falta son mellores datos do mundo real

that we can use to test and inform these models

que poderemos usar para probar e alimentar estes modelos

that we use to study marine cloud brightening.

cos que estudamos o brillo das nubes mariñas.

Now with this problem, as with many problems in the world,

Neste caso, como con moitos outros problemas do mundo,

the devil is in the details.

a importancia está nos detalles.

Many of the most uncertain aspects

Moitos dos aspectos máis descoñecidos do potencial do brillo das nubes mariñas

of the potential for marine cloud brightening

have to do with how really small-scale air motions in clouds,

teñen que ver con como pequenas correntes de aire nas nubes,

we're talking over like a few square kilometers,

en áreas duns poucos quilómetros cadrados,

respond to the addition of aerosols.

responden á adición de aerosois.

So being able to systematically study how clouds respond to aerosols,

Ser quen de estudar sistemáticamente como responden as nubes ós aerosois,

just like a single plume of aerosols,

como, por exemplo, unha única columna de aerosois,

over a small area of clouds,

afecta a unha pequena área de nubes,

could go a long way to improving these climate models.

podería supoñer unha gran mellora dos modelos climáticos.

And I want to tell you today about a powerful approach

Hoxe quero falarvos dun potente método

that our team is developing to do just that.

que o noso equipo desenvolve para conseguir iso.

So based on what I just said,

Despois do que vos acabo de dicir, non vos sorprenderá saber

you probably won't be surprised to learn

that that approach is to add a single plume of sea salt aerosols

que o método consiste en engadir unha columna de aerosois de sal mariño

to a small area of clouds over the ocean

a unha pequena área de nubes sobre o océano

and see how those clouds respond.

e ver como responden as nubes.

Basically, to make a single clean ship track.

Basicamente, fabricar un ronsel claro e único.

Now, the observations for studies like this

As observacións para estes estudos

would look a lot like those we've been doing for decades

serían moi similares ás que se fan desde hai décadas

to study how pollution aerosols are already affecting clouds.

para ver como os aerosois da contaminación afectan as nubes.

Research aircraft filled with specialized instruments

As aeronaves para investigación con instrumental especializado

can be used to measure in great detail the atmospheric conditions

poden empregarse para medir con detalle as condicións atmosféricas,

the aerosols, the clouds

os aerosois e as nubes e como todo isto varía.

and how they all vary.

The difference between what we've done here in the past

A diferenza entre o que faciamos no pasado

and what we would do with these new controlled aerosol studies,

e o que fariamos con estes novos estudos sobre aerosois

é que seriamos capaces de comparar realmente

is that we would be able to actually compare clouds

nubes que teñen concentracións de aerosois distintas

that have different aerosol concentrations

but that are otherwise the same.

pero que son iguais en todo o demais.

This would allow us to quantify where changes in cloud reflectivity

Isto permitiríanos cuantificar os cambios na reflectancia das nubes

are actually being caused by the aerosols,

que se deben realmente ós aerosois

rather than just varying due to other factors.

fronte a variacións debidas a outros factores.

Now it turns out that generating the sea salt aerosol plume

Resulta que xerar a columna de aerosois de sal mariño

with the right characteristics for doing these controlled aerosol studies

coas características axeitadas para os estudos de aerosois controlados

is a significant technological challenge.

é un auténtico reto tecnolóxico.

The aerosols need to be just right.

Os aerosois teñen que ser perfectos.

To date,

Ata hoxe, ninguén demostrou ter a capacidade

no one has demonstrated the ability to generate

de xerar tanto o tamaño como a cantidade de aerosois necesarios para estes estudos

both the size and quantity of aerosols you would need to do these studies

where you would consistently and appreciably brighten marine clouds.

para aumentar o brillo das nubes mariñas de xeito apreciable e constante.

As a climate scientist trying to better understand

Como climatóloga que intenta comprender

how aerosols affect clouds and climate,

o efecto dos aerosois nas nubes e o clima,

I am really thrilled to be part of a team

faime moita ilusión formar parte dun equipo

that is developing a new instrument to meet that challenge.

que está creando un aparello para superar o reto.

Our new cloud aerosol research instrument is specifically designed

O aparello de investigación de aerosois en nubes

está deseñado para xerar un gran número de aerosois de sal mariño

to generate a very large number of very, very tiny sea salt aerosols.

moi, moi pequenos.

These aerosols are about 1,000th of the width of a human hair,

Son aerosois mil veces máis finos que un pelo humano,

because that's the size that's ideal for marine cloud brightening.

xa que ese é o tamaño ideal para aumentar o brillo das nubes mariñas.

I'm also really excited to be able to tell you

Tamén me fai ilusión poder dicirvos

que xa empezamos os estudos científicos con este aparello.

that we've just started our first scientific studies with this instrument.

This happened just two weeks ago.

Isto foi hai só dúas semanas.

We've set up our new Coastal Atmospheric Aerosol Research and Engagement Facility

Instalamos o CAARE,

siglas da instalación de investigación de aerosois na atmosfera costeira,

on the flight deck of the USS Hornet Sea, Air and Space Museum

na cuberta de voo do Museo Marítmo, Aéreo e Espacial do USS Hornet

in Alameda, California.

en Alameda, en California.

So on the Hornet,

Neste buque, realizamos análises

we are making observations at multiple locations

en diferentes puntos da cuberta de voo

along the flight deck

of the sea salt aerosol plume

da columna de aerosois de sal mariño que xera o noso novo aparello.

that is being generated with our new instrument.

These measurements are going to allow us to study how the aerosol evolves

Estas medicións permitirannos estudar como evolucionan os aerosois

as it's transported towards clouds.

ó ser transportados cara ás nubes.

It's also letting us study whether or not this instrument is delivering

Tamén nos permiten estudar se o aparello

está emitindo os aerosois coas características axeitadas

the right aerosol, with the right characteristics

for use in later studies at sea,

para usar nos futuros experimentos no océano

of the single plume experiment and how clouds respond.

sobre a resposta das nubes a unha soa columna de aerosois.

We've set up this study specifically at a museum

Instalamos este estudo nun museo

to make it easily accessible to the public,

para facelo facilmente accesible ó publico,

educators and other researchers.

así como a educadores e investigadores.

And we consider this level of openness

Cremos que este nivel de transparencia é unha parte esencial do noso programa,

to be a really important part of our program.

And that's because we're hoping

porque esperamos que o traballo da instalación CAARE

that the work at the CAARE research facility

can be the start of broader international engagement in this research,

inicie un amplo compromiso internacional neste campo,

particularly by our colleagues in historically marginalized communities

especialmente polos nosos colegas de comunidades historicamente marxinadas,

who are the most vulnerable to climate change.

que son os máis vulnerables ante o cambio climático.

Their direct engagement in this research is absolutely critical

A súa participación directa nas investigacións é esencial

to having equitable and informed discussions

para ter debates equitativos e informados

about whether we ever would use marine cloud brightening to cool climate

sobre se nalgún momento podemos usar o brillo das nubes mariñas

para arrefriar o planeta e afrontar os riscos climáticos.

as a way of addressing climate risks.

Now don’t get me wrong,

Non me interpretedes mal.

marine cloud brightening will not reverse the effects of greenhouse gases.

Aumentar o brillo das nubes mariñas

non reverterá os efectos dos gases invernadoiro.

This is not a solution to the climate crisis.

Isto non é unha solución á crise climática.

I really have to repeat that.

Teño que insistir.

This is not a solution to the climate crisis.

Isto non é unha solución á crise climática.

However, marine cloud brightening might be a way of treating

Non obstante, aumentar o brillo das nubes

pode ser o xeito de tratar o principal síntoma do problema:

the main symptom of the problem,

which is too much heat in the atmosphere and ocean.

demasiada calor na atmosfera e no océano.

We believe that the world needs the best information possible

Cremos que o mundo necesita a mellor información posible

to decide whether approaches like marine cloud brightening

para decidir se métodos como o aumento do brillo das nubes

might be a component of how we chart a safer course

poden ser parte do camiño que elixamos como máis seguro

into a future that now includes a rapidly and dangerously warming climate.

para un futuro que inclúe un clima que se quenta de xeito rápido e perigoso.

We also believe it's really critical

Tamén cremos que é esencial

that we better understand the evolving role of aerosols

ter un mellor coñecemento do papel cambiante dos aerosois

in climate change and the climate system

no cambio climático e no sistema climático

if we don't want to be flying blind

se non queremos ir a cegas

into the coming couple decades of climate change.

nas próximas dúas décadas do cambio climático.

I hope that I've left you as excited as I am

Espero que agora esteades tan ilusionados coma min

about these new capabilities we're developing

coas novas competencias que estamos desenvolvendo

to study these really important questions.

para estudar estas importantes cuestións.

And I invite you all to come join us at our new CAARE research facility.

Invítovos a todos a visitarnos na instalación CAARE.

Thank you.

Grazas.

(Applause)

(Aplausos)