Transcript: Kate Marvel: How Climate Change Works | May 28, 2019

Steve sits in the studio. He's slim, clean-shaven, in his fifties, with short curly brown hair. He's wearing a gray suit, checkered pink shirt, and spotted gray tie.

A caption on screen reads "How climate change works. @spaikin, @theagenda."

Steve says FEEDBACK IS A TERM
USED IN CLIMATE CHANGE SCIENCE
TO REFER TO THOSE FACTORS THAT
CAN SPEED UP OR SLOW DOWN THE
PACE OF CHANGE.
FOUR ELEMENTS ARE KEY TO
UNDERSTANDING THESE EFFECTS:
CLOUDS, RAIN, TREES AND ICE.
WITH US TO EXPLAIN: KATE MARVEL,
ASSOCIATE RESEARCH SCIENTIST AT
COLUMBIA UNIVERSITY AND AT
NASA'S GODDARD INSTITUTE FOR
SPACE STUDIES.

Kate is in her late thirties, with long straight blond hair. She's wearing glasses, a dark blue blazer with a matching blouse, and a pendant stone necklace.

Steve continues AND WE ARE DELIGHTED TO WELCOME
YOU TO THE PROVINCE OF ONTARIO.
SO NICE FOR YOU TO MAKE SOME
TIME FOR US.

Kate says THANK YOU SO MUCH FOR HAVING
ME.

Steve says YOU ARE A CLIMATE
SCIENTIST WHO USES COMPUTER
SIMULATIONS TO FIGURE OUT HOW
CLIMATE CHANGE IS GOING TO
HAPPEN.
HOW DO... WE HEAR A LOT ABOUT
THIS AND IT'S VERY
CONTROVERSIAL, SO TELL US HOW
THESE THINGS ACTUALLY WORK.

The caption changes to "Simulating the future."

Kate says SO WHEN I TALK ABOUT CLIMATE
MODELS, THE THING THAT I WANT TO
MAKE REALLY CLEAR IS THAT ALL
MODELS ARE WRONG BUT SOME MODELS
ARE USEFUL.
WE ARE NEVER GOING TO HAVE A
COMPUTER SIMULATION THAT IS ABLE
TO CAPTURE ALL OF THE NUANCES OF
REALITY.
AND IF WE DID HAVE ONE, THAT
WOULD BE LIKE THE MATRIX, RIGHT?
THAT MIGHT BE PRETTY CREEPY.
AND SO WHAT WE WANT IS TO MAKE
SURE THAT THE MODELS THAT WE'RE
USING TO PROJECT FUTURE
CONDITIONS ARE RELIABLE, ARE
TELLING US SOMETHING USEFUL, AND
ARE REVEALING THINGS THAT WE
UNDERSTAND ABOUT THE PHYSICS AND
CHEMISTRY OF THE CLIMATE SYSTEM.

Steve says AND IN YOUR VIEW, HOW
RELIABLE ARE WHAT WE HAVE RIGHT
NOW?

The caption changes to "Kate Marvel. Columbia University."

Kate says I THINK THEY ARE VERY FIT FOR
PURPOSE.
I THINK WE DON'T KNOW
EVERYTHING, BUT WE DON'T KNOW
NOTHING.

Steve says HMM.
HOW FAR INTO THE FUTURE CAN
THESE CLIMATE MODELINGS TAKE US?
WITH ACCURACY?

Kate says WITH ACCURACY.
WELL, WE ROUTINELY PROJECT TO
THE END OF THE CENTURY, SO THE
YEAR 2100, AND THESE ARE
PROJECTIONS, NOT PREDICTIONS.
WE'RE NOT SAYING THESE ARE
THINGS THAT ARE DEFINITELY GOING
TO HAPPEN.
AND THAT'S BECAUSE THERE IS A
LOT OF UNCERTAINTY.
THERE'S UNCERTAINTY ABOUT WHAT
PEOPLE ARE GOING TO DO.

Steve says WE COULD CHANGE OUR
BEHAVIOUR, CHANGE THE MODELLING.

Kate says EXACTLY.
I'M A PHYSICIST.
IT'S NOT MY JOB TO TRACK PEOPLE.
BUT THERE IS ALSO SOME
UNCERTAINTY IN THE PHYSICAL
SYSTEM.
THERE'S UNCERTAINTY ABOUT HOW
THE ACTUAL CLIMATE WILL REACT TO
LOTS OF CARBON DIOXIDE IN THE
ATMOSPHERE.

Steve says YOU CAN LOOK BACKWARDS
AS WELL, LIKE THE TREES AND THE
RINGS AND ALL THAT BUSINESS?
CAN YOU TELL ME ABOUT THAT?

The caption changes to "Kate Marvel. Goddard Institute for Space Studies."

Kate says EXACTLY.
SO WE CAN RUN THE MODELS FORWARD
IN TIME AND WE CAN ALSO RUN THEM
BACKWARD IN TIME.
SO WE RECENTLY HAD A STUDY THAT
CAME OUT THAT WAS SAYING CLIMATE
MODELS ARE SAYING IN THE EARLY
HALF OF THE 20TH CENTURY YOU
SHOULD SEE A FAINT BUT
NOTICEABLE IMPRINT OF HUMAN
INFLUENCE ON GLOBAL DROUGHT
CONDITIONS, AND IT TURNS OUT
THAT IF YOU LOOK AT TREE RINGS,
IF YOU LOOK AT THOUSANDS OF
DIFFERENT TREE RINGS, WHICH GIVE
YOU A PICTURE OF DROUGHT
CONDITIONS AT THE BEGINNING OF
LAST CENTURY, THOSE SAY THE SAME
THING.
AND SO THAT WAS AMAZING BECAUSE
THAT KIND OF ENHANCED OUR
CONFIDENCE IN THE MODELS WHICH
WERE SAYING YOU SHOULD SEE THIS.
AND WHAT THE MODELS WERE SAYING
YOU SHOULD SEE WERE REFLECTED IN
THE TREES.

Steve says AND WHAT IN FACT DID
THEY SEE?

The caption changes to "Kate Marvel, @DrKateMarvel."

Kate says THEY SAID WE SHOULD SEE A
SINGLE PRINT OF HUMAN INFLUENCE.
SO DRYING AND THE AMERICAN
SOUTHWEST, DRYING IN THE
MEDITERRANEAN, A LITTLE BIT OF
DRYING IN AUSTRALIA.
AND THAT COHERENT PICTURE OF
CHANGE IS INDEED WHAT WAS HAPPENING.

The caption changes to "Connect with us: Twitter: @theagenda; Facebook, agendaconnect@tvo.org, Instagram."

Steve says WE'RE GOING TO GO
THROUGH A BUNCH OF TERMS BECAUSE
IF I'VE GOT SOMEBODY AS SMART AS
YOU HERE, IT WOULD BE SILLY NOT
TO TAKE ADVANTAGE OF YOUR
EXPERTISE TO BETTER UNDERSTAND
ALL THE DIFFERENT FORCES THAT
ARE BRINGING CLIMATE CHANGE UPON
US.
SO LET'S GO THROUGH SOME OF
THESE.
FORCINGS. WHAT ARE FORCINGS?

Kate says SO THE CLIMATE IS DETERMINED
BY THE BALANCE OF ENERGY.
WE GET MOST OF OUR ENERGY FROM
THE SUN, 99.99 percent OF ALL ENERGY,
AND THE THE EARTH TAKES THAT
SUN ENERGY, HEATS UP, AND SENDS
IT BACK INTO SPACE AS THERMAL
AND INFRARED RADIATION.
AND ANYTHING THAT UPSETS THAT
BALANCE OF ENERGY IN AND ENERGY
OUT IS WHAT WE CALL A FORCING.
SO THERE CAN BE NATURAL
FORCINGS, LIKE CHANGES IN THE
SUN'S OUTPUT, OR CHANGES IN THE
EARTH'S ORBIT, OR VOLCANIC
ERUPTIONS THAT PUT A BUNCH OF
GAS AND DUST IN THE ATMOSPHERE
AND BLOCK THE SUNLIGHT.
BUT WE KNOW THAT HUMANS CAN ALSO
FORCE CHANGE.
SO CARBON DIOXIDE, GREENHOUSE
GASES, INCREASING THOSE IN THE
ATMOSPHERE INCREASES THE HEAT
THAT GETS TRAPPED FROM THE
PLANET, AND SO THAT IS A FORCING
AS WELL, BECAUSE THAT IS
UPSETTING THAT BALANCE, THAT
VERY DELICATE BALANCE OF ENERGY.

Steve says THAT'S WHAT I WAS
GOING TO ASK YOU, HOW DELICATE
IS THE BALANCE.

Kate says I DON'T KNOW IF I HAVE A
SCIENTIFIC QUALIFICATION OF HOW
DELICATE IT IS, BUT WHEN WE...
WE GET 340 WATTS FROM THE SUN
FOR EVERY SQUARE METRE OF THE
PLANET, AND IF WE DOUBLED CARBON
DIOXIDE IN THE ATMOSPHERE FROM
PRE-INDUSTRIAL CONCENTRATIONS,
THAT WOULD BE ABOUT 3.7 WATTS
PER SQUARE METRE, SO WE'RE
TALKING ABOUT A TINY FRACTION OF
THE ENERGY THAT WE GET FROM THE
SUN, BUT IT TURNS OUT THAT THAT
HAS REALLY, REALLY SEVERE
CONSEQUENCES.

Steve says SO IT IS A VERY
DELICATE BALANCE.
WE COULD MESS IT UP WITHOUT TOO
MUCH EFFORT.

Kate says EXACTLY.

Steve says OKAY, NEXT ONE,
ANOTHER TERM THAT WE HEAR,
FEEDBACKS.
THIS IS NOT FEEDBACK LIKE FROM
THE SPEAKER SYSTEM WHEN YOU'VE
GOT TWO OF THEM TOO CLOSE
TOGETHER.
HOW DO THEY FIGURE IN YOUR
WORLD?

The caption changes to "Feedbacks."

Kate says THE WAY I LIKE TO THINK ABOUT
THIS IS IN TERMS OF THE
DIFFERENCE BETWEEN GLOBAL
WARMING AND CLIMATE CHANGE,
WHICH PEOPLE USE INTERCHANGEABLY
BECAUSE THEY'RE RELATED.

Steve says BUT THEY SHOULDN'T?

Kate says SO YOU CHANGE TEMPERATURE,
AND THAT LEADS TO CHANGES IN
ASPECTS OF THE CLIMATE.
RAINFALL PATTERNS, CLOUD COVER,
WHERE THE ICE IS, AND THOSE
CHANGES CAN THEMSELVES CHANGE
THE TEMPERATURE.
IT CAN FEEDBACK ON TO THE
TEMPERATURE.
SO THAT'S WHY WE CALL THEM
FEEDBACKS.

Steve says OKAY, LET'S GO THROUGH
THEM.
CLOUDS, HOW DO THEY CHANGE THE
FEEDBACKS?

A slate appears on screen, with the title "Climate feedbacks."

The slate shows a picture of a stormy sky over a green plain, and the word "Clouds."
Quoted from NASA's Jet Propulsion Laboratory, nasa.gov. May 17, 2019.

Kate says CLOUDS ARE ONE OF THE LEAST
UNDERSTOOD ASPECTS OF THE
CLIMATE SYSTEM, AND THAT'S
BECAUSE CLOUDS PLAY THIS DUAL
ROLE IN THE CLIMATE SYSTEM.
THEY BOTH BLOCK SUNLIGHT, WHICH
MEANS THEY HAVE A COOLING
EFFECT, BUT THEY ALSO TRAP HEAT
COMING UP FROM THE PLANETS, SO
CLOUDS THEMSELVES HAVE A
GREENHOUSE EFFECT.
SO CLOUDS BOTH WARM AND COOL THE
PLANET, AND WE KNOW THERE ARE
DIFFERENT KINDS OF CLOUDS.
THE HIGH THIN WISPY CLOUDS, THE
LOW THICK CLOUDS, THEY LIVE ALL
OVER THE PLANET, AND IT TURNS
OUT THAT THEY ARE ACTUALLY VERY
HARD TO SIMULATE IN A CLIMATE
MODEL.
AND THAT'S BECAUSE CLOUDS ARE
SIMULTANEOUSLY REALLY SMALL...
YOU GET CLOUDS WHEN YOU PUT A
DUST SCREEN IN THE ATMOSPHERE
AND TINY DROPLETS OF WATER
COAGULATE AROUND THAT DUST
GRAIN, SO THAT'S HAPPENING AT A
REALLY SMALL SCALE.
BUT THEN AT THE SAME TIME CLOUDS
COVER A REALLY LARGE FRACTION OF
THE ENTIRE SURFACE OF THE
PLANET.
SO IN ORDER TO GET CLOUDS
PERFECTLY RIGHT, YOU NEED A
CLIMATE MODEL CAPABLE OF
TRACKING EVERY DUST GRAIN AND
EVERY WATER DROPLET IN THE
ENTIRE ATMOSPHERE.

Steve says THAT SOUNDS
COMPLICATED.

Kate says WE DON'T HAVE COMPUTERS THAT
ARE POWERFUL ENOUGH TO DO THAT.

Steve says SO YOU HAVE NOT BEEN
ABLE TO DETERMINE WHETHER OR NOT
CLOUDS ARE ACTUALLY PROVIDING
MORE BENEFIT AS OPPOSED TO MORE
HARM AS IT RELATES TO CLIMATE
CHANGE?

Kate says SO CLOUDS ARE THE BIG
WILDCARD.
IF YOU LOOK AT EVERY DIFFERENT
CLIMATE MODEL USED RIGHT NOW,
EVERY SINGLE ONE OF THEM
PROJECTS WARMING IN RESPONSE TO
INCREASED CARBON DIOXIDE
EMISSIONS.
BUT THE DEGREE OF THEIR WARMING
IS COMPLETELY DIFFERENT.
SOME SAY WE COULD BE EXPECTING 2
OR 3 degrees CELSIUS BY THE END OF THE
CENTURY, AND SOME ARE SAYING 5
OR 6 degrees.
AND TO PUT THAT INTO CONTEXT FOR
YOU, 4.5 degrees IS THE DIFFERENCE
BETWEEN NOW AND THE LAST ICE
AGE.
SO WE ARE TALKING ABOUT THE
DIFFERENCE BETWEEN VERY BAD AND
CATASTROPHE HERE.
AND IT TURNS OUT THAT THE REASON
MODELS DISAGREE ON HOW HOT IT'S
GOING TO GET IN THE FUTURE IS
BECAUSE MODELS DISAGREE ON WHAT
CLOUDS ARE GOING TO DO.
BUT IN NO MODEL DO CLOUDS
REVERSE THAT WARMING TREND.
IN NO MODEL DO CLOUDS KIND OF
SAVE US FROM GLOBAL WARMING.

Steve says SO EITHER WAY,
REGARDLESS OF WHO'S RIGHT, IT
BEHOOVES US TO DO SOMETHING
ABOUT THIS?

Kate says I AGREE.

Steve says OKAY.
SECOND CLIMATE FEEDBACK,
PRECIPITATION.
WHAT EFFECT DOES THAT HAVE?

The slate reappears and the word "Precipitation" is added.

Kate says SO PRECIPITATION IS WATER
THAT COMES FROM THE ATMOSPHERE,
AND WE KNOW THAT WARMER AIR
HOLDS MORE WATER VAPOUR.
SO FOR EXAMPLE... WELL, WE KNOW
DUE TO THE LAWS OF PHYSICS THAT
YOU INCREASE THE TEMPERATURE OF
THE ATMOSPHERE BY 1 degrees CELSIUS,
YOU CAN HOLD 7 percent MORE WATER
VAPOUR.
AND WHAT THAT MEANS IS THAT THAT
IS MORE WATER VAPOUR THAT LIVES
IN THE ATMOSPHERE THAT CAN BE
DUMPED ON US IN THE FORM OF
EXTREME RAINFALL, AND SO THAT'S
WHY WE EXPECT TO SEE DOWNPOURS
GETTING HEAVIER IN THE FUTURE.
NOW THE IMPORTANT PART OF THAT
FROM A FEEDBACK PERSPECTIVE IS
THAT WATER VAPOUR ITSELF IS A
VERY POWERFUL GREENHOUSE GAS.
SO IF WE PUT CARBON DIOXIDE IN
THE ATMOSPHERE, THAT WARMS UP
THE ATMOSPHERE.
AND THEN IT HOLDS MORE WATER
VAPOUR.
THE WATER VAPOUR TRAPS MORE HEAT
AND THEN THAT FEEDS BACK ON TO
THE TEMPERATURE.
SO THAT'S AN EXAMPLE OF
SOMETHING, AND I'M REALLY SORRY
FOR THIS TERMINOLOGY, THAT WE
CALL A POSITIVE FEEDBACK,
BECAUSE WHEN NORMAL PEOPLE HERE
POSITIVE FEEDBACK, THEY THINK,
YOU KNOW, I'M DOING A GREAT JOB.
AND WHEN SCIENTISTS SAY POSITIVE
FEEDBACK, WE MEAN DESTABILIZING
PROCESS THAT COULD MAKE GLOBAL
WARMING MUCH WORSE.
SO I'M REALLY SORRY FOR THAT
TERMINOLOGY.

Steve says BUT THIS IS A CASE
WHERE POSITIVE IS ACTUALLY VERY
NEGATIVE.

Kate says EXACTLY.

Steve says OKAY.
THIRD CLIMATE FEEDBACK, FOREST
COVER, THE IMPACT IT HAS.

The slate reappears and the words "Forest cover" are added.

Kate says SO ONE OF THE BIG WILDCARDS
MOVING FORWARD IN THE NEXT
GENERATION OF MORE SOPHISTICATED
CLIMATE MODELS IS THE CARBON
CYCLE.
WHAT'S GOING TO HAPPEN TO CARBON
IN THE FUTURE?
ARE WE GOING TO GET MORE TREES
THAT ARE ABSORBING MORE OF THAT
CARBON DIOXIDE, MORE
PHYTOPLANKTON, OR ARE WE GOING
TO SEE MAJOR DECREASES IN THE
HEALTH OF FORESTS DUE TO PESTS,
FOREST FIRES, A WHOLE BUNCH OF
DIFFERENT THINGS.
SO THIS IS A REALLY BIG
UNCERTAINTY, AND THIS IS A
REALLY BIG WILDCARD.

Steve says LAST ONE, ICE AND
REFLECTION.

The slate reappears and the words "Ice and reflection" are added.

Kate says SO THIS, FOR ME, I THINK IS
THE MOST INTUITIVE FEEDBACK.
WE KNOW WHAT ICE DOES WHEN IT
GETS WARM, RIGHT?
IT MELTS.

Steve says MELTS.

Kate says AND ICE IS VERY REFLECTIVE.
IT'S VERY SHINY, AND SO RIGHT
NOW THOSE POLAR ICECAPS ARE
DOING A VERY GOOD JOB OF TURNING
BACK SUNLIGHT THAT WOULD
OTHERWISE GET TO THE PLANET.
SO THEY'RE HAVING A COOLING
EFFECT JUST LIKE THE CAR
REFLECTORS YOU PUT ON YOUR WIND
SCREEN ON A HOT DAY.
IF YOU INCREASE THE TEMPERATURE
OF THE PLANET AND YOU MELT THAT
ICE, YOU'RE GETTING RID OF THAT
REFLECTIVE SCREEN BECAUSE THAT
REVEALS DARKER GROUND OR OCEAN
BELOW.
AND SO THAT IS ANOTHER EXAMPLE
OF A POSITIVE OR A DESTABILIZING
FEEDBACK, WHERE IT GETS HOT YOU
MELT THE ICE, YOU LOSE THAT
REFLECTIVE SHIELD, AND THAT
MAKES IT EVEN HOTTER.

Steve says CAN YOU ESTIMATE FOR
US WHAT PERCENTAGE OF SCIENTISTS
BELIEVE WHAT YOU JUST LAID OUT?

Kate says WHAT PERCENTAGE OF CLIMATE
SCIENTISTS OR OVERALL
SCIENTISTS?

Steve says AS YOU LIKE.

Kate says I'M NOT A SOCIOLOGIST, BUT I
HAVE READ A COUPLE PAPERS IN
LITERATURE THAT INDICATE THAT
ANYWHERE BETWEEN 95 AND 98 percent OF
THE SCIENTISTS ACCEPT THE
CONSENSUS THAT CLIMATE CHANGE IS
REAL, IT'S HERE AND IT'S CAUSED
BY HUMANS.

The caption changes to "The power of climate modeling."

Steve says SO IF SOMEONE WERE
TRYING TO ADVANCE AN ARGUMENT
AND ESSENTIALLY POKE HOLES IN
ALL OF WHAT YOU JUST SAID, HOW
SHOULD WE REGARD THAT?

The caption changes to "Watch us anytime: tvo.org, Twitter: @theagenda, Facebook Live."

Kate says IF THEY'RE DOING IT IN THE
SCIENTIST LITERATURE, I WOULD BE
THRILLED, BECAUSE I LOVE TO
LEARN NEW THINGS.
AND ARGUING THAT CARBON DIOXIDE,
WHICH WE'VE KNOWN IS A
GREENHOUSE GAS SINCE THE 1800S,
ARGUING THAT CARBON DIOXIDE HAS
NO EFFECT, THAT REQUIRES A
REVOLUTION IN OUR UNDERSTANDING
OF PHYSICS.
AND SO IF YOU CAN MAKE THAT
ARGUMENT, THAT WOULD BE VERY
EXCITING.
BUT I HAVEN'T SEEN ANYBODY MAKE
THAT ARGUMENT CONVINCINGLY YET.

Steve says AND IF PEOPLE WERE TO
SAY THE PLANET NATURALLY WARMS
AND COOLS AS IT HAS SINCE TIME
IMMEMORIAL, THEREFORE WE DON'T
NEED TO GET AS EXCITED ABOUT
THIS AS THE 95 percent OF THE
SCIENTISTS YOU JUST QUOTED SAY
WE OUGHT TO, OUR RESPONSE SHOULD
BE WHAT?

Kate says I FEEL LIKE THAT ARGUMENT IS
LIKE TELLING A DETECTIVE ON THE
HUNT FOR A SERIAL KILLER THAT,
OH, PEOPLE DIE OF NATURAL
CAUSES.
WE KNOW THAT PEOPLE DIE OF
NATURAL CAUSES, BUT THAT DOESN'T
MEAN THAT MURDER DOESN'T EXIST.
WE KNOW THAT THE CLIMATE HAS
CHANGED BEFORE.
IN FACT, CLIMATE SCIENTISTS HAVE
DONE MOST OF THE WORK TO SHOW
THAT THE CLIMATE HAS CHANGED
BEFORE.
BUT THAT DOESN'T MEAN THAT
HUMANS ARE NOT CAUSING CLIMATE
CHANGE RIGHT NOW.

Steve says CLOUD SEEDING, THAT'S
ANOTHER TERM.
WHAT IS THAT?

Kate says SO CLOUD SEEDING REFERS TO
WHAT WE CALL WEATHER
MODIFICATION, AND THAT WAS
FAMOUSLY USED BEFORE THE BEIJING
OLYMPICS TO ENSURE GOOD WEATHER
DURING THE GAMES.
SO WE'VE HAD THIS TECHNOLOGY FOR
A NUMBER OF YEARS.
A LOT OF TIMES, BECAUSE I'M A
CLIMATE SCIENTIST, SO THAT'S
LONG-TERM TRENDS AND NOT A
WEATHER SCIENTIST, WHICH IS
SHORT-TERM VARIABILITIES, A LOT
OF TIMES THAT COMES UP IN THE
CONTEXT OF WHAT WE REFER TO AS
GEO ENGINEERING.
SO DELIBERATE MODIFICATION OF
THE CLIMATE.
SO I MENTIONED THAT CLOUDS HAVE
THIS EFFECT OF BLOCKING
SUNLIGHT, AND SO THE IDEA IS: IF
WE COULD MAKE MORE CLOUDS, THAT
WOULD BLOCK SUNLIGHT.
THEN THAT WOULD SLOW DOWN THE
WARMING AND MAYBE BUY US A
LITTLE BIT MORE TIME TO ACT ON
CLIMATE CHANGE.
NOW THAT HAS MAJOR, MAJOR SIDE
EFFECTS.
YOU CAN COOL DOWN THE PLANET,
PROBABLY, IF YOU BLOCK A LOT OF
SUNLIGHT.
BUT A LOT OF THINGS LIKE
SUNLIGHT, LIKE PLANTS.
AND THAT ALSO DOESN'T DO
ANYTHING ABOUT THINGS LIKE OCEAN
ACIDIFICATION, AND MORE I THINK
FRIGHTENINGLY, WE STILL HAVE
THOSE UNCERTAINTIES, AND WE
CAN'T TELL EXACTLY WHAT IS GOING
TO HAPPEN BECAUSE THE CLIMATE
SYSTEM IS A REALLY, REALLY
COMPLEX BEAST.
AND SO I THINK, AGAIN, THERE ARE
NO SILVER BULLETS TO CLIMATE
CHANGE, AND I WOULD BE REALLY,
REALLY WARY OF ANYBODY PROPOSING
THAT AS A SORT OF MAGIC
SOLUTION.

Steve says HOW DO YOU ACTUALLY DO IT?

Kate says SO WE ARE ACTUALLY DOING
NATURAL EXPERIMENTS, INADVERTENT
EXPERIMENTS, I GUESS, NOT
NATURAL EXPERIMENTS RIGHT NOW,
FROM SPACE.
YOU CAN ACTUALLY SEE THE SHIP
TRACKS OF MAJOR OCEAN LINERS
CROSS THE PACIFIC, FOR EXAMPLE,
AND THAT'S BECAUSE THE SHIPS
GOING ACROSS THE ATLANTIC ARE
EMITTING POLLUTION AND THAT IS
SEEDING CLOUDS IN THEIR WAKE.
YOU CAN SEE THESE TRAILS OF
CLOUDS IN THE WAKE OF SHIPS.
SO THE IDEA I THINK WOULD BE TO
DO THAT ON A LARGER SCALE AND TO
DO THAT WITH MORE DELIBERATION
AS OPPOSED TO THE INADVERTENT
WAY THAT WE DO IT RIGHT NOW.

Steve says SOUNDS LIKE IT WOULD
COST BILLIONS UPON BILLIONS TO DO.

Kate says IT WOULD PROBABLY BE CHEAPER
THAN DEALING WITH THE IMPACTS OF
CLIMATE CHANGE.

Steve says OKAY.
FAIR ENOUGH.
OKAY, WE HAVE COVERED FORCINGS.
WE ARE COVERED FEEDBACKS.
LET'S DO ONE MORE OF THESE
EXPRESSIONS THAT YOU FOLKS DEAL
WITH: CLIMATE TIPPING POINT.
WHAT ARE THEY?

Kate says SO CLIMATE TIPPING POINTS
REFER TO THINGS WHICH I WOULD
CALL UNKNOWN UNKNOWNS.
SO CLOUDS...

Steve says SOUNDS LIKE DONALD
RUMSFELD RIGHT THERE.

Kate says I'M SO SORRY.
I'M VERY INSULTED.

Steve says DON'T BE.

[Laughter]

Kate says SO FEEDBACKS ARE THINGS THAT
WE UNDERSTAND FAIRLY WELL.
SO FOR EXAMPLE, WE... ICE
FEEDBACK, MELTING THE ICE,
THAT'S A KNOWN KNOWN.
WE KNOW THAT THAT WILL HAPPEN IF
WE MAKE THE PLANET WARMER.
CLOUDS ARE AN EXAMPLE OF A KNOWN
UNKNOWN.
WE KNOW THAT WE DON'T UNDERSTAND
ENOUGH ABOUT CLOUDS, AND THAT'S
WHY WE'RE PUTTING A LOT OF
RESEARCH INTO UNDERSTANDING HOW
THEY'LL CHANGE IN THE FUTURE.
SOMETHING LIKE A TIPPING POINT
COULD BE SOMETHING THAT WE DON'T
KNOW THAT WE DON'T KNOW.
SO SOMETHING LIKE AN UNEXPECTED
RELEASE OF METHANE FROM MELTING
PERMAFROST THAT WE FAILED TO
ANTICIPATE, THAT WE HAVEN'T
INCLUDED IN OUR CLIMATE MODELS.
SO HOW TO THINK ABOUT THINGS
THAT WE HAVEN'T THOUGHT ABOUT IS
A REALLY ACTIVE AREA OF BOTH
SCIENCE AND STATISTICS, AND
HONESTLY PHILOSOPHY.
SO WE'RE STARTING TO THINK ABOUT
HOW COULD WE ANTICIPATE THINGS
THAT WE HAVEN'T ANTICIPATED.

Steve says SOUNDS LIKE THIS
CATEGORY IN SOME WAYS IS THE
SCARIEST OF ALL IF YOU ARE...

Kate says IT'S TERRIFYING.

Steve says TERRIFYING, OKAY,
THAT'S A BETTER WORD.
LET'S GO THROUGH A FEW CLIMATE
TIPPING POINTS RIGHT HERE.
OKAY, OCEAN CIRCULATION, WHAT'S
THAT?

Kate says SO HAVE YOU SEEN THE MOVIE
"DAY AFTER TOMORROW"?

Steve says WHO HASN'T.
YES.

A slate appears on screen, with the title "Climate tipping points."

A picture shows a frozen sea with chunks of ice and snow-capped mountains in the background. The words "Ocean circulation" appear.

Kate says I WANT TO BE VERY CLEAR THAT
I AM NOT ENDORSING ANY OF THE
SCIENCE IN THAT MOVIE.
BUT THAT IS A FICTIONAL EXAMPLE
OF A TIPPING POINT WHERE MELTING
ICE SHEETS INJECT A LOT OF FRESH
COLD WATER, AND THAT CHANGES THE
CIRCULATION OF WATER IN THE
ATLANTIC, THERMAL HAILING
CIRCULATION, AND THAT LEADS TO A
RAPID COOLING, WHICH IN THE
MOVIE IS... TAKES PLACE OVER A
COUPLE OF DAYS.
IN THE REAL WORLD, AS THE EARTH
WAS COMING OUT OF THE LAST ICE
AGE, WE THINK THAT THERE WAS A
PERIOD OF TIME CALLED THE
YOUNGER DRYAS WHERE ALL OF A
SUDDEN IT GOT MUCH COOLER.
AND ALL OF A SUDDEN HERE IS IN
GEO LOGICAL TERMS, NOT HOLLYWOOD
TERMS, BUT THERE IS SOME
EVIDENCE FOR DISTURBANCES TO THE
THERMAL HAILING CIRCULATION,
DISTURBANCES TO THE OVERTURNING
OF WATER IN THE ATLANTIC LEADING
TO RELATIVELY ABRUPT CLIMATE
CHANGES.
NOW IN THE SHORT-TERM, AND
SHORT-TERM BEING OUR LIFETIME,
WE MAY NOT HAVE TO WORRY ABOUT
THAT, BUT THERE ARE OTHER THINGS
THAT WE KNOW ABOUT.
THERE ARE KNOWN KNOWNS THAT I
THINK ARE MUCH MORE PRESSING AND
THAT WE DO HAVE TO WORRY ABOUT.

Steve says IF WE FIND OURSELVES
IN THOSE KINDS OF CIRCUMSTANCES,
DO YOU RECOMMEND, AS THE MOVIE
DOES, THAT WE HIDE IN A LIBRARY
AND BURN ALL THE BOOKS TO STAY
WARM?

Kate says SOUNDS GREAT.
LET'S DO IT.

Steve says ALL RIGHT.
CLIMATE TIPPING POINT, SECOND
ONE.
ICE LOST.
WHAT CAN YOU TELL US ABOUT THAT?

The slate reappears and the words "Ice loss" are added.

Kate says SO WE ARE IN A VERY PECULIAR
SITUATION RIGHT NOW WHERE WE ARE
RELEASING CARBON DIOXIDE INTO
THE ATMOSPHERE 100 TIMES FASTER
THAN WE KNOW OF IN THE LAST
800,000 YEARS OF THE EARTH'S
HISTORY.
SO THE CLIMATE CHANGES THAT WE
ARE SEEING ARE UNPRECEDENTLY
RAPID, AND THAT IS A REAL
CHALLENGE FOR SCIENCE BECAUSE
THE ICE SHEETS HAVE NEVER MELTED
THIS QUICKLY BEFORE.
IT'S NEVER GOTTEN WARM THIS
QUICKLY BEFORE.
AND SO THERE'S A LOT OF
UNCERTAINTY ABOUT WHAT HAPPENS
WHEN YOU DO THIS.
AND SO A LOT OF RESEARCH IS
GOING INTO, WELL, HOW DO ICE
SHEETS MELT.
AND THERE ARE SOME SCARY THINGS
THAT ARE COMING OUT OF THAT.

Steve says HMM.
LET'S... YOU DID REFER TO THIS A
SECOND AGO, BUT I'M GOING TO
FOLLOW UP ON IT HERE, THE RAPID
RELEASE OF METHANE.
HOW MIGHT THAT HAPPEN AND WHAT
WOULD THE IMPACT BE?

The slate reappears and the words "Rapid release of methane" are added.

Kate says SO THERE IS A KNOWN KNOWN
WHEN IT COMES TO METHANE, AND
THE KNOWN KNOWN IS THAT METHANE
IS AN INCREDIBLY POWERFUL AND
POTENT GREENHOUSE GAS, ABOUT 25
TIMES MORE POWERFUL THAN CARBON
DIOXIDE.
IT DOESN'T LIVE AS LONG AS
CARBON DIOXIDE IN THE
ATMOSPHERE, BUT THAT HARDLY
MATTERS IF IT'S BEING
CONTINUOUSLY INJECTED IN THE
ATMOSPHERE.
WE KNOW THAT THERE IS A LOT OF
METHANE LOCKED UP IN THE
PERMAFROST IN NORTHERN CANADA,
THE ARCTIC, AND AS THAT MELTS,
WE EXPECT TO SEE THE METHANE
BEING RELEASED INTO THE
ATMOSPHERE, AND THAT IS ANOTHER
EXAMPLE OF A POSITIVE OR I
PREFER DESTABILIZING FEEDBACK,
WHERE YOU PUT... YOU MELT THE
PERMAFROST, THAT PUTS MORE
POTENT GREENHOUSE GASES IN THE
ATMOSPHERE, AND THAT IN TURN
FEEDS BACK AND MAKES IT WARMER.
SO WE EXPECT THAT THAT WILL
HAPPEN.
THERE SOMETIMES HAS BEEN SOME
MEDIA ATTENTION AROUND A METHANE
BOMB, SO A RAPID RELEASE OF
METHANE FROM EITHER THE OCEAN OR
THE PERMAFROST.
AND THERE'S NOT A LOT OF
EVIDENCE TO SUPPORT A METHANE
BOMB, A SUDDEN AND RAPID RELEASE
OF METHANE, BUT THERE IS A LOT
OF EVIDENCE TO SUGGEST THE SORT
OF SLOW AND STEADY INEXORABLE
FEEDBACK.

Steve says YOU TESTIFIED A COUPLE
OF WEEKS AGO TO CONGRESS, DID
YOU NOT?

Kate says I DID.

Steve says HOW HARD IS IT TO
PERSUADE SOME PEOPLE OF YOUR
SCIENTIFIC POINT OF VIEW WHEN
YOU HAVE SCIENTIFIC DATA TO BACK
YOU UP BUT SOME OF THEM JUST ARE
NOT INTERESTED AND DON'T BELIEVE
WHAT YOU HAVE TO SAY.

Kate says SO I'VE REALIZED OVER THE
PAST COUPLE YEARS THAT
SCIENTISTS MAY NOT BE THE BEST
PEOPLE TO TALK ABOUT CLIMATE CHANGE.

Steve says WHAT?

Kate says BECAUSE WE ALWAYS THINK THAT
ONE MORE EQUATION OR ONE MORE
GRAPH IS GOING TO CONVINCE
PEOPLE.
BECAUSE THAT'S WHAT CONVINCES
US, BECAUSE WE'VE BEEN TRAINED
TO BE CONVINCED BY THAT.
BUT THAT'S NOT HOW PEOPLE WORK.
YOU SHOW PEOPLE A GRAPH.
THEIR BRAIN SHUTS DOWN AND THEY
DON'T CARE, OR THEY CAN'T TELL
THE DIFFERENCE BETWEEN THAT
GRAPH AND THE OTHER GRAPH THAT
THEY'VE JUST BEEN SHOWN.
AND SO I THINK IT'S BEEN A REAL
LEARNING EXPERIENCE FOR ME TO
REALIZE THAT FACTS ARE NOT WHAT
CHANGES PEOPLE'S MINDS.
STORIES ARE WHAT CHANGES
PEOPLE'S MINDS.
MESSENGERS ARE WHAT CHANGES
PEOPLE'S MINDS, AND ALL I CAN DO
IS GO IN THERE AND REPRESENT THE
FACTS TO THE BEST OF MY ABILITY,
AND I THINK THAT IS ABSOLUTELY
CRUCIAL BECAUSE WE NEED TO BE
TELLING STORIES THAT ARE
INFORMED BY THE FACTS, BUT THE
FACTS AREN'T GOING TO BE ENOUGH
TO CHANGE PEOPLE'S MINDS.

Steve says MAYBE SCIENTISTS HAVE
TO LEARN TO BECOME BETTER
STORYTELLERS?

Kate says I WOULD BE TOTALLY ON BOARD
WITH THAT.

The caption changes to "Producer: Sandra Gionas, @sandragionas."

Steve says YOU'VE DONE THAT HERE
TONIGHT, SO THANK YOU FOR THAT,
AND YOU'VE ALSO GOT THE BEST
NAME OF ANYBODY WHO'S BEEN ON
THIS PROGRAM.
DR. KATE MARVEL FROM COLUMBIA
UNIVERSITY AND NASA. GREAT TO
HAVE YOU HERE ON TVO TONIGHT.

The caption changes to "Subscribe to The Agenda Podcast: tvo.org/theagenda."

Kate says THANK YOU SO MUCH FOR HAVING
ME.

Watch: Kate Marvel: How Climate Change Works