A Look Back: How Heat Shaped 2020

A Look Back: How Heat Shaped 2020

Narration: Lesley Ott

Transcript:

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[MUSIC]

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This is a story about heat.

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Heat in our atmosphere, oceans, and land.

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When you think about it, events like drought,

hurricanes, fires - all of those are just

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different ways we see heat expressed throughout

the Earth’s system.

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You’ve probably been bombarded with a lot

of intense headlines in 2020.

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“Hottest temperature recorded here, largest

wildfires there..”

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It’s been a lot to take in.

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My name is Lesley Ott and I am a research

meteorologist at NASA’s Goddard Space Flight Center

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So, the reality is the stage was set many

years ago for these events.

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Over the last century, human activities have

increased the concentration of greenhouse

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gases in our atmosphere.

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These gasses act like a blanket, trapping

heat and leading to overall warming of the planet.

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Many of these gases remain in the atmosphere

for a long time, meaning that we’ll be feeling

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the consequences of this trapped heat for

many years to come.

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Which, unfortunately, means next year

is probably going to bring a lot of the same kinds

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of stories that we saw in 2020.

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But taking a look at all the different ways

our planet responds to the variations and

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movement of heat can help us better prepare

for the future.

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Maybe one of the most obvious ways we saw

heat this year was through fire.

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I know the Australian bush fires were big

news last January.

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And, when you think about it, years of prolonged

hot temperatures and drought really set the

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stage for these fires to be more likely and

more severe.

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With drought and heat waves, we typically

see an increase in the availability of dry

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fuels, which leads to more powerful fires.

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So when you have multiple years of intense

heat, it’s not surprising to have significant

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fire events like we saw in Australia.

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These fires were so extreme, that we saw smoke

injected as high as 18 miles above the surface

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- that’s really important because when smoke

is injected that high, it can have the same

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type of effect as a volcano, having these

very very broad impacts across whole hemispheres

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of the planet.

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At NASA, we use computer models like the Goddard

Earth Observing System to help us study how

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aerosols and particulate matter move through

the atmosphere.

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So we take these models and input real-world

observations and data to track fire emissions

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to help understand how they are forming, where

they are going, and how much of an impact

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they will have on you and me.

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In California, heat waves have increased fire

risk, and as a result, we saw a lot of synchronized

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fire activity, that is, many dangerous wildfires

burning at the same time.

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And unfortunately, these types of huge fire

events are becoming more and more common across

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the western United States.

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And that’s a big problem.

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This year, Siberia also had a remarkable and

active fire season.

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What we saw was that temperatures in the region

were much higher than normal for this time

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of year.

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In fact, the temperatures above the Arctic

Circle broke records in many of the same regions

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where fires were burning actively.

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In the Arctic and boreal forest ecosystems,

heat waves can exacerbate fires.

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And in the Arctic you also have to factor

in permafrost, which is soil that's

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frozen for long periods of time, and that

can make the impact of fires in high latitudes

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even more complex.

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When severe fires burn in areas with permafrost,

we lose this important insulating organic

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soil layer, which accelerates thawing, and

its potentially releasing carbon that’s

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been stored in the soil for hundreds and in

some cases, even thousands of years.

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And then you sometimes see these ‘zombie

fires’, which happen when wildfires burn

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in deep peatlands or smolder in forests under

snowfall.

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If that temperature doesn't get cold enough

to extinguish the fire, they can continue

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to burn over the winter even long after the

visible fires have been extinguished at the surface.

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So come spring, they reemerge and they continue

to burn back on the surface again.

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Studying what happens in the Arctic is really

important because it’s warming about three

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times faster than the rest of the planet.

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And all those aerosols and carbon that come

out of the Arctic doesn't necessarily stay

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there, they affect the heating and air pollution

in much larger regions of the planet.

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Another part of the planet affected by heat,

of course, is ice.

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Land ice in the form of ice sheets and glaciers,

where we’ve seen significant melt in recent

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decades, and frozen ocean water, or sea ice.

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This year, the Arctic sea ice minimum almost

reached a new record low.

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It was second only to 2012’s extent -- which

was an anomalously low year in part due to

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unusual weather conditions.

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Sea ice shrinks and grows with the

seasons.

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After reaching an annual minimum extent in

September, Arctic sea ice begins to grow again

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as sea temperatures cool off for the winter.

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This year, Arctic sea ice had an unusually

slow start to the regrowth period.

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In particular, the Laptev Sea, which is

called sometimes called a sea ice nursery

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because much of the Arctic sea ice initially

forms there, was too warm for meaningful

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sea ice growth until much later in the season

than usual.

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Oceans absorb heat from the sun and our atmosphere

prevents this heat from escaping back to space.

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The movement of this heat is one of the primary

drivers of circulation and global weather patterns.

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We can measure the temperature of the ocean

and what we saw this year was unusually high

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surface temperatures across the Atlantic.

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The warm moisture that comes off of the ocean

acts as fuel to storms.

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So, as this layer of the ocean gets even warmer,

we’re seeing that storms are becoming more

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and more intense over time.

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In fact, 2020's sea surface temperature contributed

to an exceptional year in terms of Atlantic hurricanes.

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We saw 30 named storms - a new record, and

12 of these storms made landfall in the US.

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What’s really interesting is that many of

these storms intensified really really rapidly.

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Not only are storms intensifying more quickly,

but what we’re also seeing is that they

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are stalling near coastal regions more often, which is devastating in terms of floods and storm surge.

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While we’re not 100% sure what is causing

these storms to stall, it may have to do with

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climate patterns shifting in response to rising

global temperatures.

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It’s always really tough for a scientist

to say any particular fire or any particular

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event was because of climate change.

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But we’re getting to a point where we’re

starting to see season after season of record-breaking

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wildfire, season after season of really intense

storms, that it becomes much easier to understand

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that this is likely the result of long-term

climate change.

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In general, more heat means more energy in

the Earth system.

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So, while 2020 was a significant year, it’s

important to know that this probably wasn’t

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an anomaly of a year.

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We’re likely to experience many similar

years as the Earth’s climate gets warmer.

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So, while we saw a small dip in emissions

this year due to COVID shutdowns, it was pretty short-lived.

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The vast majority of our greenhouse gas emissions

come from things like electricity generation,

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which were less affected by the shutdowns

than emissions from cars and airplanes.

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But we know that human activities have a powerful

impact on our environment.

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Long term strategies to curb human-induced

climate change would have to focus on implementing

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cleaner technologies so we can reduce

emissions without affecting people’s daily lives.

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So while this is a story about heat, it is

also a story about connections.

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Nothing on our planet happens in a vacuum,

and our actions today impact our tomorrow.

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The choices we make now can make the difference

between continued increases in greenhouse

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gas emissions and 2020 being the year that they

peaked.