Hi, I’m Karen St. Germain and i am NASA's director of Earth Science.
Often when people think of NASA, they think of human exploration or Planetary Exploration.
They might not know that NASA has 23 satellites looking down at our Earth system to help us understand our home planet.
We've been observing the Earth for decades, and we observe the atmosphere, the oceans, the land- the entire Earth system!
I'm going to talk to you today about what we know from those observations.
This is an example of the kind of sustained observation that NASA satellites make.
Starting in 1993 until just our recent launch of the Sentinel 6 Michael Freilick satellite we've been observing directly measurements of sea level height and from those data we know the sea level has risen on average 90 mm just since the early 90s.
But what's causing the sea level rise?
We all have heard about greenhouse gases and I'm going to talk to you today about two of them.
The first one is carbon dioxide.
Of course, carbon dioxide permeates our atmosphere. By just adjusting the color so I can emphasize the maximum areas of emission
I can show you where Carbon dioxide and when carbon dioxide is being emitted into our atmosphere.
Carbon dioxide accumulates most during the north northern hemisphere winter months.
Carbon dioxide is created by the burning of fossil fuels and that carbon dioxide accumulates in our atmosphere over the course of the winter
and it's only in the spring with the emergence of vegetation that it starts being removed from the atmosphere.
Carbon dioxide left in the atmosphere lasts for a very long time and that's why there's so much conversation with carbon dioxide as one of the critical greenhouse gases.
But on the next slide, I'll show you the other big greenhouse gas, Methane.
So while carbon dioxide is produced from the burning of fossil fuels, methane is produced from the extraction of fossil fuels and also from agriculture and vegetation decay.
Methane is about 20 times more potent a greenhouse gas than carbon dioxide,
but the good news is its lifetime in the atmosphere is much shorter, it lasts only around a decade.
So when we talk about mitigation types of decisions, it really matters to understand where the greenhouse gases are coming from,
and how they play in the atmosphere.
What do greenhouse gases do?
Well they trap a lot of the sun's energy in the earth system, and that is raising surface temperatures around the world over both land and ocean.
We can estimate the total extra heat trapped in the Earth System since we started making satellite observations around the year 2000.
Where does all that heat go?
Well, it turns out that today about 94% of it gets trapped in our oceans.
Water has an enormous heat capacity.
That means it absorbs a lot of heat before it's temperature goes up, and you know this if you've ever put a pot of water on the stove to boil.
But that heat doesn't stay put.
Our oceans are incredibly dynamic with currents and eddies that carry that energy around the world and impact coastlines and in coastal communities weather patterns and more.
I'll just talk to you about a few of the impact from the heat trapped in our oceans.
One of those impacts is in the Arctic.
You're looking down at Arctic sea ice. This is data from just this year showing you the extent of the Arctic sea ice. This is frozen ocean.
Well over the course in the summer, of course that's sea ice starts to melt, and that extent shrinks
We've been looking at Arctic sea ice for decades now.
We know that every year at the end of the summer there's less and less ice.
Why does that matter?
Well ice is white!
It's one of the great reflectors of the sun's energy so in the summer months when the sun is beating down on the Northern Hemisphere the last ice we have less power we have to reflect the sun's energy back out into space.
And this year, the summer minimum extend the substantially less than it has been in recent decades.
Another way that the warming oceans affect the coastline is through the impact on land ice.
So land Ice flows through glaciers to the oceans, and at that boundary that warm ocean can erode the underside of the glacier causing it to thin and eventually break off, and that is like a cork getting popped out of a bottle!
It increases the flow of ice from land out into the oceans and we know how much of that is happening.
Next slide line please.
The two biggest ice sheets are Antarctica and Greenland.
We know where that ice is flowing from land out into the ocean, and that these two ice sheets alone contribute one-third of the total sea level rise that we observe.
We know that in part because we make direct measurements of the mass of the ice on these ice sheets so we know how much mass has been lost from land transported into the oceans.
So why do we care about sea level rise?
Well one of the reason is our coastal communities.
We project a dramatic increase in just sunny day high tide flooding, when high tides ride on top of that sea level rise.
But there's more.
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Our Earth is a water planet
And you might ask “if I live inland, why does this matter to me?”
All of the water that we need to sustain life inland; to grow crops, to drink.
All of that water comes from the ocean, and it's delivered to us by the atmosphere.
That's the water cycle.
One of the things that were seen with climate change is an increase in the magnitude of that water cycle.
Wet regions get wetter.
Dry regions get drier.
Next slide.
One of the ways that wet regions get wetter is through the intensity of tropical storms and hurricanes.
We all know that tropical storm pass over warm water they intensify.
Well all of that heat that's getting trapped in the oceans and warming the oceans, that's fuel for hurricanes.
We are seeing more, and more hurricanes intensify, sometimes intensify very rapidly.
Then, of course, when they make landfall depositing all of that moisture over land.
Sometimes stalling for long periods of time causing extended flooding.
We also see flooding Inland along our rivers in our watershed areas.
Of course inland along the waterways is often where we have agriculture regions and that's impacting the agriculture yields there as well.
Speaking of agriculture, there are two ways that climate change can impact agriculture.
One we just talked about, wet regions getting wetter.
But the other extreme is also impacting agriculture.
That is a drier areas receiving even less moisture!
When the temperatures go up the demand that plants have for water also increases.
This combination of increasing temperatures and changing precipitation patterns is exacerbating drought conditions and adverse impacts on agriculture around the world.
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We can project this out into the future. I'm showing you here future projections of maize, or corn production, as well as wheat production.
Red areas will have lower yield and green areas will have higher yield.
You are seeing a dramatic shift in where and what crops can be grown.
One of the reasons that this is important to us is we might think of maize or corn as food for us or in food for animals, but also maize is used in many,many household products from wallpaper to adhesives, to batteries.
When we talk about a major change in the ability to produce maize, we're really talking about substantial economic change.
Next slide please.
With increasing drought and dry spells around the world, we are also seeing a change in the patterns of wildfires.
We are seeing extended wildfire seasons with less time for recovery in between wildfire seasons.
We're seeing more severe wildfires, and more rapid growth of wildfires.
This matters not only because the fire damages the immediate area, but it also increases the carbon dioxide in the atmosphere.
It has an adverse impact on the air quality in the region, in addition to making the region vulnerable to cascading effects like landslides when the rains do come.
Next slide please.
So I talked you through some of what we can see from our satellite and some of what we understand from our satellites.
Now, I want to talk about how we modeled those changes to give us predictive capability.
Now, I’d like to take just the last couple minutes to talk to you about how we try to bring that predictive capability to people who have decisions to make.
One of the tools we use, or we developed, is called the FIRMS tool.
This is a tool that uses our highest resolution visible and infrared imagery to identify fires around the world, whether they are intentionally set for clearing fields or other purposes or wildfires that are threatening local communities .
This tool allows decision-makers to understand where those fires are happening, and how long they have been burning.
Finally the last tool I’d like to show you is one we're really proud of.
It was a partnership between NASA and the IPCC to make the projections from the recent IPCC assessment report real to people.
Communities around the world can use this tool by just locating their position on the map.
They can zoom in, and find out what we know about sea level rise so far in their region, and also projected out into the future so they know what they may be facing.
In summary, let me end where I started.
NASA satellites are looking down at the Earth all the time - the atmosphere, the land,the ice, the oceans.
We capture those observations in understanding, and we capture that understanding in models. Those models let us predict.
We know that our climate is changing! We are at about 1.2 degrees so far.
We are still learning how the whole system works, but we do know that there's an enormous range between the best and the worst outcomes.
We are working with urgency to bring you the best observations, models, and predicted tools we can to help inform decisions locally, nationally, and internationally.
Thank you