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Landsat 2023 – A Year in Review

Landsat 2023 – A Year in Review

By Chris Burns, NASA’s Goddard Space Flight Center

Video credit: NASA’s Goddard Space Flight Center

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NASA’s 2023 is officially in the books – and what a year it was!

From the successful return of samples from a 4.5 billion year old asteroid to the announcement of the crew of the next manned mission to fly around the moon, it’s safe to say that NASA stayed busy…

And that goes double for the Landsat program, as NASA’s decades-long partnership with the USGS crosses off its 51st year in orbit, continuing to map and monitor our ever-changing planet in remarkable detail.

So let’s take a peek, not just into the past and some of the innovative ways researchers were able to put Landsat data to work in 2023, but also at how the Landsat program is preparing for its next chapter…


RIVER MINING
Even though it might evoke the image of a grizzled prospector panning for gold in 1850’s California, river, or, alluvial mining as it is known, is still used to this day as a method of extracting precious minerals.

In fact, a research paper published in 2023 demonstrates a concerning trend in river mining worldwide.

Researchers used data from Landsats 5 and 7 to track river mining at almost 400 sites across the world over a 37-year period.

Their results showed that over the past two decades river mining activity has been on the rise, particularly in tropical areas and, with that rise, has come a whole slew of negative environmental impacts such as increases in sediment deposits and deforestation as well as decreases in water quality and availability.

With the help of foundational data collected by Landsat over the last 50 years, researchers hope they can bring to light both the scale and impact of river mining, emphasizing the need for action to mitigate its environmental consequences.


GLOBAL LAKE WATER DECLINE
Follow any given river all the way to and from its source and it’s quite possible you’ll find yourself on the shore of a lake.

Lakes account for 3% of Earth’s global land area, storing vast reservoirs of freshwater essential to our planet’s ecosystems.

Water levels in these lakes fluctuate from year to year due to factors both natural and manmade – from droughts and floods to agricultural and domestic consumption.

So when researchers wanted to track water levels over the past three decades in lakes worldwide, they turned to Landsat.

A 2023 research paper analyzed almost 250,000 Landsat images to track water levels in thousands of lakes and reservoirs across the world between 1992 and 2020.

By combining Landsat imagery with climate and hydrological models, researchers were able to determine that 53% of these water bodies had experienced a significant decline in water levels over the past 30 years.

The cause of this decline?  Researchers say one factor is climate change, as warmer and drier weather around many of these lakes is driving higher rates of evapotranspiration

These findings stress the importance more effective water resource management as nearly a quarter of the world’s population live near and depend on lakes that are experiencing water loss.


RISING SEA LEVELS
While the water levels in our world’s lakes may be shrinking, when it comes to our oceans, it’s a different story altogether.

As global temperatures continue to creep higher, so too do our sea levels which puts added pressure on vital coastal ecosystems.

Mangroves, tidal marshes, coral reefs and reef islands all play key roles in protecting coastlines, providing natural habitats for animal and plant life, and capturing and storing excess carbon.

These ecosystems are known to be resilient, having adapted to gradual changes in historic sea levels, but researchers wanted to find out what effect rising global temperatures could possibly have on our world’s coastal habitats in the coming decades.

The research team used machine-learning techniques trained on millions of Landsat scenes to assess how coastal ecosystems might react to a rise in global temperature from 1.5° to 3°C.

Their results painted a dire picture –  a 1.5° to 2°C temperature rise could see a sea level rise of up to 4mm a year between 2080-2100, which would double the amount of mapped tidal marsh.

Putting those numbers in perspective, by the year 2044, our oceans could rise between 3-4 cm.

A 3 °C rise in temperature would expose almost all of the world’s mangroves and coral reefs, and a large portion of tidal marshes, to sea-level rises of at least 7 mm per year, which would hit 14 cm by 2044.

The researchers believe their study underscores the urgent need for effective global climate policies that aim at keeping temperature rise under 2 °C – any failure to do so could lead to a significant loss in biodiversity and put our vulnerable coastal communities even further at risk.


LANDSAT NEXT
These 2023 case-studies clearly demonstrate how important Landsat’s ability to look into the past can be for preparing for our future.

The Landsat program’s free and open archive puts five decades worth of Earth observations at researcher’s fingertips – a decades-long legacy of observing, managing, and adapting to change on Earth

In early 2023, the Landsat program announced plans for continuing this legacy – Landsat Next.

Representing a quantum leap forward in Earth observation, Landsat Next will be a triplet-configuration – a constellation of three satellites, orbiting in tandem, taking a complete picture of the world every 6 days.

With the improved 6-day revisit comes an increased spatial resolution, allowing Landsat satellites to capture smaller details at a finer temporal resolution than before.

And Landsat Next will be going “superspectral”, boasting 26 spectral bands, unlocking new applications for monitoring water quality, crop production, snow and ice dynamics and more.

2023 was without a doubt an exciting year for the Landsat program, with data being put to use in ways that continue to prove why the Landsat program is a cornerstone of Earth observation.

So as we bid Landsat’s 2023 a fond farewell, we can turn our gaze  forward to the exciting discoveries that lay ahead on the horizon for Landsat in 2024 and beyond…

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Related Posts

Allison Nussbaum gives a Hyperwall talk about Landsat’s free-and-open data policy and how it paved the way for data products including vegetation indices and evapotranspiration.

Landsat Outreach: Denver Edition

The Landsat outreach team participated in AAAS and Geo Week events this month to highlight the benefits of the Landsat program and how the NASA/USGS partnership facilitates the invaluable, ongoing Landsat record.

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