Global change ecologist leads NASA satellite study of rapid greening across Arctic tundra

International team of researchers finds the region has become greener as warmer air and soil temperatures lead to increased plant growth


Research News


As Arctic summers warm, Earth’s northern landscapes are changing. Using satellite images to track global tundra ecosystems over decades, a team of researchers finds the region has become greener as warmer air and soil temperatures lead to increased plant growth.

“The Arctic tundra is one of the coldest biomes on Earth, and it’s also one of the most rapidly warming,” said Logan Berner, assistant research professor with Northern Arizona University’s School of Informatics, Computing, and Cyber Systems (SICCS), who led the research in collaboration with scientists at eight other institutions in the U.S., Canada, Finland and the United Kingdom. “This Arctic greening we see is really a bellwether of global climatic change – it’s this biome-scale response to rising air temperatures.”

The study, published this week in Nature Communications, is the first to measure vegetation changes across the Arctic tundra, from Alaska and Canada to Siberia, using satellite data from Landsat, a joint mission of NASA and the U.S. Geological Survey. Scientists use Landsat data to determine how much actively growing vegetation is on the ground – greening can represent plants growing more, becoming denser or shrubs encroaching on typical tundra grasses and moss.

When the tundra vegetation changes, it impacts not only the wildlife that depend on certain plants, but also the people who live in the region and depend on local ecosystems for food. While active plants will absorb more carbon from the atmosphere, the warming temperatures are also thawing permafrost, releasing greenhouse gasses. The research is part NASA’s Arctic Boreal Vulnerability Experiment (ABoVE), which aims to better understand how ecosystems are responding in these warming environments and its broader implications.

Berner and his colleagues, including SICCS faculty Patrick Jantz and Scott Goetz along with postdoctoral researcher Richard Massey and research associate Patrick Burns, used the Landsat data and additional calculations to estimate the peak greenness for a given year for each of 50,000 randomly selected sites across the tundra. Between 1985 and 2016, about 38 percent of the tundra sites across Alaska, Canada and western Eurasia showed greening. Only 3 percent showed the opposite browning effect, which would mean fewer actively growing plants.

To include eastern Eurasian sites, the team compared data starting in 2000, which was when Landsat satellites began collecting regular images of that region. With this global view, 22 percent of sites greened between 2000 and 2016, while 4 percent browned.

“Whether it’s since 1985 or 2000, we see this greening of the Arctic evident in the Landsat record,” Berner said. “And we see this biome-scale greening over the same period as we see really rapid increases in summer air temperatures.”

The researchers compared these greening patterns with other factors and found that they are also associated with higher soil temperatures and higher soil moisture. They confirmed these findings with plant growth measurements from field sites around the Arctic.

“Landsat is key is for these kinds of measurements because it gathers data on a much finer scale than what was previously used,” said NAU professor Goetz, who contributed to the study and leads the ABoVE science team. That allows the researchers to investigate what is driving the changes to the tundra. “There’s a lot of microscale variability in the Arctic, so it’s important to work at finer resolution while also having a long data record,” Goetz said. “That’s why Landsat’s so valuable.”


About Northern Arizona University

Northern Arizona University is a higher-research institution providing exceptional educational opportunities in Arizona and beyond. NAU delivers a student-centered experience to its 31,000 students in Flagstaff, statewide and online through rigorous academic programs in a supportive, inclusive and diverse environment. Dedicated, world-renowned faculty help ensure students achieve academic excellence, experience personal growth, have meaningful research opportunities and are positioned for personal and professional success.

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September 23, 2020 2:22 pm

Barrow Alaska average monthly temps are

So we are looking at basically June, July and August. May and Sept are transition months. I’m not really sure how this effects the global environment one way or another other than more food for the polar animals in the very short summer. We aren’t going to see Palm trees there anytime soon.

Farmer Ch E retired
September 23, 2020 2:51 pm

Is any of the greening attributed to increased atmospheric CO2 concentrations or is it all due to increased temperature? CO2 is boosting plant growth elsewhere.

Jim Gorman
Reply to  Farmer Ch E retired
September 23, 2020 5:10 pm

That is exactly what I wondered. Too many studies and experiments (greenhouses) show that increased CO2 enhances the ability of plants to grow.

Why was this not the primary conclusion.

Those who have access to the study, does it mention any supporting studies or data to support the assertion that higher temps actually affect plant growth on the tundra? IOW, do increasing temps actually make tundra plants grow better?

Reply to  Jim Gorman
September 23, 2020 6:19 pm

That they didn’t even address it reveals everything that you need to know.

Reply to  Luke
September 24, 2020 4:19 pm

Yes, this just looks like an attempt to spin CO2 fertilisation into a result of “global heating”.

Full paper is available, linked at Urea Alert.

Strong positive NDVImax trends and NDVImax–SWI correlations during a period of rapid warming suggest that reductions in temperature limitations on biological and/or biogeochemical processes could have contributed to recent increases in tundra greenness in the Arctic tundra biome.

Yet another ” suggests …. could have contributed… ” pseudo-scientific claim.

They manage to squeeze a 0.68 correlation out of 20 data points of two datasets with a general upwards trend. They could have got similar correlations by comparing to rising CO2. But they did not attempt or even discuss that possibility.

Reply to  Jim Gorman
September 24, 2020 9:36 am

Agree that “CO2 as plant food” belongs in the discussion.

However, in serious ecology (as opposed to climate change ecology) the Law of the Minimum is important. In each eco niche, at a given time, there are various factors which limit growth of individual organisms and populations. In many situations there is one dominant factor. In deserts, usually water, in predator/prey cycles it may be the number of competing predators vs the availability of prey.

In the Tundra the governing minimum is likely to be the temperature. A modest increase in daily temps….or the length of the growing season….likely will dominate.

The issue IS complex. For example, though in a desert the dominant minimum is usually water, we know the many plants tolerate drought better as CO2 rises. Perhaps CO2 rising also helps plants tolerate cold.

Mark Lee
Reply to  kwinterkorn
September 24, 2020 11:08 am

Are you sure the governing minimum is the temperature? The growing season appears largely dependent on temperature, but don’t discount solstice. I grew up in Anchorage, which isn’t far enough north to really be considered the arctic. But we experienced the “midnight sun” too, just not as much as the more northerly part of the state. My recollection of the 1960’s and 70’s in Alaska was that the spring breakup occurred in April-May. When the melt started, it progressed rapidly as the amount of daily sunlight increased rapidly following the solstice. The Chugach Mountains got their first snows, i.e. “termination dust” in September. It was beautiful to see during Elementary School recess, and it advanced rapidly. Freezing nights started in September and we normally had a foot of snow on the ground by Halloween. My point is, the temperatures were very dependent on how rapidly the seasons changed due to the amount of daylight. Unless I misunderstand the concept of “arctic greening”, it refers to increased plant growth. Booming plant growth. I’d look into increased plant food, i.e. CO2 since the amount of daylight hasn’t changed.

Jim Gorman
Reply to  kwinterkorn
September 25, 2020 4:51 am

You realize that the length of the growing season is not a good indicator of Tmax or even Tmin. Coldest temps usually occur at Tmin. In most places Tavg is rising because of Tmin increasing which is what determines the length of the growing season.

That’s why I asked my question. Did the study include ANY data on growth effects of either Tmax or Tmin.

Rolf H Carlsson
September 23, 2020 2:53 pm

How about earlier warm periods, e.g. the early 29th century when the Northwest passage was open? Even if satellite surveying was not available, any other observations from that time?

Smart Rock
Reply to  Rolf H Carlsson
September 23, 2020 5:26 pm

I would guess that the length of the frost-free growing season is the limiting factor for plant growth in that harsh environment. which is, of course, indirectly related to temperature.

Also lack of wind helps plants thrive in the far north. You can see how dense the growth is in sheltered gullies, compared with open tundra.

These people should have studied daily temperature records and wind speed records instead of just assuming “warming”. The warming is real, just ask anyone who lives there, but the “average” temperature is mostly the result by higher winter minimums and fewer really cold days. Summer temperatures are up, but less dramatically, in the last 40 years.

CO2 increase would probably help a bit, but gut feeling says it may not be that important.

Their map shows greening down below 60°N, so it’s not all “Arctic” which is strictly defined as north of 66.5°N. Just to be picky.

David A
Reply to  Smart Rock
September 24, 2020 12:20 am

CO2 increase for most crops is responsible for about 18 percent of crop biomass. (If we could magically reduce our current 410 PPM atmosphere to Pre industrial 280 PPM CO2 atmosphere, we would about 18 percent less crop biomass)

For bio-mass on the tundra, I don’t know, maybe less, maybe more.

Gary Pearse
Reply to  Smart Rock
September 24, 2020 2:23 am

Smart rock. Need your gut adjusted.

“CO2 increase would probably help a bit, but gut feeling says it may not be that important.”

‘Feelings’ aren’t even opinions, let alone informed opinions. Why would CO2 be causing massive greening (and a little cooling) in the the hot dry parts of the planet, like the Sahel in Africa (southern fringe of the Sahara), Southwestern US, and desert regions in Asia. And why would greenhouse operators elevate CO2 on purpose at added expense? Bumper harvests owe their existence to agricultural advances AND higher CO2. The poker players ‘tell’ in this climate change article is the hygienic absence of even a single mention of CO2 in a subject that is otherwise hysterically pathological about this gas. Here is a link deliberately chosen from the 1970s before the climate wroughters began plying their trade.

A scientist knows he is on very shaky ground with gut feelings in such a contrary profession. A little logic helps though.

Reply to  Gary Pearse
September 24, 2020 9:18 am

CO2 causes greening in the Sahara by letting plants use water more efficiently. This only maters when plants aren’t dormant.

Reply to  Gary Pearse
September 24, 2020 9:39 am

Re the Sahel, plants tolerate drought better when CO2 rises because of the way respiration occurs at the pores on leaves

Curious George
September 23, 2020 2:53 pm

“Used the Landsat data and additional calculations to estimate the peak greenness.” I don’t know how to measure the “greenness”. There is no color scale for the image. I have a funny feeling that the image is mostly produced by “additional calculations”. And why did they exclude Iceland?

Ron Long
Reply to  Curious George
September 23, 2020 6:04 pm

Curios, Landsat has detectors which can see two aspects of “greening”. The color green (band 3 in newest Landsat 11 bands, and 2 in older 8 bands), and near infrared (bands 5 or 4), which can see pronounced chlorophyll peak. The brief report is not clear on what techniques utilized, but Landsats all have the ability to serve this purpose. CO2? No way they will credit this noxious gas with anything.

Bob boder
Reply to  Curious George
September 24, 2020 10:23 am

“Whether it’s since 1985 or 2000, we see this greening of the Arctic ”

Could it also since 1970, 1960, 1950 or anything after the end of the LIA? They notice because they have easy access to data that was not easily accessed before and all of the sudden it must be a new phenomenon.

September 23, 2020 2:57 pm

Would any of the greening be a result of enhanced CO2????

Reply to  Philip
September 23, 2020 3:21 pm

In a word, “NO”! Increased CO2 causes more plant growth, which is a huge PLUS for the world! Any warming we might experience, if ANY, is caused by other events. In reality, the long term tendency is toward global cooling. More and longer plant growth can actually increase the suns effect by absorbing more heat in the northern regions. Bottom line is: There IS no ‘climate change’ and therefore, no ‘global warming’. Any sea rising, measured in millimeters, is irrelevant. Liberals just HAVE to have something to scare the bejeesus out of themselves and anyone else who will listen to them. Does anyone here really expect to be alive 1,000 years from now?

Chris Cordle
September 23, 2020 3:15 pm

What a crisis that the earth is greening! How dare plant life try to thrive in one of the most hostile environments on planet earth!

September 23, 2020 3:30 pm

As the greening / browning around the pole is inconsistent with latitude there are the influence of factors other than purely CO2 at work.

September 23, 2020 3:47 pm

If a warming tundra is releasing methane, where is it? It isn’t showing up in the atmosphere.

Smart Rock
Reply to  MarkW
September 23, 2020 6:23 pm

Supposedly, atmospheric methane increased from about 1.58 ppm to about 1.78 ppm between 1984 and 2016. Of course, the increase is assumed, as a given, to be human-caused, either directly, or indirectly by increased methane emissions resulting from human-caused warming due to anthropogenic increase of CO2.

The percentage increase in methane over the 32 years was 12.6%, compared with the Mauna Loa CO2 increase of 14.7% over the same years.

Alarmists tend to ignore the period 2000-2007, when methane levels did not increase at all, while CO2 went up almost 5 percent.

Is methane 25 times more effective at IR absorption than CO2, or 86 times? Both numbers are regularly trotted out with dire warnings of future catastrophe. It’s not that one is based on molar concentration, and the other on concentration by weight because molar weight ratio of 44/12 is not the same as 86/25

Reply to  Smart Rock
September 25, 2020 11:46 am

What are the error bars on those calculations?

Joseph Zorzin
September 23, 2020 3:59 pm

Off topic- sorry, but-
“NYC Comptroller Stringer wants renewable energy option for Gowanus power plant ”

“He called on the state agency responsible for electric facilities to reject the Astoria Generating Company’s plans to replace old units at a plant in Gowanus, Brooklyn, with natural gas units.”

Rhoda R
Reply to  Joseph Zorzin
September 23, 2020 4:20 pm

Why does he think that NY is more amenable to solar/wind than California? Or is he talking about increasing their hydroelectric power usage?

Pat from Kerbob
Reply to  Rhoda R
September 23, 2020 7:17 pm

probably bios mass, ie burning trees

September 23, 2020 4:38 pm

This gem:

“Landsat is key is for these kinds of measurements because it…allows the researchers to investigate what is driving the changes to the tundra.

So much for settled science. We’ve all been harangued into believing that CO₂ was driving changes in the tundra.

Steve Case
September 23, 2020 4:45 pm

the warming temperatures are also thawing permafrost, releasing greenhouse gasses.

Oh yes methane at 86 times more powerful than CO2 but they NEVER tell us how much that translates into global temperature. There’s a reason for that. By 2100 methane will run up tempature less than a tenth of a degree Celsius. If any body knows that it’s much more than that, please put up a link.

Reply to  Steve Case
September 23, 2020 8:21 pm

probably the most info you will find on GWP is here
I especially like fig. 8.33 that finally shows that CH4 converts to CO2 with 12 year half life, so the often stated 22 or 25 or 86 times as much heat trapping meme by integrating over decades up to a century is exposed as extremist exaggeration.

Steve Case
Reply to  DMacKenzie
September 24, 2020 3:46 pm

DMacKenzie September 23, 2020 at 8:21 pm
Thanks for the reply; The Global Warming Potential non-sense is in all five IPCC Assessment Reports and the gist of it is that by mass, i.e., pound for pound methane does indeed have more greenhouse effect than CO2, 86 times more according the IPCC’s AR5. Methane increases a few parts per billion (ppb) every year, and by 2100 that will add up to as much as 500 ppb or 0.5 parts per million (ppm). Since the comparison is by mass, and CO2 is 2.75 times heavier than methane an equal mass of CO2 would be about 0.18 ppm. So if CO2 increases to 750 ppm by 2100 Source, the comparison is the difference between the temperature increase caused by 750 ppm and 750.18 ppm CO2. It doesn’t take a genius to see that the Global Temperature difference caused by an increase of a mere 0.18 ppm CO2 is essentially nothing, and 86 times nothing is still nothing. That explanation is a bit convoluted, and the reason why the non-sense persists.

Joel O’Bryan
September 23, 2020 4:53 pm

1985 thru 2016: 32 years. (yawn).
Wake me up when you have at least 70 years of data. I’ll be 96 then if I still alive. I’ll wait.

September 23, 2020 5:18 pm

I wonder how close the planet is to snowball Earth the last few million years.

September 23, 2020 7:45 pm

A 2017 study by CSIRO (Australia) ( maps increased greening worldwide over the period 1982-2011. The results showed widespread greening especially in northern Europe, Canada and NW South America. No data for the high arctic. These results appear to differ from the NAU study. CSIRO concluded that increased CO2 was the dominant cause of the greening.

The only long-term temperature record in the high arctic is for Svalbard (Norway), 78 degN, which has a composite record since 1899. The summer (Jun-Aug) temperatures there have increased by 2.5 degC since 1980. Similar, but lesser, temperature increases have been recorded at many locations north of 60 degN (ie north of Oslo, Anchorage, etc) since about 1970.

September 23, 2020 10:24 pm

35 years ago my brother lived in Whitehorse, Yukon. He said come mid September things cooled off and you could see the cold coming, -45F cold,and stayed cold until spring. I did a drive through the Yukon last year in early to mid-September, light frost in the morning and 20F in the day. Talking to locals the weather has been changing, they get -45F for weeks instead of months, but that may be a familiar change in the north as there were fossils and animal bones in the local museum that suggested a warmer history prior to ice age.

Climate believer
September 24, 2020 2:00 am

I find these type of graphics to be very misleading, and leave a lot to the human imagination, I cynically believe it’s intentional.
Their Browning to Greening key strip doesn’t mean anything, where are the definitions? what has “greened” and by how much? where’s the accounting of the natural ebb and flow in vegetation growth?

They say “greening can represent plants growing more, becoming denser or shrubs encroaching on typical tundra grasses and moss.”

…..and? is this bad? are we automatically supposed to believe so? change = bad.

“When the tundra vegetation changes, it impacts not only the wildlife that depend on certain plants, but also the people who live in the region and depend on local ecosystems for food.”

You have no evidence of any impact, good or bad, these statements are meaningless. Generally speaking more “green” means more wildlife not less, which is good for hunting.

They always talk as if there’s only one season, summer. What happens to the “greenness” when arctic winter comes around and plunges everything into darkness to -15°, -20°, -30°C on average?

I’m not saying there is no change, I’d be surprised if there wasn’t, but all I see here is media headline rhetoric and very little objective science.

September 24, 2020 5:51 am

I hope that some day, someone who “gets” the miasmic disconnect between the Real World and the notion that the Earth is somehow dying right in front of us, will be kind enough to explain to me why none of these people understand that this is all part of a cycle, over which we have little to no control.

I’m just trying to understand here, that’s all. 400,000 years ago, Heidelbergensis was camping out in Germany after a successful splurge of hunting Przewalski’s horse, and when the clan left the area, they left behind all kinds of junk such as bones showing butcher marks, double-ended javelins and hunting bows for both adults and children, and other bits of this and that, including their campfire. They left all that litter behind and now it’s in a museum. Then things changed and that clan of Heidelbergensis families moved on, and eventually died out, although there is some evidence that they may have met and mixed with other Hominid species. Some people have had their DNA screened to see if they have Heidelberg ancestors from Way Back Then. I may do that some day, since some of my distant ancestors came from Germany.

Things change. They change all the time. What is this desperate urge by these “researchers’ to try to stop change, when the reality is that change happens all the time. You either adapt and move on or you end up looking silly and get left behind.

What is it they are REALLY afraid of?

Reply to  Sara
September 24, 2020 9:22 am

I think you might mean Homo Neanderthalensis at 40,000 years. Genetic analysis is very limited after 70k years BP, although there is now some work on proteonomics to try to get further into the past. And, yes, Neaderthal genes persist in all peoples outside of Africa. Svante Paabo is a sure bet for a genuine Nobel.

Reply to  Fran
September 25, 2020 6:55 am

No, it was a camp site found in Germany and it was Heidelberg man, NOT Neanderthal.
Heidelbergensis evolved ahead of Neandertals and Homo Sapiens by several hundred thousand years , but lasted until about 125,000 years ago, then died out. Some modern humans may have about 2% Heidelberg DNA in their genes.

An archaeological site in Schöningen, Germany contained eight exceptionally well-preserved roughly 400,000-year-old spears for hunting, and various other wooden tools. Five-hundred-thousand-year-old hafted stone points used for hunting are reported from Kathu Pan 1 in South Africa, tested by way of use-wear replication.[54] This find could mean that modern humans and Neanderthals inherited the stone-tipped spear, rather than developing the technology independently.[54][55][56]

No forms of art have been uncovered. Red ochre, a mineral that can be used to mix a red pigment which is useful as a paint, has been found at Terra Amata in France and Bečov in the Czech Republic, but the dating of these pigments to the Middle Pleistocene is contested.[57]

The Schöningen spears are eight wooden throwing spears, dated to before 300,000 years ago, discovered between 1994 and 1998 in the open-cast lignite mine, in Schöningen, county Helmstedt, Germany, together with thousands of animal bones. They are regarded as the first direct evidence for active hunting by H. heidelbergensis (pre-Neanderthals).[58][59][60] – Wiki

Furthermore : Wilkins took close-up photographs and put the stones under a microscope to look for the tell-tale damage caused to stones whenever they are used on spears. “We know from experimental studies that, when a point is used as a spear tip, the concentration of damage is greater at the tip of the point than along the edges,” she said. “That’s the same pattern we saw in the Kathu Pan point.”
Her analysis is published today in the journal Science. Dating the stone tips to 500,000 years ago means that they were used on spears by the last common ancestor of modern humans and Neanderthals, Homo heidelbergensis. The idea that Homo heidelbergensis developed stone-tipped tools made a lot of sense, said Petraglia, because Homo sapiens and Neanderthals, which descended and split from Homo heidelbergensis around 300,000-400,000 years ago, used similar stone-tipped spear weapons.
Petraglia added that there were several other implications to the discovery that Homo heidelbergensis had used hafting to make spears. Adding stones would not only have given our ancestors an easier way to kill prey, but also to do it from a distance. “There is a big difference between thrusting and throwing,” he said. “You can kill from a distance, maybe 10 to 30 metres away. The previous ancestors did not have that technology, so it means you are now occupying a new ecological niche, you can now take animals down more efficiently.”

September 24, 2020 7:34 am

There’s almost certainly even greater summer “greening” in the northern oceans from increased phytoplankton.

September 24, 2020 8:50 am

Same old , same old-

1923- “Where formerly there were great
masses of ice, these have melted
away leaving behind them accumula-
tions of earth and stones such as
geologists call “moraines.” At many
points where glaciers extend far into
the sea half a dozen years ago they
have now entirely disappeared.
The change in temperature has
brought great changes in the plant
and animal life of the Arctic”

Climate believer
Reply to  richard
September 24, 2020 9:41 am

Fascinating, thx for the link.

Tom Abbott
September 25, 2020 4:50 am

“as we see really rapid increases in summer air temperatures.”

Rapid increases? What’s the increase in temperatures as of today? I believe it is about 0.14C per year (UAH). So this “rapid” increase is measured in tenths of a degree.

More exaggerations by the Alarmists.

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