Arctic Greening Won’t Save the Climate – Here’s Why

Yves here. I must confess to having missed this one. I can’t believe “arctic greening” is considered to be a legitimate idea, as least as a plus in the climate change category. Admittedly, I had the advantage of seeing a couple of days of presentations at the Explorers’ Club after the International Polar Year 2007-2008, where tons of scientists and some adventurer-helpers decamp to the Arctic every 10 years to take measurements and take observations. For a bunch of professional hardy realists, they were very freaked out at the degree of change since the last Polar Year.

By Donatella Zona, Associate Professor of Biology, San Diego State University. Originally published at The Conversation

Satellite images show the Arctic has been getting greener as temperatures in the far northern region rise three times fasterthan the global average.

Some theories suggest that this “Arctic greening” will help counteract climate change. The idea is that since plants take up carbon dioxide as they grow, rising temperatures will mean Arctic vegetation will absorb more carbon dioxide from the atmosphere, ultimately reducing the greenhouse gases that are warming the planet.

But is that really happening?

I am a biologist who focuses on the response of ecosystems to climate change including tundra ecosystems. For the past five years, my colleagues, students and I have tracked vegetation changes at remote locations across the Arctic to find out.

Braving Bears to Collect Evidence on the Tundra

The Arctic tundra is a vast, mostly treeless region stretching across the far northern areas of North America and Eurasia. A few feet below its surface, much of the soil is frozen permafrost, but the top layer blooms with grasses and low shrubs during the short summer months.

Satellite studies over the past decade have tracked changes in the greening of the Arctic by measuring the visible and near-infrared light reflected by vegetation. Healthy green vegetation absorbs visible light but reflects the near-infrared light. Scientists can use that data to estimate plant growth across wide areas.

But satellites don’t measure the plants’ carbon dioxide uptake.

Satellite images of the greening Arctic. NASA Goddard Space Institute.

Until recently, field studies that might verify how much carbon dioxide Arctic plants were taking up were sparse, preventing scientists from testing the hypothesis that earlier snow melt and its impact on plants helped control carbon dioxide in the atmosphere.

For our study, scientists braved bear territory and cold summer nights to collect extensive carbon dioxide measurements near plants and soil in 11 Arctic tundra ecosystems, including in Alaska, Canada, Siberia and Greenland. We focused on the most understudied Arctic areas, located over continuous permafrost.

Earlier Growth, but a Late-Season Slowdown

Arctic plants currently have only about three months in which they can grow and reproduce before the temperatures gets too cold.

When we started this study, we wanted to find out what effect the earlier start to the growing season was having on the overall amount of carbon dioxide taken up by vegetation each summer. The results surprised us: Even though the greening was evident, the overall carbon dioxide uptake either did not significantly increase or had only minor increases.

When we looked closer and compared the changes from week to week, we discovered why. While the earlier snowmelt was stimulating plants’ productivity in June, that productivity began to taper off in July – normally their peak season for photosynthesis. By August, productivity was well below normal.

The Arctic’s dominant shrubs, sedges and other wetland plants were no longer sequestering more carbon late in the season. It was like waking up earlier in the morning and being ready to go to sleep earlier in the evening.

Satellite data captured at the summer growth peak from 1984-2012 showed extensive greening in the tundra of western Alaska, northern Canada, Quebec and Labrador. It captures evidence of plants, but not carbon dioxide changes. NASA’s Goddard Space Flight Center/Cindy Starr

We still have many questions, including why plants are responding this way and whether the widely used index for plant growth based on changes in visible and infrared light, called NDVI, is definitively associated with a higher uptake of carbon dioxide. Some Arctic ecosystems have shown strong correlationsbetween NDVI and carbon dioxide uptake, while others have not. We didn’t find evidence that plants were affected by water limitations in the late season.

If tundra ecosystems are not able to continue taking up carbon dioxide later in the season, the expected increase in plants sequestering carbon may not materialize.

And there’s another problem. Normally, plants on the tundra store more carbon through photosynthesis than the tundra releases, making it a vast carbon sink. The long, cold winters slow plants’ decomposition and lock them in the frozen ground. However, when permafrost holding this and other organic matter thaws, it releases more greenhouse gases into the atmosphere.

This infographic illustrates the differences in plant growth each month. When snow melts earlier in the season, plants begin decomposing earlier. Donatella Zona

The Local Impact Goes Beyond Carbon

This isn’t just a story about plants and the climate. Vegetation changes can have wide-ranging effects on other components of ecosystems, including animals and people.

The Intergovernmental Panel on Climate Change, the United Nations body for assessing the science related to climate change, has estimated that changes in snow cover have already affected food and water security. Many local native communities depend on hunting, trapping and fishing, and earlier vegetation development can affect the delicate balance of complex Arctic systems.

If Arctic greening is only shifting seasons and isn’t increasing the overall carbon dioxide level as previously believed, that could also mean the models currently used to evaluate and predict the overall impact of climate change are missing an important piece of information. The result could be that a process we assumed would slow or mitigate climate change isn’t actually working as expected.

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  1. nippersdad

    Here in the South I am hearing reports that the early bloom periods of native plants are increasingly out of sync with when the native pollinators who rely upon them are coming out of hibernation. WRT the Arctic, it may just be a case of their models showing Tundra and Boreal Forests/Taiga not moving north fast enough into their new niche opportunities to affect carbon levels. Seems like the processes that they are looking at should have taken into account the idea that AGW is occurring much faster than the natural environment is programmed to balance. Grasses going into dormancy before the season effectively ends should be more of a tell for them; Arctic plants cannot move north three times faster just because it is suddenly three times warmer.

    I remember hearing somewhere that it may take three hundred years for the bugs that eat species Eastern redbud leaves to recognize the purple leaved hybrids as their larval host plant. Lag time is a thing. IMHO, they need to be measuring the northward march of the willows and musk oxen if they want to truly gauge the potential speed of carbon uptake in the Arctic.

    That said, as a person who only gets to read their books, I am impressed that Yves gets to actually go to the Explorers Club. That is pretty impressive.

    1. juno mas

      Excellent observation. It’s not just that the climate is changing (its been doing so over long geologic periods) it is the rate of change that is the stickler in AGW.

      As for the carbon uptake of “arctic greening”, it’s unlikely that it will be sufficient to offset the infusion of CO2 into the acidifying oceans. We need to stop looking for ridiculously “hopeful signs” and get serious about radical conservation.

      1. nippersdad

        Isn’t that right about the time that the end of the North Atlantic Oscillation is supposed to kick in?

        I agree. If we don’t do it ourselves, and soon, Mother Nature will do it for us. Its’ not nice to fool Mother Nature. I saw it on TV, so it must be true. :)

  2. Appleseed

    This is where assisted migration comes in, sowing seeds of appropriate plant species that are better adapted to take full advantage of the increased degree days available for growth and carbon sequestration. Would that destroy the integrity of arctic ecosystems? In one sense, probably. But these ecosystems will be ravaged by rapid climate change as well, so take your pick.

    1. drumlin woodchuckles

      If the whole Arctic is turned a mid-latitude green, where are the musk ox/ caribou/ polar bears/ arctic hares/ etc./etc./ etc. supposed to go? To heaven?

  3. mikkel

    This is interesting work! but the first time I’ve ever heard there was a theory that greening would help with climate change.

    Normally the talk is about how much the change in albedo will cause significantly more warming. In addition as succession takes place, deeper rooted plants will break up the top layers and accelerate permafrost melt.

    Increased photosynthesis is a rounding error comparatively

    1. nippersdad

      I was actually wondering how the shade of Arctic deciduous plants, like Larch trees, would serve to insulate the underlying permafrost in summer and raise albedo in winter. They are not particularly deep rooted, and the shade they would provide in summer might do well to preserve what permafrost may be left and prevent further off-gassing.

      But all of this talk is kind of silly. After Exxon gets its’ Canadian gas permits they wouldn’t even get the chance to try.

      1. Mikkel

        Oh great. I had only seen studies like this one which document rather mild (yet significant over time) albedo changes.

        However in searching I’ve learned that in the focus has shifted to evapo-transpiration and its effect on clouds…which in turn increases sea ice melt. That paper suggests that this is 3x larger than the albedo change and increases with deciduous plants since they have so much more evapo-transpiration

        I thought I knew all the doom loops but nature constantly surprises!

        Although since life is good at modifying the environment to further support itself, it shouldn’t be too much of a surprise.

        1. nippersdad

          All of the information out there is truly mind bending. Just off the top of my head, though, reading the precis of those studies leave me with questions. They may not be smart questions……but, anyway.

          For example: absent snow cover one is talking largely about bare ground vs. twigs and leaves. The difference in albedo between those should be minimally positive, especially in winter. Leaves absorb much of their energy from the infra-red part of the light spectrum, the part that warms such things as rocks, and given their ability to shade the earth should have the effect of lowering the ambient temperature even as they raise the albedo around them somewhat. So it strikes me that their ability to sequester Co2 should be more of an advantage than the studies let on and should change the calculation.

          Also, too, evapotranspiration by plants leads to cloud cover which, in turn, should raise the albedo over bare unshaded rocks. While the rain that such cloud cover may produce will have the effect of melting in such places as Greenland, it may also have the effect of producing snow to increase snow pack and ice formation in precisely such places. We have little floating ice anymore in the Arctic ocean in summer, but if you can replace the albedo from ice loss by introducing more clouds you should still have a net benefit, If you can bring the temperature down even just a little bit it may on balance have the effect of ultimately retaining more sea ice than you lose and thereby lowering the albedo of the Arctic ocean.

          Then there is the idea that more sunlight means more krill. More krill means more ocean carbon is sequestered in pelagic organisms going up the food chain until it is ultimately left in the vasty deeps as whale feces and corpses. From what I hear that is not an inconsiderable amount of carbon. Fertilize with some iron oxide and the algae blooms would sequester even more Co2.

          I seem to recall that the difference between an ice age and an interregnum was very small at the higher latitudes, so greening of the Arctic might have more of a positive effect than these studies suggest. Totally off topic, but not really, here in the South tree cover has been shown to lower ground temps by ten to twenty degrees depending upon the circumstances; more water leads to lower wet bulb temperatures of the sort that might be found in the Arctic. Humidity sometimes has its’ advantages.

          So, I don’t know. I am no computer modeller, but it seems like there are some things not mentioned in the models which might make the situation more heartening than they do. The boreal forests are going to move North, we can only hope that they have a better effect than our science presently predicts for them.

          1. Judith

            There are a complex set of variables affecting the changes in the boreal forest and different trees are responding in different ways. And the other members of the ecological systems also have effects, as does the specific location. An interesting book I just finished: “The Treeline The Last Forest and the Future of Life on Earth” by Ben Rawlence explores this. He travelled the boreal forest from Scotland west through Norway, Siberia, Alaska, Canada, and Greenland and spent time with scientists in each location.

            1. nippersdad

              Thank you for the book recommendation! I love books on trees, and that is one I will have to get,

              As a general proposition, though, what effect upon climate do they think that the boreal forests moving north will have?

          2. mikkel

            I haven’t read much of the paper but in general:

            While you’re right that shade lowers ambient temp, there is significantly faster snow melt and delayed snow cover/much delayed refreeze. I can’t remember off the top of my head but it was something like 2 weeks earlier melt and 4 weeks delayed refreeze. Thus overall temp is higher even if there is lower energy at the peak. In a few decades it was even more pronounced.

            Same thing for clouds although that’s much more complicated and is the biggest unknown in climate science. In general though increased humidity affects temperature in a few ways: increased trapping of heat (especially with thin clouds) and easier heat transfer from lower latitudes. While the rapid increase in humidity seems to be creating more cloud cover and acting as a negative feedback loop for sea ice minimum, refreeze is much more affected. There is some evidence that the whole system will flip at roughly the same time – meaning that sea ice will stay around where it is until the arctic is warm enough that direct sunlight isn’t the primary source of melt. This is what seemed to happen in the past and what evapo-transpiration points to.

            What do you mean by difference between ice age and interregnum? I don’t believe that forests have covered that far north in the ice age period and it’s believed that they are one of the factors for the sea being ice free millions of years ago due to very weak polar cell.

            As for krill the race between acidification and increased light will be intense…

            1. nippersdad

              “…there is significantly faster snow melt and delayed snow cover/much delayed refreeze.”

              That is interesting. It seems like that would not be the case for deciduous trees, doesn’t it? It is kind of counterintuitive. It seems like the snow would last longer due to shade in Spring and refreeze earlier in Fall were the soil temps to be kept lower throughout the short summers. I am obviously no scientist and anecdotes are not data, but my experience in WI while at school showed me that snow in shade lasted much longer and ground in the woods froze much faster.

              I can see how increased temps of seawater would be the tipping point for sea ice melt, but humidity will precipitate out when close to a source of cold, which if insufficiently cool will otherwise just cool off the ambient air. Humidity traps heat, can’t exist without it, but there has to be sufficient heat for it to become actually warm; one has lake effect cooling in August around the Great Lakes, for example. That is a lot of warming necessary to increase ambient temps over water, ice or snow. We, of course, saw that last week when temps were fifty to ninety degrees above the norm, but that is not the norm….yet, anyway.

              Re: “What do you mean by difference between ice age and interregnum?”

              Something like this:

              “One of the more recent intriguing findings is the remarkable speed of these changes. Within the incredibly short time span (by geologic standards) of only a few decades or even a few years, global temperatures have fluctuated by as much as 15°F (8°C) or more.”


              It just doesn’t need to be a lot of change to make great changes. Less than fifteen degrees to make an ice age doesn’t seem like a lot, and trees don’t have to be a part of the historical equation to make boreal cooling happen. But, I totally agree with the general consensus that more, much more, will need to be done to bring down our carbon footprint to make it happen.

              I was just speculating as to the effect of newly formed forests on carbon capture and lowering boreal temperatures. If we wait too long all the inputs in the world will not help to solve a problem that no longer includes ourselves.

  4. drumlin woodchuckles

    What would save the climate is Arctic ReWhitening, as in Arctic Re-Freezing. And saving the climate is what would ReWhiten and ReFreeze the Arctic. Sounds circular, I know.

    What would achieve that at this late date, if not already too late. Simple, but not easy. Reduce carbon skyflooding and re-raise plant-driven carbon skydraining. Skydrain more carbon than what we skyflood and hope we are net sky-draining the skycarbon fast enough to re-lower the surfacespheric level of heat retention down to where the Arctic and Antarctic and non-polar ice fields can re freeze back to where they were before.

    Can the reality-based global de-warming community force a dewarming of the global in the teeth of the fantasy based global let-heating-rip community? I don’t know. I know it can’t if the global de-warming community won’t even acknowledge that it is an existential binary Us versus Them situation.

    ” ‘We’ ? Us or not us. There is no ‘we’. “

  5. Brick

    The carbon cycle is complicated but artic greening will not in my view make a lot of difference. What happens in the artic can be critical to climate but more particularly local climate in western Europe and north America. Once you really try to pull all the threads of the carbon cycle together like the IPCC does you begin to understand how tricky predictions and the only safe thing to do is to live in balance with earth as far as you can.

    The fundamental of climate change is that the balance between outbound and inbound long wave radiation changes. CO2 for instance traps long wave radiation whilst snow/desert reflects out long wave radiation. Soot and dust even in the form of brake dust affect albedo (surface reflectivity) which can play a big part in climate change. In terms of the artic then reducing ice cover or covering it in soot reduces outbound radiation which increase global temperatures.

    On the other side of the carbon cycle to CO2 emissions are CO2 sinks which can make a big impact on climate. Anthroplogical effects on CO2 sinks through deforestation and ocean damage can be equally if not more important than CO2 emissions. Phytoplankton blooms are the oceans prime way of capturing CO2 and they tend to occur best in cool open waters. Blooms in artic waters could have a big impact on climate change. The answer though is a little more complicated due the interaction of zooplankton, fish and plants. Algae looms nearer the equator may also negate some of the impact. This is why forest fires might be neutral to climate change because they seed plankton blooms.,can%20be%20seen%20from%20space.

    The Pacific and Atlantic oceans are part of a conveyor belt of warm and cool waters. Warm waters move north and south towards the pole on the surface and then sink as they cool at deep water formation points. The cooled water moves towards the equator at depth. One of the important controllers of this process is salinity of water and the strength of the ocean thermocline. The ocean thermocline strength has been declining generally over the last 100 years possibly related to plastics or heavy metals (particularly copper). Changes in the over turning conveyor belt may not effect global climate but could significantly reduce climates locally (North America and Europe).,to%20sink%20to%20the%20bottom.&text=Places%20where%20the%20water%20is,enough%20to%20form%20bottom%20water.

    There are some natural phenomena which get thrown into the mix which complicate prediction. Movement of the north pole and changes to weather patterns as a result. Volcanic eruptions along the Gakkel ridge are acting to melt the ice in addition. Perhaps you will begin to get an idea of how the IPCC needs to meld together so many different threads of research and may well under estimate one factor compared to another. Best guess is that melting artic ice is bad for the climate.,to%20sink%20to%20the%20bottom.&text=Places%20where%20the%

  6. Jeremy Grimm

    I am not a fan of geoengineering … but I had a weird idea. Instead of putting up space mirrors to reflect sunlight away from the Earth the space mirrors should be oriented to light the Northern reaches to extend their growing seasons. [At the end of the day I share Phillip Mirowski’s views on space mirrors are plain from his lecture available on youtube: “Prof. Philip Mirowski keynote for ‘Life and Debt’ conference”,

    This lecture showed up first when I searched youtube using Phillip Mirowski as the youtube search term. I am not sure what that means … I hope Mirowski does not join Chris Hedges some time in the future.

  7. Jeremy Grimm

    Any putative carbon impacts of Arctic ‘greening’ should not be accrued without considering the carbon impacts of the side effects of the Arctic warming on global plant-life. I blame Arctic warming for pushing down the cold weather that has made my forced move of residence unexpectedly unpleasant. The same cold weather and sudden shifts to warmer weather, lead me to worry, that many plants may leaf or bloom in response only to find themselves cut off at the knees by sudden shifts to unusual and damaging cold.

    1. drumlin woodchuckles

      Space mirrors would heat the Arctic so fast that methane eruptions would outrun any increased plant-growth CO2 suckdown you might get. Space mirrors sounds like a worse idea than a sulfuric acid shround around the whole planet.

      Maybe the ChinaGov will get tired of waiting around and try both at once.

      1. Jeremy Grimm

        Watch the video I referenced in the comment before this. Phillip Mirowski thought space mirrors were quite ridiculous, making a perfect foil for his complete dismantling of neoliberal geoengineering projects in black comedy. I Like growing stuff as a geoengineering project just because I like trees and plants and growing stuff. The carbon impact runs into a little trouble when you remember there are fungi that after some delay, digest trees and other growing stuff and put the CO2 back into the atmosphere.

        1. drumlin woodchuckles

          Perhaps we should call various kinds of accelerated plant-growing by the name ecoengineering. A different word would permit different thoughts and help different thinkers speed the different thoughts along.

          There are grow-more-plants situations where some of the re-suckdowned skycarbon stays resuckdowned. Peat bogs, marshes, swamps, etc. All around the world hundreds of millions of acres of carbon-storing wetlands have been drained and reduced to farmland. The more of that land could be rewetted and reflooded and restored and reimproved back to working wetlands, the more skycarbon would be sucked down, stored and kept stored. Also, half a billion beaver ponds would be half a billion carbon resuckdown sites.

          And what about the several million square miles of still-farmed still-farmland? Do carbon farming on it. Combinations of Gabe Brown/ Garry Zimmer/ Jeff Moyer/ etc. suites of methods designed to restore high soil-carbon levels while growing and selling a crop for enough money to keep the carbon farmer in business and storing more carbon in the soil.

          Members of the global dewarming community could make a point of finding and patronizing carbon farmers before having to patronize any anticarbon farmers. They could pursue this targetted consumption-for-pay behavior as part of a wider Civil Culture War against the pro-fossil community. A Civil Culture War of cultural and economic extermination against the Fossil Fuel Sector and against all the millions of Enemies of Life on Earth who support Fossil Fuel and oppose Survival. A war designed to attrit and degrade and eventually destroy the Fossil fuel economy and destroy the personal economy of every person who supports the Fossil fuel economy, so as to destroy their anti-human and anti-life influence over public policy and public culture.

          ” ‘We’? Us. Or us not. There is no ‘we’. “

    2. nippersdad

      “The same cold weather and sudden shifts to warmer weather, lead me to worry, that many plants may leaf or bloom in response only to find themselves cut off at the knees by sudden shifts to unusual and damaging cold.”

      That is increasingly a very real problem. Ten years ago I sat in on a Master Gardener’s lecture by a meteorologist on climate, and the topic of polar vortexes came up. The lecturer said that they were just random events while others mentioned the breakdown of the polar jet stream due to warm temps at the pole and got shushed. It turns out that they are not random now at all and that they are an artifact of the breakdown of the polar jet stream.

      A couple of weeks ago we had an ill timed frost, and now we have azaleas in full bloom, replete with bees, that have no leaves. It looks very strange. I am left wondering if we lost the peach crop, again.

  8. Vernon Hamilton

    Here is a recent and relevant article in the Guardian about what the moving treeline is doing in Norway.
    Here is an interesting statement from that article –
    “On the face of it, more trees might sound like a good thing. The problem is that the greening of the tundra further accelerates the warming process, as the birch improves the soil and warms it with microbial activity, melting the permafrost and releasing methane”.

    1. drumlin woodchuckles

      We should simply deep strip-mine the whole permafrost region . . . all 4 million square miles of it . . . . and extract the methane before it escapes.

      Just wait till someone suggests that for real with a straight face.

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