A Few Things Ill Considered

Another Climate Metric: metres/day

We have another climate metric to add to W/m^2 (climate forcing), GT/year (CO2 emissions), mm/year (sea level rise) and oC/decade (temperature change) and that would be m/day.

Meters per day is for tracking how quickly climatic zones will move as a result of man-made climate change and it is actually an astonishingly high number.  David Appell at Quark Soup uses some rough numbers and comes up with a figure of 8 metres/day over the last 20 years.  He bases this calculation on an article in the Scientific American (sounds like an oxymoron these days!) by Ken Caldiera who looks at the average drop in temperature in the mid-lattitudes as you move towards the poles.  In the article, Ken looks to the future rather than the past two decades:

Without any change in our habits, Earth may warm by about five degrees Celsius (nine degrees Fahrenheit) by 2100, although the actual warming could be half or even double this amount, depending primarily on how clouds respond. This change is about the difference between the average climate of Boston, Mass., and Huntsville, Ala.

In the northern midlatitudes between 30 degrees north and 60 degrees north— a band that includes the U.S., Europe, China, and most of Canada and Russia— the annual average temperature drops two thirds of a degree C with each degree of increasing latitude. With five degrees C of warming in a century, that translates into an average poleward movement of more than 800 kilometers in that period,for an average poleward movement of temperature bands exceeding 20 meters each day. Squirrels may be able to keep up with this rate, but oak trees and earthworms have difficulty moving that fast.

20 metres per day! And as we must always do, keep in mind that this is an average and therefore some areas will experience less, and some more.  As we can already observe, warming is as much as 3 to 5 times faster in some regions (this depends on the size and the time period you wish to choose – I could have defensibly made an even larger claim).  So we are very likely talking about shifts in micro-climates of up to 100 meters per day.  I am no biology or wildlife expert, but that is clearly a death sentence for many animals and ecosystems.  I am sure mandas, who is, will have some opinions on that in the comments below.

The video here is Dr. Caldiera discussing his article.

Comments

  1. #1 mandas
    September 6, 2012

    Hi coby,

    Yes, I may have something more to say about this shortly, but it is more than just animals and ecosystems which are in trouble – it is also agriculture.

    I recall that this particular point was raised once in the past, and I posted two maps like the ones on these two pages:

    http://www.abs.gov.au/ausstats/abs@.nsf/previousproducts/1301.0feature%20article212006?opendocument&tabname=summary&prodno=1301.0&issue=2006&num=&view=

    http://www.bom.gov.au/jsp/ncc/climate_averages/temperature/index.jsp?maptype=6&period=an

    The first one shows where wheat is grown in Australia, while the second one shows mean annual temperatures. Note how the wheat growing region closely aligns with areas with mean annual temperatures of 18 – 21 degrees C.

    You might imagine what would happen over the next century if temperatures increase by 3 degrees or so. It will effectively mean that the Australian wheat industry will be destroyed, as the optimum growing climate will no longer exist on the mainland. Now it is obviously more complex than that, but it does show the scope of the problem.

    The climate map also lends support to the original article being discussed here – and suggests that the 20 metre figure may be understated. I can see that the 18 – 21 degree zone on the map is about 800 – 1000 km wide (lets call it 900). With 90 years until the end of the century, and a 3 degree change being predicted, this suggests that the distance rate of change for a 3 degree rise is about 10km per year – or about 27 metres per day.

    Scary shit indeed.

  2. #2 Ian Kemmish
    September 6, 2012

    You don’t present the actual calculation, but from the quoted excerpt, it would appear that the author is assuming a perfectly linear gradient in temperature both before and after the change in climate.

    If we know anything about climate, we know it won’t be that simple, and in fact the very notion of a single “one size fits all” figure may be harmful – people with different axes to grind will cherry-pick data from regions when the climate bands are moving particularly quickly or slowly.

    As to whether it’s alarmingly big or comfortingly small, that surely depends on the species in question. On the BBC’s website today, are some surprised Scottish scientists who’ve discovered that water voles can migrate at 2km/week.

  3. #3 Wow
    September 7, 2012

    Concern troll alert.

  4. #4 mandas
    September 7, 2012

    Ok, let me address some of the issues being raised here.

    Firstly, the speed with which animals can ‘migrate’ etc is not at issue here –any animal can move or migrate at a speed greater than that being imposed by climate change. The issue is where are they going to go, and what is going to be there when they get there?

    If climate change on this scale had occurred a thousand years ago it would not be as much of an issue, but today there are other factors that make it a huge problem for wildlife. Virtually every species in the world now lives in a small fraction of its former range, largely because of habitat destruction. Animals live in isolated remnants of native vegetation, and are unable to interact with other isolated populations of the same species. When the climate changes or when a major disturbance occurs, these isolated populations CAN’T migrate, because they can’t move out of their remnant habitat. The most likely outcome is that they go locally extinct. If too many local extinctions occur, the species becomes unsustainable and becomes completely extinct.

    Even if a species can migrate polewards, what are they going to experience when they move? The vegetation is likely to be different, as are the invertebrate populations. There is also likely to be competition from the existing species, and even different threats such as predators and disease vectors. This sets up different trophic orders, and some species – perhaps even the existing ones – will be unable to stand the changed environment.

    Almost all species will find themselves in greater conflict with humans as the human population expands, and as migrating animals try to cross agricultural land or graze on the only remaining food supplies available – crops.

    In the oceans the situation is worse. The ‘bottom of the food chain’ in the oceans is underpinned by organisms like corals, cyanobacteria and plankton. Unfortunately, as the oceans warm, increase in Ph and sea levels rise, these organisms will be unable to cope. Corals have only limited capacity to migrate, and if places like the Great Barrier Reef undergoes serious decline – which it almost certainly will with even a relatively small degree of climate change – then the whole ocean food chain will collapse. Imagine the impacts of that on human existence.

    Too many people take too narrow a view about the impact of climate change. A couple of degrees warmer and more heat waves? No problem, buy an air conditioner. But the impact of climate change is much more than that. Climate change – even a small one of 2-3 degrees – is an existential threat to many species around the world, and is an existential threat to human society as we know it.

    Every one of my colleagues is scared to death of what is to come because of climate change, and the more I look at this issue the more afraid I become.

  5. #5 Wow
    September 7, 2012

    “any animal can move or migrate at a speed greater than that being imposed by climate change.”

    Well, not in actual fact true.

    Humans tend to get *really* pissed off when animals move over “their” land and shoot them down dead.

  6. #6 mandas
    September 10, 2012

    Sorry wow – it is true that animals can migrate faster than climate change.

    I addressed your point about human / animal interactions in my post.

  7. #7 Wow
    September 10, 2012

    There are additional problems in that their food can’t migrate. Plants move much slower than animals, and their pests move much quicker.

    It’s not much use when your foodstock needs healthy loam when you’ve only got new-thawed permafrost on the ground you move to.

  8. #8 mandas
    September 10, 2012

    Yep, agree with all those things, which is why I put similar points in my post.

    Animal migration is a complex issue, but unfortunately climate change is imposing it on many species. Mammals are generally fairly adaptive animals and can tolerate a range of environmental conditions, and under ideal conditions they might be able to adapt to climate change – with a lot of limitations. Unfortunately, reptiles. amphibians and invertebrates are not so tolerant, and as these animals are part of the trophic order, if you change that you can create huge problems for all other species.

    The same goes for plant species. They cannot migrate as rapidly as animals, and both suffer because the landscape is now fractured by human occupation – be it urban or agricultural land.

    As I have suggested, climate change is more that it being a few degrees hotter, more extreme weather events or even rising sea levels inundating low lying coastal communities. It is about a fundamental change to the ecosystem and to all the plant and animal species that we rely on, and to our whole system of agriculture.

    Unfortunately the debate so far has largely overlooked this.

  9. #9 Wow
    September 10, 2012

    Jeff Harvey keeps trying to get the deniers acknowledging this over on Deltoid on scienceblogs.

    Hence a potted history here.

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