RealClimate logo

Linking the climate-ecology attribution chain

Filed under: — Jim @ 19 February 2009

Guest commentary by Jim Bouldin, Department of Plant Sciences, UC Davis

Linking the regional climate-ecology attribution chain in the western United States

Many are obviously curious about whether certain current regional environmental changes are traceable to global climate change. There are a number of large-scale changes that clearly qualify—rapid warming of the arctic/sub-arctic regions for example, and earlier spring onset in the northern hemisphere and the associated phenological changes in plants and animals. But as one moves to smaller scales of space or time, global-to-local connections become more difficult to establish. This is due to the combined effect of the resolutions of climate models, the intrinsic variability of the system and the empirical climatic, environmental, or ecological data—the signal to noise ratio of possible causes and observed effects. Thus recent work by ecologists, climate scientists, and hydrologists in the western United States relating global climate change, regional climate change, and regional ecological change is of great significance. Together, their results show an increasing ability to link the chain at smaller and presumably more viscerally meaningful and politically tractable scales.

For instance, a couple of weeks ago, a paper in Science by Phil van Mantgem of the USGS, and others, showed that over the last few decades, background levels of tree mortality have been increasing in undisturbed old-growth forests in the western United States, without the accompanying increase in tree “recruitment” (new trees) that would balance the ledger over time. Background mortality is the regular ongoing process of tree death, un-related to the more visible, catastrophic mortality caused by such events as fires, insect attacks, and windstorms, and typically is less than 1% per year. It is that portion of tree death due to the direct and indirect effects of tree competition, climate (often manifest as water stress), and old age. Because many things can affect background mortality, van Mantgem et. al. were very careful to minimize the potential for other possible explanatory variables via their selection of study sites, while still maintaining a relatively long record over a wide geographic area. These other possible causes include, especially, increases in crowding (density; a notorious confounding factor arising from previous disturbances and/or fire suppression), and edge effects (trees close to an
opening experience a generally warmer and drier micro-climate than those in the forest interior).

They found that in each of three regions, the Pacific Northwest, California, and the Interior West, mortality rates have doubled in 17 to 29 years (depending on location), and have been doing so across all dominant species, all size classes, and all elevations. The authors show with downscaled climate information that the increasing mortality rates likely corresponds to summer soil moisture stress increases over that time that are driven by increases in temperature with little or no change in precipitation in these regions. Fortunately, natural background mortality rates in western forests are typically less than 0.5% per year, so rate doublings over ~20-30 years, by themselves, will not have large immediate impacts. What the longer term changes will be is an open question however, depending on future climate and tree recruitment/mortality rates. Nevertheless, the authors have shown clearly that mortality rates have been increasing over the last ~30 years. Thus the $64,000 question: are these changes attributable in part or all to human-induced global warming?

Yes, argues a pair of December papers in the Journal of Climate, and a 2008 work in Science. The studies, by Bonfils et. al. (2008), Pierce et. al. (2008), and Barnett et. al. (2008), link observed western temperature and temperature-induced snowmelt processes to human-forced (greenhouse gases, ozone, and aerosols) global climate changes. The authors used various combinations of three GCMs, two statistical downscaling techniques (to account for micro-climate effects that aren’t resolved in the GCMs), and a high resolution hydrology model to experiment with the various possible causes of the observed climatic changes and the robustness of the methods. The possible causes included the usual list of suspects: natural climatic variability, the human-induced forcings just mentioned, and non-human forcings (solar and volcanic). Climate models were chosen specifically for their ability to account for important, natural climatic fluctuations in the western US that influence temperature, precipitation and snowpack dynamics, particularly the Pacific Decadal Oscillation, and El Niño/La Niña oscillations, and/or their ability to generate the daily climatic values necessary for input to the hydrologic model. The relevant climate variables included various subsets of minimum and maximum daily temperatures from January to March (JFM), their corresponding monthly averages, degree days (days with mean T>0ºC), and the ratio of Snow Water Equivalent (SWE) to water year precipitation (P). In each case, multiple hundred year control runs were generated with two GCMs to isolate the natural variability, and then forced runs from previous model intercomparison projects were used to identify the impacts of the various forcings.

The results? The authors estimate that about 50% of the April 1 SWE equivalent, and 60% of river discharge date advances and January-to-March temperature increases, cannot be accounted for by either natural variability or non-human forcings. Bonfils et al also note that the decreases in SWE are due to January-to-March temperature increases, not winter precipitation decreases, as the observational record over the last several decades shows. The April snow is a key variable, for along with spring through early fall temperatures, it has a great bearing on growing season soil moisture status throughout the western United States, and thus directly on forest productivity and demographic processes.

Link o’ chain, meet link o’chain.

Update: The new USA National Phenology Network is described here.

254 Responses to “Linking the climate-ecology attribution chain”

  1. 1
    mauri pelto says:

    A key measure of what you note with regard to the April 1 SWE is the snowpack-precipitation ratio. That is what percentage of the precipitation is being retained as April 1 snowpack. What is evident is the widespread reduction in this ratio in the west. The trend is spatially and temporally robust. Further the trend reflects either winter melting or more rain events both indicators of temperature rise. This trend has been noted by Pierce et al,(2008)
    and Pelto (2008) data reviewed here

    [Response: Yes, good point Mauri, thank you. The authors point out that very fact (that
    the ratio indicates how much is left on April 1, which helps to determine the cause
    for any detected trend). From a plant’s perspective, on the other hand, it’s the
    absolute amount of April 1 SWE that’s important (along with subsequent temps, melt
    rates etc., of course) as these drive the subsequent ecological processes.-Jim]

  2. 2
    Mike Tabony says:

    Excellent article. It scientifically supports Energy Secretary Chu’s warning concerning the viability of California’s agricultural industry if human induced climate change is not reduced immediately. The U.S. Chamber of Commerce sent out a “Global Warming Alarmist Alert” condemning him for his statements; maybe now they will be more inclined to listen.

  3. 3
    John Gribbin says:

    Hey — I learnt a new word! \Phenology\.

    [Response: Wiki. – gavin]

  4. 4
    Keith Whelpdale says:

    Of course the result of increased mortality without a corresponding increase in recruitment will ultimately lead to western forest changing from atmospheric carbon sinks to carbon sources.

    I think the results suggest a real need for assisted migration. Tree species with a higher tolerance for water stress should be planted in more northerly locations over time. In order to avoid problems associated with introduced species the selection of species should focus on those species that would normally be able to migrate from the current southerly locations to more the more northern locations but are unable to do so due to human factors such as cities blocking the way or the rate of climate change occurring too quickly for an adequate natural response.

    [Response: Yes, and it doesn’t take much to turn many old growth forests into a source, but
    keep in mind the time scale: some western old growth forests are elevated from their
    presettlement carbon stock means due to fire frequency reductions, so what might
    appear to be a transition from sink to source in the short term is not so in the
    longer term. Also, some are indeed arguing for assisted migration in just such
    cases and it may turn out to be necessary, but has to be done with some precaution

  5. 5
    Ray Ladbury says:

    Keith Whelpdale, Hell, why not plant kudzu while you’re at it. “Assisted migration” will merely place native trees under even greater stress. Remember this is an ecosystem we are talking about.

  6. 6
    Alan Millar says:

    An intersting article in the Guardian UK shows that tropical forests, in reaction to rising CO2 levels, are soaking up far more CO2 than was was thought, equal to the whole CO2 output of the USA.

    This sort of ‘real’ science on the ground (instead of playing around with computer programs) shows how little we really know about how the Earth reacts to changes and how impossible it is to forecast the future based on the puny amount of observed and verified data technological man has aquired so far.

    “Trees across the tropics are getting bigger and offering help in the fight against climate change, scientists have discovered.

    A laborious study of the girth of 70,000 trees across Africa has shown that tropical forests are soaking up more carbon dioxide pollution than originally thought. Almost one-fifth of our fossil fuel emissions are absorbed by forests across Africa, Amazonia and Asia, the research suggests.

    Simon Lewis, climate expert at the University of Leeds, who led the study, said: “We are receiving a free subsidy from nature. Tropical forests are absorbing 18% of the CO2 added to the atmosphere each year from burning fossil fuels.”

    The study, published tomorrow in Nature, measured trees in 79 areas of intact forest across 10 African countries from Liberia to Tanzania, and compared records going back 40 years. “On average the trees are getting bigger,” Lewis said.

    Compared to the 1960s, each hectare of intact African forest has trapped an extra 0.6 tonnes of carbon a year. Over the world’s tropical forests, this extra “carbon sink” effect adds up to 4.8bn tonnes of CO2 removed each year – close to the total carbon dioxide emissions from the US.

    Although individual trees are known to soak up carbon as they photosynthesise and grow, large patches of mature forest were once thought to be carbon neutral, with the carbon absorbed by new trees balanced by that released as old trees die.

    The discovery suggests that increased CO2 in the atmosphere could fertilise extra growth in the mature forests.

    Lewis said: “It’s good news for now but the effect won’t last forever. The trees can’t keep on getting bigger and bigger.”

    Helene Muller-Landau of the Smithsonian Tropical Research Institute in Panama, said the growing forests could recovering from trauma – droughts, fire and human activity – going back hundreds or even thousands of years.

    The research comes as efforts intensify to include protection for tropical forests in carbon credit schemes, as part of a new climate deal to replace the Kyoto protocol.”


    [Response: Alan, thanks for the link to what I consider to be a significant new article. I
    encourage everyone to at least read the story synopsis in Nature: What Lewis
    have found confirms the atmospheric inversion-based studies (which are based on
    completely different methods) by Stephens et. al (2007; Science 316:1732-), that the
    tropics are a stronger sink, and the temperate zone weaker, than had previously been
    believed. It is very important to keep in mind that sinks always have limits–trees
    can only get so big for biophysical reasons, and generally as they reach that upper
    limit their sink strength decreases. Furthermore, if CO2 fertilization (or N or
    H2O) is the dominant driver of the sink strength, that strength will decrease before
    the biophysical limits come into play, should other factors become limiting, which
    they very often do.-Jim]

  7. 7
    James Staples says:

    Trees are a good indicator; but, if you lived in the Midwest US (Omaha, Offutt AFB area) from 1974-81, then moved away and then came back from 1985-95, you’d have no doubt that Global Warming was real for other reasons.
    I can remember, during the 70’s, having to pop out a window on our back porch so that I could climb out and shovel away the snow that’d drifted out door shut, many times. When I came back in the late 80’s and 90’s, I never even saw a snow drift ONCE (well, maybe once or twice; but it never snowed us in!); as the precipitation had changed over to freezing rain and sleet – with hardly ever any accumulated snow fall.
    I read Dr. Hansens report in the early 70’s; and I’ve never had any doubt about it’s verity, if only because of this fact!

  8. 8
    duBois says:

    If the Amazon is “soaking up” more CO2 than anticipated, what is soaking up less CO2 than anticipated? CO2 concentrations in the atmosphere are still going up. And more rapidly than anticipated.

    [Response: Good questions, which are under very active research, and are the subject of the
    NACP (, happening as we speak. It’s not
    necessarily that another sink has been under-estimated: you have to factor emission
    rates into the equation.-Jim]

  9. 9
    Hank Roberts says:

    duBois, ‘anticipation’ is not precise. There’s a new satellite up (maybe two) that will be giving more accurate local measurements and may help. The atmosphere is only part of the pattern. Possibilities suggested include a decrease in effectiveness of the southern ocean carbon sink; that may be a change in the biology or the wind/wave/mixing or the overturning from deep thermohaline circulation. We are living in a complicated planet.

  10. 10
    kevin says:

    Presumably this is the same Simon Lewis who is an author on the 2004 paper about increasing biomass in Amazonian rainforest trees. The phenomenon of trees growing a bit more than they otherwise might have is certainly interesting, but not new, and I would wager it is accounted for in some climate models. Perhaps one of our hosts can confirm or disconfirm that. At any rate, Alan shows his colors when he contrasts “real science” to “playing around with computer programs” and then commits the old chestnut fallacy of implying that since we don’t know everything, we must know nothing (or at least not enough to draw important conclusions). Alan seems to be a vector for an aggressive type of ignorance, to which most readers here have developed an immunity, but which is still worrying to see making its way through the wild.

    [Response: Carbon cycle changes are more commonly incoporated into separate carbon cycle
    models which are then coupled to GCMs, although maybe some GCMs incorporate them
    directly, I don’t know.-Jim]

  11. 11
    dhogaza says:

    This sort of ‘real’ science on the ground (instead of playing around with computer programs)

    Except, of course, the computer model (“programs”) they used to extrapolate their limited on-the-ground data to a worldwide figure for CO2 absorption by tropical forests.

    This use of computer models is acceptable to you because you believe it overturns the bits of climate science you don’t like. Not because it’s better science.

    And, as duBois says, we know CO2 is increasing in the atmosphere. All this work does is potentially provide a better estimate of how much CO2 is being absorbed by the Amazon vs. the ocean etc. It doesn’t change the “in the air science” of observed increasing CO2 concentrations in the atmosphere, which is in no way derived from those evil computer programs you rant about (except for the one you love used by the researchers in this particular paper you seem to believe is “real” science, as opposed to “fake climate science”).

  12. 12
    Ray Ladbury says:

    Alan Millar says “This sort of ‘real’ science on the ground (instead of playing around with computer programs) shows how little we really know about how the Earth reacts to changes and how impossible it is to forecast the future based on the puny amount of observed and verified data technological man has aquired so far.”

    Alan, I’m more than willing to admit the YOU are utterly ignorant of anything to do with the climate. I mean, one minute, you’re telling us that 385 ppmv is way too puny to have any effect on climate and now you’re telling us it’s growing super-trees down in the Amazon.

    Newsflash, dude: CO2 is still rising, and faster than expected. The oceans are absorbing less and less CO2 and will eventually become a source. These super-trees will eventually die and decay, returning the sequesterd carbon to the atmosphere–as CO2, or worse CH4. So why don’t you get it straight in your head what YOU think and then you can come back here and we can tell you why you’re wrong.

    Oh, and by the way, if you ever want to actually understand the “real science,” those models might be helpful.

  13. 13
    Lynn Vincentnathan says:

    And the 1st link in the chain — I forgot my shopping list and had to make 2 trips via my I.C.E. car to the store instead of one, and other such behaviors of inefficiency/non-conservation/non-alt-energy-usage throughout the world.

  14. 14
    Ken Boettger says:

    It is such a simple thing. Go to the NOAA website and download the last 50 years of temperature data from your small local airports. Here in Ellensburg, our winters traditionally hit 20 below zero (8 in 10 years). We barely hit zero this winter. And we have never been below -10 in the last 12 years. The data is there and NONE of you are looking at it! NOT A DAMN ONE OF YOU! Note also that here in Ellensburg at the Bowers Air Field, our data shows one in ten winters to 30 below zero. This since records began in the 30’s. It is so phucking blatant and none of you are looking at it. You people have your head stuck so far in your books you cannot see the real world around you. WE ALREADY HAVE A 20 PLUS DEGREE TEMPERATURE CHANGE IN ELLENSBURG, WASHINGTON. The sumnmer data is the same. For fourty years since the 30’s our highs were in the 80’s and rarely in the 90’s. Last summer, as in the previous ten summers, we have hit over 110! I do not know what else to tell you idiots. The data is right there in front of you and you so called ‘professionals’ have entirely lost all credability for not doing your SIMPLE homework. God forbid.

    [Response: Please calm down. You’ll find dispassionate analysis far more persuasive here. – gavin]

    [Response: 14. Try not to fall into the same trap as many denialists, thinking that things are “obvious” based on this or that set of limited observations. Attribution is very much more a sophisticated and comprehensive business.-Jim]

  15. 15
    Doug says:

    Even if forests shift from becoming a carbon sink to a carbon source, there will be regional differences, and continued forest conservation will help mitigate the consequences. If we fail to conserve forests (even declining forests) we will only accelerate emissions. If we conserve forests (including declining forests) we will be slowing the rate of emissions from forests, just like we are trying to slow the rate of emissions from fossil fuels. Same principles apply.

    Here is a slide show clarifying many misconceptions about forests, logging, and carbon:
    (For full effect click “full” in the lower right.)


    [Response: Thank you for your terrific work Doug. Indeed, many misconceptions about
    logging, disturbance, carbon storage, conservation, etc. Preserving old-growth has
    many benefits, and is simple and effective as a carbon management strategy. All

  16. 16

    One of my denialist “friends” just sent me this (abridged version):
    NSIDC: satellite sea ice sensor has “catastrophic failure” – data faulty for the last 45 or more days * (“Although we believe that data *prior to* early January are reliable, we will conduct a full quality check in the coming days. …it became clear that there was a significant problem – sea-ice-covered regions were showing up as open ocean. …”

    My guess is that the report is probably true but of no particular cansequence. Am I right?

    [Response: Always best to go to the actual source of the information, rather the blogs: NSIDC. It’s always a shame when a sensor fails, but in this case there appears to be enough redundancy so that they’ll be be able to maintain a continuous record. It also serves as a salient reminder that no source of data is fool-proof and that drifts, failures and corrections for them are always ongoing. – gavin]

  17. 17

    Re #14 Ken Boettger’s cogent rant: Thanks RC for posting that. Ken, so many of us accept your facts and your sentiment and have felt similar emotions.

    I am not sure that dispassionate analysis is ALWAYS the most persuasive. Maybe to this readership. But the tools of persuasion are not just scientific. RC does have a nice lock on the science of global warming.

    Humans are persuaded by so much more. Climate studies that cross into economics, game theory, risk analysis and psychology are such messy branches of science compared to climatology – which seems far more understandable by comparison.

  18. 18
    Bill DeMott says:

    Nice post. I was exited to learn yesterday that my contributon was accepted for a special issue of Limnology and Oceanography. The special issue is titled (something like) “Lakes as sentinels and integrators of climate change.” In some sense it is fortunate that pollution/eutrophication concerns from the 60s and 70s stimulated longer term monitoring studies that are showing strong climate signals in lake food chains. The special issue of Limnology and Oceanography has received some publicity in Science and elsewhere over the past week or so. The number of ecological studies on climate change and climate warming effects on natural systems is increasing at a very high exponential rate. I have been analyzing data from large, deep European subalpine lakes. These have seen marked improvements in water quality due to efforts at reducing phosphorus loading but are now being impacted by climate warming.

    [Response: 18. Bill, congrats. I look forward to learning more about the topic. I was lucky
    enough to spend a couple of months at the U Wisconsin limno lab at Trout Lake WI
    this fall, doing field work, and saw reference to a pub very similar in title to
    what you mention, but had no time to explore it. Did ESA or somebody put out
    something very similar recently?-Jim]

  19. 19
    larrydalooza says:

    I wonder how often actually terrarium type experiments are utilized. I saw one terrarium experiment where a CO2 concentration of around 800 ppm made for a beautiful plant filled environment with only negligible heat gain. And this was under conditions where heat could not escape into a bitterly cold outer space. I just think that the simple mindedness errs more on the alarmist side than the status quo side. I don’t call it denialist… because that would insinuate truth.

  20. 20
    Bob Coats says:


    Thanks for doing this; great job. In the Tahoe Basin, I have found (recently submitted to Climatic Change) that the shift in timing of peak snowmelt runoff, and trends in ave. monthly Tmax and Tmin are somewhat greater than in the surrounding region. The snow->rain shift is also strong. Two hypotheses may explain why the basin is warming faster than other parts of the Sierra. First, soot in snow may be reducing the snowpack albedo, contributing to the shift in snowmelt timing, and to higher spring temperatures. See this just-out paper: Qian, Y., W. I. Gustafson Jr., L. R. Leung, and S. J. Ghan (2009), Effects of soot-induced snow albedo change on snowpack and hydrological cycle in western United States based on Weather Research and Forecasting chemistry and regional climate simulations, J. Geophys. Res., 114, D03108, doi:10.1029/2008JD011039; available at:

    Second, the lake itself, with low albedo and high heat capacity, may interact with increasing GHGs to produce a higher rate of change in air temperature over the lake than over the land.

    [Response: Bob, thanks, Very interesting. Higher rate of change over the water–not at all intuitive. These spatial variability/scale questions are fascinating and important. Will try to read the paper when I get a chance.-Jim ]

  21. 21
    Jim Steele says:

    I am curious about the SWE’s calculations. The timing of snowfall here in the Sierra will have a great impact and its impact is not apparent if only total precipitation is measured. Some years such as last January 2007-2008 there was tremendous snowfall in late December and January and then absolutely nothing. Other years there are heavy snowfalls in April. I look at this data trying to assess vegetation and bird populations, so I am curious how they described that variable. It wasn’t obvious in your post.

    [Response: Hi Jim. The April 1 SWE is just the water content of the snowpack on April 1,
    with that date chosen because it falls very near the long term maximum, and
    immediately precedes rapid spring warming. It’s not perfect for every location
    because of elevation and other differences, but works well as a compromise when
    considering the entire western USA, or the Sierra in particular. To the extent that
    post April 1 snowfall would be substantial and unrelated to April 1 SWE, its
    perfomance as a hydrological/ecological prediction index would suffer. But since
    the trend is in the other direction (warming, more rain etc), it is–as long as
    there is some snowpack–a sensitive indicator of likely hydro/eco effects and trends
    throughout the warm season. [By the way, Jim’s avoiding self-promotion, but he is
    the director of the Sierra Nevada Field Campus of San Francisco State University.
    If you want a high quality introduction to a wide variety of topics in Sierran
    ecology and natural history in a very cool setting, I highly recommend it, based on
    my experience there as a student a few years ago. – Jim Bouldin]

  22. 22
    Richard Ordway says:


    Well, the evidence is pretty strong that the Earth’s average surface temps are rising (with the attendant problems)and that it is mostly human caused (IPCC 1991, 1995, 2001, 2007; written scientific evidence dating to Saussure “Travels in the Alps” 1779-96; Fourier 1824; Tyndall 1859; Arrehieneus 1896, etc.).

    Just remember a definition for climate change is: averages, averages, averages. No one single location can be used as definitive proof…you need them from around the Earth for 30+ years. Some places have not changed their temperatures much…but the average is pretty startling for 100 years.

  23. 23
    Pat N says:

    Since you have recently expanded your study to include Minnesota, you may be familiar with the reseach work of Lee Frelich. Dr. Frelich is director of the University of Minnesota’s Center for Hardwood Ecology in the Department of Forest Resources. Recent article at:

    Last night I attended a showing of the video “The Great Global Warming Swindle”. John Christy and Richard Litzen claimed that greenhouse warming is insignficant because of less warming seen in mid-levels of the atmosphere compared to more warming near the surface.

    However, less albedo over snow-free areas has contributed to strong warming near the surface in winter and early spring, in the northern Great Plains and Midwest. Strong February warming has been especially evident at climate stations in MT, ND and MN. The importance of less albedo due to shorter snow cover periods discounts the arguments by Christy and Litzen and strengthens the case that much of the global warming is greenhouse driven. A decrease in snow cover and albedo throughout the Great Plains and Midwest also helps explain why warming in the month of February has especially sharp.

    Plots of earlier snowmelt runoff & temperatures at Minnesota climate stations:

    Earlier in the Year Snowmelt Runoff and Increasing Dewpoints for Rivers in ND, MN and WI

    Other links:

    WCCO meteorologist: Global warming ‘extremism’ uses ‘squishy science’
    May 20, 2008 by Paul Walsh, Star Tribune:

    Global Cooling or Global Warming?
    Minnetonka Community Education

    [Response: Yes, I met Lee last summer and am very familiar with his research work. He is
    an excellent scientist and has done pioneering work on historic forest disturbance
    regimes in Great Lakes forests, among other things. Great guy. Then on the other
    hand there’s a “cpa by day and concerned citizen by night” teaching “global cooling
    theory” at Minnetonka CC. Looks like we’ve covered the spectrum there. – Jim Bouldin]

  24. 24
    Aaron Lewis says:

    This is a prime example of academic understatement. This is scientific reticence at its best. Go out in the fields and look at what is happening! Plants are blooming at the wrong time – not synchronized with their pollinators. Pollinators are not synchronized with the blooming of the plants that they depend on.

    This is serious business. No! This is catastrophic. My fruit trees started blooming today and the bees are not ready. The bees want 3 weeks from peak of the ornamental pear bloom to rear brood for the fruit tree bloom. However, there was a humming bird in the orchard this morning. Five years ago, we never saw even errant humming birds this time of the year. Three years ago we started seeing errant humming birds in the winter. This year we had a resident humming bird all winter. That humming bird by itself, was nothing. That humming bird as part of a trend, is everything. This was the first year that we had bloom in the yard all winter. Again, the culmination of a trend.

    A decade ago, garden was landscaped to provide continuous waves of bloom from the first of March to the end of October. However, plants that 10 years ago time bloomed in March, now bloom in November. Plants that in our climate of six or seven years ago, bloomed in May, now bloom in February. And, plants that only 5 years ago went dormant from November to March, now stay green and bloom all winter, hence the humming birds. Trees that in the past, were dormant for 4 months were dormant for only 4 weeks this year.

    Ten years ago, I tried very hard to grow plants that would bloom and support humming birds all winter and they all frosted out. I stopped trying. Now, plants that were in the yard prior to that time have changed their bloom season, and seem to support humming birds through the winter. (Maybe someone in the neighborhood is feeding them, but I saw them investigating blooms in my garden on a daily basis.) In the last decade, global warming has changed the ecology of the area.

    You may want to dismiss this as “just weather”, but how many years of the weather trending in the same direction, year after year, consistent with global warming does it take before we admit that we have a trend that is affecting our agricultural plants? If you really want to know about global warming – go count native bees on native plants.

    I look for pollinators almost every day. I did that this morning. The number of native bees this morning was 0. Exactly what I expected. What I did not expect was the number of native species that would be blooming this time of year. I did not expect most of my fruit trees to be blooming today. Only a decade ago, they started blooming at the end of February or early March, and this was the week that I sprayed for mites. Every year since then, it has been a bit earlier. Today the pluots, plums, and apricots also started blooming. In the past, these bloomed sequentially, after the nectarines. The ornamental pears should have just started blooming. In fact, they have been blooming for 5 weeks (and today there are honey bees working those pears. There are more honey bees than I would expect at this time of the year, but not nearly enough to service what is now blooming and what will bloom in the next few days.) If the earlier blooming was from natural variability, there would have been years when the bloom was a bit later, and the average bloom date over a decade would have stayed about the same. However, the bloom date has consistently moved forward. That is not natural. If we had “a climate” the bloom date would stabilize. However, we do not have a stable bloom date, we have a trend toward earlier blooming. Similarly, native plants are also blooming earlier. And, what will the native bees find to feed themselves in the season when those plants traditionally bloomed, now that those plants have already bloomed for this year?

    Dead trees in old growth forests are factoids with long term importance. However, bloom pollination is critical for the year to year survival of our current agricultural production and native ecosystems. Like it or not, even the most reticent scientists need to start thinking of the effects of global warming on food production and ecosystems, not in some model of the future climate, but in the fields and meadows of today.

    [Response: Aaron you raise a number of great issues, which in toto refer to the potential
    effects of climate change on species-specific phenology patterns, which are likely
    to be complex and to create a mess. I don’t argue with any of it. But what you see
    as reticence, those of us familiar with scientific practice see as care to minimize
    the chance of over-stating the case, which brings with it the chance of
    under-stating the case. For those interested in being part of a larger citizen
    science documentation of the phenological changes Aaron is describing, please check
    out: – Jim Boudlin]

  25. 25
    SecularAnimist says:

    duBois wrote: “If the Amazon is ‘soaking up’ more CO2 than anticipated, what is soaking up less CO2 than anticipated? CO2 concentrations in the atmosphere are still going up. And more rapidly than anticipated.”

    Well, among other factors, anthropogenic emissions of CO2 have been increasing much more rapidly than anticipated.

  26. 26
    SecularAnimist says:

    Aaron Lewis wrote: “This is a prime example of academic understatement. This is scientific reticence at its best.”

    If medical doctors told their cigarette-smoking patients “while smoking increases the risk of cancer, no individual case of lung cancer can be attributed to smoking cigarettes” as often as climate scientists tell us “while global warming increases the risk of extreme weather events, no individual extreme weather event can be attributed to global warming”, I suspect that many more people would die from lung cancer.

    Captcha says “turbo Katarina” … hmm.

  27. 27
    David Emmo says:

    re #6 Alan Millar

    Maybe somebody here could provide the relevant links as I am not at my desk but I recall there have been studies that relate changes in the growth rates (girth) of trees through times of increases in atmospheric CO2 concentrations, with the relative density of carbon stored in annual growth rings.

    My impression was, that girth alone is not a very effective way to estimate CO2 uptake.

  28. 28
    David B. Benson says:

    Not precisely on-topic, still warrents the link.

    “One-fifth Of Fossil-fuel Emissions Absorbed By Threatened Forests”

  29. 29
    Michael says:

    Aaron Lewis, in a decade the global mean temperature would have risen about 0.1 degree F. Do you think anyone would be able to see global warming with thier own eyes within a ten year period as you suggest?

  30. 30
    Lynn Vincentnathan says:

    I think the scientists are doing remarkably well. We need to understand that they have high standards of proof and have to avoid making false positive claims (saying GW is causing such&such, when they do not have good proof) to maintain their reputations. And when I read this report above I thought, I can pretty much trust their conclusions, the evidence and science is now in on it.

    It is the rest of the people in the world that need to be chastized for failing to avoid false negatives (assuming nothing is wrong & doing nothing while the world burns).

    Denialists are the most culpable, & policy-makers, & the media (which for nearly 20 years virtually ignored the issue, or sowed seeds of doubt with their pro-con format), followed by typical Americans, who contribute per capita the most GHGs (and don’t forget to add in all the GHGs related to products we consume that are made in other countries), followed by the rest of the world. Even poor people in poor countries might find ways to reduce GHGs without lowering their living standards, and improve their living standards in efficient/conservative/ ways.

    So we’re all pretty much to blame at various levels. But the scientists are just doing their jobs as best they can, sometimes even having their findings suppressed or having their jobs threatened, or denialists attacking their integrity. The scientists’ job does not include informing the public at large, but in this vacuum they’ve stepped up to that plate, as evidenced by RealClimate.

    The scientists are pretty much the heroes in this battle.

  31. 31
    James says:

    Jim Steele Says (19 February 2009 at 3:52 PM):

    “The timing of snowfall here in the Sierra will have a great impact and its impact is not apparent if only total precipitation is measured. Some years such as last January 2007-2008 there was tremendous snowfall in late December and January and then absolutely nothing. Other years there are heavy snowfalls in April.”

    Another thing that seems to have changed around the Tahoe area is the timing of the first significant (which to me means enough to cross-country ski on) snowfall. In the late ’70s-early ’80s, it wasn’t uncommon to have skiable snow in October, sometimes in September. For the last decade or so, it’s been moving to late November or December. This year we didn’t have much of anything until Christmas.

    And of course this is self-reinforcing. The lack of snow cover keeps the albedo lower, which keeps the ground warmer, so that any snow that does fall early melts before long. Snowlines move higher up the slopes, meaning less snowpack, and less snow-covered ground to reflect spring & early summer heat… Just one more small set of facts, any one of which might be happenstance. But while one is happenstance and two are concidence, three times is enemy action.

  32. 32
    Hank Roberts says:

    Recollect excursions happen. Have and will.

    It’s important to remember that the change from the added CO2 is a _weak_ signal just emerging from the background with statistical analysis. It will always be a weak signal, in paleo terms. Doesn’t mean unimportant, but that’s because of how _fast_ not how _strong. _Nothing_ we’re going to see in our lifetimes is going to be outside what’s been possible. Nothing people’s grandchildren will see either.

    This doesn’t lessen the human contribution to the problem, which is mostly rate of change — we’ve pushed _faster_ not _harder_.

    In terms of changing the rate of acceleration of climate change, humans are jerks. Most other factors are nudges, or tickles, by comparison. Those are all units of acceleration. We’re not just pushy, we push harder and faster by far than any other force.

    California’s had droughts in the past exceeding _anything_ imagined as a consequence of global warming. But those were excursions around a mean.

    We’re changing the mean, quite suddenly, by three degrees C or so.

    After the last little California earthquake, Loma Prieta, I read up on the jerk experienced by people in 1906. It was greater than one gravity sideways. People literally had the Earth yanked out from under them. When I feel like trying to explain that to people I say it feels like having someone walk up and grab you by every cell in your body and move you very suddenly sideways several feet.

    That’s kind of like what people are doing. Not moving you cross town, not throwing you a mile, just — giving you one big jerk.

    In geologic time, that is. We’re making another of those thin dark lines in the paleo record — ours will have nanomachines in it, probably. It certainly has far more fossils below it than can possibly be formed after our time.

    But _still_ remember, there have been droughts that lasted centuries before and will be again. We’re not changing that. We’re changing how often the extremes happen, a little bit in geological terms. In our own short lifetime terms, time will tell.

  33. 33
    JCH says:

    “The Intergovernmental Panel on Climate Change reports that globally human activity emits 32 billion tonnes of CO2 each year, but only 15 billion tonnes actually stays in the atmosphere adding to climate change. The new research shows exactly where some of the ‘missing’ 17 billion tonnes per year is going. …”

    Read the rest of the explanation of what the study says here.

  34. 34
    Chuck Booth says:

    RE # 14 Ken Boettger:

    The data is there and NONE of you are looking at it! NOT A DAMN ONE OF YOU!

    I’m curious to know the basis for this statement – are you absolutely sure no scientist has looked at those data? If, how do you know this?

    It’s facinating to see how the skeptics and denialists argue that climate scientists are too alarmist, while other, such as Ken, and Aaron Lewis, and Secular Animist complain here that the climate scientists aren’t alarmist enough.

  35. 35

    24 Aaron Lewis: I think you mean that your fruit crop will be very poor this year. Is this true?
    Could you comment on the idea of moving your orchard north to a place that has the climate your present land used to have? I suspect that you would find different soil. etc. but I don’t know. What do you think of the idea of farming on melted tundra in the warm future? Again, I suspect that your bees wouldn’t understand the 24 hour daylight, the soil would be unsuitable, etc. but I would like to hear what a farmer would think. And yes, there are few things more critical to maintaining civilization than the food supply.

  36. 36
    John A. Davison says:

    There is another question involved here. Is evolution finished? Is the present biota a terminal one which cannot undergo further evolutionary change beyond rather trivial subspecific or varietal adaptation? Such was the view of Julian Huxley and Robert Broom who pointed out that a new Genus had not appeared in the last two million years. I have extended that generalization to include true verifiable species. There is no question that we are now witnessing rampant species extinction but therre is very little evidence that new species are replacing those that have disappeared. I have summarized that literature on my webpage.

    I realize this is a dismal prospect but one which should not be dismissed until convincing evidence for species replacement can be documented. Just as the development of the individual ends with death, so apparently does evolution end with extinction. While new life forms definitely replaced their predecesors in the distant past, that is no longer evident.

    In any event the Darwinian notion of a continuing gradual evolution is currently being widely questioned as creative evolution no longer seems to be in progress.

    One thing is certain. We are the primary cause of the rapid alterations that are now taking place in the climate domains of the world. Global warming and climate change are no longer matters for conjecture.

  37. 37
    Tony O\'Brien says:

    Response to response to 14.
    Simple stories for a single location may not be sound science but it could well enhance understanding by the lay population. It does not prove AGW scientifically but it well illustrates it.

    Johnny Horton sang “When it springtime in Alaska it’s 40 below” I doubt anywhere in Alaska was 40 below last spring let alone Fairbanks which had days over plus 20 Celcius.

  38. 38
    Sekerob says:

    There’s great confusion of tons and tonnes and billion tonnes and giga tonnes or tons (factor 0.9 or so). NASA published not long ago that 2007 9.4 GT CO2 was emitted from fossil fuel burning and slight over 50% was taken out. The percent taken out decreasing!!! Believe the atmosphere number was on the range of 760 GT. Anyway, I think there is room for some clarification and maybe a conversion table for the different values and amounts in circulation. Spencer’s folly being of course that it’s all natural. And the more they inflate the total annual cycle volume, the more concerned I get, for a hyper inflated system should have been well able to take out the extra few billion tonnes produced by man… evidently not.

  39. 39
    Paul Gosling says:

    I am afraid that I found the paper by van Mantgem rather disappointing, leaving me with more questions than answers. They may be correct that increased temperatures are driving increased mortality, but I don’t think its fair to conclude this from their paper. If increased temperatures leading to increased drought stress is the strongest driver, why did the authors not consider plot aspect or soil type/depth. These would surely have a strong influence and may explain why some plots did not show increased mortality. Furthermore, I found their dismissal of air pollution as a significant factor to be too swift. They did not even consider a role for nitrogen deposition in increased mortality, despite the fact that this association has been shown repeatedly. More work to be done I think.

  40. 40
    Keith Whelpdale says:

    Ray Ladbury – re assisted migration; I think you need to read my comment again as you apparently didn’t understand it. I was clear that problems associated with introduced species needed to be avoided.

    While AGM is a serious problem that needs to be addressed governments and individuals have shown that most are very unwilling to make the changes necessary to avert significant warming. Unfortunately AGM is not the only significant stress that humans have placed on the planet. Huge tracts of cleared lands will prevent what would be the normal northward migration of many species in a warming world and the rate of change may confound even those species most able to move (unlike trees) in their attempt to relocate.

    Shrill comments around kudzu do nothing to improve the discussion.

  41. 41
    Ray Ladbury says:

    John A. Davison
    1)Evolution is OT.
    2)If you think evolution is finished, you don’t understand evolution.

  42. 42
    Chris Colose says:


    your responses are off by one post in some of the above comments (e.g., 19 and 20) [fixed – thanks]

    As for your post, thanks, it was very informative.

  43. 43
    kevin says:

    #29 Michael: Global mean temperature change is probably the wrong number to consider in a case like Aaron Lewis describes. There are regional variations, so some places have experienced change well beyond the global mean. Also, the biosphere will respond to factors other than the yearly mean, such as changes in the timing of annual temperature change, and changes in temperature range (daily/weekly/monthly/seasonal mins/maxes). So we probably should not limt ourselves to thinking about the global mean temperature, right?

    And as to your question “Do you think anyone would be able to see global warming with thier own eyes within a ten year period as you suggest?”: Can one see *global* warming with one’s own eyes, in a decade or any other timespan? No, or at least not without doing a whole lot of traveling. But Aaron Lewis described in some detail evidence of *local* warming that he has witnessed. So if your question is whether there has been observable change in any given region over the last 10 years as a result of warming, the answer is a resounding yes. Look at Arctic sea ice, look at the Antarctic peninsula, talk to people living in the far North almost anywhere. Look at Aaron Lewis’ orchards, apparently. The answer to “would one really be able to see it” is yes, it has been seen, by many, many people. If I’m misunderstanding your question, I apologize.

  44. 44
    Steve says:

    I disagree with the portrayal of forest conservation as the best mitigation strategy given by #15 (Doug).

    There is a large body of scientific literature that conservation of forests as a strategy for mitigating climate change will be most effective if it is done within a framework of sustainability that includes the harvest of a portion of the forest area for use of wood in either long-lived products replacing higher embodied energy building materials, or to replace fossil fuel energy (especially coal). This is the gist of the conclusion of the Fourth IPCC assessment report (

    There are numerous peer review journal articles concluding that harvesting forests (with reforestation to replace forest C stocks) and using their wood products is a promising strategy for mitigation. To quote only one of many examples, Eriksson et al. in 2007 (Canadian J Forest Research Vol 37) conclude that “Not harvesting the forest would cumulatively increase the carbon emission over what would otherwise be possible if the forest stand were harvested and used”.

    Other examples (among many more) supporting sustainable harvest of forests as a climate change mitigation strategy are: Apps et al. in Environ. Science & Policy (1999); Gerilla et al. in Building and Environment 42: 2778–2784 (2007); Gustavsson et al. in Mitigation and Adaptation Strategies for Global Change 11: 667–691 (2006); Richter, in Carbon Dioxide Mitigation in Forestry and Wood Industry. pp. 219–248. Springer-Verlag, Berlin (1998).

  45. 45
    Hank Roberts says:
    Society for Integrative and Comparative Biology (SICB)


    1) Understanding the organism’s role in organism-environment linkages—Understanding the consequences of climate change and environmental degradation for ecological health and human welfare depends on understanding the biology of diverse organisms. Communities and ecosystems are composed of organisms laced together by a network of interactions among individuals, and feedbacks between organisms and the physical environment. Current global and ecosystem models are overly simplistic owing to inadequate knowledge about basic organismal inputs and the dynamics of organismal responses to environmental changes. To understand the resilience and robustness of critical species and systems in the face of climate change, as well as protection of organisms vital to ecosystem services (e.g., clean
    water, chemical decontamination, pollination, carbon sinks), we need data in the following key areas:
    • Physical, physiological and genetic factors that constrain or promote adjustment to changing environments over different time scales (e.g., behavior, acclimation, plasticity, adaptation)
    • Mechanistic bases of organism-environment feedback systems
    • Functional and systems-level attributes of organisms that make them resilient or fragile in the face of environmental change …

  46. 46
    Chris S says:

    Re: #36 John A Davison – “Serving the Intelligent Design Community”

    I’d be interested in having a look at your papers on this but I don’t have access to Rivista di Biologia (and it seems from your citation record not many others do too), would it be possible for you to put some pdfs up on your site? Also, looking at the ISI Web of Knowledge database I’m curious – are you the same JA Davison who has published on both opthalmology and breast augmentation?

    Re: #24 response
    For those in the UK interested in similar ‘citizen science’ schemes can I derect you to the Woodland Trust Phenology network ( ) the BRC recording schemes ( )and the various BTO surveys ( ) all of which welcome enthusiastic amateurs and their invaluable contributions.

  47. 47
    Michael says:

    Kevin, it would seem that seasonal temperature variation would dwarf any trend he could extrapolate from his observations.
    And I’m sure you could find many ten year trends in temperature records and find just as much variation as the last ten. Is it accurate to look at global or local climate as a stable system? And isn’t it way too easy to place too much value on anecdotal evidence?

  48. 48
    Rod B says:

    SecularAnamist (26) if you change “attributed” to “definitely attributed”, both of your statements are true. And more people might or might not die of lung cancer…, or from lightening or tornadoes or heat or cold.

  49. 49
  50. 50
    Keith Whelpdale says:

    John A. Davison – you make an interesting observation about the lack of new genus for over 2 million years. However if you go much farther back in history the evidence from the Burgess Shale shows us that there were many more phylum previously than currently exist.

    What this shows us is that once existing species are established those species will evolve to take advantage of changing conditions but the new species can only evolve out of existing species so a new genus, family, phylum etc cannot appear as the existing species have a huge upper hand in being able to fill any new niches that appear.

    However the diversity of life is as great or greater in the current era than at any time in the past as specialization of species within the existing genus has continued unabated.