A globally coherent fingerprint of climate change impacts across natural systems

Camille Parmesan and Gary Yohe. Nature 421: 37-42. A globally coherent fingerprint of climate change impacts across natural systems


What is climate change? (From Keep Queensland beautiful.)


Isabel Jones

A few weeks ago Lynsey bribed me with some really very delicious cake to write a guest blog here. Well I say bribe, it’s quite an honour really, so I chose one of my all-time favourite papers that I consider a ‘classic’: Parmesan & Yohe ‘A globally coherent fingerprint of climate change impacts across natural systems’ published in Nature, 2003. This research ties together the differing ways of viewing the world of biologists and economists, to clearly show that there are systematic biological trends being caused by climate change: poleward range shifts averaging 6.1 km per decade (or meters per decade in altitude) and spring events coming in on average 2.3 days earlier per decade.

This paper was in answer to disagreements within the IPCC as to whether changes in biological systems could be attributed to climate change, or not. And what a way to answer! Parmesan & Yohe combine methodologies of biologists and economists – engaging both schools of thought – and analyse a comprehensive dataset on species ranges and phenology, across diverse taxa and regions, to find out if there is a general response of species to climate change. They do this using meta-analysis, categorical analysis and probabilistic modelling of range-boundary shifts in birds, butterflies, and alpine herbs; and phenology changes in herbs, shrubs, trees, birds, butterflies and amphibians.

So often you can get lost in the murk of confounding factors which obscure small changes in a species’ range or phenology, when looking at a single species or region. Land-use change for example has huge impacts on species, and its immediate effects could overshadow the small and long-term changes caused by a steadily changing climate. These small, niggling, persistent changes in ranges and phenology have the ability to fundamentally alter communities over hundreds of years, their interactions, and even cause biomes to shift position or switch from one type to another. A whole biome switching. Quite a thought. I like that Parmesan and Yohe have stepped back from the immediate – and granted very pressing causes for biological responses – to see big picture changes coming from tiny alterations in range and phenology year on year.

Given the impacts that climate change could have from local- to biome-scale, it still baffles me that there isn’t more action being taken to curb emissions and mitigate negative impacts of climate change sooner rather than later. Perhaps one of the reasons is because there isn’t enough interaction between researchers and policy makers, but papers like this one, which help improve dialogue between different the parties and provide a nice summary of evidence, are surely what’s needed.

My one gripe with this paper is the use of the term ‘global’ as in ‘global fingerprint’, and that’s because the majority of studies used in the analyses come from the temperate Northern hemisphere. This is because long and high-quality datasets come from here, but I wonder what would happen to the global fingerprint of climate change impacts identified if we added more studies from the Southern hemisphere, the poles, and the tropics. If there was more time, perhaps long-term data collectors could switch their biomes too.

Lynsey McInnes

Lynsey McInnes

So far, I am really enjoying the ‘classics’ angle we are running on PEGE as it gives me a chance to actually re-read (sometimes just read) papers with 1000s of citations and remember why they are so. While writing up my PhD, the contrary part of me used to hate citing the ‘most cited’ paper on a topic because I liked a diversity of citations. Hm. Sometimes classics are classics for a reason.

This is an awesome paper. You can almost hear the authors’ sighs as they sit down at the their desks, hands on table and decide – let us sort this shit out. Enough of people swinging this way and that, let’s compile the evidence and just let it speak for itself. Beautiful.

Saying that, I’m sure many people remain that are unwilling to be convinced by the weight of evidence presented or just don’t care. Their world view is such that any evidence for responses in other directions or greater risk or impact from other factors is enough to convince them that climate change doesn’t matter.

Beyond being staggered by the strength of the argument being portrayed here and the admirable way in which it was portrayed, here follows a selection of thoughts that popped into my head (yep, it’s one of those posts).

– I wonder how much bigger the dataset could be made today, 11 years on.
– I wonder (like Izzy) what the ‘answer’ would be if the dataset was more evenly global in scope.
– I wonder what’s going on with annoyingly small and difficult to sample biodiversity.
– I wonder how to put together P&Y take two where community/ecosystem wide responses are recorded to see whether these distributional and phenological shifts actually matter for ecosystem functioning (however you might like to define that).
– I wonder, if you didn’t care about conservation of species from a – they are here and morally should be saved – outlook, what shifts and losses really matter for ‘functioning.’
– I wonder what is really going to happen to high latitude regions which are set (at least sometimes) to gain biodiversity.
– I wonder if you could do a P&Y take 2b and identify a combined fingerprint of climate change and other threats such as fragmentation (probably not land use change – when its gone its gone after all).
– I wonder if this hybrid biological – economic approach is well suited in the debate on what ecosystem functioning is. Can economic theory and practices be put to good to use when quantifying what a functioning ecosystem is and how to keep it that way.

I think that’s enough for now before I get overly-philosophical. In short, I really, really enjoyed reading this paper for its measured, no nonsense approach to evidence. I don’t think it is the final word on people believing climate change affects species. It’d be great to hear what the authors think about the ensuring 11 years of research and whether we are anywhere closer to a. understanding what is going on and b. doing something (what?) about it.

Yes, I’m aware the above was a very ‘academic’ post – I’m sure I could enter the non-academic literature and find out answers to a lot (though probably not all) of the musings above. Maybe I will.

Will Pearse

Will Pearse

This paper has been extremely influential, and I remember reading it in 2008 in my first undergrad conservation biology class. So I’d like to be self-indulgent and write about how my views on climate change have changed over the last few years. I’m no expert, so if you are you may well find what I have to say quite unsurprising.

The authors hope that if we measure enough things (range shifts), and then combine those things, we’ll understand more than if we just looked at each of those things separately. It isn’t helpful to ask whether each shift was ‘significant’ (), we’re interested in drawing inferences about the total ‘population’ of range shifts, and getting a good sample of that. If that sounds controversial to you, think of it like this: if you were measuring the average length of toads, you wouldn’t ask whether a particular toad was significant, you’d measure a sample of them to make an inference about the single population from which those toads were drawn. Each measurement has very little information, but the whole is equal to the sum of its parts, and samples help us understand the population they’re taken from.

In biology, small changes add up in the long-run, and the authors focus a lot on the different time-scales in economics and the rest of the world. Discount rates have a rather profound effect on what is rational behaviour! However, we now know that it’s wrong to characterise climate change as a strong, steady force – that would be scary enough, but it’s much worse than that. As the climate shifts every aspect of it becomes more erratic and unpredictable, and the its rapid fluctuations indicate an impending catastrophic shift (that’s actually the technical term). When you undergo such a shift, pretty much all information you had about the system before is now worthless. You’re now drawing from a different population. Using observed range shifts now to measure shifts in the future assumes that the basic properties of the system will stay the same – and once we pass the tipping point, they won’t. Under the conditions we’re approaching, all bets are off. Frankly, if that doesn’t scare you, I don’t know what will.


About will.pearse
Ecology / evolutionary biologist

2 Responses to A globally coherent fingerprint of climate change impacts across natural systems

  1. seanken says:

    Hey! Great post/ choice of article, I really enjoyed it! Just to let you know I think your link to the paper goes to the wrong article– no big deal since it is easy enough to find by google, but just thought you might want to know!

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