Climate change’s observable impacts on humans

Great Debates
1

This thread asks questions that are based on a rudimentary understanding of climate science. Questioning or denying the basics of climate science should be done in another thread. If possible, I would like to ask the mods to consider outright or stealth (i.e. “I’m only asking questions” or needlessly pedantic semantics) denial of basic science as intentional attempts to derail the thread and prevent the desired discussion from taking place. There are plenty of other threads to participate in—plus you can always start your own thread here or in the Pit. This is not the place to say that climate change is not, cannot, or is unlikely to happen or to debate the merits of the scientific underpinnings. Please understand that while I anticipate there will be debate over answering the question itself, it is a debate that at the very least starts with an understand* and acceptance *of the major contents and conclusions of the Fourth IPCC Report.

Onward:

I last asked this in 2009. Given the passage of time (and influx of new members), I’m wondering if there is anything new to add.

I’m working on some materials for Rio+20 (holy cow, it’s been twenty years?!) and am again encountering a range of citeless claims about how climate change is affecting humans—the claims being written in the present tense. As in, I’m changing or challenging a sentence like:

“Humans are experiencing extreme weather events, increased drought and expanded disease and pest vectors…”

to

“Humans [del]are experiencing[/del]will experience extreme weather events, increased drought, expanded disease and pest vectors…”

My position is similarly weak—my cite is my ignorance. Given that I spend most of my time in the policy realm, I’m not very current with the scientific literature. I haven’t seen anything yet that has a high degree of confidence and a high degree of buy-in by the scientific community that relates a specific weather or other incident to climate change. Not that its not possible that climate change has exacerbated or caused something, just that there is not yet evidence that it * has* caused something. Note, for a moment, that I’m talking specifically about impacts on * human* health and security. Receding glaciers and other physical manifestations of climate change that do not directly affect humans on a large scale are a bit outside the scope of this question.

So:

Do I need to do some serious back-pedalling and research—has climate change been proximate cause of human harm?

If not, at what point will it be safe to say that it is? This is the GD part of the thread. Right now, any local weather event or apparent annual pattern shift can be attributed to either noise or climate change effects (oh, forgive oversimplifications within). Assuming that mitigation efforts fail (likely :(), at what point will I be able to confidently shift to the present tense when describing the effects of climate change? I’m not asking so much for a scientific prediction, more a philosophical and rhetorical outlook. For example, if after five (ten?) years of above average global temperature, or a ? period of above average number/severity of hurricanes, or a constellation of something…

Thoughts?

Thanks—and again, thank you for not posting if you want to debate the underlying premises.

Rhythm

2

Well, that warming has to go somewhere, and it is now appearing as an increase of the chances or more droughts and extreme weather events.

http://thinkprogress.org/climate/2012/03/23/450537/warming-fueled-texas-drought-cost-farmers-76-billion-no-one-alive-has-seen-drought-damage-this-extent/

As pointed before, warming caused by humans was a factor in the past century, but not the driving one, after the sun activity connection with the warming parted ways in the 70’s humans are the driving cause of the recent warming.

What is next? Even more of the same and worse if nothing is done.

http://rsta.royalsocietypublishing.org/content/369/1934.toc

3

I’m not sure you’ll ever be able to shift your tense quite that way. At least not if you mean right now you’re saying “in the future we’ll experience extreme weather events” (just as an example) and you expect to some day say “this summer’s extreme storms are because of climate change.”

I just don’t think it will ever work that way. It’s more like fifty years from now you can say “the increased global temperatures had global effects that lead to x, x, and x.”

In the present tense I think we’re too close to the realm of “anecdote” to be able to do what you’re looking to do (what I mean is individual events are by themselves not super important and would be difficult/impossible to direct link to climate change.) Unless something fundamentally changes I think climate change is something that’s effects will be best/easiest described in the aggregate and in the past tense. (Which is probably why it presents a major policy hurdle.)

4

I’m probably missing to total meaning of your question, but…what do you call ‘harm’?

If you look at the effects of permafrost melting in AK. At least on village has moved back from the coast line. ( Shishmaref, Alaska - Wikipedia )

The TX drought (if attributed to climate change?) has decimated much of the US beef herd, so expect higher prices because a lot of the breeding stock has been sold off now. (We’re also exporting more beef, so that is also expected to play a role in increased prices).

Some regions of France can no longer support their native grape varieties (seasons have grown too warm or too wet) and that has the potential to impact wine production. Similar effects are being observed over other countries as well and given that it takes decades to establish a good vinyard, grape selection for new vinyards is a bit dodgey right now.

Northern states are seeing increased rates of crop diseases and pests that had never been a problem in the past, but are now able to over winter.

5

Nit picky question: Were those grapes actually native to the area, or brought in from elsewhere?

6

**Enkel’**s cited effect is what I would’ve chosen to chime in on. A 1 to 1.5 degree C rise in the average temperature for the area doesn’t seem like a lot, but is enough to raise Winkler scale values by 400-500 degrees over the 214 day typical wine grape growing season (April 1-October 31) 400-500 degrees is enough to shift a region to the next higher classification. Different wine grape varieties do better in different growing degree day classifications: Riesling makes better wine when grown in a cooler climate than Cabernet Sauvignon, and so on. The vine will still produce grapes, and you can still make wine, but the wine may not taste quite like it did when the region was cooler.

Now, this may overstate things. I certainly wouldn’t call it, “Can no longer support their native grape varieties”. For one, wine grapes stop producing above a given temperature, and the actual growing season for most varieties doesn’t extend from 1 April to 31 October, but it does give you an idea that the effect can potentially be significant.

Well, by that definition, nothing wine grape related is native, given that 99.9% of Vitus vinifera vines in Europe (and the U.S.) are grown on rootstock from American vines. (V. aestivalis or other.) From the wiki for Bordeaux, the vines have been there at least since 48 CE, when the Romans planted them around St. Emilion. Granted, they were probably Carmenere, since neither Cab Franc, Cab Sauvignon (cross between Cab Franc and Sauvignon Blanc), or Merlot (‘relative’ of Cab. Franc) had been bred and isolated yet.

OTOH, the wiki for Carmenere lists a potential ancestor as Vidure, which is supposedly yet another clone of Cab. Sauvignon. So maybe Cab. Sauvignon was native to Bordeaux, or at least it was first created there. Close enough, IMHO.

7

We are actually going away from anecdote, and as I see from **Enkel **there is some information that is missing and there is a need to clarify what is going on.

It is not that saying “if attributed to climate change” is not quite accurate, it is that many times because of ignorance or later by denialist efforts that we get reports from people that are not asking the proper questions.

If one asks researchers if extreme weather events are caused by global warming, the normal and most accurate answer will be that it does not, natural causes are still there, but then the misrepresentation (and it is not coming from the posters here but I have seen it from so many dubious sources that it is becoming a new myth) comes for not reporting to the people what the proper question is:

Are the extreme events made worse or the chances of they appearing more often a result of global warming?

That is the case.

http://thinkprogress.org/climate/2012/04/08/460221/tom-friedman-on-climate-change-and-the-other-arab-spring/

8

My point being, I think you can say definitively looking retroactively “climate change caused an x% increase in serious storms.” I don’t know that you can say “this specific storm was the result of climate change.” I’m not a climatologist, of course, but to me there are still too many normal variations in storm behavior (storms just being an example to discuss) so that even extremely violent storms could happen without the impact of climate change. That’s why I think it’s easier to demonstrate in the aggregate than in the specific.

9

Well, it is like the analogy with baseball and steroids, you can not definitely say what specific home runs were made thanks to the steroids, but one can calculate the increase by how many (and how much farther) home runs a baseball player normally scored before the steroids entered the picture and compare it to the unnatural increase after a player takes them.

10

This is the kind of thing I’m dealing with. I need to go back to this collaborator (that’s an unexpectedly chilling word) and say “no, there are not millions living as climate change refugees.” Weather-related refugees, perhaps, but in a chapter discussing greenhouse gas-related climate change, this is wholly inappropriate.

I’m grateful for the responses. So far it sounds like a few individuals have made statements that some weather events have roots in climate change, but I still can’t find a robust, peer-reviewed paper that makes any attempt to quantify or account for it on the level I’m looking in to (that is, I’m prepping for Rio+20 and my immediate focus is on the developing world; impacts on grapes my be an excellent indicator, but it’s not exactly in line with what I need to use).

The baseball analogy is good, except it should be tweaked so you know some steroids have been sold on the black market in a team’s city, but you cannot say for sure if any team members have taken them yet–or rather, if they have, it’s not clear they’ve put on sufficient muscle to have a measurable effect on their game performance.

Is it possible that sea level rise is be measurable enough such that flood predictions can be compared to pre- and post- measured increase? That is, if a flood of x height reaches y distance inland, a flood of x + (sea level rise) will reach y’ distance. Or am I confusing river heights with storm surges and the like?

11

Yes there is, normally high temperature records and cold records should be about even, now there are three heat records for every cold one.

12

Well with that premise anything is fair game.

You could probably attribute every death in the world in some way as harm.

13

Global warming has (on the whole) been largely beneficial to human society.
For example, the Medieval Warming Period (ca. 950 AD-1300 AD, coincided with:
-the Viking colonization of Iceland, Greenland, and Vinland
-a major growth of population in Europe
-wine grape production in England, and along the Rhine in Germany
-agriculture in the high Alpine meadows of Switzerland (no glaciers)
-no disastrous floods in the lowlands of the Rhine delta (Holland and Flanders flourished)
When things cooled off (ca. 1350 AD), things got bad-there were famines and outbreaks of disease, and cases of cannibalism were recorded (the grain harvests failed for several years).
Global warming rocks!:cool:

14

The problem is that this warming is not stopping here.

http://thinkprogress.org/climate/2012/06/04/494357/global-warming-may-reduce-us-nuclear-and-coal-power-output-up-to-16-percent-by-2060/?mobile=nc

Not cool at all.

And no the warming is not stopping there.