Nature - Flood Risk Associated With Warming Badly Underestimated - AFP

[hatrack]

Global warming may carry a higher risk of flooding than previously thought, according to a study released on Wednesday by the British science journal Nature. It says efforts to calculate flooding risk from climate change do not take into account the effect that carbon dioxide (CO2) -- the principal greenhouse gas -- has on vegetation.

Plants suck water out of the ground and "breathe" out the excess through tiny pores, called stomata, in their leaves. Stomata are highly sensitive to CO2. The higher the level of atmospheric CO2, the more the pores tighten up or open for shorter periods. As a result, less water passes through the plant and into the air in the form of evaporation. And, in turn, this means that more water stays on the land, eventually running off into rivers when the soil becomes saturated.

In a paper published in February 2006, British scientists said the CO2-stomata link explained a long-standing anomaly. Over the last 100 years the flow of the world's big continental rivers has increased by around four percent, even though global temperatures rose by some 0.8 degrees Celsius (1.35 degrees Fahrenheit) during this period.

EDIT

By widening the picture to include the CO2-stomata factor, the likelihood is that the risk of flooding will be worse than thought, but the risk of drought rather less so. "The risks of rain and river flooding may increase more than has been previously anticipated, because intense precipitation events would be more likely to occur over saturated ground," it says. "In contrast, the risks of hydrological drought may not increase as much as expected on the basis of meteorological changes alone."

EDIT

http://www.terradaily.com/reports/Flooding_risk_from_global_warming_badly_under-estimated_study_999.html

[aquart]

1. Is land in the center of Canada becoming pricey?

[emmadoggy]

2. Interesting.

We just had historic flooding in my part of the world. Rochester, MN, LaCrosse, WI, and Madison, WI all set new records for wettest August ever (and that was with more than a week left in the month). This month also qualified as not just the wettest August ever, but the wettest MONTH ever for both Rochester and LaCrosse. A new 24 hour rainfall record was established in MN (near Hokah, MN) with a 24-hour rainfall of 15.10 inches, which SHATTERED the old record of 10.85 inches.

Here at our house, we lucked out of the worst of the flooding - but we still had over 16 inches of rain in 2 weeks time. It has been a very strange month.

A big part of this situation was a stationary boundary that perched over us for days and days right about the time Erin was dissipating and supposedly a lot of that moisture was funneled up and over this boundary and dumped on us. But even just prior to that event and also since that boundary finally moved out, we still had several rain/heavy rain events.

:shrug:

[OKIsItJustMe]

3. Flooding

My folks have lived in the same house for about 50 years.

3 years ago, they experienced a "100 year flood." 2 years ago, they experienced a "250 year flood." Last year they experienced a "500 year flood."

(What're the odds?)

[emmadoggy]

4. That's horrible.

There have always been wacky weather events, but it sure seems like the last 10 years or so, we have been hearing about SO many more than just the occasional fluke.

:cry: :scared: :scared: :scared:

[amandabeech]

5. How are the crops doing?

I'm glad that you're okay, don't get me wrong, but the world often doesn't do too well with its food surpluses if the Midwest has a really bad year. You've been flooded. Lots of good farmland in nothern Ohio was flooded. Texas, Oklahoma and Kansas were flooded.

I'm wondering how well corn, beans and wheat plants dry out.

[emmadoggy]

6. I'm not really sure.

I haven't heard much talk yet about the effects this will have on the harvest. My husband and I went for a drive yesterday into the more flood-ravaged areas and it was surreal to see all of these huge mudslides along the bluffs of the Mississippi. Some of which took out whole houses.

As for the crops, it's hard to say. We have seen a lot of corn that is looking, well....peaked (pekid). Some corn, especially in higher areas, looks pretty good. Starting to dry. But a lot of the corn in the lower valleys doesn't look too great. Will that translate to poorer yields? I have no idea. I suppose it depends on what kind of fall we have and if the corn will have time to recover and dry out. In this immediate area, there doesn't seem to be nearly as much bean crop as there is a little further west of here, but the beans around here that I have seen look ok. Again, I think a lot will depend on what kind of weather we get in the coming weeks. This past week has been warm and sunny which helps, but there is still a LOT of drying-out to do and there is rain in the forecast for later this week. Most of the rest of Iowa, MN, and WI saw a lot of rain, but not as much as my immediate vicinity, so the bulk of the crop may be ok. I'm no expert though, so I can't really say for sure.

Found this graphic from our National Weather Service website for total August precipitation. I live in the northeastern most county in Iowa.