Planet Likely to Become Increasingly Hostile to Agriculture

[one...two...tree 2,762]

The Horn of Africa is in the midst of its worst drought in 60 years: Crop failures have left up to 10 million at risk of famine; social order has broken down in Somalia, with thousands of refugees streaming into Kenya; British Aid alone is feeding 2.4 million people across the region.

That's a taste of what's to come, say scientists mapping the impact of a warming planet on agriculture and civilization.

"We think we're going to have continued dryness, at least for the next 10 or 15 years, over East Africa," said Chris Funk, a geographer at the U.S. Geological Society and founding member of the Climate Hazard Group at the University of California, Santa Barbara.

Funk and other experts at the American Geophysical Union meeting in San Francisco cautioned that East Africa is just one example. Many recent events - discoveries from sediment cores in New York, drought in Australia and the western United States, data from increasingly sophisticated computer models - lead to a conclusion that the weather driving many of the globe's great breadbaskets will become hotter, drier and more unpredictable.

Even the northeastern United States - a region normally omitted from any serious talk about domestic drought - is at risk, said Dorothy Peteet, a senior research scientist with NASA's Goddard Institute for Space Studies.

A series of sediment cores drilled from New York marshes confirm that mega droughts can grip the region: One spanned from 850 to 1350 A.D., Peteet said. And shorter, more intense droughts have driven sea water far up the Hudson River, past towns such as Poughkeepsie that depend on the river for drinking supplies.

"We're just beginning to map the extent, but we know it was pervasive," she said. "There are hints of drought all the way up to Maine."

Of course, climate change can't be blamed for all the food shortages and social unrest, several researchers cautioned. Landscape changes such as deforestation can trigger droughts, while policy choices exacerbate impacts.

Some hard-hit African countries have the highest growth rates on the planet, and gains in agricultural productivity simply have not kept up with those extra mouths. Per capita cereal production, for instance, peaked worldwide in the mid-1980s, Funk said, and is decreasing everywhere. But no place on the globe is decreasing faster than East Africa.

Simple policy decisions can blunt a crisis. Malawi, in southeastern Africa, gave farmers bags of seed and fertilizer and saw food prices fall and the percentage of its population classified as undernourished drop by almost half over a decade, Funk added. Kenya, in contrast, saw its policies stagnate; prices and malnourishment rates both rose.

Meanwhile, researchers probing the climate in pre-Columbian Central America figure that widespread deforestation had a hand in the droughts thought to have toppled the Mayan, Toltec and Aztec civilizations.

More than 1,000 years ago, "significant deforestation" throughout Central America suppressed rainfall upwards of 20 percent and warmed the region 0.5ºC, said Benjamin Cook, a NASA climatologist.

The forest - and local moisture - rebounded with the population crash that followed European contact, he added. But today the region is even more denuded than during its pre-Colombian peak.

But with the frequency of droughts expected to triple in the next 100 years, researchers fear the resulting variability and stress to agriculture and civilization could prove destabilizing for many regions.

"We should take it seriously," Peteet said.

http://www.scientificamerican.com/article.cfm?id=planet-likely-to-become-increasingly-hostile

[Danno 1,228]

Some folks can't deal with an evolving eco system.

With any luck Greenland will be green again.

[Misha & Ira 113]

We need to pump more CO2 into the atmosphere then....

Agriculture (Species -- Wheat: CO2 vs. Stress of Drought) -- Summary

Atmospheric CO2 enrichment typically enhances photosynthesis and biomass production in wheat plants under normal growing conditions (see, for example, our Subject Index Summaries pertaining to Agriculture (Species - Wheat: Photosynthesis and Biomass). But what happens when environmental conditions are less than ideal? In this brief recapitulation of the results of studies for which we have produced Journal Reviews, we report on what has been learned when lack of water limits the growth of wheat.

In a study of the ecosys crop growth model, Grant et al. (1999) compared their model calculations of wheat biomass production in response to elevated CO2 at high and low soil moisture contents with observed values measured in a FACE experiment conducted on spring wheat grown at atmospheric CO2 concentrations of 350 and 500 ppm near Maricopa, Arizona, USA. They report that in that very realistic experimental study, the observed CO2-induced percentage increases in biomass were determined to be 10% in the high soil moisture regime but 18% in the low soil moisture regime.

In a subsequent FACE study conducted at the same location, Li et al. (2000) grew wheat plants at close to the same CO2 concentrations (370 and 550 ppm) under well-watered conditions and a water-stressed regime where the plants received only 50% as much irrigation water as the well-watered plants; and in this case, much as in the prior study, the CO2-enriched well-watered plants exhibited a grain weight increase of 14%, while the CO2-enriched water-stressed plants experienced a grain weight increase of 24%. At the same time, in an ancillary study of the same wheat crop, Wall (2001) observed that as the amount of moisture in the soil decreased, leaf water potentials of the CO2-enriched plants were always higher (less negative) than those of the ambiently-grown plants, as a consequence of CO2-induced improvements in both drought avoidance and drought tolerance. In fact, during the driest part of this two-year study, the CO2-enriched plants in the "dry" irrigation treatment exhibited leaf water potentials that were similar to those measured on ambiently-grown plants in the "wet" irrigation treatment. Thus, the extra 180 ppm CO2 of this study completely ameliorated the effects of water-stress in these plants under the driest conditions they encountered, as inferred by leaf water potential data. Also of interest in this regard, the study of Lin and Wang (2002) suggests that elevated levels of atmospheric CO2 may well have a greater impact on increasing drought resistance in inherently less-drought-tolerant species than they do in more-drought-tolerant species, which is to say that atmospheric CO2 enrichment may help those plants most that need help most.

Other researchers have obtained similar results. Schutz and Fangmeier (2001), for example, grew spring wheat for an entire season under well-watered and water-stressed conditions in pots located within open-top chambers maintained at atmospheric CO2 concentrations of 367 and 650 ppm, finding that the elevated CO2 stimulated yield by 40% in the well-watered treatment but by 57% in the water-stressed treatment. In like manner, Dong-Xiu et al. (2002) grew spring wheat in open-top chambers maintained at atmospheric CO2 concentrations of 350 and 700 ppm and soil moisture contents of 40 and 80% field capacity, finding that the extra CO2 of their study increased net photosynthesis by 48% in the high soil water treatment but by 97% in the low soil water treatment.

Based on results such as those described above that have been obtained from many real-world experimental studies, Reyenga et al. (2001) ran a cropping system model designed to reveal how predicted climate changes might impact wheat production in the southern part of Australia with an atmospheric CO2 concentration of 700 ppm in combination with several computer-generated scenarios of warmer temperature and reduced rainfall. They found that under most climate change scenarios, cropping range expanded northward due to the "carbon dioxide fertilization effect." In addition, the elevated CO2 increased yields by 13 to 52%, with the greater responses occurring in the drier climates.

In light of these several observations, it is clear that the ongoing rise in the air's CO2 content should have its greatest relative impact on the growth and development of wheat where a lack of sufficient soil moisture currently reduces grain yields below their genetic potential. As a result, people around the world who are forced to farm marginal lands beset by water shortages should most benefit, relatively speaking, from this phenomenon.

http://www.co2science.org/subject/a/summaries/agwheatdrought.php

[Obama 2012 1,714]

let's see... it's normal for this to happen and the only solution is what Hitler tried to do to an entire race. Interesting. I always knew the left supported genocide. Good job Steven!