Posts Tagged: climate change
Keeping global warming below 2 degrees C (3.6 F) can be achieved only by reducing greenhouse gas emissions from all sectors, including land and food, said the United Nations' Intergovernmental Panel on Climate Change in a report released Aug. 8, 2019.
The panel of scientists said agriculture, deforestration and other land use - such as harvesting peat and managing grasslands and wetlands - generate about one-third of human greenhouse gas emissions and 44% of methane emissions. The panel suggests that farmland be reduced and forestland increased to keep the earth from getting more than 1.5 degrees C hotter than in the pre-industrial era. Global temperatures have already risen about 1 degree C in the past 150 years.
Currently, about 50% of the globe's vegetated land is dedicated to agriculture — and about 30% of cropland is used to grow grain for animal feed. Given how much land it takes to grow food to feed livestock, meat production is a leading cause of deforestation, reported National Public Radio.
Cattle ranchers dispute the UN report that links cows to climate change, said a story on CBS This Morning, which quoted UC Cooperative Extension animal science specialist Frank Mitloehner. Mitloehner studies livestock and air quality. He told the news station that Americans should focus on the energy wasted on food they don't consume.
“Forty percent of all food produced in this country goes to waste and you know who the main culprit is? You and I,” Mitloehner said. “So if you're really concerned about your personal environmental footprint around food, well, waste less.”
The more different the root architecture, the greater potential to store more carbon
The greater the diversity of the rooting network, the greater diversity of pores
It's not just the biomass that stores the carbon, it's the diversity of the pores
So plant a greater diversity of plants to increase stored soil carbon
EAST LANSING, Mich. -- Alexandra Kravchenko, Michigan State University professor in the Department of Plant, Soil and Microbial Sciences, and several of her colleagues recently discovered a new mechanism determining how carbon is stored in soils that could improve the climate resilience of cropping systems and also reduce their carbon footprints.
The findings, published last week in the scientific journal Nature Communications, reveal the importance of soil pore structure for stimulating soil carbon accumulation and protection.
"Understanding how carbon is stored in soils is important for thinking about solutions for climate change," said Phil Robertson, University Distinguished Professor of Plant, Soil and Microbial Sciences, and a co-author of the study. "It's also pretty important for ways to think about soil fertility and therefore, crop production."
The study was conducted through the MSU Great Lakes Bioenergy Research Center, funded by the U.S. Department of Energy, and the Kellogg Biological Station Long-term Ecological Research program funded by the National Science Foundation, or NSF, and it was supported by NSF's Division of Earth Sciences.
Over a period of nine years, researchers studied five different cropping systems in a replicated field experiment in southwest Michigan. Of the five cropping systems, only the two with high plant diversity resulted in higher levels of soil carbon. Kravchenko and her colleagues used X-ray micro-tomography and micro-scale enzyme mapping to show how pore structures affect microbial activity and carbon protection in these systems, and how plant diversity then impacts the development of soil pores conducive to greater carbon storage.
John Schade, from the NSF Division of Environmental Biology, said the results may transform the understanding of how carbon and climate can interact in plant and soil microbial communities.
"This is a clear demonstration of a unique mechanism by which biological communities can alter the environment, with fundamental consequences for carbon cycling," Schade said.
"One thing that scientists always tend to assume is that the places where the new carbon enters the soil are also the places where it is processed by microbes and is subsequently stored and protected," Kravchenko said. "What we have found is that in order to be protected, the carbon has to move; it cannot be protected in the same place where it enters."
Scientists have traditionally believed soil aggregates, clusters of soil particles, were the principal locations for stable carbon storage.
Recent evidence, however, shows that most stable carbon appears to be the result of microbes producing organic compounds that are then adsorbed onto soil mineral particles. The research further reveals that soil pores created by root systems provide an ideal habitat where this can occur.
Of particular importance are soils from ecosystems with higher plant diversity. Soils from restored prairie ecosystems, with many different plant species, had many more pores of the right size for stable carbon storage than did a pure stand of switchgrass.
"What we found in native prairie, probably because of all the interactions between the roots of diverse species, is that the entire soil matrix is covered with a network of pores," Kravchenko said. "Thus, the distance between the locations where the carbon input occurs, and the mineral surfaces on which it can be protected is very short.
"So, a lot of carbon is being gained by the soil. In monoculture switchgrass the pore network was much weaker, so the microbial metabolites had a much longer way to travel to the protective mineral surfaces," explained Kravchenko.
Robertson said the research may prompt farmers to focus on plant diversity when attempting to increase soil carbon storage.
"We used to think the main way to put more carbon in soil is to have plants produce more biomass either as roots or as residue left on the soil surface to decompose," Robertson said.
"What this research points out is that there are smarter ways of storing carbon than such brute force approaches. If we can design or breed crops with rooting characteristics that favor this kind of soil porosity and therefore that favor soil carbon stabilization, that would be a pretty smart way to design systems that can build carbon faster."
Nick Haddad, director of the Kellogg Biological Station Long-term Ecological Research program, said research that builds from these findings will continue to discover ways to improve the sustainability of agricultural ecosystems and landscapes.
"Long-term research shows surprising ways that a diversity of plants can benefit the microbes needed for a resilient agricultural system," Haddad added.
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One of the forces driving agricultural experiments in California's fertile San Joaquin Valley is climate change, reported Mark Schapiro on Grist.org. Although some sources still don't feel completely comfortable with the concept.
"Whether it's carbon built up in the atmosphere or just friggin' bad luck, the conditions are straining us," said John Duarte, president of Duarte Nursery.
The state's fruit and nut orchards are taking the most heat as conditions change. A fruit or nut tree planted today may be ill-suited to climatic conditions by the time it begins bearing fruit in 5 or 10 years. Between 1950 and 2009, “chill” hours trees needed annually to reboot trees' metabolic system for the spring bloom had already declined by as much as 30 percent, according to a California Department of Food and Agriculture study.
“If trees haven't had that low-chill period when they wake up in the spring, it's like being up all night and then trying to go to work.” said Mae Culumber, a nut crop advisor with UC Cooperative Extension in Fresno County.
Researchers have already observed that cherry, apricot, pear, apple, pecan and almond trees are often less productive than they used to be.
The article said farmers may turn to pistachio trees to weather a warmer and dryer California. Pistachio trees require one-third to one-half as much water as almond trees. During droughts, pistachio tree metabolism slows and when water returns, they start producing nuts again. And they can produce nuts for 80 years or longer, almost four times the life span of an average almond tree.
For field crops, scientists are looking at improving the soil and transforming growing systems to help farmers adapt to the warming climate.
“When I drive to the Central Valley, I get goosebumps; I feel the urgency,” UC Davis agronomist Amélie Gaudin said. “I see an agriculture that is basically hydroponics. It's like a person being fed/kept alive by an IV.”
“What happens when you no longer have the sugar-water?” she adds.
Gaudin is focusing on using agroecological principles to develop efficient and resilient cropping systems. Planting cover crops and reducing tillage show promise for mitigating the impact of climate change in the valley.
KQED reporter Mark Schapiro discovered a "center of insurrection" at the UC West Side Research and Extension Center in Five Points, where UC Cooperative Extension cropping systems specialist Jeff Mitchell has been building soil on a research plot for 20 years.
Schapiro's story was part of a series titled "Reckoning in the Central Valley," a collaboration between Bay Nature magazine and KQED Science examining how climate change is exposing the vulnerabilities of California agriculture.
In the Central Valley, climate change is disrupting the predictability that is key to maintaining a profitable industrial agriculture system. Mitchell believes that employing practices that build soil - such as reducing or eliminating tillage and planting cover crops - will help farmers ride the wave of climate change.
It's that cover-cropped field “that is the real disruptor here," Mitchell said.
The soil in test plots where cover crops were grown are loaded with far more organic matter than soil in fields where cover crops were not grown. The organic matter improves water absorption, making the land more resilient to drier conditions. Fields with cover crops also sequester carbon and produce crops that may be more nutritious.
“What you see in Five Points,” said Daphne Miller, a physician who studies the links between the health of the foods we eat and the soil in which they're grown, “is that the plots with the greatest diversity of cover crops had the most diverse microbiome in the soil.”
In 2018 the Ojai Valley Land Conservancy (OVLC) accepted a grant from the Resources Legacy Fund on behalf of Watershed Coalition of Ventura County (WCVC) for a study of projected climate changes in Ventura County. OVLC contracted with Drs. Nina Oakley and Ben Hatchett, climatologists with the Desert Research Institute (DRI), to evaluate historic climate variability and projected changes in Ventura County. This information is needed to “paint a picture” of future climate in the watersheds of Ventura County (Ventura River, Santa Clara River, and Calleguas Creek) to support and inform climate change-related decision-making. This study provides important information for the amendment to WCVC's Integrated Regional Water Management (IRWM) Plan
You can find a copy of the report on the DRI website at: https://wrcc.dri.edu/Climate/reports.php.
To view presentations and other information from the two WCVC Climate workshops conducted with Drs. Oakley and Hatchett in October of 2018, and April of this year please visit: http://wcvc.ventura.org/documents/climate_change.htm
Some of those most interesting findings for me, are the historical data. For example, data for the years 1896 – 2018, show a tendency toward increasing maximum temperatures over the period, especially the last 10 years (Fig 1.2). But most interesting, is the increasing minimum temperatures (Fig 1.3) as compared to the maximum temperatures. Winter where is thy sting? The 2018-19 winter was the coldest in my memory, with the heater on full time at night, but there was no general frost damage this year. I can remember 1990 and 2007.
Precipitation in the South Coast region exhibits high interannual variability over the period examined. No notable long-term trends are observed (Fig. 1.4). Since approximately 2000, the 11-year running mean decreases, associated in part with the 2012–2019 drought. It is unclear whether this trend will continue in subsequent years.
There's a lot more information in the report. READ On.
But something to keep in mind, is that we had a terrible heat wave last July, and it could easily happen again. Growers who had their trees well hydrated before the heat arrived, sustain less or no damage to the trees and much less fruit drop. Trees that were irrigated on the day it started to get hot, never had a chance to catch up with the heat. Once the atmosphere starts sucking the tree dry, water movement through the soil, roots and trunk cant keep up with the demand. Weather forecasting is pretty accurate 3 days out, and if heat is forecast, get those trees in shape. You can run water to reduce the temperature and raise the humidity in the orchard to reduce transpirational demand which helps some.
Something we learned last year. What we saw and what to expect:
Map of elevational changes in Ventura County and how