Scientists agree that human activity by emitting heat-trapping gases is causing global warming with extremely serious environmental and human health effects. Following is a statement on the impacts from the Union of Concerned Scientists:
Causing serious disruptions to our environment and lives . . .
As the Earth continues to warm, there is a growing risk that the climate will change in ways that will seriously disrupt our lives. While on average the globe will get warmer and receive more precipitation, individual regions will experience different climatic changes and environmental impacts. Among the most severe consequences of global warming are:
- a faster rise in sea level,
- more heat waves and droughts, resulting in more and more conflicts for water resources;
- more extreme weather events, producing floods and property destruction; and
- a greater potential for heat-related illnesses and deaths as well as the wider spread of infectious diseases carried by insects and rodents into areas previously free from them.
If climatic trends continue unabated, global warming will threaten our health, our cities, our farms and forests, beaches and wetlands, and other natural habitats.
What impact do agricultural practices have on global warming? Much of the fascinating answer is contained in the writings of Professor R. Lal, School of Natural Resources, The Ohio State University, Columbus, Ohio, USA.* Carbon dioxide is the principal, heat-trapping gas causing the greenhouse effect and our global warming. Consequently, the world-wide carbon cycle is of vital and basic importance. "World soils, an important and active pool of organic carbon, play a major role in the global carbon cycle." In fact, the carbon content of soil is "about twice that of the atmospheric pool and about three times that of the biotic pool." Thus, the increasing atmospheric carbon, the greenhouse effect, and all our global warming problems have been and are much affected by even small changes in world-wide soil carbon content.
If climatic trends continue unabated, global warming will threaten our health, our cities, our farms and forests, beaches and wetlands, and other natural habitats.
Lal points out that conventional agriculture degrades the soil by leaving it bare, breaking up its tiny humus-containing aggregates, and failing to return plant residues. Of course, both the humus and the plant residues are wonderful sources of organic carbon. Consequently, the rise of conventional agriculture has contributed to the atmospheric increase in carbon dioxide, methane, and nitrogen oxide compounds - the greenhouse gases.
Conservation tillage uses the crop residues and keeps the soil covered most, if not all of the time - all the way from planting through and beyond harvest. This practice by intelligent and forward-looking farmers is increasing. Often it involves using cover crops and crop rotations. Along with keeping the crop residues, these farmers retain and sometimes increase the biomass of their soil, which is essential for its health, productivity, and for retaining its organic carbon content. Thus, devastating soil erosion - common in conventional agriculture - from water and/or from wind is avoided.
Restoration of degraded soils is an important option for carbon sequestration and mitigating the greenhouse effect. It is a win-win situation. While improving productivity through enhancing soil quality, restoration of degraded soils can also sequester carbon and minimize risks of the greenhouse effect. The data . . . show that goals of increasing soil organic carbon content . . . by residue management, conservation tillage, and restoration of degraded soils can effectively mitigate the current rate of increase of atmospheric CO2 [carbon dioxide] concentration.
In other words, balance and thus take care of all other human greenhouse gas
emissions worldwide.
All this hauling of "yard waste" uses energy, which generates pollution and greenhouse gases. Meanwhile, the local gardens lose their own fertilizer and throw away carbon -- each in their own small way contributing to global warming.
Let us think for a moment of our
own immediate situation: I myself have a small urban plot around my bungalow.
Years ago, before we converted to all native plants, herbs, etc., we had a small
lawn both in front and in back. In the fall when many maple leaves fell on both
lawns, our children would run happily through piles of dry leaves with our push
mower, grinding them up as fertilizer for the grass and clover that made up
our lawns. Any extra so-called "yard waste," we would put on our beds
of flowers. Before changing over to no lawn, we had our soil tested for humus
content. It was off the chart! On the other hand, every fall, it amazes me to
see the many, many bags of leaves that neighbors everywhere have racked up from
their lawns and beds to give away -- leaving their soil bare -- unfertilized
and subject to erosion. All this hauling of "yard waste" uses energy,
which generates pollution and greenhouse gases. Meanwhile, the local gardens
lose their own fertilizer and throw away carbon -- each in their own small way
contributing to global warming. What a waste!
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*Lal, R., "Residue management, conservation tillage and soil restoration
for mitigating greenhouse effects by CO2 enrichment," Soil & Tillage
Research, 43:81-107, 1997.
Article from NOHA NEWS,
Vol. XXIX, No. 1, Winter 2004, pages 7-8.