The Times Are Changing and So's the Land!

We as humans have dramatically changed the earth’s surface in the last 150 years. Changes in global land use has lead to more and larger urban centers, thousands of square miles of subsistence and commercial agriculture, the loss of millions of square miles of forest, and much more. These land use changes can and have had detrimental effects on the environment and its ability to supply and service our constantly growing population. Among these detrimental effects are: changes to the atmospheric composition, disruption of ecosystems, biodiversity loss, and the degradation of soil and water.

Food production is one of the biggest environmental concerns because of the large amount of land it uses-croplands and pastures cover about 40% of the earth’s surface-and the resource intensive nature of modern agriculture. Agriculture has changed and grown substantially in the last 40 years. Cropland area has grown by about 12% while fertilizer use has increased by 700%. This can be at least partially attributed to the “Green Revolution” which promoted the use of fertilizers and machinery to increase crop yield.  While these changes have lead to increased crop yield-global grain production has roughly doubled in the last 10 or 20 years-they also have devastating effects on the environment.

Land use also greatly affects the hydrologic cycle. The over use of fertilizers leads to damaging run off that both degrades water quality locally and downstream as well as causing algal blooms and “dead zones”-when the fertilizer reaches the ocean it causes a boom in algae growth, the algae use all the oxygen in the water and nothing else can survive there, thousands of fish wash up on the shore dead during these blooms. Agriculture accounts for 85% of global water consumption and a lot of that water is being pumped unsustainably from underground sources. Some of these sources have salt in the water which ends up on the soil when the crops are irrigated. This salinizes-think salt-the soil and makes it impossible to grow anything there. Deforestation, increased impervious surfaces like roads and parking lots, and urbanization also degrade water quality and disrupt the hydrologic cycle.

In the last 300 years humans have cleared around 7-11 million square km of forest for agriculture or timber harvesting purposes. While reforestation projects are helping build back the forests the biodiversity and some of the ecological services that were lost in the original clearing will likely never fully recover. These changes to vegetation mass, land use, and the hydrologic cycle have impacts on our atmosphere and climate as well. With increased human development have come increased emissions. The earth has natural systems to regulate the composition of gases in the atmosphere one of which is forests which act as natural carbon sinks. However, it is not capable of handling the added weight of our emissions and we already cut down 7-11 million km² of our carbon-absorbing forests. The earth is warming and it’s at least mostly if not entirely because of humans how we have used and reshaped the land.

Modern land use practices are sacrificing the long-term health of the environment for short-term rewards. Human actions need to take a sharp turn towards sustainability if we want to continue to enjoy the ecological services that our environment provides. Sustainable land-use would not only preserve ecological services for future generations, but would also seek to increase the resilience of that ecological service. For example, creating a plan for a cropland that would have environmental, social, and economic benefits would seek to increase the yield per unit of fertilizer, land, and water input thus reducing the environmental impact. Increasing green-spaces in urban places can reduce runoff and the “heat-island” effect while providing parks to play in and gardens to harvest. The ultimate goal is to find a way to coexist with and leave natural ecosystems as unchanged as possible. Life was around for billions of years before humans and it had a pretty good thing going before we threw a wrench in the works. Working with the natural systems the environment already had in place—using ladybugs to control aphids instead of insecticide—usually gives the best results.

What about GIS?

            GIS was probably used to gather most of these statistics and learn the full extent of these land-use changes. GIS can also be used predict their progression and map potential threats or areas of concern. GIS is a powerful tool for anyone interested in looking at how the surface of the earth has changed, is changing, and will likely change in the future.

Works Cited

Foley, J. A., DeFries, R., Asner, G. P., Barford, C., Bonan, G., Carpenter, S. R., ... & Snyder, P. K. (2005). Global consequences of land use. science,309(5734), 570-574.