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.
