Video - Water pollution

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Del curso dictado por University of Western Australia

Agriculture, Economics and Nature

170 calificaciones

University of Western Australia

Agriculture, Economics and Nature

170 calificaciones

Sound economic thinking is crucial for farmers because they depend on good economic decision making to survive. Governments depend on economic information to make good policy decisions on behalf of the community. This course will help you to contribute to better decision making by farmers, or by agencies servicing agriculture, and it will help you to understand why farmers respond to policies and economic opportunities in the ways they do. You can use this course to improve your skills and knowledge, and to assess whether this is a subject that you'd like to study further. The course includes high-quality video lectures, interviews with experts, demonstrations of how to build economic models in spreadsheets, practice quizzes, and a range of recommended readings and optional readings. Assessment is by a final exam. The key economic principles that we’ll learn about can help us understand changes that have occurred in agriculture, and support improved decision making about things like agricultural production methods, agricultural input levels, resource conservation, and the balance between agricultural production and its environmental impacts. There are literally thousands of agricultural economists around the world who work on these issues, so there is a wealth of knowledge to draw on for the course. Watch a brief video about our course here: https://www.youtube.com/watch?v=T_IeYGpeqV8

De la lección

Resource and environmental challenges facing agriculture

Week 2 addresses the agricultural issues of water availability, peak phosphorus, herbicide resistance, and climate change.

Video - Water pollution6:25

Conoce a los instructores

Professor David Pannell, BSc(Agric), BEc, PhD
UWA School of Agriculture and Environment
University of Western Australia
Jacob Hawkins, BA(Biol), MESM, PhD
School of Agricultural and Resource Economics
University of Western Australia

This week we're going to talk about some of the key resource

challenges that face agriculture currently and into the future.

And we'll cover issues like water pollution, pesticide

bans, salinity, phosphorus availability, water shortages,

herbicide resistance, and climate change--

starting today with water pollution

So water pollution can arise from agriculture

in a variety of ways, a variety of causes.

It can be caused by sediment by nutrients, by pathogens,

by pesticides.

And these can all occur in groundwater

or in surface water.

So there are a variety of different types

of water pollution problems arising from agriculture.

Let's start with nutrients.

Some nutrients from fertilizer run off into waterways

and/or leach into groundwater.

And this can affect the ecosystem,

and it can affect human health.

And around the world, there are many different water bodies

that have been or are being affected in this way.

So some very prominent examples include Chesapeake Bay

in the USA, the Gulf of Mexico, which famously

has what's called a hypoxic zone or a dead zone,

a zone with no oxygen in the water-- also in the US.

The Great Barrier Reef in Australia-- a much less serious

case than the Gulf of Mexico currently

is, but still a concern.

The Gippsland Lakes in southeastern Australia,

and many, many other rivers and lakes,

and inshore marine waters around the world.

Another cause of water pollution is sedimentation.

So when areas are cultivated or plowed

for crops or grazing of livestock loosens the soil,

this can lead to soil erosion.

And the eroded soil washes or blows,

usually washes, into waterways with a variety

of different impacts.

Impacts can include pollutant accumulation,

sometimes pollutants are attached to the soil.

Phosphorus is as a common example there.

Shallower waterways, which means that there's reduced capacity

for water to flow through those water bodies.

Or in some cases, shallower dams.

There's been cases of quite a lot of sediment

washing into dams that have been created

and slowly but surely filling up those dams

and reducing their usefulness as dams.

Reduced light penetration and ecosystem damage.

So economic perspectives on this include the idea

that water pollution from agriculture

is what's called an externality, or an external cost.

What this means is that the people with the potential

to fix the problem or avoid creating the problem

don't bear the cost of the problem.

The costs of water pollution aren't

reflected in the costs of agricultural production.

So that means that farmers don't fully

recognize the costs that some of their actions are causing.

And economists recognize that that potentially

means that there's a justification for a response

by government to step in and try and reduce water pollution.

Here's a supply and demand diagram

that illustrates this point.

This is showing the supply curve purely from the perspective

of farmers, and you can see the point

where the supply and the demand curve

intersect, indicating the level of production

and the price that would occur in free market.

But then if we were to allow for the fact

that there is an additional cost that's not captured or not

felt by farmers due to water pollution,

then that means that the marginal cost of production

is higher.

So this new supply curve, which I've

labeled there, the social marginal cost,

is higher than the private marginal cost,

because it also factors in this cost of pollution.

And if we could make this marginal cost be the one that

determined what level of production there was

and what the price would be, you can

see that the production would be a bit lower,

and the price would be a bit higher.

If we were to do that, we would have achieved

what economists call, "internalizing."

We have an externality, and we can achieve

and we can manage that externality appropriately

by internalizing it.

And it effectively means that in this case,

we'd have a different supply curve.

So the effect of the externality is

that to produce an extra unit of grain,

it not only costs the farmer inputs such as fertilizer,

herbicides, labor, fuel, and so on, it also

costs society a reduction in environmental quality.

And so the total cost, the social cost

is higher than the private cost.

And once this is factored in, the optimal quantity of grain

is a bit lower.

So it reflects that we've struck a different balance,

or we've struck a balance between production

and the environment.

An example of an externality that I've mentioned already

is water pollution affecting the Great Barrier

Reef in the northeastern part of Australia.

And there's various types of pollution affecting the Great

Barrier Reef.

An important one is nutrient pollution

coming from sugar cane production, which

you can see in this photo.

Here's a quote from the Great Barrier Reef Marine Park

Authority to illustrate the problem.

"The reef continues to be exposed

to increased levels of sediments, nutrients

and pesticides.

In particular, there are significant effects

in inshore areas close to developed coasts,

such as mangrove dieback and increased algae on coral

reefs."

So in summary, the main pollutants from agriculture

are nutrients and sedimentation, and water pollution

is an example of an external cost, which

is an additional cost to the community on top

of the farmer's cost of production.

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