Lecture 22: Climate Change and Sustainability

what are the trends in land cover from 1700 to 2007?

savanna/grassland is giving way to pasture

cropland increasing at the expense of forest/woodland

what is the issue with land use change?

can lead to habitat loss, biodiversity decline, and increased carbon emissions

soil organic carbon loss is ______ with increasing land use

increasing

cropland per capita

how much cropland there is in relation to world population

what has been the trend with cropland per capita? what are the implications of this?

declining; means we are producing food from a smaller land base

what was Dasgupta’s conclusion about economics and biodiversity?

a lot of things about nature that support biodiversity are invisible, silent, and mobile

what does it mean for biodiversity to be invisible?

soil carbon is below ground and hard to measure

what does it mean for biodiversity to be silent?

loss of a species can go unnoticed

what does it mean for biodiversity to be mobile?

species can migrate and adapt to changing environments, making their presence less stable, which affects jurisdiction and statutes

about __% of the world’s harvested cropland is now irrigated, about half of it with water pumped mostly from wells, with about __% of the irrigated land being in ____

18, 70, Asia

where is the use of nitrogen fertilizer highest?

East Asia, Europe, and North/Mideast of the US

what are the impacts of groundwater withdrawals?

land subsidence- land drops due to groundwater withdrawals

Haber-Bosch process

an industrial method used to synthesize ammonia from nitrogen and hydrogen gases, enabling the large-scale production of nitrogen fertilizers

total anthropogenic fixed nitrogen

refers to the amount of nitrogen fixed by human activities, significantly contributing to global nitrogen levels through fertilizers and other means

the rise in anthropogenic fixed nitrogen is largely due to

increased fertilizer use

what are natural ways of fixing nitrogen?

legumes, lightening, manure, bacteria

plant growth depends on

nitrogen

deadzones

areas in aquatic environments with low oxygen levels caused by excessive nutrient pollution, particularly from nitrogen and phosphorus (plants die and the oxygen is sucked out of the water)

run-off fertilizer into the ocean creates

deadzones

what has happened to the conversion of energy to fertilizer?

it has become more efficient but we have reached close to the limit for how efficient it can be

what does Smil think is the biggest challenge in the climate crisis?

fertilizer use; we are so dependent on fertilizer use and its difficult to find something that can scale the way fertilizer can

what are the effects of climate change on global food production?

it will impact where food is grown; the amount of food the world will be able to produce will not change much; there will be some varaibiltiy in places that will see a decrease in food production (lower latitude countries) and places that will see an increase in food production (higher-latitude countries)

what are the non-climate stressors that are putting the food system under pressure?

population growth, income, demand for animal sourced products

agriculture contributes greatly to climate change, but its contribution is less than the ______ sector

energy

what part of food production contributes the most to GHG emissions?

livestock and fisheries

land use contributes __% to the overall GHG emissions caused from food production?

24

what are some of the supply-side actions that would reduce GHG emissions in the food system?

efficient production, transport, and processing

what are some of the demand side interventions that would reduce GHG emissions in the food system?

modification of food choices and reduction of food loss and waste

how does sequestering carbon benefit both the climate and agriculture?

enhances soil health, increases crop yields, and mitigates climate change by reducing atmospheric CO2 levels

there is evidence that affirms what about global variation of emissions?

there are farms producing the same thing in the same parts of the world, with the same growing practices with differing emissions

per unit of output, the US has some of the ____ GHG emissions

lowest

per unit of land, the US has some of the _____ GHG emissions

highest

why is GHG per unit of land high in the US?

density of cattle (aggregate emissions per unit of land is high)

why does Africa have a high per unit of output emissions?

cattle production is inefficient compared to other parts of the world

the _______ model is more efficient and has lower GHG emissions per unit of output

industrial

what is the per unit of land emissions in India like? why?

relatively high because there are a lot of cows in India due to religious reasons

how to improve the food system from an environmental perspective?

reducing impacts means focusing on different areas for different producers and, by implication, adopting different practices

practices like conservation agriculture or organic farming is not a solution in themselves but an option producers can choose

what solution to improve the food system do Godfray and Garnett propose?

sustainable intensification

sustainable intensification

a radical refocusing of food production on the twin aims of increasing yields and improving environmental performance

the results of this will be very much location specific

true or false: the market alone can achieve sustainable intensification

false

what are the conclusions about how to improve the food system climatically?

wean agriculture off fossil fuels

reduce off-farm inputs

embrace local variation (value diverse landscapes, genetic variation of plants, find efficiency in heterogeneity)

intensify through labor

what does it mean to intensify through labor?

increasing output and production through labor rather than through technology

labor is often inexpensive in other parts of the world but capital inputs are costly

per unit of land, what kind of system produces the most?

gardens; the labor unit is large