Friday, August 8, 2008

Climate Change and the Global Harvest

These are my notes from reading the aforenamed book in the title of this post. I mentioned this book in a previous post.

So what did I find out from reading Climate Change and the Global Harvest? Unfortunately, the book was published in 1998, so it doesn’t have any of the most current research. But here’s what I found:

Climate change will result in both positive and negative effects for agriculture.

Crop yields depend on temperature, CO2 concentration, water, soil, fertilizer inputs, solar radiation, albedo, pests, weeds etc. You get the idea. It’s a complex issue, so it’s difficult to say whether climate change will result in a net benefit or loss (globally).

Because of these effects, there will be a geographical re-patterning of agricultural activities.

The balance of positive and negative effects will be different everywhere in the future due to climate change. In other words, places that are great for agriculture now may suck in the future. Conversely, some places that totally suck now may be much better for agriculture in the future.

Gains in some regions may not fully compensate for losses in others.

That means a structural shift in global production levels and a global food crisis are distinct possibilities.

Aside from higher mean temperatures and precipitation, there will also be greater variability in these two factors in the future.

We are already seeing greater variability in the weather today. Like humans, plants hate unpredictability. If cultivars that can tolerate wide swings in temperature and water availability are not developed, crop yields may take a hit. Or we could suffer from greater variability in harvest yields, i.e. chronic famine. Monoculture makes us more vulnerable. So does loss of seed diversity.

Adaptive measures and intervention can help to mitigate the negative effects of climate change.

This generally means using better technology, irrigation, cultivars, subsidies and better farm management practices.

Adaptive measures are contingent on resource availability and socioeconomic factors.

Poor countries may not have the wherewithal to implement adaptive measures. Again, this emphasizes the irony that poorer countries that are less responsible for climate change will suffer disproportionately more from its effects.

Availability of fresh water will be a major issue.

You will see this point again and again in major climate change studies. It’s incidentally also a great growth industry to invest in. T. Boone Pickens thinks so too.

Regions that face the greatest risk tend to be least able to adapt. Conversely, some countries will be net beneficiaries of climate change. Places at higher latitudes and altitudes will see more positive effects, while places at lower latitudes and altitudes will see more negative effects.

The point on differential effects based on latitudes will be repeated again and again in climate change studies. Little data is available on places outside Europe and North America, particularly on South America. But this much is known. Under the most likely climate change scenarios, and I stress that these are just projected scenarios, and not what is definitely going to happen:

Sub-Saharan Africa, South Asia and Southeast Asia will likely experience negative effects. In the event of significant sea-level rise, many important crop-growing regions will suffer lower productivity. These include many river delta systems: the Nile (Egypt), Irrawaddy (Myanmar), Hong and Mekong (Vietnam) [I would add that China damming the Mekong is a potential geopolitical flashpoint], Ganges-Brahmaputra (Bangladesh) and Chao Phraya (Thailand). Even if permanent flooding doesn’t occur, soil and water salinization would still negatively affect crop yields.

Japan is likely to see slightly improved crop yields.

China is a mixed bag (and a big country if I may add). There are externalities like desertification and urbanization.

France and Italy would probably need to change the crops they plant to favor those that are better adapted to hotter, drier conditions. Spain might suffer from drier climate. Agriculture should improve in more northerly parts of Europe as climate change drives temperatures up. Wine is an interesting harbinger of this change in fortunes.

The USA will feel some negative effects, but is likely to be much less vulnerable for many reasons (lower dependence on irrigation, better technology, agriculture employs fewer people, large export crop etc).

Australia can mitigate the negative effects, if fresh water shortage is not an issue (and that’s a big IF).

Canada, Russia and New Zealand are likely to see improved crop yields, mainly because warmer weather lengthens the growing season and opens up regions that are currently unsuitable for agriculture. In general, poleward and altitudinal effects are positive, while the lower latitudes will see negative effects.

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