World Bank _Agriculture Percent

Climate change is likely to cause an expansion
of land suitable for growing crops globally, but on average the
quality of land will decline, a new study shows.

A warmer world would mean more cropland for
northern latitude countries such as China, Russia and Canada, but
there are trade-offs elsewhere, with much of Africa having to
manage with less cropland and fewer harvests per year.

Suitable cropland

Not everywhere in the world is suitable for
growing crops. Some areas are too dry, or too cold, while other
areas have poor quality soil or are too hilly. The climate plays a
significant role in determining what we can grow and

At the moment, about 40 per cent of the Earth’s
land is used for farming, though there are huge
between countries. For example,
over 60 per cent of India is used for agriculture, whereas the
figure for Canada is much lower, at just seven per cent.

You can see in the map below how this varies across
the world; the darker the red colour, the more land is used for

Percentage of land used for agriculture in 2011.

World Bank

A new study, just published in the journal PLOS
, analysed 23 regions around the world to determine their
suitability for agriculture. By considering the present day and at
the end of the century, the study looked at how this suitability
might be affected by changes in climate.

High latitudes

Globally, the researchers found an increase in suitable cropland
of 4.8 million square kilometers (sq km) under climate change.

The northern high latitudes would see
most of the rise in usable farmland, as we see areas that are too
cold for crops warm up through the century. These areas are shown
by the green bands in the map below, extending across much of North
America, northern Europe and Asia.


Map of change in agricultural suitability between
present-day and the end of the 21st century. Green areas show
increases, yellow and brown show decreases. Zabel et al.

According to the research, Russia, Canada and China, would see
increases of 3.1 million sq km, 2.1 million sq km, and 0.9 million
sq km, respectively.

However, while the changing climate should, in
theory, make more land suitable for farming, reaping the benefits
is unlikely to be that straightforward, the study

New cropland would be in sparsely populated
areas that wouldn’t necessarily have the labour and infrastructure
in place to take full advantage, say the authors. So establishing
farming in any of the new areas might require a lot of

Declining quality

As well as changes in farmable area, the
researchers found a decline in the overall quality of farmland
worldwide. The study shows a reduction in the amount of the highest
quality cropland by 0.7 million sq km. Dr Florian Zabel, lead
author of the paper, tells us:

“Our results suggest that globally,
there will be more area suitable for agriculture by the end of the
century, while at the same time the average global suitability is
worsening. This means that we will have fewer ‘highly suitable’
sites but more ‘marginally’ and ‘moderately suitable’ sites.”

In terms of food production, this means land
management and farming practices, such as irrigation and choice of
crop variety, will become increasingly important. Zabel

“[E]ven a ‘marginally
suitable’ site can be managed perfectly and thus be more productive
or profitable than the ‘best suitable’ site if this is badly
managed. In my opinion, it is an important (scientific) challenge
to support farmers with best knowledge for management practices and
technology in order to archive a more efficient and sustainable

Benefits in some parts of the world come with
tradeoffs elsewhere. The study found climate change will reduce
cropland in other parts of the world, shown by the yellow and brown
areas in the map. The largest reduction is found in sub-Saharan
Africa, at over 2 million sq km, but much of southern Europe,
Australia, and the Middle East are also affected.

Multiple cropping

In some areas of the world, the growing season is long enough to
grow two or three crops on the same land in a single year, known as
‘double-cropping’ or ‘triple-cropping’. The dark green areas in the
map below show triple cropping mainly occurs in the tropics.

Zabel _Multiple Cropping

Map of suitable areas for single, double and
triple cropping for present-day. Zabel et al. (2014)

Climate change has a huge impact on the areas
suitable for multiple cropping, the study concludes.

Brazil and sub-Saharan Africa look set to be the worst-affected,
losing 29 per cent (2.9 million sq km) and 20 per cent (1.7 million
sq km) of triple-cropping land by the end of the century,

There are countries that could benefit, however.
China, India, Japan, Middle East/North Africa, Russia and the USA
could all become suitable for multiple cropping in the future. But
these increases are vastly outweighed by the losses elsewhere, the
authors note.

And these losses will be keenly felt in those
parts of the world that are particularly vulnerable to climate
impacts. Regions such as sub-Saharan Africa, which already has
highest proportion
of people facing food
insecurity of anywhere in the world.

Zabel F, Putzenlechner B, Mauser W (2014) Global Agricultural
Land Resources – A High Resolution Suitability Evaluation and Its
Perspectives until 2100 under Climate Change Conditions. PLoS ONE
9(9): e107522. doi:10.1371/journal.pone.0107522