Past, Present, and Future Climate Change: Can Palaeoecology Help Manage a Warming World? - Biodiversity Conservation and Environmental Change - page 94

plant crops later in the growing season, thereby reducing the chances of crop failure. Meeting
in June each year to plan the season's planting, farmers observed that in good rainfall years,
the star cluster known as the Pleiades appears bright, whereas it is dim in drought years. Sci-
ence has only recently caught up with the farmers' observations; the drought years are asso-
ciated with El Niño, which brings high-altitude clouds and westerly winds, blocking the
transport of wetter air from the east and causing seasonally low rainfall (Figure 5.6) (Orlove
et al. 2002).
Further adaptations that protect crops and increase water availability include irrigation
and the cultivation of species and varieties that can grow rapidly and are adapted to low
water availability (García et al. 2007). Today, vulnerability to drought is exacerbated by euca-
lyptus plantations that deplete underground water resources and increase the risk of fire,
further endangering indigenous vegetation. Adaptations like fire control and agroforestry
systems including indigenous trees like Polylepis , which conserve water, might help to buffer
some of the aridification effects and sustain livelihoods. A return to more traditional farming
techniques, which have been declining in recent decades, may all enhance sustainability
and resilience of agriculture in a warming climate (Gilles et al. 2013). The use of manure, for
example, not only raises nutrient content, but also increases the water-holding capacity of
soil, and thus buffers against drought and frost. Planting multiple varieties of potato, rather
than the recent trends towards monoculture, provides a greater range of maturation dates
and climate tolerances, thus increasing the resilience of this staple crop and contributing to

Pleiades
appearance
(late June)

Normal year

Andes
plentiful rainfall
(October-March)

South America

Pleiades
appearance
(late June)

EI Niño year

high clouds
(10 km)

sparse rainfall
(October-March)

Figure 5.6 How farmers in the Andes use the stars to predict drought years. In normal years, high level
winds over the Andes blow east to west, bringing in moist air from the northern Amazon basin into the
Andes. In an El Nino year, high level winds blow west to east, preventing humid air from the Amazon
reaching into the Andes. In El Niño years, the Pleiades appear dim in midwinter because of thin, high
cloud over the tropics, enabling farmers to predict a dry year.