Climate Exchange

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Climate variability and change:

perceptions, experiences and realities

K.P.C. Rao and A. Oyoo, International Crops Research Institute for the Semi-Arid Tropics;

and W.G. Ndegwa, Kenya Meteorological Department

arming in the semi-arid tropics, where climatic condi-

tions are marginal and highly variable, is a risky

enterprise. The main source of this risk is the vari-

ability in rainfall that occurs at many different timescales,

ranging from seasons to years to decades and beyond.

Farmers operating under these conditions make decisions

based on their perceptions and experiences gained from

several years of keen observation and practice in the field.

However, perceptions are influenced by many factors, both

real and subjective. For agriculture, factors like farm produc-

tivity, crop, market and local preferences, capacity to invest,

willingness to take risks and soil quality play an impor-

tant role. While the role and significance of some of these

factors on productivity and profitability can be perceived

more easily due to their relative predictability, extreme vari-

ability in climate and the random nature of that variability

makes it difficult for farmers to accurately perceive trends

in climate. In the absence of detailed measurements, percep-

tions can be biased and unreliable. Climate information can

play an important role in helping farmers better understand

this variability and its associated risks, and enhancing their

decision-making for effective risk management.

Inter- and intra-seasonal variability in rainfall have been the key

climatic elements that determine the productive efficiency of

rainfed agriculture. While the amount and distribution of rainfall

have a direct impact on the productivity of agriculture, its vari-

ability contributes to the uncertainty in the expected benefits from

investments made, and to the rates of return that farmers receive

from these investments. Farmers, operating under these highly

variable climatic conditions must have a good understanding of

the risks and opportunities such conditions create for them to

make best use of available resources. With a good understanding

of the historical and current climatic conditions including climate

forecasts, it is possible to tailor the management of agricultural

systems in a way that capitalizes on opportunities and minimizes

risks. While farmers have developed a good understanding about

the climate variability at their locations through keen observation,

experimentation and practice, there are problems in their percep-

tions that arise from the complex nature of agriculture and an

inherent problem in separating climate impacts from other drivers

that also affect agricultural production. Since farmers take deci-

sions based on their perceptions it is extremely important that,

while assisting farmers to adapt to climate variability and change,

the perceptions, experiences and actuality of changes in climate

are placed in the context of the impacts of various

drivers on the performance of agriculture. Our work

with farmers in Eastern Africa – mainly in Kenya –

on managing risks associated with variable climatic

conditions, has identified three common perceptions

that can be effectively addressed through provision

of more accurate climate information to extension

officers and farmers. These studies were conducted in

the Machakos, Makueni, Kitui, Mwingi and Mutomo

districts in semi-arid Eastern Kenya, where the average

annual rain fall varies from 500 mm in the lowlands to

over 1,050 mm in the hilltops. The annual rainfall is

distributed almost equally over two rainy seasons that

fall during the periods of March-May (also referred to

as ‘long rains’) and October-December (‘short rains’).

The studies involved structured surveys, group discus-

sions and interpreting and presenting seasonal climate

forecast information in the form of agro-advisories.

Perception 1: the climate has already changed

Farmers across the study locations strongly believe

that the climate in their area has changed for the

worse. This response is consistent with results

reported from surveys conducted elsewhere in Africa.

In all these studies, most farmers identified declin-

ing rainfall, increased variability in the distribution

of rainfall within and across the seasons, and shifts or

even disappearance of seasons as the major changes

observed. However, the changes that farmers have

identified are not obvious from the available rain-

fall records. Detailed analyses of long-term daily and

monthly records from five sites in Kenya where these

interviews were conducted indicate no major detect-

able change in the rainfall during the last four or

five decades. For example, at Machakos, Kenya, the

longest dry period that the region has ever experienced

was between 1966 and 1975, during which the annual

and seasonal rainfall was below the long-term average

in at least seven out of 10 years. This strong belief

among farmers that the climate has changed for the

worse despite lack of evidence in the climatic data to

support this, is prompted by the declining yields in

the area which are more likely due to diminishing soil

fertility, low levels of use of inputs, and the expansion

of agriculture into marginal lands as the population

ommunities