<p>Climate and agriculture affect each other in a reciprocal fashion. In agrarian countries like
Bangladesh, agricultural activities are mostly defined by seasonal climatic cycles. Failure of
agricultural adaptations to keep pace with climate change and variabilities have the potential
to impact food production, and eventually, food security. Exploration of agricultural impacts
of climate change in coastal areas of Bangladesh, one of the globally top ranked climate
vulnerable countries, was the guiding focus of this study. Literature review, farmer interviews,
agricultural office visits, government organizational databases, global climate model
ensembles, and tide gauge records were used to collect primary and secondary information.
Field data was collected from randomly selected 381 farmers from 10 selected subdistricts
across the coastal areas of Bangladesh during September–October 2018. A wide range of
statistical and econometric approaches were applied to reveal the complex relationship between
farmers’ perception, climatic data, farming variables and socioeconomic characteristics.</p><p>Farming decisions in relation to adaptations under climate change largely depend on perception
of climate change, and their feasibility is linked to the accuracy of their perceptions. Last 30-
year (1988–2017) average temperature shows 0.45 °C spatial differences among the visited
subdistricts. Yearly precipitation gradient could be >100 cm from the drier western to the wetter
eastern coasts. While monthly averages of coastal temperature had increased except in early
winter (October–December), while pre-monsoon and November rainfall had decreased with an
increase in monsoon precipitation. Onset of monsoon rainfall was found to be delayed in the
coastal areas. The farmers, in general, mentioned a warmer temperature and less rainfall in the
recent decade (2009–2018) compared with the past decade (1999–2008). Their perceptions
were mostly consistent with meteorological records though the observed decrease in winter
temperature and the change in rainfall in some locations did not match with their perceptions.
About one-third (30%) of the farmers accurately identified the changes in annual rainfall and
temperature (annual, summer and winter average). Cluster analysis flagged 58.8% of the
farmers as weak perception group. However, 41.2% of them were found in the moderate
perception group characterized by younger age, better education, smaller family size, richer
economic status, larger farm size, more affiliation with non-farm jobs, users of more
communication media, closer to the marketplaces, and more distant from the sea. Thus, they
were comparatively economically better-off than the weak perception group.</p><p>Farm productivity had a mean value of 1.98 in terms of revenue-cost ratio as reported by the
farmers during the interviews based on the previous cropping year. Over one in ten (11%) of
the farmers opined that their farm productivity had currently declined compared with the past.
Majority (64%) of the farmers thought that this decline was due to climate change and its
consequences, such as changes in temperature, precipitation, floods, droughts, and salinity.
Outputs of the logistic regression shows that the farmers with greater level of education, more
awareness of climate change, less communication with extension agents, stronger belief in
decreased cyclone and salinity, and weaker belief in decreased flood had perceived that climate
change was responsible for the decrease in their farm productivity. The farmers identified dry
season soil salinity, coastal inundations and floods were the climate change induced issues that
had adversely affected crop productivity.</p><p>To keep the farm productivity at desired levels, the farmers had adopted on average 10–11 farm
management practices out of the 22 selected adaptation options. Two-thirds (67%) of the
farmers mentioned that they had changed the farm management practices because of climate
change. The farmers performed the crop-related adaptations more than the livestock, fisheries
or general agricultural adaptations. According to the discriminant function analysis, the farmers
with stronger belief in climatic impacts on their farm management were younger in age, had
higher level of education, more involvement with non-farm jobs, greater affiliation with farmrelated organizations, more awareness of climate change, and greater accuracy of perception
of changes in climatic variables.</p><p>Similar to the changes in farm management practices, 64% of the farmers had changed their
farming systems due to climate change. In recent years (2009–2018) compared with the
previous years (1999–2008), three farm enterprises, namely rice, vegetables, and livestock, had
decreased, while three others, namely fisheries, forestry, and fruit farming, had increased. The
random forest algorithm has identified that larger family size had negative effect, while age,
education, and cultivated land had positive effects on the probability of believing that climate
change had impacted their changes in farming systems. The farmers who more accurately
perceived the changes in temperature, rainfall and cyclones and had better awareness of climate
change agreed in greater magnitude that their farming systems had changed due to the influence
of climate change.</p><p>Farmer opinions highlight the adverse effects of salinity intrusion, temperature, rainfall, floods,
and cyclones on their agricultural activities. Therefore, we modelled coastal inundation in Bangladesh by semi-empirical approach using downscaled and bias corrected 28 global climate
models. Singular spectrum analysis was undertaken to separate the trends from the time series
of temperature and tide gauge data for the period of 1980–2100. The model shows that sea
level is likely to rise at a rate of 6.69–9.88 mm/year which would result in up to 1.15 m sealevel rise by 2100 inundating at least 2098 km2
of the coast which has =1 m elevation. Though this inundated part is located mostly outside the river and coastal embankments, saline water
intrusion and groundwater contamination are likely to increase in a changing climate.</p><p>During historical disasters (ten selected flood and cyclone events) between 1970 and 2017,
coastal areas had lost 12.10% of crop production which was 2.54% higher than the non-coast.
Temperature and precipitation affect crop yield and production in two ways—through their
trends and variabilities. The mixed effects model reveals that these variables explain 12% of
the variance in crop production. Climate trends and variabilities are likely to reduce crop yield,
respectively, by 2.75 and 2.91%, which equates to 2.4 million metric tons of crop loss per year. </p><p>Farmers’ concerns and data-driven analysis establish the fact that coastal agriculture is
increasingly under climatic threats and in more precarious conditions than the inland
agriculture. Climatic impacts on coastal farming cannot be stopped but there is scope to keep
it viable under climate change. This study suggests that economically worse-off farmers should
be attended and communicated with updated climate change information by extension agents
to enhance their adaptation actions. Failure of around one-third of the farmers to detect the
climatic impacts on farm productivity, farm management and farming systems implies that they
need to be updated with farm-related climatic knowledge to motivate them to adopt agricultural
adaptations. Enhancing involvement of the farmers with agricultural extension associations is
likely to improve their climate change awareness and perception of changes in climatic
variables. Limited capacity of the farmers to keep the coastal farming sustainable warrants for
external support. For example, maintenance of river and coastal embankments should continue
to be the first priority of coastal agricultural planning. This research provides information and
insights of climatic impacts on coastal farms from both farmer and empirical perspectives,
which are necessary for agricultural policy formulation. Information generated through this
study is expected to help policymakers and extension agents to formulate and implement
coastal agricultural development programmes in Bangladesh. Researchers and academicians
could benefit from the approaches and methods used here to apply in various socioeconomic
and ecological constellations.</p>