ASSESSING CLIMATE CHANGE IMPACTS ON CROP YIELD: A CASE OF TULSIPUR, DANG
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IOE Pulchowk Campus
Abstract
Climate change has created a serious concern for food security, extreme hydrological
conditions, environment, ecology, health, and even entire human civilization. A developing
country like Nepal is even more vulnerable to climate change impacts due to our weak
infrastructure. Climate change is projected to have devastating impacts on crop yield. This study
aims to assess the impacts of climate change on crop water requirements and crop yield in
Tulsipur, Dang. It also aims to aid climate research in Nepal by the development of climate
information system and projection of future climate in the region using Global Climate Models
(GCMs).
Temperature and precipitation data from stations all over Nepal were acquired in a gridded
format by Kriging with External Drift (KED) interpolation. For the projection of future data,
five CMIP6 based GCM models were used, and bias corrected to form an ensemble. Future
climatic data was obtained under two Shared Socioeconomic Pathways Scenarios (SSPs):
SSP245 and SSP585. The multi-model ensemble (MME) approach was used to minimize
uncertainty associated with model predictions, and GCMs proposed were selected. The quantile
mapping (QM) method was used for correcting the biases in the GCMs, and the RQUANT
method was chosen for rainfall data, while the ‘PTF: linear method’ was used for temperature
data. A crop simulation model (AquaCrop) was calibrated and validated using cultivar-specific
and less conservative parameters obtained from farmer surveys, input climatic daily data, and
soil properties. The calibrated model was then used to predict future crop yield scenarios for
rice and wheat under different irrigation strategies and fertility stress levels.
The data acquired from the climate information system has shown a good fit (R2 = 0.913) with
nearby station data in Tulsipur and hence shows promising utility in replacing station data as
starting point for future climate studies. Additionally, climate projection studies show that Dang
is expected to experience progressive warming and increased rainfall in future (2021-2100).
Wet seasons are projected to continue receiving more rainfall and rising temperatures which is
likely to induce extreme events such as flooding. Conversely, dry winter seasons are likely to
be drier and hotter in the future, which is detrimental to winter crops. The results of our study
show a positive response of crop yield to climate change. Rice yield is projected to increase by
as much as 112% by 2100 under extreme carbon emission scenarios. Similarly, wheat yield is
projected to increase as much as 165% under similar ideal conditions. On the other hand, crop
water requirements are projected to increase for both rice and wheat. The study also provides
useful information for climate change adaptation and mitigation strategies in Nepal and
recommends further research to improve the accuracy and reliability of crop simulation.
Description
Climate change refers to the long-term variation in observable climate statistics such as
precipitation, temperature, CO2 concentrations, etc., as shown in Figure 1.1 and Figure 1.2. The
scientific community is still divided on whether a distinction should be made between climate
change attributable to human drivers and natural causes