Agricultural activity is highly dependent on weather, climate, and water availability. Weather and climate-related disasters adversely affect agricultural production. Global warming is predicted to have a generally negative effect on plant growth due to the damaging impact of high temperatures on the development of the plant.
The increasing threat of extreme climatic conditions, including very high temperatures, might lead to catastrophic loss of crop productivity and result in widespread famine. Here, we try to assess the impact of global climate change on agricultural crop production.
What is a Heat Wave
The US National Weather Service and National Oceanic and Atmospheric Administration (NOAA) has defined a heat wave as a period of uncomfortably and abnormally hot. The period is unusually humid weather which typically lasts two or more days. Geneva-based World Meteorological Organization (WMO) has several definitions of a heat wave.
Scorching weather is where the maximum temperature, the minimum temperature, and the daily average temperature over a region persists for at least two consecutive days. This occurs during the hot period of the year based on local climatological conditions, with thermal conditions recorded above-given thresholds.
You must know the basics governing the phenomenon of the heatwave. The readings of air temperature or the dry-bulb temperature given by the meteorological agency are recorded in a “shade,” typically two meters above the ground. The temperature under direct sunlight is much higher, by about five to eight degrees Celsius, depending on air movements.
Another essential concept is apparent temperature or the temperature that the body feels. The process of evaporation requires heat. As the temperature of the body increases, perspiration takes place. Evaporation of bodily moisture takes heat from the body to cool itself. The higher the temperature, the more it sweats in an attempt to cool itself.
Heat Wave Decoded
The evaporation rate is directly related to the amount of moisture in the atmosphere. As the humidity increases, the rate of evaporation of sweat decreases. The body’s heat is not removed efficiently at the decreased evaporation rate. Consequently, the body ‘feels’ like the temperature is higher than it is. The apparent temperature considers the amount of moisture in the atmosphere to simulate how the body ‘feels’ and how hot it is.
As per the heat index chart developed by the US National Weather Service and National Oceanic and Atmospheric Administration, if the air temperature is 38 degrees Celsius and the relative humidity is 40 percent, the apparent temperature, or the temperature that the body feels, is 43 degrees Celsius. In the future, the frequency of heat waves will increase and be more severe. Human beings are the culprit. Heavy fossil fuel burning adds more carbon dioxide to the atmosphere, which traps heat.
Some environmental interventions can minimize the severity of heat waves. Installing white roofs can help in reducing heat build-up in cities. Current research shows that making surfaces more light-reflecting can significantly impact high lowering temperatures. For instance, Los Angeles has coated several streets in a light grey paint to reduce road-top temperatures by as much as six degrees Celsius. Trees and green areas also beat the heat waves.
The phenomenon of urban heat islands is well known (countryside areas are cooler than city areas). In cities, the building materials and roads absorb solar radiation. The darker the surface, the more the heating. Fresh asphalt reflects only 4pc of sunlight compared to as much as 25pc for trees and grass. Rooftop gardens are now gaining momentum in many cities.
Heat Waves due to Climate Changes
There is a differential effect of heat waves in terms of geographic location. The crops are likely to show the most extreme reductions in yield due to expected extreme temperature fluctuations and global warming in general.
High-temperature stress has a wide range of effects on plants regarding biochemistry, physiology, and gene regulation pathways. However, there are strategies for crop improvement for heat stress tolerance.
Heat Waves as a Risk for Global Food Security
Abiotic stresses are generally interrelated, either individually or in combination. They cause physiological, morphological, biochemical, and molecular changes that adversely affect plant growth, productivity, and yield.
Heat, drought, cold, and salinity are the significant abiotic stresses that induce severe cellular damage in plant species, including crop plants. Temperature fluctuations occur naturally during reproduction and plant growth. However, extreme variation in term during hot summers can damage these interactions required for proper development.
Consequently, it impairs fruit set and plant development. The increasing threat of heat waves as a part of climate change is already substantially impacting agricultural production worldwide. Heat waves cause significant yield losses with great risks for future global food security.
Extreme climates with very high temperatures are predicted to negatively affect plant growth and development, leading to catastrophic loss of crop productivity and widespread famine. Future agricultural production and global food security will encounter additional challenges from human population growth.
Monetary Impact of Heat Wave
The impact of a heatwave on farming can be direct. It means that it can be physical damage to animals, crops, and trees caused by extreme hydro-meteorological events. In indirect impact, you can lose its production capacities, lose potential production due to the disturbed flow of goods and services, and increase production costs. You can measure this impact in monetary terms or terms of anxiety, inconvenience, disruption, or fear of future natural disasters and stress-induced health hazards.
Heatwave impacts crop growth at different levels like soil moisture, respiration, plant water uptake, root and shoot growth, and the final yield. Heatwave competes for soil moisture by hastened evaporation. It leaves almost no moisture for uptake by plants. Heatwave causes overall environmental degradation, a significant factor contributing to the vulnerability of agriculture, forestry, and rangelands to heatwaves.
Quite often, poor people work on agricultural lands. When exposed to extreme heat, this undernutrition and weak, poor people are knocked down health-wise. This is another factor that adversely affects the agrarian problem.
Impact of Heat Wave on Agriculture
There are two types of natural disasters. Firstly, hydro-meteorological disasters include:
- Landslides, droughts, avalanches, famines, heatwaves, floods, hurricanes, extreme temperatures, and windstorms.
- Waves, surges, insect infestation, and forest fires.
- Geophysical disasters (earthquakes and volcanic eruptions).
Agricultural activity is dependent on climate, weather, and water availability. Weather- and climate-related disasters adversely affect agricultural production.
The impact of a heatwave on agriculture can be direct (physical damage to crops, animals, and trees caused by the extreme hydro-meteorological events) or indirect (loss of potential production owing to disturbed flow of goods and services, lost production capacities, and increased costs of production).
This impact can be tangible (one that you can easily measure in monetary terms) or intangible (anxiety or fear of future natural disasters, inconvenience, disruption, and stress-induced ill health).
Heatwave impacts crop growth and development at different levels like soil moisture uptake, root and shoot growth, photosynthesis, respiration, plant water uptake, and final yield. It competes for soil moisture by hastened evaporation, leaving almost no moisture for uptake by plants. Heatwaves lead to overall environmental degradation, a significant factor contributing to the vulnerability of agriculture, forestry, and rangelands to heatwaves.
Quite often, poor people work as manual laborers on agricultural lands. When exposed to extreme heat, they fall sick due to malnutrition. This is another factor that adversely affects the agrarian problem.
Agricultural activity is affected by water availability. Due to extreme heat, there is a great demand for water in municipal sectors, leaving restricted water for agriculture.
Heat Wave and Heat Stress Tolerance
Heat stress tolerance is a polygenic character measured using complex traits such as yield under stress, which implicate many processes and mechanisms. Therefore, the introgression of a gene by conventional or modern breeding is usually insufficient to develop heat-tolerant lines unless there is a significant effect on a particularly critical process.
In addition, achieving the highest genetic gain via classical methods requires a just choice for the appropriate breeding strategy. Multiplying significant regulatory genes through biotechnology is more efficient than conventional breeding through serial hybridizations. Linking several beneficial genes into a commercial variety via the transgenic approach is also likely to provide a pivotal route to crop improvement.
It is a well-accepted fact that one can only tackle the complexity of the heat wave with a holistic approach. This holistic approach integrates the examination of crop heat tolerance properties by the classical and modern molecular genetic tools with agronomic practices. This leads to superior crop genotypes.
The polygenic basis of heat tolerance and the issues of detecting minor QTLs with molecular markers strongly limit using MAS to identify heat tolerance-related properties by classical genetics. High throughput sequencing and the predicted decline in genotyping costs will assist in obtaining a denser genome-wide marker coverage for all crop species.