From fields to tables: How rising temperatures are altering the food we eat

Climate change can minimise yields in some places, block the transportation of food, and drive down the nutritional value of staple grains.
Published June 19, 2024

It may not be obvious in grocery stores and wholesale food markets, but behind the stacks of bread and bags of rice we purchase are hundreds of thousands of farmers and agriculturists who are scrambling to keep up with the impact of climate change.

From the lush green fields in Punjab to the magnificent mountains of Khyber Pakhtunkhwa, put a finger anywhere on Pakistan’s map and you will find disruption in the fields. Warmer temperatures are obstructing the crop cycle in some areas and sending a host of new pests to others. Some fields are bone dry due to drought while others are drowned in flood water.

The decade-old patterns of summer, rain and frost — never entirely predictable but once reliable — seem to have broken down. Almost everyone agrees that something unusual is happening.

“Sudden changes in the weather, occurring for several years now, include heatwaves, extended winters and seasonal shifts,” said Asad Imran, an agricultural expert at WWF-Pakistan.

“These events have a huge impact on crop production, from where the food chain begins.”

Hotter days, massive floods and prolonged droughts can minimise yields in some places, block the transportation of food, and drive down the nutritional value of staple grains. Unexpected rains, on the other hand, make it difficult for farmers to earn a living.

Rising temperatures

On a sunny morning in the March of 2023, Sami Khan, a farmer in KP’s Charsadda, woke up to a buzzing house. After months-long wait, the ‘katai ka din’ or harvest day had finally arrived. The excitement, however, was everywhere but on Sami’s face. He was hiding a secret.

The agriculturist, who grows wheat, knew that the rest of the year would be difficult to get by. His fields, known for tall and yellow crops, were now lifeless. Like many in his neighbourhood, Sami’s crops had borne the brunt of a scorching heatwave that had swept the country.

Not just Pakistan, last year was the hottest globally since records began in 1850, according to the 2023 Glo­bal Climate Highlights rep­ort. It said that 2023 marked the first time on record that every day within a year exceeded 1°C above the 1850-1900 pre-industrial level.

This year too, an intense heatwave has gripped south and southeast Asia. In the last few weeks, Pakistanis saw temperatures hitting 50°C. Karachi recorded above 40°C for the first time this summer. And this is just the beginning. The climate change ministry has warned of more heatwaves this month.

Heatwaves occur when there is a development of high pressure in the upper atmosphere, Chief Meteorologist Sardar Sarfraz told When this happens, the warmer air holds more moisture and can make precipitation worse.

These extreme precipitation events, which are becoming increasingly common, can directly damage crops, ultimately resulting in decreased yields, he said.

This is exactly what happened with Sami, whose yields dramatically decreased due to last year’s heatwave. To prevent this, he harvested his crops earlier this year, but that didn’t exactly solve his problem.

“The temperature during March-April was better but unexpected rains during these months disturbed the crop cycle,” he said. The leaf rust disease, fungal pathogens that can significantly lower crop yields, attacked his crops.

Rust can thrive in environments that are cool at night, warm during the day (55–80°F), and have a lot of dew or a wet wheat canopy. The wheat canopy must have free moisture for six to eight hours for all rusts to infect it. The disease has been responsible for severe damage to yields in the past.

However, Sami, who has been struggling to make ends meet, couldn’t afford to spray his fields chemically to eradicate the disease due to his poor financial position.

Disruptions in growth cycle

According to the Food and Agriculture Organisation (FAO) of the United Nations, the crops most vulnerable to climate change include cotton, rice, maize, sugarcane, wheat and vegetables — all major food crops in Pakistan.

Every crop requires a certain temperature in each stage of its growth cycle. With wheat, for example, when the mercury rises, the grain matures early without gaining the required weight. The same is the case with other crops as well.

 The chart depicts the impacts of heat stress on a wheat crop. — courtesy Cereal Crop Research Institute
The chart depicts the impacts of heat stress on a wheat crop. — courtesy Cereal Crop Research Institute

Yasir Hussain Junejo, an abadgar from Sindh’s Larkana, recalled that the taste and aroma of the rice he grew five years back were different from today’s produce. “Back then, we would get water in the fields by May, but now, the water comes in late around June or July. This affects the productivity and yield of our crops,” he said.

To prevent economic losses that may occur from the impact of climate change, he has moved to hybrid seeds for his rice fields. And even though his yield and profits have increased, Junejo cannot help but miss the taste and smell of the pre-hybrid rice.

What Junejo witnessed is one of the many impacts climate change has on crops.

Erratic weather patterns disrupt crucial growth stages of a crop such as flowering, boll formation and fruit setting, diminishing grain size, yield and produce quality, said Dr Aamer Irshad, head of programmes at FAO Pakistan.

“During heatwaves, increased temperatures elevate the transpiration rate, causing plants to lose water rapidly. This adversely affects photosynthesis, leading to reduced growth and lower crop yields,” he elaborated.

Excessive heat, he continued, also reduces the size of fruits and grains, as plants struggle to allocate resources efficiently under stress.

On the other hand, excessive rainfall and floods cause lodging in standing crops such as wheat and maize, where plants are physically knocked over, making harvesting difficult and shrinking the overall yield. “Standing water in fields and orchards leads to water logging which suffocates plant roots and fosters conditions for root rot and other fungal diseases.

“This diminishes the quality and quantity of the produce and can lead to long-term soil degradation and agricultural productivity,” Dr Irshad added.

Another impact of the volatile change in temperatures is pest pressure. Junejo told that dry and wet weather has brought new and more resistant pests to his fields such as white flies. “This was not the case 10 years ago.”

Nutrient loss

Plants use carbon dioxide to make their food. But while more CO2 in the atmosphere may enhance crop yields in some areas — given conditions such as soil moisture and water availability are favourable — these benefits can be offset by extreme weather, drought or heatwaves.

Recent research has documented declining nutrient value in staple crops due to rising atmospheric carbon dioxide levels. A 2018 study, conducted by the Harvard TH Chan School of Public Health, tested rice and found that higher CO2 levels reduced its protein, iron and zinc content.

Studies have also shown that barley, wheat and potatoes have 6pc to 15pc lower concentrations of protein when grown at those levels of CO2.

Over the years, the climate crisis has only accelerated concerns about crops’ nutritional value.

Rabia Gohar, a researcher at the Women’s University in Swabi, conducted a study on the impacts of heat shock on the productivity and quality of wheat at different growth stages. Speaking to, she said that the temperature across the globe is rising by 0.1°C every decade, which affects both the growth cycle of the crop and its quality.

“Due to the rise in the mercury, crops move across the stages of their growth cycle rapidly. This, in turn, shortens the cycle of photosynthesis where food is transported, reducing the number of grains and their weight and thus affecting the per/kg productivity of a unit area,” Rabia explained.

Elaborating on the impact on the quality, she stated that the required protein content in a wheat crop is up to 13pc, but as the temperature rises, the subunits of protein are disturbed.

In easier terms, when the protein content in a wheat crop diminishes, it negatively impacts flour consistency — used for the bread we consume — oftentimes making it less nutritious.

Dr Irshad of the FAO highlights this nutrient loss as particularly concerning, given that Pakistan relies on wheat for about one-third of its total calorie intake. This poses serious harm to the 10.5 million people in the country who are already facing acute food insecurity.

Breaking backbones

Sheema, a houseworker hailing from Bahawalpur, has lost two of her newborn children in as many years. “It all started with the 2022 floods that snatched everything from us; our house, our fields and even our children,” she rued.

The waters that Sheema once considered holy now had blood on them. She recalled that the currents from the Sutlej and Chenab rivers swallowed her house, belongings and crops. The 37-year-old lived in a makeshift shelter along with her husband and children for months and survived on one meal a day.

Eventually, Sheema and her family moved to Karachi to make ends meet. “Even today, I cannot help but blame myself for not being able to feed my children, for watching them die in my hands, for being so helpless,” she said with remorse.

According to the Pakistan Nutrition Humanitarian Overview 2022, the country has a global acute malnutrition rate of 17.7pc, exceeding the emergency threshold. Young children and pregnant or breastfeeding women are most prone to malnutrition — when one’s diet does not contain the right amount of nutrients — in most of South Asia.

The most common deficiencies include those of iron, protein, vitamin A, vitamin D, zinc and folic acid. Iron deficiency affects children the most, especially in the first two years of life.

In Pakistan, malnutrition exists because of the inability to meet standard nutritional targets due to the scarcity of food available across the country, and climate-related disasters exacerbate this problem.

“It is important to accept the ground reality that 58.7 million people in Pakistan dwell below the poverty line,” said Dr Shaikh Tanveer, the CEO of non-profit organisation Hands Pakistan. “This means that they earn less than $2 a day, and this factor, in essence, hinders their access to food and water.”

He explained that most people in the country were dependent on agriculture for their livelihoods but climate change was endangering not just their lives but also their livelihoods.

“After the 2022 floods, we saw many people shift from vegetable farming to cash crops, primarily to meet the industrial demand and earn more profits. But this has deprived them of protein intake,” Dr Tanveer said. “When a farmer grows vegetables on his land, it is likely that a portion of that produce would be inculcated in his family’s food.

“However, the focus now has moved to profits, and the cash they get is used to meet other needs.”

Another reason for this shift, as highlighted by Dr Tanveer, was the lack of better technology and preservation techniques. Warmer temperatures reduce the shelf life of foods and exacerbate losses and wastage of perishable commodities — tomatoes are one such example. This also leads to more cases of food poisoning, diarrhoeal diseases and associated fatalities.

On the other hand, erratic weather patterns such as heatwaves, floods and droughts are putting the well-being of livestock at risk. “Livestock is the backbone of food security in rural and urban areas. People rely on their cattle for milk, meat and eggs. But when these animals fall sick, they lose a big chunk of nutrition from their diet,” Tanveer explained.

“All of these factors put people, particularly children, at the risk of malnutrition.”

The way out

Climate change is a global menace. Unfortunately, Pakistan is among those countries that are bearing the brunt of its impact, despite hardly contributing to carbon emissions. There are, however, some measures that can be taken to minimise the impact of extreme weather events.

For one, plant trees. “The minimum requirement of forests is between 20pc to 25pc. But in Pakistan, our total forest cover is hardly 4pc to 5pc. In some cities, all you see is cement and stones,” Dr Muhammad Akmal, a university professor from Peshawar, pointed out.

Forests are very important for our ecology. They help slow the rate of climate change by removing carbon dioxide from the atmosphere and storing it. Simultaneously, they also act as hurdles in the way of fast-flowing waters and absorb it in their roots, preventing floods.

The second is to bring technology into agriculture. WWF’s Imran believes that scientists and agriculturists along with the government should work on introducing crop varieties that are resistant to droughts and heatwaves.

“We should build the capacity of farmers on how they can improve their irrigation techniques. If our reserves are shrinking and the water table is going down, we ought to move towards better irrigation techniques and efficient uses of water such as the concept of ‘more crop per drop’,” he said.

The good thing is that research and development on this has already commenced in some parts of Pakistan. In KP, the Agriculture and Seed Department is working on countering the rising population of pests through mechanical ways.

“We are developing six to seven varieties of wheat that are resistant to the rust disease and droughts,” Murad Ali Khan, the department’s director told, adding that research was also under way on speedy breeding.

“We want to save the nature and ecology which has been disturbed,” he added.

Apart from this, the government should focus on enhancing investment in resilient agricultural infrastructure, such as improved irrigation systems and climate-smart storage facilities. Expanding access to weather forecasting services and climate information will also empower farmers to make informed decisions.

“Accelerating investment in sustainable agrifood systems is crucial to address the long-term impacts of climate change on agriculture while ensuring food security, environmental sustainability and resilience for vulnerable communities,” Dr Irshad emphasised.

That said, it is very difficult to predict all the challenges to human health resulting from climate change. But the guess is that there will be many more surprises as we tamper with the environmental conditions on the planet.