As average global temperatures begin to rise due to human activity, scientists say the drastic effects of climate change continue to take effect all over the world.

One of the most severely affected sectors is the field of agriculture. In the past decades, extreme weather conditions caused by climate change have disrupted global food production.

"The food system is already stressed in many ways," said Professor Navin Ramankutty of the University of British Columbia, an expert on global food security and sustainability.

With the adverse effects of climate change, Ramankutty said the phenomenon is becoming an additional stressor to global food production.

The Effects Of Climate Change On Global Cereal Harvests

Ramankutty is the senior author of a new study featured in the journal Nature, which examined the link between weather-related disasters and food production.

Along with a team of researchers from UBC and McGill University, Ramankutty found that extreme heat waves and droughts have reduced global cereal harvests such as maize, wheat and rice by 10 percent in a span of 50 years.

The impact persists even in areas where farming is technologically advanced, researchers said.

In the study, the team looked into the "fertilizing effect" in which high levels of carbon dioxide in the atmosphere could have visible effects on crops, an effect that could outweigh the damage caused by droughts and heat waves.

Ramankutty and his colleagues analyzed records that contained national food production of 16 different cereal crops in 177 countries, and compared the effects of 2,800 weather disasters that occurred from 1964 to 2007.

After evaluating their data, the team created a detailed snapshot of how extreme weather conditions affected global cereal harvests.

In North America, Europe and Australia, droughts and heat waves had both caused an average reduction in cereal harvests by about 20 percent. They also found that the average reduction in cereal harvests caused by droughts and heat waves increased from 6.7 percent in the mid-1980s to 13.7 during more recent years.

Nations With Advanced Agricultural Technologies

Pedram Rowhani, a co-author of the study, said they found that the production cut was far worse in richer countries, and they predict that these extreme weather conditions will continue in the future.

The team also found that nations with advanced agricultural technologies and farming methods were more susceptible to heat waves and droughts compared to nations that are less advanced.

Corey Lesk of McGill University, the first author of the study, said crops and farming methods across North America are very uniform across huge areas. If a drought hits and damages the crops, it will result in a massive domino effect and all the crops will suffer, he said.

In the developing world, the farming systems are made up of patchworks of small fields with diverse crops.

"If a drought hits, some of those crops may be damaged, but others may survive," said Lesk.

With that, Rowhani said that if governments do not adapt agricultural systems to become more resilient to these shocks, more losses will occur in the future.

Still, Lesk said farmers in developed nations rarely rely on harvests for direct food, and they usually have access to crop insurance in case of extreme weather. Their optimal strategy should be to maximize yields instead of minimizing the risks of weather-related crop damage, he said.

On the bright side, the study also found that extreme weather conditions have no significant and lasting effects on food production in the years following weather-related disasters.

"Our findings may help guide agricultural priorities and adaptation efforts, to better protect the most vulnerable farming systems and the populations that depend on them," said Ramankutty.

Scientist Says Agriculture Benefits From Carbon Emissions

Meanwhile, a former delegate of the Intergovernmental Panel on Climate Change said climate change provides several benefits for agriculture.

In a report, Indur Goklany, a science and technology policy analyst at the U.S. Department of the Interior, said carbon has the ability to fertilize plants, and that it has led to an increase in fossil fuel emissions.

This plant fertilization greatly contributes to the health of crops and is accountable for increasing crop harvests by 10 to 15 percent, he said.

Aside from that, wild places on the planet have turned greener because of the increase in carbon dioxide levels in the atmosphere. Plants had also become stronger during droughts because carbon dioxide has boosted plants' water-quality.

Contrary to previous notions that only look at the negative effects of global warming, the benefits of carbon dioxide are only being realized now.

"My report should begin to restore a little balance," added Goklany.

Photo: Elias Gayles | Flickr