Climate change is threatening global wheat production, according to a new study published in the journal Nature Climate Change. The study, which was conducted by researchers at the University of Chicago, found that climate change is expected to reduce wheat yields by an average of 4% per degree Celsius of warming.

The study's lead author, Michael Mann, said that the findings are "a major wake-up call" for the global food system. "Wheat is a staple food for billions of people around the world, so any reduction in yields is a major concern," he said.

The study found that the impact of climate change on wheat production will vary depending on location. In some regions, such as the Middle East and North Africa, yields are expected to decline by as much as 10% per degree Celsius of warming. In other regions, such as the United States and Canada, yields are expected to decline by only 2% per degree Celsius of warming.

The study also found that the impact of climate change on wheat production will be felt sooner in some regions than others. In the Middle East and North Africa, for example, the impact of climate change is expected to be felt as early as 2030. In the United States and Canada, the impact of climate change is not expected to be felt until 2050.  The findings suggest that climate change is a major threat to global food security. The researchers call for urgent action to reduce greenhouse gas emissions and to develop more climate-resilient wheat varieties.

In addition to the impact of climate change, the global wheat supply is also under threat from the war in Ukraine. Ukraine is a major exporter of wheat, and the war has disrupted exports. As a result, wheat prices have risen sharply in recent months.

The combination of climate change and the war in Ukraine is creating a major challenge for the global food system. The researchers call for urgent action to address these challenges and to ensure that everyone has access to affordable and nutritious food.