Bjorn Lomborg, who is known for not being a big fan of controls on carbon emissions, is concerned about the food supply.

Affordable, nutritious food is one of people’s top priorities everywhere, and one in nine people still do not get enough food to be healthy. With today’s population of 7.3 billion expected to reach 8.5 billion by 2030 and 9.7 billion in 2050, food demand will increase accordingly. Along with more mouths to feed, stresses on food supplies will include conflicts, economic volatility, extreme weather events, and climate change…

Investment in research and development is vital. According to research conducted for Copenhagen Consensus, which I direct, investing an extra $88 billion in agricultural R&D over the next 15 years would increase yields by an additional 0.4 percentage points each year, which could save 79 million people from hunger and prevent five million cases of child malnourishment. Achieving these targets would be worth nearly $3 trillion in social good, implying an enormous return of $34 for every dollar spent.

Scientific breakthroughs also play a key role in fighting specific nutritional challenges such as vitamin A deficiency, the leading cause of preventable childhood blindness. Robert Mwanga was awarded this year’s World Food Prize for inspiring work that resulted in the large-scale replacement of white sweet potato (with scant Vitamin A content) by a vitamin A-rich alternative in the diets of Uganda’s rural poor.

More R&D seems like a great idea. But I wonder if Bjorn is making the mistake of just projecting past trends linearly into the future. In the past, crops were often limited by the availability of water and nutrients. Once you solve those problems, you can work on breeding plants that make maximum use of the sun’s energy to produce plant parts that humans and animals can eat. Once you solve that problem, the next limit would seem to be sunlight itself, which you can’t increase.