Stephen Patrick Long is a British-born American environmental plant physiologist and member of the National Academy of Sciences studying how to improve photosynthesis to increase the yield of food and biofuel crops. He is the Stanley O. Ikenberry Chair Professor of Plant Biology and Crop Sciences at the University of Illinois and Distinguished Professor in Crop Sciences at Lancaster University. His work, published in Science, proved that photosynthesis can be manipulated to increase plant productivity—an idea once considered the holy grail of plant biology. Long has added to our understanding of the long-term impacts of climate change, such as rising levels of carbon dioxide and ozone on plants. He has briefed former President George W. Bush and the Vatican, as well as Bill Gates and Anne, Princess Royal, on food security and bioenergy.

Realizing Increased Photosynthetic Efficiency (RIPE) is a translational research project that is genetically engineering plants to photosynthesize more efficiently to increase crop yields. RIPE aims to increase agricultural production worldwide, particularly to help reduce hunger and poverty in Sub-Saharan Africa and Southeast Asia by sustainably improving the yield of key food crops including soybeans, rice, cassava and cowpeas. The RIPE project began in 2012, funded by a five-year, $25-million dollar grant from the Bill and Melinda Gates Foundation. In 2017, the project received a $45 million-dollar reinvestment from the Gates Foundation, Foundation for Food and Agriculture Research, and the UK Government's Department for International Development. In 2018, the Gates Foundation contributed an additional $13 million to accelerate the project's progress.