The intended nationally determined contributions were adopted as the national plans for addressing the climate change challenge after 2020, aiming at limiting global warming to 2 or 1.5 degrees C. In this context, energy-saving R&D has become an important way for reducing GHG emissions. This study used a climate-economy integrated assessment model to study the carbon reduction and climate mitigation effects of R&D investment by scenario simulation. The results show that most of the major carbon emitters cannot achieve their INDC targets by continuing their current R&D growth trends. Unless the R&D investment rates of countries increase to radically high levels, global warming by 2100 cannot be controlled to below 2 or 1.5 degrees C even when the major carbon emitters have approached or achieved their INDC targets. Low-carbon technology transfer will obviously reduce the carbon emissions of developing countries, but cannot achieve the 2 degrees C target. Considering the actual R&D capabilities of countries and the economic loss under excessive R&D input, raising R&D rates to approximately 4 or 5 percent and combining them with technology transfer and production damage measures will be a more realistic approach. (C) 2018 Elsevier Ltd. All rights reserved.