The Intergovernmental Panel on Climate Change 2013 report claims that climate change from human-induced greenhouse gas emissions will cause increasing temperatures in many regions and various detrimental effects such as rising sea levels, ecosystem changes, droughts, and floods. This study proposes a method for assessing the climate risks resulting from climate change as well as a tool that companies can use to assess those risks. The method for assessing climate risk is proposed in accordance with the ISO 31000 risk management process. We then design a web-based tool to implement the climate change risk assessment process. The data the tool generates enable companies to identify and analyze their climate risks to reduce potentially negative future financial impacts. The data on potential damage costs indicate that climate change is no longer an environmental issue but rather an economic one for companies, and the results presented through the proposed assessment method can be used to establish countermeasures and sustainable planning at companies. The results of this research are significant in that they provide companies with the critical information needed to improve their planning and response to climate risk.