Restructuring Environmentally Sound Pensions in Order to Negate Disaster Act of 2021 or the RESPOND Act of 2021 This bill addresses issues related to the impact of climate change on the economy, including federal retirement plans. The Federal Retirement Thrift Investment Board must establish an advisory panel on the economics of climate change to advise on how the board may invest in clean and renewable energy and make investments in a manner that helps ensure net zero greenhouse gas emissions in the United States by 2050. The board must then assess whether implementing low-carbon investment strategies is profitable and consistent with its duties. If the board cannot implement such strategies, the bill establishes the Climate Choice Stock Index Fund as part of the Federal Employees Retirement System's Thrift Savings Plan. This fund is established as an investment portfolio that performs similarly to other plan index funds, but does not invest in fossil fuels. Finally, the Federal Reserve Board and the Securities and Exchange Commission must annually report on the economic costs of climate change.