Climate change is impacting the human population and environment of Japan. In recent years, the country has observed notable changes in its climate patterns, with rising temperatures serving as a prominent indicator of this phenomenon. The nation experiences a broad range of climates, spanning from the frigid winters of Hokkaido to the subtropical climates of Okinawa. Changes in temperature patterns have the potential to disrupt ecosystems, impact agricultural productivity, modify water resources, and pose significant challenges to infrastructure and human settlements.

Japanese government is increasingly enacting climate change policy to respond. The government has been criticised for lacking a credible plan to get to its pledged net zero greenhouse gas emissions by 2050. As a signatory of the Kyoto Protocol, and host of the 1997 conference which created it, Japan is under treaty obligations to reduce its carbon dioxide emissions and to take other steps related to curbing climate change.

Out of the global GHG emissions, Japan is responsible for 2.6%. The average rate of CO₂ emissions per person in Japan is almost double the global average. Emissions have been slightly reduced since 2013 and the net zero emissions are set by 2050.

Japan has pledged to become carbon neutral by 2050. In 2019 Japan emitted 1212 Mt CO_2eq, The per capita CO₂ emissions were 9.31 tonnes in 2017 and was the 5th largest producer of carbon emissions. As of 2019^[update] greenhouse gas emissions by Japan are over 2% of the annual world total, partly because coal supplies over 30% of its electricity. Coal-fired power stations were still being constructed in 2021 some may become stranded assets.

Calculations in 2021 show that to give the world a 50% chance of avoiding a temperature rise of 2 degrees or more, Japan should increase its climate commitments by 49%. For a 95% chance, it should increase the commitments by 151%. For a 50% chance of staying below 1.5 degrees, Japan should increase its commitments by 229%. A March 2021 analysis by Climate Action Tracker said that Japan should reduce greenhouse gas emissions so that by 2030 the emissions are 60% below 2013 levels; this would support a goal of limiting warming to 1.5 °C.

Furthermore, Japan has witnessed a decrease in its annual emissions, with a 5.3% reduction in industrial emissions due to decreased steel production. Residential emissions fell by 1.4%, while vehicle emissions rose by 3.9%. Despite these changes, Japan still heavily relies on fossil fuels, which constitute about 70% of its power generation. In terms of renewable energy, Japan aims for 10 gigawatts of offshore wind capacity by 2030 but is currently projected to only reach 4.4 gigawatts.

On 18 February 2025, Japan has set new targets to cut greenhouse gas emissions by 60% by 2035 and 73% by 2040, while aiming for renewables to provide 50% of its electricity by 2040. The revised energy and industrial policies focus on decarbonization, energy security, and economic growth, despite challenges in offshore wind energy and nuclear power.

The transportation sector accounts for 20% out of the total emission of Japan. Within the transportation sector, it is mainly oil that is being used. This particular sector currently relies on fossil fuels and is projected to continue doing so for a while. One challenge to decarbonize the transportation sector is the cost of such technologies required for the transformation. Emissions have been decreasing within the sector since 2001 due to fuel efficiency of cars and population decline.