You could put signed particles, say sulfuric acid particles -- sulfates -- into the upper atmosphere, the stratosphere, where they'd reflect away sunlight and cool the planet.
粒子状物質 特に硫酸塩や硫酸微粒子を 上層大気ー成層圏に散布すると 太陽光線を反射して 地球の温度を下げます