Consider the following statements about stratospheric aerosol intervention (SAI):
1.SAI is a geoengineering technique designed to reduce global warming.
2.SAI involves the introduction of aerosols into the stratosphere.
3.SAI has potential unintended consequences for the environment, including the ozone layer, hydrological cycle, monsoon systems, and crop yields.
How many of the above-given statements is/are correct?