Since every studio is unique in how much control the owner has over the physical space and utilities, only general recommendations can be made here.
If you pay your own electricity bill, check with your utility to see if they offer a 100% renewable option. If your electricity is generated by fossil fuels (coal or natural gas are common), find ways to reduce electricity use as much as possible.
Reduce use of plastics - especially single use plastics like bottled water. Not only are most plastics made from fossil fuels, but their manufacture releases greenhouse gases.
Improve the energy efficiency of the space with weatherstripping and insulation to reduce energy use for heating and air conditioning.