There may not be any harmful effects of e-ticketing systems directly on our ecosystem. But the computers based on which e-ticketing works, have effects.
1. E-ticketing solution uses computer hardware. The monitors used for display contain some harmful substances, which are not eco-friendly. The discarded computer materials are called e-waste. The may contain lead, cadmium etc. SO exposure to harmful components of e-waste is not good. The mobile phones are also used for e-ticketing. They are also part of e-waste when discarded.
Recycling of e-waste can reduce the emission of greenhouse gases.
2. Use of e-ticketing system increases the use of electronic telecommunication signals in the air. It uses the telecommunication satellites in space.
3. E-ticketing system uses computer print out or stationary. Paper comes from wood pulp and hence from the trees in forests. Thus e-ticketing causes cutting of trees. The trees have to be regenerated using a disciplined and planned method.
4. I am not sure of these:
The inks used in the printers or the toners may contain some non eco-friendly substances. They may be prepared by use of some non eco-friendly processes.
5. These computers along with all the networking hardware, are always on. The computers dissipate heat energy continuously.