Volcanoes emit so much carbon dioxide from themselves that the contribution of all mankind to the problem of the greenhouse effect looks negligible against their background. Many components of rocket fuel are toxic, like their combustion products , and therefore the release of carbon dioxide as a product of methane combustion looks like the least evil possible.

I would think somebody with an Master in Engineering should be able to research correctly befor posting something.

Volcanoes have a very small amount in Greenhouse Gas emissions compared to human emissions by a factor of about 20 - 40 over the last decades.

Today, there are thousands of active volcanoes in the world, several hundred active eruptions occur annually, which emit billions of cubic meters of various contents into the earth's atmosphere. Rising from the bottom of the oceans, methane affects the temperature of the atmosphere many times stronger than carbon dioxide. Before complaining about someone's pants, you should check your own first.

Space launch activity cannot be exempt from environmental impact. The problem is not related only to greenhouse gas emission but it is wider. Every technology has its own issue.

Solid propellants emit HCl and alumina particulate. HCl causes acid rain and, in combination with alumina and UV light, local ozone depletion is obtained. Moreover, small particles stay in the stratosphere and contribute to the radiative forcing of the Earth (balance between incoming and outgoing radiation from the outer space).

Liquid propellants (kerosene/oxygen) emit quite large amount of CO and soot. Also in this case, soot participates to radiative forcing of the Earth.

Liquid propellants (hydrogen/oxygen) emit water vapor and a huge amount of unburnt hydrogen. This H2 mixes in the plume with the atmosphere and causes post-combustion, incrementing local temperature as high as 2500 K. Locally, NOx are produced due to high temperature and, again, ozone is locally depleted.

Hybrid rockets emit soot. They are based on a diffusive flame so they are prone to carbon black formation.

Strictly speaking about greehouse gases, probably hydrogen/oxygen are less impactful. Currently, these effects are quite local but in the future we may consider them. this year we have just overcome the number of 100 launches in one year. Current forecasts are predicting a linear increment of launch rate in the next 20 years.

A clearer picture can be obtained reading the works by Marvin Ross, who is working on space launchers environmental impact since long time.

Here you can find one example.

DOI:10.1002/2013EF000160

Best

Filippo

metal based propellants

new cryogenic solid propellants, carbondioxide-metal etc....