Do all rocket engines emit harmful gases into the atmosphere during launch?

Yes. Water vapor is the only exhaust from a LOX hydrogen fueled rocket. Climate alarmist have correctly recognized that water vapor is the strongest and most persistent greenhouse gas. All other rocket engines, liquid and solid, burn some form of hydrocarbon that emits CO2 among other gases.

One of the most prolific papers supporting anthropic climate warming, “Optimized Climate Fingerprinting,” by Allen and Tett, 1999, published in the Journal of Climate Dynamics was overturned in 2021. “Suboptimal Climate Fingerprinting,” by Ross McKitrick published 2021 in the Journal of Climate Dynamics overturned Allen and Tett. In doing so, it overturned 19/50 or 38% of the climate models in the UN IPCC climate suite.

Therefore, it seems prudent that humanity becomes an interplanetary species now. Humanity must become interplanetary at some point in order to survive as a species.

How does a 45-year-old man get a girlfriend?

There is however good statistical evidence to support two cosmic cataclysmic events a due to hit Earth. One is a major asteroid impact of Tunguska size or greater. The other is a Miyake EMP event that will be over 100X the magnitude of the Carrington event. Either event would likely collapse civilization through mass starvation that leads to major war.

Therefore, I wouldn't let your panties get in a wad over rocket exhaust.

Also, reusable rockets will likely lead to the end of the use of solid fuel rockets that are most harmful to the environment. In 15–20yrs I expect solid fuel rockets to be history. The technology might hang on longer in missiles.

First Map Made of a Solid’s Secret Quantum Geometry - quantamagazine.org

Celebrate Jesus! Celebrate rockets! Ignore climate alarmist until they have solid experimental science!

I just wish the climate alarmist had solid experimental evidence that CO2 is a greenhouse gas strong enough to effect the climate. They don't because it's not.

Climate alarmist point to ancedotal correlation in the past few centuries that suggest an anthropic relationship to climate warming. Once you go back tens of thousands of years and more that ancedotal evidence falls apart fairly quickly. There multiple periods where climate warming precedes CO2 levels rise indicating that climate warming causes increased atmospheric CO2.

Do you believe that Jesus was God on Earth?

The points being is that climate hysteria is based on psuedo science, without good experimental evidence to support CO2 as a significant greenhouse gas.

The UN in 2001 adopted Allen and Tett’s paper as the “gold standard” and subsequently accepted several climate models that were improvements on Allen and Tett.

In short, if you believe the climate alarmist, “He dies. She dies. They die. We all die excruciatingly painful deaths from climate change.”

Moderate liberals, if any use leftist Quora, how do you feel about being associated with those who enjoy burning American flags, supporting Hamas, having men competing against women in sports, open borders, green new deal and general wokery?

Several climate modelers used Allen and Tett's data that was flawed. Allen and Tett had over 12 errors in their paper and most of them were mathematical.