Though eating less mean is better for the enviornment, it only affects short term global temperatures.
The production and consumption of meat has a net 0 impact on "long term" global warming (caused by new carbon increases to the oceans and atmosphere and water cycle). The cause of global warming is the burning and use of fossil fuels. Eating meat is the burining and usage of cows.
Just be aware average global temperatures has a net increase in the short term due to methane emissions from large animals, however and temperatures will go slighltly down after changing the global human diet, however the hockey stick graphs cause and the cause of global warming itself is fossil fuels.
By chance we use fossil fuels in the feeding of cattle and in meat production however we use the same fuels for everything else and only by eliminating their usage AND also by carbon capture can we return global temperatures to a sustainable range.
So, yes eating less meat is good for many reasons (it would take hours to list them all), however if we changed our diet the change to global temperatures would be minor, but not enough to undo the effects of global warming (long term). However in the shortterm we would see a very modest drop in global temperatures due to less methane in the atmosphere.
This is the famous, making an error in the effect of the taylor expansion in math error... it happens when you consider a small effect as significant.