Livestock is the globe's primary contributor of human-caused greenhouse gas

As the IPCC rolls out its climate appraisal, the overall impact of industrial animal farming bears thinking about.
The FAO's last livestock report, a 2006 assessment titled Livestock's Long Shadow, found that farms breeding chickens, pigs, and cows for meat and dairy products, produced a disconcerting 18% of global greenhouse gas emissions.
Despite being called into question, that figure strengthened the case for vegetarianism: it was shown to be higher than the greenhouse gas discharge from cars and planes combined.
The latest FAO study lowers that number to 14.5%.
and...
...when it comes to livestock, reducing emissions isn't the only challenge.
"Around 30% of global biodiversity loss can be attributed to livestock production, such as the spread of pasture land or turning over forests and savannahs…to feed production."
There's also the role that consumers play in driving unsustainable industries—a feature that was beyond the scope of its current report, the FAO explained.
but...
...FAO asserts that meat and milk consumption is going to rocket by 70% by 2050.
so...
...it is not about bashing meat-eaters and attempting to convert the globe to vegetarianism. 
Consumers of chicken, pork, and beef should rather feel empowered, since they are the indisputable drivers of an industry that has the capacity for immense change. 
Meanwhile, vegetarians can rest at ease, confident that one of their most important arguments for avoiding meat has not been undermined.

With such good argumentation, it seems obvious why we should eat less meat.
But please, do not turn to fish!
Fish was not included.
Fish production has not such high GHG emissions anyway.
But it has high biodiversity loss and environmental impacts on the ecosystem that we still do not know.
It is underwater and spreads all over the ocean...the impacts and the fish:
fish caught in Africa, lands in Europe, is processed in Asia, and sold in USA.
So it makes it difficult to evaluate the all picture of the problem.