Most Pressing Global Environmental Issue

I know that there are many pressing environmental issues that are causing widespread fear and concern for the future of our planet. Some of these include climate change, deforestation, species extinction, and water degradation. Although the problem of climate change or global warming may be the most concerning and has definitely gained the most attention in the media as of recently, I feel like it may be the hardest to undo. Don't get me wrong, I definitely agree that more money and time should be allocated to environmental projects that will benefit our earth and stop it from the supposed "heating up" that is taking place, but the effects of human actions and behaviors on this planet will be incredibly difficult to reverse. There is a different issue that is of particular concern to me that has been affecting human populations for ages now. The problem of improper or insufficient food circulation bothers me to no end. I can't understand how this globe has the capability of providing every person on this earth with enough food and nourishment to live comfortably, yet much of the earth's population goes to bed starving every night. Too many people are malnourished and dying from starvation and lack of a proper diet. Meanwhile, countries like the U.S. are full of people stuffing their faces with hamburgers and having an incredible excess of food. If I had 100 billion dollars,  I would dedicate about half of it to solving this problem of food partitioning. The remaining 50 billion dollars would then be divided among problems such as climate change, energy conservation, land degradation etc.