My guess is that a vast majority of the planet's inhabitants would be glad to chip in only 0.3% of their wealth in order to achieve the humanitarian goals you write about.
Why doesn't it happen? I suspect that the problems are a lot more complicated than just chipping in money.
I think good intentions exist in abundance but there is a dearth of effective good intentions. What are the ways forward?
Fencepost.

We do need to care for humans if we intend to care for the planet. It is the humans, rich and poor who are seeking the use of environmental resources.

I believe people do care but the human problem is huge and sometimes our lack of personal empowerment - knowledge and poor networking skills ... means we can go NUMB.

Yes the economic comfort zone is a major contributor... our value systems are based on material well-being and not unfortunately on the non-material values, our own evolution, as in subjective aspects based on our humanity.

The questions you raise are the current ones we need to revisit.

We have extremes here, and it is good to question "why" with what we each know in our hearts.

Knowledge through exchange is the key eh, and we need to make that safe, by communicating, between all sectors ?

Thank You Amanda. I hope you write more on these topics.

Environmentalism is the "enlightened self interest" middle class response to globalisation. Those who have not personally encountered 'prostitution and sweat shop labour' can't really see the urgency of bringing these issues to the forefront. They do however, become irritated when their sense of aesthetics is disturbed. 'Trees' are pretty, poor people are an eye sore.

“Healthy people, healthy planet” – unarguably, there should be empathy for improved prospects for human beings wherever they are born.
But, this is just a feel-good article failing to recognize that, no matter how much money is spent, the issue of the apartheid relating to well-being can not be overcome for present numbers of people and their continuing proliferation.
Water-borne disease, malnutrition, AIDS, social disadvantage, will all persist while human pressure continues. It is the fundamental cause of destruction of the environments upon which those same people depend.
The author’s prescription would have human populations continuing to build up, until a lemming-like population explosion is reached, as already evidenced, and environmental capability has been exceeded. Then death, destruction, attempted migration, follow.
Maybe, as suggested, US100 billion can address the problem this year, each year. But will the environment, which makes human existence possible, be able to afford it.?
Indications are, for present rates of birth and death, the planet will have to support 9 billion in a generation or so. The planet’s biosphere already groans under the weight of 6 billion – affluent and otherwise. Its ability to provide life-services for the human race is already severely compromised.
Can it, rather than just our economic system, continue to carry the cost? Especially if the proposed expenditure enables an increased rate of population growth by concentrating on the rate of dying alone
By all means spend $100 billion a year. Affluent societies must be able to afford it. But, it will be totally unproductive if excessive fertility is not addressed as an essential component of the spending.
“I should not be worried, seeing humanitarian aid programs engaged in environmentalism, but thankful that someone thought to see the bigger picture.” The bigger picture that should frighten the hell out of us is the fact that the expansion of human numbers so closely parallels that of the famous lemming population explosions. Even more frightening is the continuing attitude of human aid proponents who turn a blind eye to the fundamental necessity of aid for reproductive rights for women in the less developed world