Two of the biggest myths about climate change have been busted: The first is that we have time to deal with human beings' impact on our planetary climate system. Time is up and we're now living with the beginnings of a changed climate, including more intense storms, drier droughts, scarier floods and hotter wildfires.

The second myth is that mitigating climate change will cost so many billions that we can't possibly afford to do it and that such action would take money away from the poorest people who need it most.

According to a new study, the opposite is true.

In an article in the journal Nature, researchers found that if human beings fail to reduce greenhouse gas emissions to the levels designated in the Paris Agreement, the economic cost would range from $150 trillion to as much as $792 trillion by 2100.

The United States signed the Paris Agreement in 2015 along with 190 other nations, but in August 2017, President Trump filed with the United Nations to withdraw from the agreement — though due to the terms of the original agreement, that withdrawal won't be effective until November 2020. The agreement aims to keep global warming below 2 degrees Celsius. Already, the globe has warmed more than 1 degree.

The basis of the Paris Agreement is voluntary actions (NDCs) that nations will take to mitigate CO2 emissions, but so far, few countries have been able to meet their targets, although over 30 cities worldwide have gotten it done.

But even the targets of the Paris Agreement probably aren't enough: "A number of studies have proved that current [NDCs] are not enough to achieve the global warming targets," Biying Yu, from the Beijing Institute of Technology, and co-author of the paper in Nature, told CBS News. She explained that even with the agreed-upon reductions, 3 degrees of warming is projected.

The costs of not tackling climate change (that $150 trillion and up) come from the destruction wrought by even fiercer storms, flooding, droughts and fires, not to mention the extinctions of animal extinctions and all the other variables that create a very different world.

What if we take action?

Yu and her colleagues looked at ways countries could improve their NDCs while maximizing gains and minimizing the effect on the economy, which would require global cooperation.

The net benefit of climate change mitigation would be $127 trillion to $616 trillion by 2100 — that's how much would be gained in economic benefit minus expenses.

Seems like a no-brainer, right? The problem? Like many things in our own lives (a more efficient car or furnace), a big cash outlay is needed at the beginning to reap those later economic benefits.

"Since many countries and regions would have a negative net income in the early stage due to the large amount of [greenhouse gas] abatement cost, they may refuse to ratchet up current climate actions in the near term and choose to neglect the long-term climate damage, which makes a severe obstacle in achieving global warming targets," Yu told CBS News.

As far as climate-change mitigations taking money from those who need assistance, it's worth remembering that it's the poorest and most vulnerable who will be hardest hit by rising tides and devastating storms. So money spent now would protect them later. And when it comes to those populations, we're talking life and death.

It seems like the choice is clear.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

The cost of tackling climate change is less than the cost of doing nothing
The economic cost of doing nothing to reduce greenhouse gases is higher than fighting the problem, study finds.