The head of the International Monetary Fund has warned that our planet is "perilously close" to a dangerous tipping point which will usher in "merciless" climate change.
Speaking in London last week week, Christine Lagarde called for a carbon tax, and cut in fossil fuel subsides: "We are subsidizing the very behaviour that is destroying our planet. Both direct subsidies and the loss of tax revenue from fossil fuels ate up almost $2 trillion in 2011. This is about the same as the total GDP of countries like Italy or Russia."
Her stark warning echoes similar efforts made by her counterpart at the World Bank last month. Taking a historic step, Jim Yong Kim called on investors to dump their holdings in oil, gas and coal:
"Long-term investors must recognize their fiduciary responsibility to future pension holders who will be affected by decisions made today."
Over the past year, the movement to divest away from fossil fuels has been gaining momentum.
According to Carbon Tracker, if goverments stand by their pledge to rein in emissions in 6 years time, over $600 billion in oil, gas and coal investments could become worthless.
And, that would be include oil from the Canadian tar sands. In fact, it would be the first fossil fuel to be dumped.
Why? Because it's the dirtiest fuel on earth. According to the US Environmental Protection Agency, it releases over 80% more carbon emissions than conventional sources of crude.
It's so filthy, it has the power to raise global temperatures by 0.4 degrees celsius. That marks half of the warming already experienced by our planet.
No wonder billionaire investor Jeremy Gratham thinks that "the tar sands will end up as a stranded asset in the next decade or two."
Looking at the Keystone pipeline from this perspective, it makes poor economic sense.
Obama should throw down the gauntlet to Canada, and reject what has been dubbed as the largest carbon bomb on the planet.
Although the state department argues that Canada will develop its tar sands with, or without the pipeline, alternative modes of transport such as rail will not be in the offing until 2030. By then, the tar sands will no longer be worth pursuing.
That means by rejecting the pipeline, Obama has the power to curtail one of the most polluted projects on earth.
Alternatively, if he approves it, for the sake of 50 permanent jobs, he will become an accomplice to the "merciless" demise of our climate.
And, as 350.org founder Bill McKibben notes: "Mother Nature has already filed her comments."
"Caused by warmer weather over the Pacific Ocean, typhoon Haiyan was over 40 kilometers wide and ratcheted speeds of up to 322 kilometers per hour.
It was the third super storm to strike the archipelago last year, coming 12 months after hurricane Sandy tore across the northeastern seaboard to leave much of New York City submerged under water.
Once regarded as black swans, such storms have become part of the new normal for life on a hotter planet."
Both storms came during some of the hottest years on record. And, according to the UN, things are only going to get much hotter: up to 6 times hotter.
As the fate of our planet hangs in the balance, it is clear to see how the Keystone pipeline has come to represent such an emotive issue in the fight against climate change.
Over the past three years, it has grown into a national movement, inspiring one of the largest environmental protests in US history as over 30,000 people marched outside the White House last February.
Needless to say, Obama's decision on Keystone XL will cement his legacy as the 44th president of the United States.
Given our planetary odds, climate scientist Michael Mann asks "If the president won't protect us, who is he protecting?"
According to Friends of the Earth, the primary contractor responsible for the state department's final Keystone review has financial ties to TransCanda, the group hoping to build the pipeline.
The state department is currently reviewing these allegations.
Last June, Obama asked the American people: "Will we have the courage to act before it's too late?" That's a question the president will have to ask of himself in the months that lie ahead.
In the words of Bill McKibben: "If Obama shows some moxie and stands up to Big Oil, he will be the first world leader to have actually stopped a project because of the climate."
Now, that's a legacy worth fighting for.
Six years ago, euphoria swept across the nation when Obama became America's first black president. It's time for him to make history again, and say no to Keystone XL, for in his own words: "That bright blue ball rising over the moon's surface, containing everything we hold dear -- the laughter of children, a quiet sunset, all the hopes and dreams of posterity -- that's what's at stake."