Helen Clark

Hanging in the imposing nave of the iconic Notre Dame cathedral are six tapestries depicting our natural world. As rich in color as in theme, they are the work of the late Dom Robert, a French monk, who once noted: "There is one thing that never deceives and that is nature. Nature is the true reality."

How wonderful it would be if those old tapestries hung, not in their impressive setting in central Paris, but a few kilometers north, in the altogether less imposing halls of Le Bourget conference center. There, not only would the beauty of Robert's work serve to underscore what we stand to lose to global warming, but it would allow any decision-maker daring to take an earnestly close look to see how tightly each thread must be woven in order to create a magnificent whole.

The symbolism would likely not be lost on Helen Clark, former prime minister of New Zealand and current Administrator for the #link:http://www.undp.org:United Nations Development Programme (UNDP)# who is all too aware of the tight-knit nature of the problems facing our careless new world.

One of the jobs of the UNDP, she says, is to "join the dots between agendas," thereby highlighting the intrinsic relationships between sustainable development and our changing weather.

"This more erratic, unpredictable extreme climate we are already experiencing is impacting hardest on the poorest, most vulnerable communities, countries and people," she said, adding that an increased regularity of such events wipes out development gains.

Citing her home region of the Pacific as an example, she says rising sea levels around low-lying atoll nations are threatening "a way of life and the ability of humans to survive where they've survived for many many centuries."

They are already seeing water encroaching on the limited land they have, and as seawater seeps into groundwater, it affects their crops, thereby making people more dependent on rain, threatening food security and potentially leading to migration. The story in other developing nations might read a little differently in terms of consequence - drought, flooding, soil erosion to name but three - but the cause is one and the same. Climate change.

Vulnerable countries are leading the call for the 1.5 degree threshold that has been part of the COP21 vernacular. But Clark doesn't think that lower cap will be written into any treaty emerging from Paris in the coming days. She is, however, hopeful that the final agreement will contain "a review clause that matches the ambition of a lower level."

"The debate is shifting," she said. "The conventional wisdom was that two degrees was the tipping point, but now we are seeing many more voices coming in behind a lower threshold."

She hopes the review will be set for a "very short" number of years. Anything else, she says, would make it almost impossible to stop the catastrophic and irreversible impacts of climate change.

As Dom Robert wrote, there is no escaping what nature tells us. And as the bells of Notre Dame toll towards the end of this, the 21st Conference of the Parties, the time to listen to what it says, is now.