The climate change summit – COP21 – in Paris was already "so much water under the bridge” even as it went on, with one of the key sticking points being to what extent global temperature should be allowed to rise.

Global temperatures have been rising and currently stand at around 1 Degree Celsius from pre-industrial levels. There’s no question they will continue the rise. 

Small island states, in partnership with many African and other developing countries, have been pushing for a temperature target to hold global warming at 1.5 degrees, and not the 2 degrees being pushed for by some of the major emitters of greenhouse gases.

Experts have always known that the last time the planet was 2 degrees warmer eons ago the oceans were 4 to 6 meters higher. This is likely to recur with climate change.

This very fact threatens to wipe out some countries. Some small islands, specifically, have their very existence at stake — the highest elevation in the Maldives, for instance, is 2.4 meters.

But the threat is closer to home than many people would expect. As this column observed some time ago, a study by the Stockholm Environment Institute projected that Rwanda could suffer economic costs amounting to 1 percent of annual GDP by 2030 due to global warming.

The institute predicts a temperature rise of between 1.5 and 3 degrees Celsius by the 2050s. (See "Between the three-stone fireplace and climate change”, The New Times, June 26, 2013)

The study notes that a large proportion of the rural population in Rwanda currently lives at altitudes beyond the normal mosquito habitat. It explains that as temperatures rise, so will the threshold altitude, increasing by 150% the number of Rwandans at risk of Malaria by 2050. The potential healthcare costs are of the order of $50 million per annum.

Coral reefs off the East African coast, which support vast biodiversity and livelihoods of entire populations, are particularly vulnerable with the vagaries of climate change being very real in Zanzibar.

A recent newspaper report explains how seaweed (mwani in Kiswahili) has been one of Zanzibar’s key exports for over two decades. Mwani is used as a base for cosmetics, lotions, toothpaste, medicines and food.

At its peak, the trade contributed over $8 million a year to the Zanzibar economy. In the process, it had lifted many women out of poverty. But many women in recent times have abandoned seaweed farming blaming rising sea temperatures for a mass dying of seaweed.

The cost of climate change is, therefore, very real. And, as I write this, negotiators are hard at it to whittle down confusing texts full of noncommittal brackets in the draft climate change agreement reached last Saturday.

Fears have been expressed that "the excessive bracketing of the draft agreement will delay its delivery.” Some of the issues under discussion included losses and damages – as the Zanzibar case may illustrate – climate finance to raise at least $100 billion for the Green Climate Fund kitty, among a variety of other concerns.

From the over 900 "square brackets” there are now 300, as I write. The negotiations continue, and perhaps by the time you read this something will have come of it.

We also may not forget Pope Francis during his recent speech at the UN Environment Programme headquarters in Nairobi, just a week before COP21.

He noted the environmental crisis facing humanity and commented that transforming current development models was a "political and economic obligation” that required nations to consult.

The Pontiff’s was reminder – a voice of concern given failures of past COPs to deliver.

Even as Africa and the small island states push for 1.5 degree, as one commentator captured it, the Paris summit comes after more than 20 years of climate negotiations, and 18 years after the Kyoto Protocol was agreed. Having failed to act decisively in Copenhagen in 2009, this is probably the last chance for the international community to avert temperature rises beyond 2 degrees.

May the commitment and political will be found all round by the big and small states to take climate change more seriously and avert looming global catastrophe.