Negotiators at the UN climate change talks in Paris are close to setting a more ambitious target of 1.5°C for limiting the increase of average global temperatures.
The more radical group gained support in the final days of the conference after US Secretary of State John Kerry voiced his support for an ambitious deal.
Backed by the European Union and tens of African, Caribbean and Pacific states, the 1.5°C temperature increase target - considered much safer for vast areas of the world - is still being challenged by many, including the oil-dependent Arabic countries.
The latest draft of the new climate agreement recognises the need to aim for the 1.5°C goal although it officially keeps the 2°C target.
However, it has been said that greenhouse gas emissions cuts proposed are nowhere near what’s necessary even for the less ambitious goal. Instead, the agreement expects the restrictions to be tightened gradually in future.
The initial attempt to include recommendations of the 1.5°C target was blocked by Saudi Arabia last week.
India, which has led demands for richer countries to take a bigger share of the load, offered conditional support for a 1.5°C target if those developed nations accepted bigger emissions cuts.
According to climatologists, limiting the rise of average global temperatures to a maximum 2°C compared to pre-industrial times is necessary to prevent excessive disruption of the planet’s ecosystem as well as devastating effects for low-lying and coastal countries.
Average surface temperatures have already risen by 1°C and greenhouse gases already emitted and locked into the system are likely to push the rise past 1.5°C within a few decades.
The UN's main scientific body, the Intergovernmental Panel on Climate Change (IPCC), has said that just aiming for a 1.5°C long-term pathway would put countries on course to meet the 2°C goal, but concedes that research is incomplete.
"There is limited evidence of the likely impact of 1.5°C and more research needs to be done," said IPCC head Hoesung Lee.
Measures proposed by each of the negotiating countries ahead of the conference have been described as insufficient for achieving even the less ambitious target, more in line with keeping the temperature increase below 3°C.
According to analysts, adopting a stricter target would mean that deployment of carbon capture and storage technologies and take-up of renewables would have to speed up.
"If you want to get to 1.5°C, you need to deploy them five, 10 or 20 years sooner," said Michiel Schaeffer, a researcher with Climate Analytics.
The necessity to review and tighten the measures on a regular basis was laid out as a key requirement by European countries leading the "high ambition coalition".
"Without the five-year cycles, the agreement is meaningless,” said European climate action and energy commissioner Miguel Arias Canete. “If we want a long-term target we must take stock every now and then - we think every five years is a reasonable period - to assess, how far are we from the trajectory the IPCC has established as necessary.”
It has been reported the conference may overrun its Friday afternoon deadline as countries are still battling over other controversial points, including whether established industrial economies should assume more responsibility to allow developing countries to benefit from fossil fuels in a way they once did.
The question of compensations to countries damaged by the climate change has also been unresolved.
According to a study published today by the University of Edinburgh, the world might be set to see the average global temperatures increase by staggering 8°C, if greenhouse gas emissions keep growing at current rates.
The researchers said such warming would have a catastrophic effect, threatening food supplies and leaving billions of people suffering from extreme heat, draught and devastating weather events.
"Estimates vary over the impacts of climate change,” said Professor Roy Thompson, who carried out the study. “But what is now clear is that society needs to take firm, speedy action to minimise climate damage."
The study, published Earth and Environmental Transactions of the Royal Society of Edinburgh, used historical temperatures and emissions data and accounted for the cooling effects of atmospheric pollution.