When the Paris Agreement was sealed in late 2015, the reaction of one major French media outlet was typical when it described the 195-nation accord as an "historic deal in Paris to stop global warming".
Forged through the UN's Framework Convention on Climate Change, the agreement set the aim of limiting the increase in average global temperatures to "well below 2°C above pre-industrial levels", while making efforts to keep them to 1.5°C.
In highlighting 1.5°C, the agreement was more ambitious than previous deals, including those struck in Copenhagen in 2009 and Cancun in 2010, when 2°C was the key figure.
Concerns from small island nations over rising sea levels were central to the decision to place the focus on 1.5°C, said Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics.
"At 2°C, the projections of sea level rises would continue into the next century and reach levels that would wipe out the small island states," he said.
The world’s climate is now about 1.1°C warmer than in pre-industrial times, taken to be the period between 1850 and 1900, before fossil fuels were burnt in vast quantities by humans, UN figures have shown.
If the world is to restrict the average temperature increase to 1.5°C, emissions must be cut by 45 per cent by 2030 compared with 2010 levels, while net zero must be achieved by 2050, the UN has stated.
The Paris Agreement aims to keep the rise to 1.5°C by requiring countries to submit nationally determined contributions (NDCs) that represent their pledges on limiting carbon emissions.
NDCs have to be updated at least every five years in a process that operates on a ratchet mechanism, whereby each successive set of pledges is expected to be more ambitious than the last.
The wrong direction
But far from having fallen by 45 per cent, global emissions in 2030 are set to be 11 per cent higher than in 2010 based on national commitments, the UN has said.
"Current pledges – a pledge is completely different from actually doing something – take us to about 2.2°C of average global warming if everything is done, if energy is transformed, if transport is transformed," said Asher Minns, executive director of the Tyndall Centre for Climate Change Research at the University of East Anglia in the UK.
It is, Mr Minns said, "quite likely" the average global temperature rise will end up exceeding this figure, which is itself higher than what scientists say is required to avoid the worst effects of climate change.
Based on temperature data so far, there have been predictions that the world’s climate this year is likely to be at least 1.5°C higher than the pre-industrial average.
For the Paris Agreement’s target to be breached, temperature rises of this magnitude would have to be sustained for many years, rather than happening for a single year that was hotter than average.
This year is likely to have been warmer than average in part because the world’s climate is now in an El Nino phase, which involves warmer conditions in the eastern tropical Pacific Ocean, with global knock-on effects.
Mr Ward said a sustained increase in temperatures of more than 1.5°C above pre-industrial levels, which would reflect a breach of the Paris Agreement’s target, would probably be reached "over the next couple of decades" and without concerted action, higher increases were likely.
'Ambition is there, but short-term thinking is a problem'
Mr Minns said there was "huge will and huge ambition globally" to tackle climate change, but turning this into practical measures was proving difficult.
"It comes up against short-term political thinking and short-term economic thinking," he said.
He said that as the Cop28 summit approached, countries would "say the right words and pledge and promise to do more", but there needed to be "a different type of political and economic thinking" to turn these into action.
Other analysts, too, have said curbs on emissions so far fall well short of what the science indicates is necessary to prevent severe climatic effects.
"My optimism is rather limited, bearing in mind that we’ve managed not to keep the promises from the Paris Agreement," said Walter Leal, professor of climate change management at Hamburg University of Applied Sciences in Germany and professor of environment and technology at Manchester Metropolitan University in the UK.
"There have been increases in the emissions instead of noticeable reductions. The situation is not getting better, it’s getting worse.
"We have to intensify global efforts to reduce the emissions of greenhouse gases, especially CO2 and methane. It can only work if efforts are concerted. It makes little sense if the UK or Germany reduce their emissions but other countries do not."
Signs of hope on emissions
But there are significant signs of an energy transition that will ease the dependence on fossil fuels. A report from the Ember think tank indicated global carbon emissions from energy production may peak this year, with investments in sectors including solar and wind power having been central to this.
A transition from fossil fuels to renewable forms of energy is the key reason why carbon emissions from energy generation are set to peak soon and then fall, even though global energy consumption is not dropping.
Worldwide, emissions from the power sector were only 0.2 per cent higher in the first half of this year compared with the same period in 2022, Ember calculated, suggesting emissions are close to plateauing before potentially falling.
The slow pace of action on emissions overall means it will be necessary to remove carbon dioxide from the atmosphere later this century, Mr Ward said.
"We’ll have to be sucking CO2 out of the atmosphere and storing it underground," he said.
"That’s going to be difficult, but I think it’s going to be required now."
As well as taking measures to limit the continued warming of the atmosphere, the world will have to cope with intensified effects of climate change, he said.
These include continued sea level rises, stronger storms, more frequent rain and flooding, along with a greater risk from heatwaves, drought and wildfires.
"It is a long list of damaging impacts that we’re going to see, with greater severity and frequency, and we’ll have to bring temperatures down quickly," he said.
'No country immune to effects of climate change'
Analysis from the UN’s Intergovernmental Panel on Climate Change in recent years has shown, Mr Ward said, that if average temperatures reached 2°C above pre-industrial levels, it would not only be small island states but many other countries that would face significant detrimental effects.
There would also, he said, be increased risks of major thresholds being passed that destabilise ice sheets in Greenland and West Antarctica.
It is important to plan ahead and consider even "worst-case scenario" increases of as much as 4°C above pre-industrial levels, Mr Minns said.
Such preparations could take the form of ensuring that housing and infrastructure, including pipelines, can cope with such magnitudes of temperature increases, given that projects constructed now could last for half a century.
Agriculture is another sector that could face significant pressures. Prof Leal said the effects of climate change could exacerbate hunger, particularly in sub-Saharan Africa.
"Water availability would also be affected, because high temperatures are usually associated with high levels of evaporation. It means water is less available," he said.
"We’re right now facing situations where many countries are facing water shortages. Both rich countries and developing ones are experiencing such shortages.
"So, no country should believe it is immune to the impacts of climate change."