Research predicts food production issues, water scarcity, and economic losses if the Paris goals cannot be reached.

The Paris Agreement’s aim is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius.

A group of recent research papers have found that limiting warming to 1.5°C, in the context of sustainable and equitable development, is still possible.

However, the same Paris Agreement themed issue of the Philosophical Transactions of the Royal Society A outlines serious impacts if the effort fails.

One paper examines the extent to which it is still feasible to limit warming to 1.5°C by the end of the century.

“We find that the lower bound of future cumulative CO2 emissions from fossil fuel combustion over the 21st century is 570 billion tCO2 even if we push all levers to reduce emissions to the extreme,” it states.

“This means that in all but the most optimistic assumptions about the remaining 1.5°C CO2 budget the deployment of CDR will be necessary to keep the 1.5°C limit within reach.”

Another reviews the ‘Legal Character and Operational Relevance of the Paris Agreement's Temperature Goal’.

Politically and symbolically, 1.5 °C goal reflects an acknowledgement that the planet's most vulnerable countries and communities consider a temperature rise beyond that limit, as an existential threat.

But the experts say the Paris Agreement falls short of converting the long-term temperature goal into a provision with specific legal force applicable to the actions of individual parties.

“The existential aspirations of the most vulnerable countries that the goal represents will continue to rest on the quality of the political discourse the Paris Agreement is able to create - both internationally and domestically - and on our individual and collective conscience,” it states.

Scientists have also predicted changes in climate extremes, fresh water availability and vulnerability to food insecurity at 1.5°C and 2°C global warming.

Impacts of 2°C global warming are larger than those of 1.5°C.

“Temperature extremes increase by more than the global average warming. Hydrological impacts such as flooding and drought show complex changes but generally most models project wetter conditions in most areas, with increased flooding risk and, mostly, reduced drought risk,” the paper states.

“However, increased drought risk is still projected by most models in some areas, and by a minority of models in many areas, so should not be overlooked.

“Vegetation productivity is projected to increase, especially if climate sensitivity is relative small and higher concentrations of CO2 are required to reach 1.5C or 2C global warming.”

A separate report found uncertain impacts on economic growth when stabilising global temperatures at 1.5°C or 2°C warming

Using a new set of climate projections and empirical estimates of how climate affects economic growth, experts assessed economic outcomes under 1.5°C and 2°C warming following the Paris Agreement.

“Economic growth under 1.5°C warming is near indistinguishable from current climate conditions, while 2°C warming suggests lower growth rates for a large set of countries,” they said.

“Median projected global average GDP per capita is 5 per cent lower at the end of the century under 2°C warming relative to 1.5°C, and 13 per cent lower than under no additional warming.

“Projected economic losses are greatest in low income countries suggesting increased inequality under future climate change.”

Other studies looked at solar geoengineering as part of an overall strategy for meeting the 1.5°C Paris target.

Solar geoengineering refers to deliberately reducing radiative forcing by reflecting some sunlight back to space, in order to reduce anthropogenic climate changes.

One of the leading ideas is to add aerosols to the stratosphere.

If future mitigation proves insufficient to limit global mean temperatures to less than 1.5°C above preindustrial, “it is plausible that some additional and limited deployment of solar geoengineering could reduce climate damages, as part of an overall strategy to manage climate change risks”, the report found.  

Model projections suggest that a 1.5°C climate achieved with geoengineering is closer to a 1.5°C climate achieved through mitigation alone than either is to a 3°C climate.

Mounting concerns over climate risks above the Paris Agreement temperature targets are increasing calls for atmospheric experiments to test the efficacy of solar geoengineering technologies.

“Researchers and funders eager to move forward with solar geoengineering field experiments should participate in and await the outcomes of meaningful processes of engagement on the risks and implications of solar geoengineering with a broad cross-section of civil society stakeholders and be explicitly open to multiple potential outcomes, including societal rejection of the solar geoengineering research enterprise,” one new paper argues.