So far, international climate targets have been restricted to limiting the increase in temperature.
But if we are to stop the rising sea levels, ocean acidification and the loss of production from agriculture, CO2 emissions will have to fall even more sharply.
... a study carried out by climate researchers based in Bern shows that the focus on the temperature increase alone is by no means enough to meet the ultimate, overarching objective – to protect the climate system from dangerous anthropogenic interference ... for the sustainability of ecosystems and food production. All of this can scarcely be realised by the two-degree target alone.
This is why Dr. Marco Steinacher, Prof. Fortunat Joos and Prof. Thomas Stocker are proposing a combination of six different specific global and regional climate targets in their work, which has just been published in the «Nature» journal.
They say that a global temperature target is «neither sufficient nor suitable» to avoid further damage that is relevant for communities and ecosystem services. These include in particular: rising sea levels, ocean acidification – which threatens coral reefs – and production on agricultural land.
...The researchers have now used extensive model calculations to show which levels of CO2 emissions would still be allowable in order to meet the proposed combined targets. ... "When we consider all targets jointly, CO2 emissions have to be cut by twice as much than if we only want to meet the two-degree target," explains Steinacher.
The objective of limiting ocean acidification proved particularly challenging and is achievable only through a massive reduction in the emissions of CO2.
The three researchers ... recommend that further studies of this type be carried out. However, further relevant climate targets need to be set out by policy makers and by society, they say.
"Ultimately, the magnitude of environmental changes we are able to cope with and the amount of risks we are prepared to take is a social and political question. But the constant rise in CO2 emissions is increasingly limiting our options to act," says Fortunat Joos.
[Ellipses, bolding, and illustration added]