So whereas the Paris agreement delays strong action for decades, and serious carbon drawdown till the second half of this century, the brutal fact is that present greenhouse gas levels are such that we will steam past 1.5°C, and are heading to 2°C as a result of what we have already done.And that is why all “1.5°C scenarios” actually “overshoot” to around 2°C before cooling the system by a theoretical, massive-scale carbon drawdown.
by David Spratt The climate system will heat well past 1.5 degrees Celsius (°C) and perhaps up to 2°C without any further fossil fuel emissions.That’s the conclusion to be drawn from new research which should also help demystify the rhetoric from the 2015 Paris climate talks of keeping warming to below 1.5°C .Eliminating methane from animal husbandry and rice production would cut methane emissions by 20%. On the other hand, it is expected non-anthropogenic methane emissions from wetlands and the Arctic will increase.If the planet warms enough, large polar permafrost and/or methane clathrate carbon stores will be mobilised, releasing large amounts of both methane and CO2, and introducing large positive feedbacks to long-term climate change.It is possible and necessary to reduce the warming impacts of the short-lived gases impacts, which is calculated to be around 0.9°C, of which methane is the largest component.
Half the methane emissions are natural, primarily from wetlands.
And half are from human activities, the most important sources being extracting and processing fossil fuels (26-32%), livestock (26-28%), and landfills/waste (20-27%).
Stopping the use of fossil fuels would reduce total methane emissions by 15%.
It’s not that 1.5°C isn’t dangerous: in fact, at just 1–1.1°C of warming to date, climate change is already dangerous.
A safe climate would be well below the present level of warming, unless you think it is OK to destroy the Arctic ecosystem, tip West West Antarctic glaciers into a self-accelerating melt, and lose the world’s coral reefs, just for starters.
We’ve already expended the vast majority of the budget for remaining under 2°C. The work uses the latest generation of climate models, in which the aerosol-cloud interaction is more sophisticated, and also examines each aerosol component discreetly, rather than lumping them together as some simpler climate models do.