Global Warming...New Report...and it ain't happy news

Among a flurry of posts on social media last weekend, US president Donald Trump declared “good riddance” to a specific emissions scenario used in global climate projections.

The “RCP8.5” scenario, which envisages a future of very high carbon emissions, was “wrong, wrong, wrong”, the president wrote in block capitals.

This was “just admitted” by the UN’s “top climate committee”, he falsely claimed, referring to the Intergovernmental Panel on Climate Change (IPCC).

The post was quickly picked up by right-leaning media, amplifying Trump’s misrepresentation of emissions scenarios and the role of the IPCC.

His claim follows the publication of a new set of emissions scenarios that will feed into the next IPCC reports.

While the new scenarios no longer include such high emissions as in RCP8.5, they also show it is “not possible” to limit global warming to 1.5C above pre-industrial levels without significant “overshoot”, one of the authors tells Carbon Brief.

Moreover, projections suggest that the world is still on course for between 2.5C and 3C of warming, another author says.

This level of warming was previously described as “catastrophic” by the UN.

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"Temperatures on this scale were once exceptional even at the height of summer," said Friederike Otto, a professor of climate science at Imperial College London, in a statement. "This record-breaking heat has the fingerprints of climate change all over it."

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Butterflies, often considered a “sentinel of change”, are on the move across every continent they inhabit, shifting to survive as global heating reshapes their environment.

About one in 10 species have already expanded or contracted their geographic range, or shifted in altitude, according to a global study published in Nature Ecology & Evolution.

Lead author Dr Shawan Chowdhury, head of Monash University’s Global Change Ecology Lab, said the study, which analysed shifts in 1,758 species across 105 countries, revealed the “astonishing” scale of change, largely driven by climate change and extreme weather.

“Butterflies are early‑warning indicators and are signalling a warning across the entire planet. If their ranges shift this dramatically, it signals profound changes across ecosystems.,” he said.

About 80% of butterflies that shifted expanded their ranges, often moving into newly suitable areas as temperatures rise.

Some moved surprisingly fast, he said. The tawny coster butterfly – originally native to India, Bangladesh and Sri Lanka – entered Australia in 2012 and has moved at a rate of 135km per year since. An expanding range wasn’t necessarily good news, he said, particularly if the insect was moving into less suitable habitat and populations were low.

About 27% of species – including Cupido minimus, the United Kingdom’s smallest butterfly – saw their ranges shrink, disappearing from areas they used to occupy. Others moved altitude, shifting to higher or lower elevations.

Range expansions occurred across all continents, particularly in the tropics, while contractions were mainly in Europe and North America, the paper said. Shifts in elevation were almost exclusively in the northern hemisphere.

Climate change and severe weather were the main drivers, although other factors played a role, such as habitat loss and agriculture. In Germany, a species known as the cranberry fritillary (Boloria aquilonaris) has lost much of its original habitat due to bog drainage. In Romania, agricultural intensification drove a contraction for the Danube clouded yellow butterfly (Colias myrmidone). In Brazil, the blue butterfly Godartiana byses has expanded from the states of Rio de Janeiro and Bahia to São Paulo in response to climate warming.

Some species experienced range expansion in one part of their distribution and contraction in another, Chowdhury said, which was “quite concerning”. “You don’t really know what’s going to happen for that species, whether they’re going to be endangered or whether they are going to be least concern in the long term.”