Norfolk’s iconic Swallowtail Butterfly at risk from climate change – UEA

By Paul Homewood

h/t Dave Ward

The latest nonsense from the UEA:

Norfolk’s butterflies, bees, bugs, birds, trees and mammals are at major risk from climate change as temperatures rise – according to new research from the University of East Anglia.

Researchers carried out the first in-depth audit of its kind for a region in the UK to see how biodiversity might be impacted in Norfolk as the world warms.

The study finds that the region’s Swallowtail Butterfly, which can’t be found anywhere else in the UK, is at risk – along with three quarters of bumblebee, grasshopper and moth species.

Dr Jeff Price analysed local populations of 834 species found throughout Norfolk to show how they might fare as climate change reaches 2°C – the upper end of the UN’s Paris Climate Agreement goals. He also looked at what will happen at 3.2°C – the current global trajectory if countries meet their international pledges to reduce CO2.

The results, published today in Transactions of the Norfolk and Norwich Naturalists’ Society, are sobering.

At risk at 2°C of global warming

The project reveals that at just 2°C, 72 per cent of bumblebees in Norfolk could be lost, along with 75 per cent of grasshoppers and bush crickets, and 68 per cent of larger moths.

The new climate potentially becomes unsuitable for 15 species of birds including Lapland Bunting and Pink-footed Goose. Meanwhile the Common Shrew, Roe Deer and European Badger are among seven mammal species which may be lost from Norfolk.

The Swallowtail Butterfly, local only to the Norfolk Broads, and Red Admirals are among 11 types of butterfly which could be affected.

The Common Frog, Great Crested Newt, Adders, and the Common Lizard could also be lost.

At risk at 3.2°C of global warming

As climate change reaches 3.2°C, temperatures would be largely or completely unsuitable for mammals including Grey Squirrels, Whiskered Bats and Reeves’ Muntjac and trees including Silver Birch, Horse Chestnut, Scots Pine and Norway Spruce.

Additionally, 83 per cent of shield bugs, 84 per cent of moths, 78 per cent of bumblebees, and 45 per cent of butterflies including the Small Tortoiseshell could also be affected.

The findings come after UEA research revealed that up to half of all plant and animal species in the world’s most naturally rich areas could face local extinction by the turn of the century due to climate change if carbon emissions continue to rise unchecked.

Lead researcher Dr Jeff Price, from UEA’s Tyndall Centre for Climate Change Research and School of Environmental Sciences, said: “This research shows that climate change really will pose increasing risks to biodiversity both globally and in Norfolk.

“This is a comprehensive investigation of how climate change will impact Norfolk’s biodiversity. I was able to carry out this research thanks to a long tradition of citizen science in the county. The Norfolk and Norwich Naturalist’s Society was founded in 1869 and their members provided data used in the study.

“Robert Marsham (1708-1797) of Stratton Strawless, Norfolk, is considered to be the founding father of the science of phenology through his painstaking studying over 60 years published as Indications of Spring. The effect of changing seasons on plants and animals is now one of the well-documented consequences of climate change.

“The important thing to remember here is that global warming has already reached 1°C above pre-industrial levels. We’re currently on a trajectory for 3.2°C if international pledges to reduce CO2 are genuine. If so, major changes need to be made to how we use and produce our energy.

“Norfolk’s offshore wind turbines are an excellent example of the beginning of the transition that is needed worldwide to protect biodiversity here in Norfolk and everywhere else.

“The Paris Climate Agreement aims to put the world on track to avoid dangerous climate change by limiting global warming to 1.5°C. If this is achieved, the climate would still be suitable for the majority of wildlife in Norfolk.

“But 2°C is a tipping point at which climate conditions will become largely or completely unsuitable for many species.

“Insects are essential food to many other species. Their decline will have a knock-on effect for the food webs of Norfolk’s ecosystems of the Broads and the Coast.

“The loss of bumblebees potentially has a major impact on pollination of crops and other plants,” he added.

https://www.uea.ac.uk/about/-/norfolk-s-iconic-swallowtail-butterfly-at-risk-from-climate-change

The report is here.

The study is based on, you guessed it, models. In particular, some already developed under the Wallace Initiative.

These models attempt to link together global biodiversity with climate data, thus implying that it is climate alone which determines where plants and wildlife exist. In reality, this is a grossly simplistic assumption.

But first, let’s take a look at some of the climatic factors used in the models, and how they apply to East Anglia – basically maximum summer temperatures, annual and seasonal rainfall and extreme rainfall:

https://www.metoffice.gov.uk/climate/uk/summaries/datasets

There is no evident trend in any of the datasets. Many summers in the past have been as warm as recent ones, the climate is not getting wetter or drier, and the most extreme rainfall events occurred prior to 1971.

As is always the case with UK weather, the year to year variability swamps any underlying climatic trends.

Swallowtail Butterfly

According to UK Butterflies:

The Swallowtail is our largest native butterfly, and also one of our rarest. This spectacular insect is our only resident butterfly of the Papilionidae family, which is one of the largest butterfly families in the world. The British race is the subspecies britannicus which is confined to the fens of the Norfolk Broads in East Norfolk. This is partly due to the distribution of the sole larval foodplant, Milk-parsley. Seeing the adult butterflies flying powerfully over the Norfolk Broads is a sight to behold, and one near the top of the list of most British butterfly-watchers.

In some years, there are reports of the gorganus subspecies arriving from the continent. This subspecies is less fussy and will use many kinds of Umbellifer, such as Wild Carrot, as the larval foodplant. 2013 was an exceptional year for this subspecies, with sightings from 13 sites across Hampshire, Sussex and Kent, and a single site in Buckinghamshire. These sightings included evidence of egg-laying and the resulting larvae and pupae have been followed through to spring 2014. On April 14th 2014 a single continental Swallowtail was seen and photographed at the Magdalen Hill Down Butterfly Conservation reserve near Winchester in Hampshire.

http://www.ukbutterflies.co.uk/species.php?species=machaon

From a purely climate point of view therefore, the Papilionidae family is perfectly able to flourish in all sorts of climate across Europe, and indeed elsewhere.

The Swallowtail is only restricted by the availability of milk-parsley, which can only grow in wetlands, such as the Broads.

In 2014, the BBC reported:

The swallowtail is one of Britain’s finest butterflies. Its large and distinctive wing shape and beautiful markings make it eyecatching.

Swallowtails were once found in wetlands across the UK but their numbers declined sharply in the 1920s. Nowadays careful management of the habitats in which they thrive is enabling a slow reversal of their fortunes.

Swallowtails are currently found on the Norfolk Broads, at one privately-owned site in Suffolk and at Wicken Fen in Cambridgeshire.

Swallowtail distribution is wholly dictated by the availability of milk parsley, its caterpillar food source.

When the Norfolk Broads were actively managed by reedcutters who harvested both reed and sedge for thatching, areas were left clear enabling milk parsley, and consequently swallowtail butterflies, to flourish.

Around World War One demand for thatch declined sharply as other roofing materials became more popular. By the 1980s many of the Broadland reed and sedgebeds had become overgrown and neglected.

Milk parsley had been all but choked out, depriving swallowtail caterpillars of their lunch. Conservationists now recognise the necessity of regular reed and sedge cutting to nurture swallowtails and other Broadland wildlife.

At several places on the Norfolk Broads, principally Norfolk Wildlife Trust’s nature reserve at Hickling Broad, regular cutting is providing more open areas where swallowtails can flourish.

http://www.bbc.co.uk/norfolk/your/extra/swallowtail.shtml

So, the big decline in the 20thC had nothing at all to do with climate, but the draining of wetlands and the lack of maintenance of them.

As for milk-parsley itself, this is a very widespread plant and is native to most of Europe. If Norfolk does get a bit hotter in the next century, the effect on milk-parsley is likely to be zilch.

The UEA study appears to have fallen into the trap of assuming that because the butterfly does not exist in warmer climes on the Continent, it will not be able to survive in a warmer climate here.

Unfortunately, the Swallowtail is a bit of an evolutionary dead end, which has become overspecialised in its reliance on a single source of food.

Common Shrew

Incredibly this little varmint also appears on the UEA’s death list, under the category “Climate largely or completely unsuitable by 2°C”.

According to the BBC Nature:

Common shrews are one of Britain’s and northern Europe’s most abundant small mammals.

They inhabit a wide variety of habitats and climates. The idea that Norfolk might get a bit too warm for them is frankly piffle.

Which just about sums up the whole UEA study!

Laughably at the end of the UEA’s press release, we get this:

At least they’ve got a sense of humour!