Warming climate leaves its varied marks

Northern pocket gophers have lost up to 70% of their range in Nevada. Image: By US National Park Service

The warming climate is changing the globe: mountain species climb higher, valley floors sink and animal numbers fall, while their living space shrinks.

LONDON, 28 September, 2018 – The Earth’s warming climate is already reshaping the planet. A new study confirms that plants and animals unique to the mountains are climbing ever higher to survive.

A second research team has taken a closer look at the valley floors of Central California to find that one of them is now, thanks to drought conditions, sinking by up to half a metre a year.

In central and eastern Europe, German scientists have found that the Danube – on which people used to skate every winter – has frozen only a handful of times in the last 70 years.

And far to the south, French scientists report that one of the world’s largest colonies of king penguins has dwindled by 88% since 1982.

In all cases, researchers identify a possible environmental cause: and in all cases the changes could be linked to global warming. In three instances out of four, climate change has already been implicated by other studies.

“The scientists calculate that for every 1°C rise in temperature, species are moving an average of 100 metres uphill”

Years ago, Swiss scientists observed a steady uphill migration of alpine butterflies and birds; while US scientists have charted change in mountain flora in the Rockies and Danish scientists revisited an Andean mountain first explored by the great Alexander von Humboldt to find that the plants he recorded had climbed 500 metres in 210 years.

Now Canadian scientists report in the journal Global Ecology and Biogeography that they set themselves the challenge of the global picture: they reviewed studies of elevation shifts in 975 species of plant, insect and animal.

In the French Pyrenees, the mountain burnet butterfly has shifted uphill by 430 metres and surrendered 79% of its range. In the Himalayas, where temperatures have risen by 2.2°C in 150 years, one meadow flower has migrated more than 600 metres and lost 28% of its preferred habitat. In Nevada’s Ruby Mountains, the northern pocket gopher has responded to a warming of 1.1°C in 80 years by climbing higher and surrendering 70% of its living room.

Altogether, the scientists calculate that for every 1°C rise in temperature, species are moving an average of 100 metres uphill.

In the mountains of California, the peaks are getting ever higher because the reduced mass of snowfall no longer depresses the rock.

Sinking feeling

Paradoxically, thanks to the combination of sustained drought and relentless abstraction of groundwater for agriculture, things are going downhill in the San Joaquin valley of California,, according to scientists from Cornell University who report in the journal Science Advances. The valley is home to 75% of California’s irrigated farmland. It supplies 8% of US agricultural output and it has a long record of slow subsidence.

The Cornell scientists report that between 1962 and 2011, the valley lost groundwater at the rate of 1.85 cubic kilometres a year. Between 2012 and 2016, during the state’s worst-ever drought, the same basin lost 40 cubic kilometres of groundwater, and the ground fell at 50 cms a year, except for a slowdown in subsidence during the heavy rains of 2017. The previous rate of subsidence has resumed.

The Danube Commission has kept records since 1836 of the behaviour of Europe’s second largest river as it flows from the Alps to the Black Sea. Researchers from Germany’s Alfred Wegener Institute write in the journal Scientific Reports that archivists reported ice cover almost every year, ice thick enough to bear skaters.

But between 1951 and 2016, the river froze only 10 times. Although more people live in Europe than ever before, and discharge more outflow into the Danube basin, the researchers identify global warming as a substantial cause: winter temperatures have risen and are now more than 1.0°C warmer than in the first half of the 20th century.

Problems for penguins

And rising temperatures might be at the heart of the crisis for king penguins on the Iles Crozet archipelago in Antarctica: French scientists report in the journal Antarctic Science that in 1982 the colony was home to 500,000 breeding pairs and two million specimens of Aptenodytes patagonicus.

Now the colony has shrunk, and vegetation cover has expanded. The loss might be linked to lack of food, or a major natural warming event such as El Nino, or to disease such as avian cholera.

But global warming and climate change have already been linked to alarms over the king penguin elsewhere, and to the possible fate of the emperor penguin.

The research is based on aerial imagery and satellite studies, and on-the-ground research is still needed to explain quite why a colony which once supported 500,000 breeding pairs should now number only 60,000 penguin couples.

“The cause of the massive decline of the colony remains a mystery, and needs to be resolved,” the French scientists say. – Climate News Network

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