Climate Change Dilemma: Rescuing Nature Through “Assisted Migration” vs Invasive Ecosystem Disruption

Guest essay by Eric Worrall

Scientists trying to help species migrate North far outside their natural range, to help the species survive global warming, are encountering objections from people who think it is wrong to disrupt ecosystems by introducing new species. But supporters of the scheme are worried the climate is changing too fast for nature to keep up.

‘Playing the hand of God’: scientists’ experiment aims to help trees survive climate change

Scientists use a strategy called assisted migration in an attempt to rescue tree species from inhospitable conditions

Ashley Stimpson
Published onWed 8 Jul 2020 20.00 AEST

Since 2013, TNC has planted more than 2,000 longleaf pine seedlings in fields not far from the Delaware state line. Today, clumps of longleaf stand together like gangly kids at recess, their eponymous green needles shooting out like pompoms in every direction.

But longleaf is not native to Maryland, and many scientists believe they should not be planted at Plum Creek, or anywhere outside of theirnatural range. These relatively young trees are part of an experiment to determine if human intervention could help the pines migrate north as climate change alters its natural range.

Not everyone’s onboard. Assisted migration has been accused of being expensive and risky, a case of humans playing God.

But “I do not believe longleaf pine could move quickly enough at the rate the climate is changing,” explains Dr Deborah Landau, a TNC restoration ecologist.

Landau says that, on Facebook, TNC’s longleaf project has been accused of “playing the hand of God”. She dismisses the criticism. “There’s so little nature left that we haven’t already had a heavy hand in,” she says.

Despite the detractors, Landau has seen a shift in attitudes about assisted migration in the decade since Ricciardi and Simberloff’s article was published.

“Now that climate change is here, people are more open to the prospect of aiding species that won’t be able to keep up,” she says. “It’s happened. It’s happening. We need to respond.”

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The suggestion nature cannot keep up with climate change is not supported by historical evidence.

The Younger Dryas was an abrupt multi-degree Northern Hemisphere return to ice age conditions which occurred 12,800 years ago and lasted around 1,300 years. The initial cooling may have occurred in as short timeframe as a few months, certainly no more than a handful of years – orders of magnitude faster than today’s global warming.

Until now, it was thought that the mini ice age took a decade or so to take hold, on the evidence provided by Greenland ice cores. Not so, say William Patterson of the University of Saskatchewan in Saskatoon, Canada, and his colleagues. 

The group studied a mud core from an ancient lake, Lough Monreagh, in western Ireland. Using a scalpel they sliced off layers 0.5 to 1 millimetre thick, each representing up to three months of time. No other measurements from the period have approached this level of detail. 

Carbon isotopes in each slice revealed how productive the lake was and oxygen isotopes gave a picture of temperature and rainfall. They show that at the start of the Big Freeze, temperatures plummeted and lake productivity stopped within months, or a year at most. “It would be like taking Ireland today and moving it up to Svalbard” in the Arctic, says Patterson, who presented the findings at the BOREAS conference in Rovaniemi, Finland, on 31 October. 

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The multi-degree return to warm conditions which followed the Younger Dryas was also extremely rapid (see the graph at the top of this page).

My point is, most Northern Hemisphere species alive today survived past abrupt climate shifts both up and down, of far greater magnitude and pace than today’s gentle global warming. The abrupt Younger Dryas climate shift was disruptive, but it was not a significant extinction event. Nature is resilient, it does not need our help.

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via Watts Up With That?

July 12, 2020 at 12:01AM