'Nowhere On Earth Safe' From Climate Change As Survival Challenge Grows

Fairfax - Peter Hannam

As if humans weren't making it hard enough for the world's creatures great and small.
Evidence continues to mount that global warming is having an impact on ecosystems across the planet in a myriad of ways, altering both individual species and ecological communities.

Thirty years of Arctic ice decay
Incredible animated video released by NASA shows the drastic change of the Arctic ice shelves over thirty years.

"There's really nowhere on earth where the natural systems are not being affected by climate change," Lesley Hughes, a professor of biology at Macquarie University, said.
"Climate change is simply an additional stress on already stressed ecosystems," Professor Hughes said, listing habitat loss, pollution and over-exploitation among the existing challenges.
A recent paper in Science surveyed research on 94 core ecological processes and found 82 per cent were already revealing climate change impacts as temperatures warmed.
James Watson, a conservation biologist at the University of Queensland and one of the paper's authors, said people often fixated on polar bears, penguins or another emblematic species.
"They think, 'that's miles away from me; it's a pity but it doesn't affect me'," Professor Watson said. "It's everything that's affected."
Here are six key areas of change:

Physiology
Warming temperatures alter the sex ratio of offspring of certain marine and terrestrial species.

Polar bears get much of the media attention about how climate change is affecting species - but the struggles extend far wider, scientists say. Photo: SeppFriedhuber

As  Fairfax Media reported, sea turtle eggs incubate at a uniform 29 degrees, with the male-female ratio changing according to temperature. If temperatures reach 30.5 degrees all offspring will be females. (Should the species survive long enough without males, 33 degrees is enough to ensure no embryos make it.)

The oceans are home to some other big changes, such as increasing acidity as waters absorb more carbon dioxide.
Corals are among the species in the firing line, as are creatures with shells, such as tiny pteropods, the Science paper said.
"Severe levels of shell dissolution" were reported for some Antarctic pteropods, according to a paper in Nature Geoscience.
"As deep-water up-welling and CO2 absorption by surface waters is likely to increase as a result of human activities, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand," the paper said.
These kinds of changes "have the capacity to undermine and change dramatically the structure of marine food webs, which ultimately underpin much of the protein sources for humans", Professor Hughes said.

Genetics
Species with short generation spans, such as phytoplankton, are changing fast, but not fast enough.
In the Gulf of Cariaco, off Venezuela, phytoplankton have managed to adjust their ecological thermal niche by 0.45 degrees over a 15-year period. The response, though, lagged the 0.73-degree warming of waters over that time.
For others, such as the southern flying squirrels on North America, hybridisation with "cousin species" the northern flying squirrel is one response. (See image below of northern flying squirrel, via www.nature.ca )

Since 1995, a series of unusually warm winters has marked the start of a northward surge of 240 km in the range of the southern squirrel, the Daily Climate reported, based on work published in Global Change Biology.
Similar hybridisation is evident elsewhere, generating other concerns.
"The interbreeding has several consequences, none well understood: It could increase genetic diversity, helping species weather rapid ecosystem changes," the Daily Climate said. "It also could dilute the genetics of at-risk animals such as polar bears, perhaps even diluting them beyond recognition. And the changes threaten to wreak havoc with conservation efforts."

Morphology
Individuals of some species are shrinking in size, as scientists have expected, as creatures with larger surface-to-volume ratios are favoured as temperatures rise.
The body size of six woodland salamander species in the US Appalachian Mountains has shrunk an average of 8 per cent over the past 50 years, Science said.

Species of butterflies, dragonflies and birds are also changing colour, other studies showed, with some becoming darker or lighter, depending on local advantages. The skull shape of alpine chipmunk has "revealed significant changes" in California over the past century as its ranges narrow and its diet changes.

Phenology
The timing of many life processes of species – such as the budding of plants, the hatching of birds and migration timings – is closely tied to climate variation. Climate shifts are throwing such processes out of whack.
"Across marine, freshwater, and terrestrial ecosystems, spring phenologies have advanced by 2.3 to 5.1 days per decade, the Science paper said. "A combination of climate warming and higher atmospheric CO2 concentrations has extended the growing period of many plant populations."
Examples include reduced fledging success of tawny owls in the UK as hatchings over the past 27 years have become synchronous with its principal prey, the field vole.
Another predator-prey mismatch is evident among blooms of spring diatoms, which have advanced more than 20 days since 1962, triggering declining populations of its main grazer, the water flea.

Distribution
A shift in species' location is one of the most rapid responses observed especially for marine creatures with fewer connectivity issues compared with land-based ones, Science said.
Professor Watson said changing seasonal rains mean Australia's savannah regions are experiencing more intense fires later in the season, killing off grasses. The result is that rainforests are expanding to fill the ecological gap

Elsewhere, corals around Japan have shifted their range by as as much as 14 km per year over the past 80 years, the paper noted.
In the mountains of New Guinea, birds have shifted their distributions, moving up the slopes by as much as 152 metres between 1965 and 2013, according to other research.

Inter-species relations
As species are becoming redistributed, existing interactions between species are being disrupted.
Off Western Australia, for example, overgrazing of subtropical reefs by the pole-ward spread of tropical browsing fish hampered the recovery in 2013 of kelp killed by a previous heatwave event, according to research published by Ecology Letters.
Feeding rates by the browsing fish were about three times higher than previously observed on coral reefs.
Elsewhere, woody plants are invading arctic and alpine herb-dominated communities in response to rapid warming in recent decades, triggering secondary shifts in distribution of other plants and animals, Science said.

In  one example from Sweden, resident birds, such as the great tit, had become better able to adapt to warmer temperatures and out-compete with the pied flycatcher, the sole long-distance migrant.
In general, movements of many species are becoming more erratic and harder to predict, Professor Watson said.

'Almost incomprehensible'
"The frightening thing is that we have only had a degree of warming so far [since pre-industrial times], Professor Hughes said, adding that the rate of warming will be three times even if nations "perfectly kept" promises made in the 2015 Paris climate agreement.
"The changes that would go along with 3 degrees are almost incomprehensible," she said.
A paper out this week published by The Royal Society examined how fast ecological niches occupied by various species were adapting and how much they would need to change over the next 55 years.
The analysis of 266 populations of plants and animals showed rates of change in climatic niches to be dramatically slower than rates of projected climate change, in the order of 200,000-fold for temperature.
Species in the tropics – typically the most various on earth – were less capable of adjusting than those at higher latitudes, the authors led by the University of Arizona found.
Professor Hughes said species in the Darwin region might only need to tolerate a temperature range over the year of about 30-35 degrees, while those in the Sydney region might endure a 0-40 degree range.
"Those species in the tropics probably have a far narrower range of variability that they can cope with," she said. "That predisposes them to being more vulnerable" in a warming world.

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