Climate change shrinking animals and plants, experts warn

ANIMALS and plants all over the planet are shrinking because of climate change, scientists have warned.

It could also lead to extinctions as ecosystems are thrown into disarray, robbing living things of the resources they need to survive, experts say.

Organisms become smaller as warmer and drier conditions affect early development and growth, according to the researchers.

They point to a century of evidence of plants and animals reducing in size as a result of climate change.

Examples include grasses and trees, toads, tortoises, goshawks, gulls, woodrats, Soay sheep and red deer.

Even polar bears are starting to get smaller in response to the loss of sea ice, it is claimed.

Cold blooded animals, which make up the majority of life on Earth, were said to be especially vulnerable. Size reduction made creatures such as amphibians more susceptible to desiccation — or extreme dryness — from evaporative heat loss.

Experimental research had also shown that for every degree Celsius of warming, plants of various types shrank by between 3% and 17%.

Each degree rise in temperature was also known to decrease the body size of marine invertebrates by 0.5% to 4%, of fish by 6% to 22%, of beetles by 1% to 3%, and of salamanders by 14%.

Studies had also shown that corals, oysters, scallops and other calcifying ocean dwellers suffer stunted growth as a result of climate change acidifying the sea.

The research, led by Dr David Bickford from the National University of Singapore, is reported in the journal Nature Climate Change.

The scientists pointed out that by 2100 average temperatures could rise by as much as 7C.

This mirrors the dramatic changes seen during the Palaeocene-Eocene Thermal Maximum (PETM) 55 million years ago, when temperatures rose by 3% to 7% and precipitation levels fell by around 40%.

Preserved soil burrows show over this period invertebrates such as beetles, bees, spiders, and ants shrank in size by 50% to 75%.

Other animals ranging from single-celled diatoms to squirrels and woodrats were also known to have shrunk during past episodes of warming.

The consequences of species getting smaller were “not yet fully understood, but could be far-reaching for biodiversity and humans alike”, said the scientists.

One “extreme response” to size reduction resulting from climate change was extinction, they wrote.

An important factor was that different types of organism did not shrink at the same rate. This was likely to upset delicately balanced ecosystems.

“If producers shrink faster than consumers, then consumers are likely to suffer from a lack of resources that could reduce body condition, increase susceptibility to disease, lower birth rates, and increase mortality,” said the scientists.

They warned shrinking fish and crustaceans could adversely affect the nearly one billion people who get their main sources of protein from the sea.

There would also be an impact on crops. “Feeding the billions of additional people expected by 2050 will become increasingly difficult as many areas become drier and crop plants are unable to grow as large,” the researchers wrote.

They concluded: “Although there will be adaptive responses that natural selection will favour, ecosystem services and global ecological processes will most likely be altered, but not in ways that will benefit human livelihoods.

“Reduction in nutrients, food availability and water will probably have negative implications and are inter-related with climate change and shrinking organisms. Furthermore, extreme climate events might prove to be at the critical limit of some species’ survival. We need to understand how and why organisms are shrinking, how feasible it is to mitigate or adapt to such climate change effects, and what it means for biodiversity and humanity if we are unable to change this pattern.”