Humans Shrink to Hobbit-Size in Warmer World

Let’s say the world doesn’t get its act together and scientists’ worst fears come true – what will happen to humans and animals if global temperatures rise by 6°C during this century? 

Animals and humans will likely shrink in size because "hobbit-sized humans have the best chance for survival in a less nourishing world, say scientists.

Last time the earth became so warm that’s exactly what happened – dwarfism was a successful strategy to avoid starvation for a large range of species including horses, many insects and even earthworms. It helped them cope with the heat, but mostly it helped them get enough nutrition. Many plants became less nutritious so they had to eat more to survive, says Paul Brown on Climate News Network. The smaller they are, the less they need to eat.

An international group of scientists are discovering these adaptation measures by studying fossils in Wyoming that date back to 55 million years ago – when the Earth’s temperature suddenly rose as it is today.

Many climate change deniers like to point to the Earth’s changing climate as a natural cycle, but there’s one major difference they overlook. When temperatures rose 55 million years ago, it took 10,000 years for it to gradually rise.

Over that time, many animals, plants and insects migrated north or evolved into new forms. Alligators, for example, were able to navigate to the Arctic and completely new species emerged in the tropics. Even then there was mass extinction because most species could not adapt.

Today, we are seeing the same temperature rise compressed into a couple hundred years.

That doesn’t leave any time for species to adopt evolutionary protection, including humans. Long-lived species, such as trees, don’t have time to evolve and migrate, and animals that try to find gentler climates are boxed in by human development everywhere.

In a much warmer world, food supplies would be drastically reduced, creating catastrophic conditions for our overpopulated world.

"The result will be mass extinction, and for the survivors, humans, animals and insects, there will be a scramble to eat a diminishing and less nutritious food supply," says Brown.

As carbon rises in the atmosphere, although plants may grow faster, they become less nutritious. "Plant growth experiments have shown that concentrations of both nitrogen and the protein Rubisco, which regulates carbon dioxide fixation, decrease under higher CO2 conditions, making many plant tissues less nutritious," he says.

"To get the same calories herbivores would have to eat more plant matter.  Humans would be forced to grow more crops to get the same nutrition from food and spend more time eating it. Farm animals would also get smaller in response, making meat more difficult to obtain. Competition from insects eating food crops would be fierce."

Dwarfism would allow survivors – humans, animals and insects – to mature earlier with less food and so reproduce before they starve.  

"For me this just shows how pervasive the impacts of altering the global carbon balance really are" one of the scientists, Dr Jardine, told Brown. "Even if future climate change isn’t a convincing enough argument to decrease carbon emissions, increasing atmospheric CO2 concentrations has a very real possibility of reducing the viability of our own food supplies, by compromising the base of the food chain for ourselves and the animals that we farm and eat."

"The impacts of this on a large and growing human population could be catastrophic, especially in the developing world and when changes in other resources, for example water, are factored in as well," says Jardine.

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