NATURE SHOWING WIDESPREAD CHANGES FROM JUST ONE DEGREE OF WARMING--MORE TO COME

A few years ago I was backpacking in California's Sierra Nevada. Sitting by an alpine lake late in the afternoon, I noticed something interesting. On the hillsides rising up from the lake the stands of pine trees showed a striking pattern. On the lower slopes there were only the remains of dead trees--tall, scraggly skeletons with a few bare branches. A bit higher up the slope was populated by clusters of trees, not the age or height of the dead giants below, but a substantial, growing population. And above them were saplings, staking out still higher ground. "Look at that," I said to my hiking buddies, "the trees are migrating up the slope."

June Lake, Sierra Nevada Range/Credit: Don Graham

At the time, we were pretty sure that we had stumbled upon one, small, local impact of climate change, although of course we knew that what we were seeing could be explained in other ways, and that one case doesn't prove anything.

However, our intuition was probably right. A new study in the prestigious journal Science surveys multiple studies from around the world and finds that 82 percent of the vital biological functions they examined showed clear changes in response to the 1 degree C the Earth has warmed since the beginning of the industrial revolution.

"Genes are changing, species' physiology and physical features such as body size are changing, species are shifting their ranges and we see clear signs of entire ecosystems under stress, all in response to changes in climate on land and in the ocean," says wildlife ecologist Brett Scheffers, at the University of Florida.

Climate change impacts on ecological processes in marine, freshwater, and terrestrial ecosystems/Credit: Scheffers et al., Science, 11 November, 2016

The authors explain that the genetic, physical and population changes they documented represent crucial aspects of the healthy functioning of Earth's ecosystems, biological systems on which human well-being depends. These impacts varied from 60 percent for genetic changes to 100 percent for changes in species distribution. And, these wide-ranging impacts are happening sooner than many experts expected.

"Some people didn't expect this level of change for decades," said environmental researcher James Watson, at the University of Queensland, Australia. "The impacts of climate change are being felt with no ecosystem on Earth being spared."

It's important to recognize that these changes are not just abstractions of interest to scientists and nature lovers. They impact us all directly. The authors write:

Disruptions scale from the gene to the ecosystem and have documented consequences for people, including unpredictable fisheries and crop yields, loss of genetic diversity in wild crop varieties, and increasing impacts of pests and diseases. 

Since we're seeing these across-the-board changes sooner than expected, and with only one degree C of human-caused warming, it becomes all the more urgent to do everything we can to reduce CO2 and other greenhouse gases, and to move as quickly as possible to alternative energy sources such as solar, wind and hydro.

With the coming Trump administration threatening to do everything it can to reverse the progress towards climate-change mitigation that the US has made in recent years, we will have to look to the rest of the world to recognize the need to sustain a healthy and habitable planet, and act to preserve it.