Twelve years.

More than the maximum number of years your hot water heater should last, that figure represents the amount of time humans have left to significantly curb climate change to avoid widespread environmental devastation, according to a new study out of the United Nations (UN).

The authors warn that, should the global temperature rise more than 1.5°C, we will begin to experience some of the worst effects of climate change to date — at which point, they say, the consequences will drastically increase. This translates to more extreme weather conditions and heat, drought, floods, poverty and, ultimately, the destruction of ecosystems and the extinction of species.

“This is the largest clarion bell from the science community, and I hope it mobilizes people and dents the mood of complacency.”

“Every extra bit of warming matters, especially since warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems,” Hans-Otto Pörtner, a member of the study panel, said in a press release.

Conducted by the UN Intergovernmental Panel on Climate Change (IPCC), which included 91 authors and review editors from 40 countries, the study was released in early October. Its findings are meant to be an admonition, an attempt to drive humans — cities, states, and countries — to action.

“It’s a line in the sand, and what it says to our species is that this is the moment and we must act now,” Debra Roberts, co-chair of IPCC Working Group II, told The Guardian. “This is the largest clarion bell from the science community, and I hope it mobilizes people and dents the mood of complacency.”

The global temperature, however, has already been increasing at a rate of 0.7 to 0.9°C per century since 1901, according to data from the National Oceanic and Atmospheric Administration (NOAA). But the rate at which it is warming is accelerating — in fact, nearly doubling since 1975 to 1.5 to 1.8°C per century.











Previous commitments made by some nations to curb CO 2 emissions would allow for temperatures to reach 3°C by the year 2100 — much too high, scientists now argue. We have until 2030 to curb emissions enough to prevent the global temperature from exceeding the 1.5°C threshold, according to the IPCC report. But we’ll also have to stop all such emissions by 2050 or begin removing more CO 2 out of the atmosphere than we put into it.

While humans have been impacted in somewhat less recognizable ways by climate change, some of the most visible damage caused by increasing global temperatures is occurring among wildlife. Vulnerable to the slightest changes in climate, some mammals have specific requirements with regard to weather conditions and habitat that are necessary for their survival; according to a report from the Climate Resource Center (CRC), these often involve snow, sea ice or temperatures within a certain range for hibernation.

“They need places to hide, eat, drink, and breed, and in many cases, these places are distinct and may change seasonally.”

Animals are likely to be affected on a more basic level as well. “They need places to hide, eat, drink, and breed, and in many cases, these places are distinct and may change seasonally. Thus, there are many opportunities for climate change to disrupt mammalian life histories,” the CRC report reads. “In general, they will not be able to effectively hide in microhabitats; in contrast, many plants can persist as rare endemics long after the climate has changed.”

Even at the 1.5°C threshold, changes in ocean temperatures are expected to “drive some species (e.g., plankton, fish) to relocate to higher latitudes,” according to the IPCC report. Unable to move, ecosystems such as kelp forests and coral reefs will experience high rates of mortality, researchers say, which will have far-reaching effects as these underwater habitats, according to NOAA, are home to millions of species.

The risks with regard to the loss of mammals and therefore extinction are much lower at or below the 1.5°C threshold, authors of the IPCC study say. “The number of species projected to lose over half of their climatically determined geographic range … is reduced by 50 percent … at 1.5°C versus 2°C of warming,” they wrote. “Risks associated with other biodiversity-related factors such as forest fires, extreme weather events, and the spread of invasive species, pests, and diseases, are also reduced at 1.5°C of warming.”

Notwithstanding this evidence for the need to further limit climate change and its harmful effects, rising temperatures are already impacting North American wildlife. Delayed winters across parts of the country, for instance, are enabling parasites to thrive, which is taking a toll on wildlife. Take for example the moose that were the focus of the recent New York Times article titled “47,000 Ticks on a Moose, and That’s Just Average. Blame Climate Change.”











The author, Kendra Pierre-Louis, explores one professor’s research into an uptick (pun intended) in tick populations in Maine and New Hampshire over the last three years. For moose calves, Professor Peter J. Pekins told the Times, a large number of ticks can be fatal. “Anything over 35,000 is trouble for a calf moose,” he said. One calf being tracked by Pekins — host to more than 50,000 ticks — was found dead as a result of anemia and extreme weight loss.

“While salmon might currently be on the menu, climate change is expected to impact major commercial and recreational fishing industries in the coming years.”

Other animal species feeling the effects of climate change, per the U.S. Department of the Interior’s (DIO) website, include snowshoe hares, sea turtles, puffins, Alaskan caribou, polar bears, salmon, and others. Salmon need cold, fast-moving streams in which to reproduce, but warming waters and the changing of currents in the Pacific Northwest are affecting some populations.

“Higher temperatures have also led a harmful salmon parasite to invade Alaska’s Yukon River,” DOI’s website states. “So while salmon might currently be on the menu, climate change is expected to impact major commercial and recreational fishing industries in the coming years.”

With so many factors that influence wildlife and each other — weather, habitat, parasites, disease, food supply, availability of water, reproduction, migration — one of the beauties of the natural world, its interconnectedness, seems doomed to play a leading role in its demise.

Yet humans are not immune to the same forces.