Year in review: Climate warnings heat up

Carbon emission cuts are planned

SPEED UP The collapse of West Antarctica’s glaciers may be unavoidable, and the ice sheet’s demise could raise global sea level by as much as 4 meters, researchers reported. In recent years, the flow of these glaciers into the ocean has largely accelerated (red), which exacerbates melting.

J. Mouginot et al/Geophysical Research Letters 2014

By Beth Mole

December 15, 2014 at 9:00 am

Climate change is here and the world is unprepared, scientists and policy makers declared multiple times in 2014. Meanwhile, researchers continued to tally the environmental fallout of rising greenhouse gas levels while searching for signs of missing heat from Earth’s surface.

In March, the Intergovernmental Panel on Climate Change reported that the world is generally unprepared to protect vulnerable communities from outcomes such as food shortages and flooding. In April, another IPCC report suggested strategies to cool global warming’s consequences, including adopting more alternative energy sources and capturing more greenhouse gases (SN: 9/6/14, p. 22; SN Online: 4/13/14). In November, the IPCC reemphasized that human activities are to blame for climate change and that a global response is urgently required.

In June, President Barack Obama released a plan to cap carbon pollution from power plants. By 2030, the proposed rule would reduce U.S. emissions by 30 percent compared with 2005. In October, European Union leaders agreed to slash greenhouse gas emissions by 40 percent in 2030 compared with 1990. And in November, Obama announced a deal with China to cut carbon pollution in the United States by 2025 and in China by 2030. China is the world’s top carbon emitter; the United States is second.

The carbon-cutting plans came after a new record for atmospheric carbon dioxide: April was the first month in recorded history in which average carbon dioxide levels in the Northern Hemisphere were at or above 400 parts per million (SN: 6/28/14, p. 18).

Throughout 2014, scientists continued to uncover climate change effects. One analysis found that bouts of extreme heat on land are on the rise (SN: 4/5/14, p. 12). Researchers also discovered that West Antarctic glaciers have reached unstoppable melting (SN: 6/14/14, p. 11). The West Antarctic ice sheet’s demise could boost global sea level by as much as 4 meters in coming centuries.

Uncertainty lingers about where all of the heat is, exactly. Since around 2000, researchers have noted a plateau in global surface temperatures despite rising greenhouse gas levels. Scientists suggested that strong winds over the Pacific shoved heat deep into the water (SN: 3/22/14, p. 12). Another study suggested that natural heat-moving conveyor belts in the Atlantic and Southern oceans have switched into overdrive, concealing the bulk of the warmth (SN: 9/20/14, p. 10).