Major report: Ice-free Arctic summers by 2050, more snow, more heat

The Arctic Ocean will be “practically ice-free” at its summer minimum at least once by 2050, a major new report projects, warning many consequences of climate change are now unavoidable.

The Intergovernmental Panel on Climate Change, a group of scientists convened by the United Nations, released its first large-scale assessment of climate science since 2013 on Monday. The report makes clear that global warming will now intensify for decades to come, no matter what countries choose to do.

However, the scientists say, drastic action can still prevent some of the worst-case scenarios.

Global warming of 1.5C, now considered all but locked in by 2050, is expected to cause increasingly deadly heat waves for up to a billion people, regular and severe droughts for hundreds of millions of people, and a big jump in extreme weather worldwide – well beyond the wildfires and floods that have caused misery in recent months.

But allowing that increase to get to 2C, 3C, or 4C would come with ever-worsening impacts, making the heat, water, and fire even deadlier, threatening the existence of some island nations, and risking the irreversible loss of vast ice sheets at the poles.

Monday’s report includes region-specific briefings and an interactive atlas that can be used, for example, to examine how scientists expect northern North America’s seasonal temperatures to change if, as is likely, global warming reaches 2C.

An average of various projections suggests reaching such a scenario by 2050 would warm NWT winters by 6C or more and summers by 3C, vastly altering the climate northerners know.

“Temperature increases are projected to be very large compared to the global average, particularly in the winter,” the IPCC said, summarizing its report. The report expects increased amounts of winter snow in the NWT, too, though that doesn’t necessarily translate to more spring snow cover – in some regions, snow cover has been falling year-on-year and is set to continue doing so.

For the Arctic as a whole, the IPCC declared it is “virtually certain that surface warming will continue to be more pronounced than the global average warming over the 21st century.”

Arctic sea ice cover is at its lowest level since at least 1850, the report found, and “is projected to reach practically ice-free conditions at its summer minimum at least once before 2050 under all scenarios.”

A near-total loss of Arctic summer sea ice could have catastrophic consequences for animals like polar bears that rely on the ice as part of their habitat. In turn, there could be major changes to the traditional lifestyles of northern communities reliant on the Arctic ecosystem.

Sea level rise is considered virtually certain to continue along the Arctic coast, contributing to “more frequent and severe coastal flooding and shoreline retreat.” Communities like Tuktoyaktuk are already spending millions of dollars relocating homes in the face of coastal erosion.

Wildfire seasons are expected to lengthen in the NWT and be more of a problem in tundra regions. Permafrost warming is expected to play havoc with northern infrastructure while simultaneously releasing carbon, risking a positive feedback mechanism that only worsens conditions.

The IPCC says permafrost thaw is likely to cause enough warming “to be important, but not enough to lead to a ‘runaway warming’ situation, where permafrost thaw leads to a dramatic, self-reinforcing acceleration of global warming.”

A full FAQ document walks through the basic climate change science underpinning the latest report, which is backed by 195 nations. World leaders will gather in Glasgow this fall to discuss action on climate change.

That meeting is widely expected to result in promises of stronger climate change targets, which the IPCC report makes clear must now extend well beyond anything pledged to date in order to make any real difference.

However, any action in Glasgow will be too late to avoid major changes, the IPCC concludes.

“As the climate moves away from its past and current states, we will experience extreme events that are unprecedented, either in magnitude, frequency, timing or location,” a briefing document accompanying the report states.

“The frequency of these unprecedented extreme events will increase with increasing global warming. Additionally, the combined occurrence of multiple unprecedented extremes may result in large and unprecedented impacts.”

UN Secretary General Antonio Guterres said: “If we combine forces now, we can avert climate catastrophe. But, as today’s report makes clear, there is no time for delay and no room for excuses.”