The impact of climate change is accelerating across the globe, and countries have to act now to cut fossil fuels to avoid further warming that could be catastrophic to people and the planet.
That's according to a nearly 4,000-page report released Monday by the United Nations Intergovernmental Panel of Climate Change. The highly anticipated report is the panel's sixth climate report and the first one since 2013.
It is "unequivocal" that humans have heated the atmosphere, ocean and land, the report says, noting humans have caused the global surface temperature to increase by about 1.1 degrees Celsius (2 degrees Fahrenheit) since 1850-1900.
Human-induced climate change is already impacting every region across the globe, causing heat waves, heavy precipitation, droughts and rising sea levels, among other changes in weather and climate extremes. And many changes caused by greenhouse gas emissions are irreversible for "centuries to millennia," especially changes to oceans, ice sheets and the global sea level.
"Current and future sea-level rise are almost irreversible at this point — that’s like tapping the breaks on a high-speed train," meteorologist Sven Sundgaard told Bring Me The News. "Glaciers and ice caps will continue to melt rapidly for many decades even if we shut off CO2 today. But, we can avoid further absolutely catastrophic rises by starting that process now and again with drastic emission cuts."
Even if countries take action now to cut emissions, it is expected the global temperature will warm approximately 1.5 degrees Celsius over the next 20 years — the level experts and officials have been trying to avoid.
At that level of warming, the intensity and frequency of heatwaves, heavy precipitation and droughts will increase. And If the global temperature hits 2 degrees Celsius of warming or more, climate extremes will be more widespread and climate events that happen once per century will occur at least annually or more by 2100, the report explains.
What this means for Minnesota
Summers like the one we've had this year — hotter temperatures, longer heatwaves and severe droughts — will likely be more numerous in Minnesota and much of the Upper Midwest in the decades to come, the report says. While winters will be warmer, with less ice on the lakes and less snow cover.
"Minnesota is an extreme climate by nature and those extremes will continue to amplify," Sundgaard said, explaining that heat waves will get longer, wet periods will be wetter and dry periods will be drier.
The mean temperatures across North America will be warmer in the years to come, with the highest increases at higher latitudes, like Minnesota, and in the winter months, the report says.
"We’re warming much faster in winter than summer — in fact by double the rate," Sundgaard said. "'Normal’ winters have become exceedingly rare now. When we think we had a cold winter, it wasn’t it was usually just a cold month."
Extreme cold temperatures have "dramatically dropped off," he added, noting Minnesota used to reach 20-below zero Fahrenheit or colder two to four times per winter, on average, around 1900 and before. Now, Minnesota averages that kind of temperature about once every two years.
"We’ll still get cold snaps — and they garner lots of attention because everyone thinks those are supposed to be gone in global warming — but they are most definitely less frequent, less severe, and less in duration," Sundgaard said.
With warmer temperatures, there will be a shift in the timing of the seasons, increasing the number of crop growing days, reducing chill hours, and lengthening pollen and allergy seasons, the report notes. The frost-free season will be longer, which will equate to a longer construction season and longer orchard production seasons.
A longer warm season and warmer winters mean less ice on the lakes and greater potential for winter thaws, which could heighten the threat of ice jams and reduce the seasonal viability of ice roads and frozen lakes for recreational use, the report says.
And warmer temperatures combined with precipitation will continue to degrade Minnesota's lakes due to hypoxia and algae blooms, Sundgaard said.
When it comes to rain and snow, heavy precipitation events are expected to be more widespread across North America. Sundgaard says these events will become more extreme in Minnesota, noting 2-inch rainfall events in summer have already increased "dramatically."
Overall, seasonal snow cover will shrink and snowfall will decrease over time. But Sundgaard says it's a little more complicated than that — "a warmer atmosphere also holds more moisture, so storms can be more powerful with higher snowfall amounts," Sundgaard said.
You can explore the predicted changes to Minnesota's climate, and elsewhere on earth, on an interactive atlas here.
What can be done
To avoid the worst of climate change and prevent the planet from getting any hotter, countries must stop adding carbon dioxide to the atmosphere by 2050. This would require a shift away from fossil fuels, and fast.
“Stabilizing the climate will require strong, rapid, and sustained reductions in greenhouse gas emissions, and reaching net-zero CO2 emissions. Limiting other greenhouse gases and air pollutants, especially methane, could have benefits both for health and the climate,” IPCC Working Group I Co-Chair Panmao Zhai said in a statement.
Doing this would benefit air quality rather quickly, but it could take 20-30 years to see global temperatures stabilize.
While it's likely that the earth will warm to 1.5 degrees Celcius relative to 1850-1900, if nations cut back emissions it is more likely than not the global surface temperature would go back below 1.5 degrees Celsius toward the end of the 21st Century, the report says.