The New U.N. Climate Report Shows an Even Hotter Future—Unless We Start Acting

 

The new U.N. Intergovernmental Panel on Climate Change (IPCC) report on the current climate crisis has made news this week for offering a bleak picture of the state of global climate change, especially poignant while major fires and heat waves blanket California, Greece, and Siberia. The world could look very different, with more and more extreme weather and heat effects, unless we change global industry very soon.

The report is based on the contributions of over 200 scientists from around the world, and it combines more than 14,000 research works into one master report on the state of the entire world’s climate as both a point in time and as part of our near and further future.

Humans are causing the change

The report explicitly calls out the human effects on things like greenhouse gas emissions that have caused the climate to warm and change compared with a control simulation where there are no human activities. To make this comparison, the report’s authors compared attribution studies from around the world that showed a persistent, notable increase in global temperature and “well-mixed greenhouse gases” that are attributable to human activities like industry.

Aerosols mask some of our impact

Aerosols are clouds of particulate that can act as tiny sunblocks basically, helping to keep heat out by bouncing it away back into space. Aerosol cooling, the IPCC says, has helped to “mask” or mitigate the human impact on climate change. Aerosols are generated by industry in the form of black carbon soot, for example, and in nature as volcanic ash. Some scientists want to try solar geoengineering, a process in which we intentionally use aerosols as a way to mitigate climate change, but so far, scientists have hesitated to commit to studies in this space.

Extreme weather has increased and will continue

Heat waves have increased in severity and frequency, while cold extreme events have decreased as the planet is warmed. Even heavy rain events have increased in frequency and severity, along with an increase in tropical cyclones. The report says compound extreme events around the world, like heat and drought, have increased since the 1950s, likely caused by anthropogenic, or humanmade, climate change.

The report says it’s “very likely” that precipitation events like monsoon rains will continue to increase, with a rate of 7% more daily precipitation events for each degree of climate change—a proportional increase as the Earth grows warmer. In some scenarios where the climate changes just 1.0 or 1.8° Celsius, that may seem like not such a big deal. But without changes to global emissions, our temperature could increase 5° Celsius or more.

Hot temperature extremes like heatwaves that previously happened once in ten years will be up to 9.4 times more likely to occur depending on just how much the global average temperature increases, up to 5° Celsius. Hot temperature extremes that happened once in fifty years will be up to 39.2 times more likely to occur based on the degree of warming. Heavy precipitation will be up to 2.7 times more likely to occur, and droughts will be up to 4.1 times more likely to occur.

It’s going to get hotter, but by how much?

The report posits five possible futures to explore the impact of climate change. These range from the most conservative estimate, where the surface warms just 1.8° Celsius by 2050, to where the surface warms 5.7° Celsius, both compared to the control time period 1850-1900.

“The last time global surface temperature was sustained at or above 2.5°C higher than 1850–1900 was over 3 million years ago,” the report explains.

The report also explains that land mass as well as Arctic ice are likely to bear the brunt of surface cooling compared with the oceans, which makes sense considering how much more energy it takes to heat deep water compared with air or the surface of a solid material. (Think about frying an egg versus boiling a pot of water for pasta.)

The Arctic may melt

Permafrost is the term for soil and ice that are permanently frozen, often above the Arctic Circle or at high elevations of lower latitudes. The report says that permafrost and sea ice will both melt severely under all five of the report’s theoretical futures, from conservative to most extreme: “The Arctic is likely to be practically sea ice free in September at least once before 2050 under the five illustrative scenarios considered in this report, with more frequent occurrences for higher warming levels.” Permafrost thaw alters the arctic climate as well as releasing trapped greenhouse gases that were previously held in frozen “carbon sink” conditions.

We’ll exceed nature’s carbon sinks

The oceans and land masses both absorb some amount of carbon, which has started to lead to the acidification of the oceans, for example. Acidification reduces sealife’s access to building blocks like calcium carbonate, killing off shelled organisms. In the IPCC’s five future scenarios, all exceed nature’s ability to absorb carbon emissions, but this number grows larger as the emissions far overtake how much our oceans and land can absorb.

Many changes will take millennia to reach equilibrium

The report states that many of the changes we have induced with human global emissions will last for millennia even without any further heating or increased carbon emissions. Sea levels will continue to rise, they say, because of the warming deep ocean and other changes that are already set into motion. Glaciers will continue to melt for “decades or centuries.”

There’s still hope, and a mandate for change

In the report’s most conservative future, the climate still changes up to almost 2° Celsius by 2050—this isn’t a fantasy future where nothing bad happens. But even so, we have the opportunity, the necessity, to rapidly reduce emissions around the world and curb many of the effects of climate change during the 21st century.

“From a physical science perspective, limiting human-induced global warming to a specific level requires limiting cumulative CO2 emissions, reaching at least net zero CO2 emissions, along with strong reductions in other greenhouse gas emissions,” the report explains. “Strong, rapid and sustained reductions in CH4 emissions would also limit the warming effect resulting from declining aerosol pollution and would improve air quality.”

If we make serious changes today, like reduction of global carbon emissions from heavy industry, that means we could begin to see reversals in some of the telltale effects of climate change beginning in as little as 20 years, which is the blink of an eye in Earth’s lifetime but a key window of time for humankind.