The newest United Nations climate report says that humans have postponed cutting fossil-fuel emissions for so long that they can no longer stop global warming from getting worse over the next 30 years -- but there is still a short window to prevent the worst-case scenario. Via the New York Times:
Humans have already heated the planet by roughly 1.1 degrees Celsius, or 2 degrees Fahrenheit, since the 19th century, largely by burning coal, oil and gas for energy. And the consequences can be felt across the globe: This summer alone, blistering heat waves have killed hundreds of people in the United States and Canada, floods have devastated Germany and China, and wildfires have raged out of control in Siberia, Turkey and Greece.
But that’s only the beginning, according to the report, issued on Monday by the Intergovernmental Panel on Climate Change, a body of scientists convened by the United Nations. Even if nations started sharply cutting emissions today, total global warming is likely to rise around 1.5 degrees Celsius within the next two decades, a hotter future that is now essentially locked in.
At 1.5 degrees of warming, scientists have found, the dangers grow considerably. Nearly 1 billion people worldwide could swelter in more frequent life-threatening heat waves. Hundreds of millions more would struggle for water because of severe droughts. Some animal and plant species alive today will be gone. Coral reefs, which sustain fisheries for large swaths of the globe, will suffer more frequent mass die-offs.
To stop it from getting even worse would require a coordinated effort among countries to stop adding carbon dioxide to the atmosphere by around 2050, and removing vast amounts of carbon from the air. If that happened, the report says, global warming could level off at around 1.5 degrees Celsius.
If we fail? Well, according to the report, every additional degree of warming brings ever more vicious floods and heat waves, worsening droughts and accelerating sea-level rise that could threaten the existence of some island nations.
"The hotter the planet gets, the greater the risks of crossing dangerous 'tipping points,' like the irreversible collapse of the immense ice sheets in Greenland and West Antarctica," the report concludes.