If greenhouse gas emissions persist at their current rate, we could see temperature increases of 2.7 degrees Fahrenheit above preindustrial levels by 2040, according to a report from a panel of United Nations science advisers called the Intergovernmental Panel on Climate Change (IPCC).
Previously, most research focused on the impacts of a temperature increase of 3.6°F, as this was the threshold at which most scientists believed the most severe climate change impacts would start to materialize. The IPCC report, however, shows that some of these severe effects could begin at 2.7°F. The report paints a frighteningly possible future but also outlines steps we could take to avoid the most severe impacts.
According to the report, by 2040 the world may be seeing more severe food shortages, wildfires, and flooding as well as the widespread death of coral reefs.
More than 50 million people in the United States, China, India, Indonesia, Bangladesh, and elsewhere could start to be affected by coastal flooding. At 3.6°F, the world would see a rapid evacuation of people from tropical regions, causing national borders in some places to become essentially irrelevant due to the massive influx of displaced people.
Climate change is also expected to have severe economic impacts. The report's authors estimate the impact of 2.7°F of warming at $54 trillion. Every 1.8 degrees of warming could cause the United States to lose about 1.2 percent of its gross domestic product, they wrote.
What Can Be Done
The report's authors noted that it is technically possible to make the changes needed to avoid a 2.7°F increase. They also, however, recognized that this is unlikely politically.
To prevent the 2.7°F increase, the report said, we will have to reduce our greenhouse gas emissions by 45% from 2010 levels by 2030 and by 100% by 2050. One method the report's authors suggest for achieving this is a tax on carbon dioxide emissions. The price would have to be quite high, though, to attain the necessary reductions — between $690 and $27,000 per ton by 2100.
An alternative, the authors wrote, is that the world could overshoot the targets and then bring temperatures back down later. While some impacts such as melting sea ice would reverse, others, such as the death of coral reefs, would be permanent.
No matter which route the world takes, we need to start preparing for the impacts of climate change. These climate resilience efforts will involve building structures that are more resistant to extreme weather events. We also need to ensure access to food and water following natural disasters. Drinking water should be a priority, since going less than a week without it can be deadly.
More than 180 countries, including the United States, accepted the IPCC report's summary for policymakers. The U.S. State Department, however, was careful to say that accepting the report did not mean the US endorsed the findings.
This stance demonstrates the political challenge that making the changes needed to avoid disastrous warming will entail. We need to do more to convince leaders to make fighting climate change a priority. Preventing 2.7°F of warming is technically possible, but we need the political will to do it.