The National Research Council of the United States National Academies recently released a report summarizing projected climate-change impacts and what we need to do to protect ourselves from some very serious risks.
The basics: The average temperature of the globe, has increased 1.3 degrees Fahrenheit over the past century. This closely tracks the increase of carbon dioxide (CO2) emissions by humans. Within 20-30 years, we are projected to have produced enough CO2 to cause a 3.6 degree Fahrenheit (2 degree Celsius) increase in temperature. The report found that, to avoid further temperature increase, we would need to cut carbon pollution by 80 percent – to the amount we polluted in 1950.
Hitting a 3.6 degree Fahrenheit increase in temperature will greatly affect people and change natural areas. Here are some of these impacts identified in the report:
- 4 to 8 times the area burned by wildfires in many parts of the western U.S.
- 5 percent to 10 percent less total rain in southwest North America, the Mediterranean, and southern Africa per degree Celsius of warming
- 5 percent to 10 percent less stream flow in some river basins, including the Arkansas and Rio Grande, per degree Celsius of warming, which could cause water shortages
- 5 percent to 15 percent lower yields of some crops, including U.S. and African corn and Indian wheat, per degree Celsius of warming
Without strong climate policy, CO2 concentrations in our atmosphere could easily lead to an increase in temperature of around 9 degrees Fahrenheit (5 degrees Celsius) over the course of the next several generations. With a 9-degree increase in temperature, the impacts described above would be even greater and additional impacts would likely occur:
- Many millions of people at risk of coastal flooding
- Sea-level rise causes a loss of coastal areas totaling greater than the size of the United Kingdom
- Nine out of 10 summers warmer than the warmest summer ever experienced in the 20th century
- Agricultural yield losses in most regions and potential doubling of global grain prices
Even if we are able to put the brakes on the world’s CO2 pollution, temperature increases will still likely double over the following decades and centuries as the warming effects of the CO2 we’ve already produced settle in and the climate comes to an “equilibrium.”
And, we will be stuck with climate change for a very long time. The report found that only a small portion of CO2 could be reabsorbed naturally within 100 years. And depending on how much CO2 is created, it could take 10,000 to more than 100,000 years to get back to the CO2 concentration the globe was at in 1900.
This report makes is clear that we need climate policy that acts now. Some elements of a strong U.S. climate policy would include:
- Significantly reduce greenhouse gas emissions from all major emitting countries, industries, and sources
- Reduce emissions from deforestation and forest degradation (REDD) and recognize this as a key strategy in fighting climate change
- Ecosystem-based adaptation approaches that help protect natural areas, while providing the people protection against climate change impacts
Evan Girvetz is a senior scientist with The Nature Conservancy’s Global Climate Change Team
Graphic from The Nature Conservancy’s Climate Wizard. (This map shows that “business as usual” without any policy safeguards on carbon pollution could cause temperature increases averaging around 9 degrees Fahrenheit.)
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