Scientists predict that Earth’s climate will continue changing, depending in large part on the additional amount of greenhouse gases that humans emit into the atmosphere, leading to negative consequences for life on Earth. To avoid the most harmful effects of climate change, the world needs to become carbon neutral by 2050, according to the Intergovernmental Panel on Climate Change (IPCC). The United States is among the countries with the highest greenhouse gas emissions per person. In a new study reported in the journal AGU Advances (January 2021), researchers modeled eight different and affordable pathways that the United States could follow to become carbon neutral by 2050. Common to all these pathways were increased energy efficiency, renewable energy, electrification where fossil fuels are now used, and a minimal amount of carbon capture, if necessary. See also: Climate modeling; Global climate change; Global warming; Greenhouse effect
Nearly all of the technology needed to become carbon neutral already exists. On the path toward carbon neutrality, the existing carbon-producing infrastructure needs only to be replaced as it becomes obsolete, instead of abandoned. The most effective step included in all the scenarios is a transition to wind and solar energy (that is, renewable energy) and the retiring of coal-fired power plants. Still, a small amount of natural gas-fired electrical power will probably be needed for energy balance. According to the report, renewable electricity is cheaper to produce than biofuels or hydrogen fuel. Increasing renewable energy will also allow for greater electrification through use of electric vehicles and heat pumps, and less reliance on fossil fuels. See also: Coal; Electric power generation; Electric vehicle; Fossil fuel; Heat pump; Solar energy; Wind power
All the pathways investigated have tradeoffs in terms of decarbonization and cost. The significance of the report, however, is that reaching zero net emission of carbon dioxide by 2050 can be accomplished through various pathways without excessive disruption or costs to the country. The transition to renewable energy would represent the bulk of the cost in all the scenarios to reach carbon neutrality. The cost per year is estimated to be affordable at roughly U.S. $1.00 per person per year (about U.S. $120–150 billion total per year), which represents about 0.2–1.2% of the United States’ gross domestic product (GDP). GDP is a measure that policymakers use to determine whether public spending is affordable.