What might the future look like if we took climate change seriously?

A new analysis lays out several detailed “pathways” to a low-carbon future for the United States, and offers practical guidance for policy makers. The bottom line finding is that there are multiple ways we can significantly reduce greenhouse gas emissions, with known technologies and with an incremental cost equivalent to less than 1 percent of gross domestic product. But the choices we make in the short term matter a lot if we want to avoid the most catastrophic effects of climate change.

This work is important because the negotiations in Lima last week set a positive direction for the international climate agreement planned for next December in Paris. As the United States considers its strategy, it is important to reflect on what it would take – on a nuts and bolts level – to meet an aggressive climate target. This includes talking about sources of energy, power lines, industrial facilities, homes and buildings, cars and trucks and the fuels they run on – the physical infrastructure necessary to massively reduce our greenhouse gas emissions.

Thumbnail image for Thumbnail image for 1.jpgWith all the international dialogue and ongoing climate modeling, there has been surprisingly little analysis done on what needs to happen to respond to climate change from the perspective of physical infrastructure. And while sure, no one can predict the future, we need to start imagining (in detail) the range of options that would enable the United States to meet an aggressive climate target over the longer-term. We need to be able to credibly ask whether proposed policies can reduce emissions enough – or whether they lead to dead ends that may meet short term targets but foreclose upon the future we need to build.

Fortunately, the United States has an important new resource to help answer these questions. The Deep Decarbonization Pathways Project (DDPP), convened by several nonprofit organizations affiliated with the United Nations, recently released a preliminary technical report and identified four technology “pathways” that America could take to reduce its greenhouse gas emissions by 80 percent below 1990 levels by 2050. This is a target that would allow the United States to do its part to limit global average temperature rise to 2 degrees Celsius, an objective agreed upon by the international community to avoid the most catastrophic effects of climate change. The United States is not doing this analysis in isolation. There are 14 other high-emitting countries (including China, India and Brazil) that are part of the DDPP doing similar concrete analyses to identify pathways to reduce their carbon emissions (i.e. to “decarbonize”). The United States team includes the consulting firm Energy and Environmental Economics (E3), Lawrence Berkeley National Lab, and Pacific Northwest National Laboratory.

The results are stunning both in their detail and in the stark clarity of the key principles they highlight. The analysis explores four scenarios described by the technology they use most heavily to meet the GHG target: High Renewables, High Nuclear, High Carbon Capture and Storage (CCS), and a Mixed Case that uses a combination of these technologies. They find that it may be possible for any of these technologies, or a combination, to meet the target at a relatively modest cost – less than 1 percent of gross domestic product. And that doesn’t account for the benefits of avoiding the human and infrastructure costs of climate change and air pollution.

The analysis team developed a model that includes the minutia of the United States’ physical infrastructure, including sources of electricity, types of fuels used, buildings and the equipment they house, industrial processes, our transportation infrastructure and so on. They use largely conservative assumptions. For example, they deploy only existing technologies, no brand new innovations (which is unlikely over 35 years). Other assumptions include: costs of existing technologies don’t come down significantly (which they probably will), they only “retire” infrastructure and equipment at the end of its useful life, no use of international offsets, and only modest increases above our historic improvements in energy efficiency. They also assume that we maintain our (very high) levels of energy reliability and that the American economy continues to grow robustly. In other words, we keep enjoying our current lifestyle, but with FAR fewer emissions. Not bad!

While there are a number of ways to reach the target, there are some key principles that are constant across the scenarios and that are vital to combating climate change according to this analysis. Here are my top three takeaways from the report:

1. We need to take path-dependence seriously

This means that our short-term choices may determine what our options are in the longer term, and may allow or prevent the United States from significantly reducing emissions. This analysis shows that what we buy and build in the next 10 years matters, especially for long-lasting infrastructure and equipment (the stuff we won’t get rid of or replace in a few years). The graph below shows how many “replacements” will happen before 2050 for a range of items from buildings to lighting systems. Getting the long-lasting items right matters because we won’t have many chances to replace them with a low-carbon alternative. So what matters most? Buildings. Power plants. Boilers. Basically anything that lasts longer than 25 years, we have to get right in the next decade if we want to realize a low-carbon future. And every time we replace one of these long-lasting items, we have to think about 2050 and beyond, because it’s going to last a long time and affect our ability to reduce emissions.


Source: DDPP, Stock Lifetimes and Replacement Opportunities

The danger is that we could reach an interim emissions reduction target, say for 2030, and actually hit a dead end for getting to the 2050 target. For example, switching from coal to natural gas for electricity generation might get us short-term emissions reductions, but the DDPP analysis shows that natural gas (at least with current technologies) will not get us the reductions we need by 2050. And if we make big investments in natural gas power plants in the short-term, we could get locked into a path that is headed toward failure.

This also implies that “market forces” alone will not be enough. Even if we put a price on carbon, which is an important step, we cannot just sit back and watch the magic of the market at work. The cheapest, easiest, market-driven path to short-term emissions reductions may not be sufficient to get us the longer-term savings we need to limit global average temperature rise to 2 degrees Celsius (or other aggressive climate target). This means “successful implementation depends on ‘directed technological change’ – that is technological change that is propelled through an organized, sustained, and funded effort engaging government, academia, and business with targeted technological outcomes in mind,” as the DDPP described in the 15-country preliminary report released earlier this year. In other words – research, development, demonstration, and deployment initiatives that are informed by analyses like this report.

2. Electrify, Electrify, Electrify.

All of the scenarios require cleaning up our electricity supply – moving to renewable energy, nuclear power, or fossil power plants with carbon capture and storage – and using electricity for as many things as possible. This analysis shows that electricity generation will need to approximately double while its carbon intensity is reduced to 3 to 10 percent of its current level. This means electric space and water heating in buildings. Electrified transportation (through plug-in electric vehicles, or perhaps cars and trucks running on hydrogen produced with electricity). Under the scenarios, the very limited use of fossil fuels like natural gas and oil would be reserved for activities that are extremely hard to electrify, including some industrial processes and heavy duty vehicles.

3. Energy efficiency is required to keep costs low

Energy efficiency is a cornerstone of all four scenarios. Affordable deep decarbonization requires highly-efficient homes and buildings, equipment and appliances, transportation, and industrial processes. This analysis starts with the Annual Energy Outlook projections for efficiency and adds to them in several areas. The assumptions are appropriately aggressive for some end uses like lighting, which in the model moves almost entirely to LED technology by 2050. But the assumptions about the potential for overall building performance and other improvements we’re likely to see, based on past experience, appear to be conservative. That’s good news – we can do even better, which may give us some additional breathing room to reach the emissions reduction target.

No one knows exactly what the world will look like in 2050. But this kind of analysis is required to start imagining, in detail, the path forward so that we can choose a path (or paths) that will allow us to combat climate change and avoid hitting a dead end. We don’t know everything, but we know enough to make informed choices today about what to build, invest in, and experiment with to move in the right direction. And, as this analysis shows, the choices we make in the next 10 years will impact our ability to safeguard our world in the long run.

About the Authors

Merrian Borgeson

Senior Scientist, Energy program

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