Updated: Mar 18, 2021
The material in this blog is taken from Chapter 1 of the book Net Zero by 2050: Technology for a Changing Climate.
Seventeen of the 18 warmest years in the 136-year record all have occurred since 2001.
Jem Bendell, Institute for Leadership and Sustainability, 2020
Climate change represents an urgent and potentially irreversible threat to human societies and the planet.
IPCC (Intergovernmental Panel on Climate Change), 2018
We are as gods and might as well get good at it.
Stewart Brand, Whole Earth Catalog, 1968
The only people who think you can have infinite growth on a finite planet are mad men and economists.
Our climate is changing, and it’s changing fast. Temperatures are rising, storms are fiercer, wild fires are raging, tropical forests are disappearing, sea levels are rising, and previously fertile lands are suffering from chronic drought. These changes are largely caused by climate change caused by our willful dumping of enormous quantities of greenhouse gases, particularly carbon dioxide (CO2), into the atmosphere. The CO2 is created when we burn carbon-based/fossil fuels — primarily coal, oil and natural gas. If we continue on our present trajectory then we face wrenching and scary changes within the lifetimes of many of the people reading this book. Action is needed; time is not on our side.
Figure 1.1, which is taken from a U.S. Government site (Lindsey, 2020), shows how global temperatures have increased over the pre-industrial baseline during the last 50 years. (The pre-industrial baseline is set sometime around the year 1880. Although the industrial revolution was gaining momentum at that time, human activities had not been enough to materially change the concentration of CO2 in the atmosphere.)
Global Temperature Increase
At first glance, a temperature increase of just one or two degrees seems to be nothing worth worrying about. After all, temperatures change by much more than that on a daily basis. However, these small increases are important, as can be seen by using an analogy with the human body. If our body temperature increases by as little as 1.0°C (2°F) we start to feel unwell. A temperature increase of 2 °C / 4°F indicates that we are ill. Anything higher than that is a symptom of serious fever. So it is with the planet; small temperature increases are enough to make the Earth feverish.
Reports to do with climate describe how small temperature increases can have a large impact. For example, there is a significant difference between a 1.5°C and 2°C, as discussed by (Levin, 2018) and (Schleussner, 2016).
Paris and the IPCC
In response to this urgent situation, leaders from almost all of the world’s nations assembled to develop a unified policy. Their work resulted in the 2015 Paris Agreement, a legally binding treaty. It called for countries to hold the increase in the global average temperature to well below 2°C and to pursue efforts to limit the temperature increase to below 1.5°C. Figure 1.1 shows that this goal is not being achieved; temperatures have continued to climb since the year 2015. A simple extrapolation suggests that we reach the 1.5°C mark somewhere around the year 2040. The 2°C target is exceeded somewhere between 2050 and 2060. (Recent modeling suggests that global temperatures are actually now climbing at a faster rate than what is shown in Figure 1.1.)
Recognizing that they were not likely to meet the targets that they had set, the signatories to the Paris Agreement asked the IPCC (International Panel on Climate Change, a United Nations organization) to determine what actions would be needed to hold temperature increases to the 1.5°C level. The IPCC responded with the publication of their 2018 report Global Warming of 1.5°C. The report is discussed in detail at the web page The IPCC 1.5°C Report (Sutton, The IPCC 1.5°C Report, 2021). The report also provides the foundation for much of the discussion and analysis in later chapters of this book.
The IPCC report confirmed that, without corrective action, we reach the 1.5°C threshold before the year 2040, and cross the 2.0°C threshold somewhere around the year 2050. And it doesn’t stop there. Without an effective response temperatures will continue to rise.
The IPCC also provides a glimpse as to what the world may look like as temperatures rise. Even the lowest increase that they talk about, the 1.5°C target, is bad.
The world will see catastrophic effects of climate change if temperatures climb to 1.5 degrees Celsius over pre-industrial levels. These effects include extreme heatwaves, severe droughts, the death of coral reefs, mass extinctions, and sea-level rise. We're on track to hit that 1.5-degree temperature rise by 2040. If we reach 2 degrees C of warming, the effects will be even more disastrous.
Books such as The Uninhabitable Earth (Wallace-Wells, 2019) and Our Final Warning — Six Degrees of Climate Emergency (Lynas, 2020) provide insights as to what the world may look like if temperatures rise into the 4-6°C range above the pre-industrial baseline. Their conclusions make for scary reading.
The concentration of CO2 in the atmosphere is shown in Figure 1.2. Development of this chart was started by David Keeling in the year 1956, therefore it is often referred to as the Keeling Curve. In order to minimize local perturbations, he located his measuring instruments near the summit of the volcanic mountain, Mauna Loa, in Hawaii.
Atmospheric Carbon Dioxide Concentration
The initial 1956 value was 316 parts per million (ppm). The value has risen steadily since then; it is now 411 ppm. In other words, in spite of all the reports and international agreements to do with slowing down climate change, there has been no measurable progress in slowing down the rate at which we add CO2 to the atmosphere over the last 60 years. The temperature and the CO2 concentration curves are rising in tandem.
This is an unacceptable trajectory. If we do not find ways of generating energy without the use of carbon-based fuels then climate change will lead us into a world where entire ecosystems will collapse and human civilization in its current form may be threatened — all within the lifetimes of people living now.
Society can respond to this quandary in one of two ways. The first response is to radically reduce our consumption of energy from fossil fuels. This approach will lead to a drastically reduced material standard of living for most people. The second approach is to switch to alternative sources of “green” energy, i.e., energy that provides the power we want without adding greenhouse gases to the atmosphere. (A third approach, which looks as if it may be the most likely, is to combine the two strategies, i.e., use alternative sources of energy, but accept that we will have to cut back on our overall energy consumption.)
In response to this looming crisis, many organizations have adopted a ‘Net Zero by 2050’ target. The basic idea is that we rapidly reduce the rate of our CO2 emissions such that, by the year 2050 — just 29 years from now — those emissions are close to zero. We do this by switching from carbon-based fuels such as coal, oil and natural gas to alternative, “green” sources of energy such as solar, nuclear and geothermal. Any CO2 emissions that do occur are counteracted by carbon capture and sequestration, i.e., we remove CO2 that is already in the atmosphere then sequester it underground (possibly in old oil wells).
Implicit in most ‘Net Zero’ programs is an assumption or hope that we can maintain our current, energy-profligate lifestyle.
It is hoped that a switch to alternative energy sources combined with CO2 capture will lead to the change shown in Figure 1.3.
Projected Temperature Trends
The blue line represents Business as Usual (BAU). It assumes that no corrective actions are taken. It shows that temperatures steadily increase well beyond the targets of 1.5 and 2.0°C. The brown line assumes that alternative energy sources and carbon capture technology are developed and implemented, world-wide, very quickly. In this scenario temperatures exceed the 1.5°C goal — there is overshoot — but then the temperature increase flattens out such that the 2.0°C target is met. After that, the carbon capture technology can actually reduce CO2 concentrations and atmospheric temperatures.
Based on progress to date, the chances of actually achieving the mitigation line are slim indeed. We have seen that the actions that have been taken to this point have not had a significant impact of either CO2 levels or on global temperatures. Therefore, the brown line in Figure 1.3 is aspirational. The reality, barring some major calamity, is that actual conditions will lie somewhere between the BAU and Mitigation lines.
Anyone who takes a deep dive into the climate change literature, such as we have done in the preceding paragraphs, usually comes to the surface feeling pretty shaken. The prospects are dire, the time line is short, and, our actions to date have fallen far short of what is needed. Yet, we have known about climate change for decades but, by and large, have not done much about it. Climate change is not something that will happen in the future — it happened in the past, it is happening now, and it will get worse in the future. We cannot make it go away.
Had we acted say 30 years ago then we could have solved the climate change “problem”. But that was 30 years ago — now it appears as if we have to respond and adapt to the climate change “predicament” that we face. Problems have solutions — predicaments do not. When faced with a problem we can take the actions that make it go away. When faced with a predicament we can respond and adapt, but we cannot make it disappear. This is where we now find ourselves with regard to climate change; we can take actions to slow down the pace of change, or to ameliorate the consequences. But we cannot return to the world of the 1960s, the “old normal”. We have left it too late, we have wasted too much time.
In spite of this gloomy assessment, it is our responsibility to take whatever actions we can to at least slow down the pace of climate change. We must also keep in mind that some technical development may be a pleasant surprise that allows us to approach the Mitigation line more quickly than we had anticipated. In this book we systematically look at many of the technologies that have been proposed to address climate change. The aim is to identify those that give us the best chance of bending the curves shown in Figure 1.3.