Before the creation of modern industrial society, it’s hard to say that life for humans was “good” in any meaningful capacity. More than half of children died before age 15 (compared to one in 20 now), life expectancy was less than half what it is now and countries such as the United Kingdom had per-capita food supplies in the Middle Ages that would be considered abysmally low today.
If you believe that this magnitude of human suffering was offset by greater environmental benefits, think again. For as long as we have existed on this planet, we have changed our environment to suit our needs, often destructively. Humans hunted animals such as the wooly mammoth and the giant armadillo to extinction and deforested Great Britain long before the steam engine or spinning jenny. While the development of modern industrial society may have relieved much human suffering, it doesn’t come without its costs — namely, carbon emissions from oil, coal and natural gas that powered the industrial revolution, and the associated global warming.
There has been real progress towards reducing carbon emissions, especially in advanced economies. The U.S. emits as much carbon dioxide per capita as we did in 1918, for instance. However, there is still a lot of progress necessary to limit warming to 1.5–2 degrees Celsius (the target set out in the Paris Agreement).
Rising ocean temperatures, especially, have been a large concern — 2023 saw some of the highest temperatures in recent history, and 2024 appears to be set for even higher ocean temperatures. However, this is coming against a backdrop of slowing (yes, slowing) growth in carbon emissions. Growth in carbon emissions fell to their lowest level since the Great Depression in 2023 thanks to the proliferation of clean electricity, and while carbon emissions are still rising, such a rise in ocean temperatures cannot be explained by the greenhouse effect alone. The rise in ocean temperatures appears to be primarily traceable to a different source — a decrease in pollution.
In 2020, the United Nations International Maritime Organization implemented a rule that limited sulfur content in ship fuel. Before, container ships running on sulfurous bunker fuel emitted sulfates into the atmosphere, creating “ship tracks” as the sulfates seeded clouds in the ship’s wake. Clouds reduce the amount of sunlight hitting the Earth, and with the loss of cloud cover, temperatures spiked. A similar effect was seen from the 1940s–1970s, as aerosols from burning coal reduced the amount of sunlight hitting the Earth. The greenhouse effect was still present, but it was hidden by coal pollution — once we started transitioning away from coal, temperatures started to rise.
I do not propose that we return to putting sulfur in ship fuel or start burning coal again — rather, this is to illustrate an important fact. What we put in the atmosphere can have simultaneous, opposite effects — carbon dioxide from burning fossil fuels increases temperatures, aerosols reduce them. As the negative effects of a warming planet become increasingly prevalent — as the heat waves in India and the southern United States exhibit — our solutions must become more potent.
This is where solar radiation modification (SRM) provides an effective solution. SRM uses a very simple fact — if solar radiation, combined with the greenhouse effect, increases temperatures, then limiting solar radiation will help reduce temperatures, even if the greenhouse effect remains. The most studied form of SRM is known as a stratospheric aerosol injection (where planes or balloons release reflective compounds in the atmosphere well above where it may affect the air humans breathe, shielding the earth from excess solar radiation). The Intergovernmental Panel on Climate Change (IPCC) believes that stratospheric aerosol injection could be an effective way to limit increases in global temperatures to 1.5 degrees Celsius.
The idea is controversial, and detractors will be quick to cite that it doesn’t solve the fundamental problem — that what we do to power modern industrial society creates harmful carbon emissions. All SRM does is allow us more years of burning fossil fuels before we inevitably transition to non-carbon-emitting sources of energy. Clearly, it’s useless, right?
It’s important to reiterate that SRM to engineer our climate would not be a particularly extraordinary case of humans changing our planet — after all, we’ve been emitting carbon dioxide into the atmosphere for upwards of two centuries. Obviously, SRM does not solve all problems related to excess carbon dioxide in the atmosphere, but the question is not “is this solution perfect?”; the question is, “will this solution take us in the right direction, and if so, how quickly?” SRM provides a hopeful answer to both questions: it will take us in the right direction, and can be implemented today.
There are genuine signs of progress towards fighting climate change. Clean energy has fallen in price dramatically (with the cost to produce solar photovoltaic electricity dropping 89 percent between 2009 and 2019) — but clean energy takes time to bring to the grid. There are proposals for carbon-free concrete and steel, new innovations in mass timber construction and efforts to create lab-grown meat, all of which will dent carbon impacts from major sources — but it will take time for them to become cost-competitive with their carbon-intensive counterparts.
Heat waves, on the other hand, have continued to become more severe, with forecasters saying with nearly 98 percent certainty that 2023–2028 will be the hottest years on record. If avoiding a fraction of a degree of excess warming will save thousands of lives, restricting global temperatures via SRM only becomes that much more important.
Delaying the worst of climate change allows us time to implement our best solutions — the dilemma is not “implement SRM or solve climate change,” it’s “implement SRM or suffer the worst effects of climate change.” I would choose the latter any day.
Contact Avinash Iyer at iyera@oxy.edu.
