According to a new paper in Oxford Open Climate Change, the strategies humanity must pursue to reduce climate change will have to include more than reducing greenhouse gases. This comes from an analysis of climate data led by researcher James Hansen.
Scientists have known since the 1800s that infrared-absorbing (greenhouse) gases warm Earth’s surface, and that the abundance of greenhouse gases changes naturally as well as from human actions. Roger Revelle, who was one of the early scientists to study global warming, wrote in 1965 that industrialization meant that human beings were conducting a “vast geophysical experiment” by burning fossil fuels, which adds carbon dioxide (CO2) to the air. CO2 has now reached levels that have not existed for millions of years.
Understanding Climate Sensitivity
One of the most pressing questions in climate science has been, “How much will global temperatures increase in response to a specific rise in CO2 levels?” Back in 1979, a study by the United States National Academy of Sciences suggested that if we were to double the atmospheric CO2 levels, keeping ice sheets constant, we could expect a global warming effect between 1.5 and 4.5° Celsius. However, this range was quite broad, and there was further uncertainty due to the potential delay in warming caused by our planet’s vast oceans.
A recent study has revisited this issue of climate sensitivity, armed with improved paleoclimate data. The researchers found that our climate might be more sensitive to CO2 changes than we previously thought. Their best estimate for a doubling of CO2 levels is a global warming effect of 4.8°C, which is significantly higher than the 3°C estimate given by the United Nations Intergovernmental Panel on Climate Change.
The Role of Aerosols
The researchers also discovered that a significant portion of the predicted greenhouse gas warming over the past century has been counteracted by the cooling effect of human-made aerosols—tiny particles suspended in the air. Since 2010, the amount of aerosols has been decreasing due to reduced air pollution in China and global restrictions on aerosol emissions from ships. This reduction in aerosols is beneficial for our health, as particulate air pollution is responsible for several million deaths each year and negatively impacts the health of many more.
However, this decrease in aerosols is starting to reveal the true extent of greenhouse gas warming that had been previously masked by aerosol cooling. The researchers believe that this is a long-term trend that we need to monitor closely.
The concept of aerosol cooling has been likened to a “Faustian bargain”. This is because, as we gradually reduce air pollution, we are faced with the inevitable consequence of increased warming.
Acceleration in global warming
A recent study suggests that we will soon see a noticeable acceleration in global warming, beyond the level of natural climate variability. The rate of global warming from 1970 to 2010 was 0.18°C per decade. This rate is predicted to rise to at least 0.27°C per decade in the years following 2010. As a result, we are likely to surpass the 1.5°C global warming level within this decade, and the 2°C level within the next two decades.
In the realm of policy, Hansen shares his insights based on years of experience in trying to influence government policies. Firstly, he is of the opinion that to achieve a rapid reduction in CO2 emissions, we need to implement a rising domestic carbon fee. This should be coupled with a border duty on products from countries without a carbon fee. He also advocates for the support of modern nuclear power to supplement renewable energies.
Secondly, Hansen argues that the West, being the main contributor to climate change, has a responsibility to collaborate with developing nations. This cooperation should aim to help these countries establish energy paths that are conducive to a favorable climate for all.
Lastly, despite these efforts, Hansen believes that global warming will reach levels with severe consequences. He argues that we should also invest in research and development for temporary, purposeful actions to combat this.
Let’s talk about Earth’s energy imbalance. It’s a big deal, and it’s getting bigger.
Remember when, about ten years ago, scientist James Hansen pointed out that our planet was out of energy balance by 0.6 W/m2 (watts per square meter)? That meant we had more energy coming in (thanks to absorbed sunlight) than going out (as heat radiation to space). This excess energy, which is the main culprit behind global warming, was equivalent to the energy of 400,000 Hiroshima atomic bombs per day. And guess where most of that energy was going? Right into our oceans. Now, mainly due to decreasing aerosols, this imbalance has doubled to about 1.2 W/m2.
This massive imbalance is the direct cause of accelerated global warming and increased melting of polar ice. This could potentially shut down overturning ocean circulations and cause large, rapidly rising sea levels later this century. Scary, right?
But there’s hope. The paper suggests that we need to take action to avoid the greater geotransformation that will occur if we do nothing. Some of the potential actions include injecting stratospheric aerosols (volcanoes provide relevant but inadequate test cases for this) and spraying salty ocean water by autonomous sail boats in regions susceptible to cloud seeding.
Hansen has a message for the younger generation. He urges them to focus on a fundamental problem that has developed in western democracies, especially in the United States: “The ideal of one person/one vote has been replaced by one dollar/one vote,” Hansen argued. “Special financial interests—the fossil fuel industry, the chemical industry, the lumber industry—have too much influence.”
So, let’s get to work, folks. Our planet needs us.
“Let’s face it, we’re in a bit of a pickle. Our planet is in a state of crisis, and it’s largely due to the fact that big corporations—like those in the fossil fuel industry and the food industry—are given free rein to buy off politicians. It’s no surprise then that our climate is spiraling out of control, environmental toxicity is threatening to wipe out insects (including our crucial pollinators), our forests are being poorly managed, and our agriculture is more focused on profit than on providing nutritious food and promoting public health.”
James Hansen, a leading voice in the fight against climate change, puts it this way: “We’re living on a planet where the climate’s response is delayed, which is a recipe for injustice that spans generations. It’s crucial that young people understand the gravity of this situation and the actions needed to ensure a brighter future for themselves and their children.”
Photo: Freepik.com
