Thursday, December 08, 2022

How not to solve the problem of climate change

When politicians talk about reaching “net zero” emissions, they often rely on trees or technology that can remove carbon dioxide out of the air. What they don’t mention is how much these proposals or geoengineering would cost to allow the world to burn fossil fuels.

There are many proposals for removing carbon dioxide, but most distinguish only at the edges, and carbon dioxide concentrations in the atmosphere continue to rise, even through epidemics.

I have been working on climate change for more than four decades. Let’s take a minute to come up with some rhetoric about climate change and clear the air, so to speak.

What is the cause of climate change?

As has been well established for several decades now, the global climate is changing, and this change is caused by human activities.

When fossil fuels are burned for energy or used in transportation, they release carbon dioxide – a greenhouse gas that is the main cause of global warming. Carbon dioxide remains in the atmosphere for centuries. As more carbon dioxide is added, its increasing concentration acts like a blanket, trapping energy near Earth’s surface that would otherwise escape into space.

When the amount of energy coming in from the Sun exceeds the amount of energy going back into space, the climate heats up. Some of that energy raises temperatures, and some increases evaporation and fuels storms and rain.

Illustration Of Energy From The Sun Versus Energy From The Earth In The Greenhouse Effect
How does the Greenhouse Effect work?

Because of these changes in atmospheric composition, the planet has warmed by an estimated 1.1 °C (2 F) since about 1880 and is on the way to 1.5 °C (2.7 F), which was highlighted as a target. was not to be crossed. The Paris Agreement has led to possible global warming and a gradual increase in temperature, with all kinds of weather and climate extremes, from floods to droughts and heat waves, causing enormous damage, disruption and loss of life.

Studies suggest that global carbon dioxide emissions will need to reach net-zero carbon emissions by mid-century to have a chance to limit warming to 2 C (3.6 F).

China is currently the main source of carbon dioxide. But accumulated emissions matter most, and the United States leads the way, followed by Europe, China and others.

Pie Charts Show Co2 Emissions From Fossil Fuels Over A Year Compared To The Cumulative For The Top Emitting Countries.  China Has The Largest Share In 2018;  Cumulatively The Us Has The Largest Share Of
The estimated share of carbon dioxide emissions from fossil fuels in 2018 compared to cumulative emissions over time, based on data released by BP.
kevin trenberth, author provided

What works to slow climate change?

Modern society needs energy, but it should not be from fossil fuels.

Studies show that the most effective way to address the problem of climate change is to decarbonize the economies of the countries of the world. That means rapidly increasing use of renewable energy – solar and wind cost less than new fossil fuel plants in most parts of the world today – and the use of electric vehicles.

Unfortunately, this shift to renewables has been slow, in large part due to vast and expensive infrastructure related to fossil fuels, as well as huge amounts of dollars that can buy politicians’ influence.

What doesn’t work?

Instead of drastically cutting emissions, companies and politicians are holding onto alternatives. These include geoengineering; carbon capture and storage, including “direct air capture”; and planting trees.

Here’s the issue:

Geoengineering often means “solar radiation management”, which aims to simulate volcanism and add particles to the stratosphere to reflect incoming solar radiation back into space and generate cooling. It may work partially, but it can have side effects.

The problem of global warming is not sunlight, but the infrared radiation emanating from the earth is being trapped by greenhouse gases. There is a complete weather and climate system and hydrological cycle between incoming solar and outgoing radiation. Sudden changes or poor distribution of these particles can have a dramatic effect.

Illustration Of Solar Rays Bouncing Off Man-Made Aerosol Layers And Other Sources
Some of the methods of solar radiation management that have been proposed.
Chelsea Thompson, NOAA/CIRES

The last major volcanic eruption of Mount Pinatubo in 1991 sent enough sulfur dioxide and particulates into the stratosphere to produce slight cooling, but it also caused a loss of rainfall over land. This cooled the land more than the ocean, allowing monsoon rains to move offshore, and slowed the water cycle over a longer period of time.

Carbon capture and storage has been researched and tested for more than a decade, but has a huge cost. Only about a dozen industrial plants in the US currently capture their carbon emissions, and most of it is used to increase drilling for oil.

Direct air capture – technology that can pull carbon dioxide out of the air – is being developed in several places. However, this uses a lot of energy, and while this could potentially be tackled by using renewable energy, it is still energy intensive.

A Man Holding A Small Tree Talks To Reporters.
Boris Johnson, the then Mayor of London, planted a tree in 2008.
Peter McDiarmid/Getty Images

Tree planting is often adopted as a solution to offset corporate greenhouse gas emissions. Trees and vegetation take up carbon dioxide through photosynthesis and produce wood and other plant material. It is relatively cheap.

But trees are not permanent. Leaves, twigs and dead trees rot. The forest burns. Recent studies suggest that the risks to trees from stress, forest fires, drought and insects will also be greater than expected as temperatures rise.

How much does all this cost?

Scientists have been measuring carbon dioxide since 1958 in Mauna Loa, Hawaii, and elsewhere. The average annual increase in carbon dioxide concentrations has ranged from about 1 part per million volume per year in the 1960s to 1.5 in the 1990s, to 2.5 in recent years since 2010.

This continued increase through the pandemic and despite efforts to cut emissions in many countries shows just how big the problem is.

Chart Showing Rising Co2 Over Time.
Carbon dioxide concentration in Mauna Loa, Hawaii. The monthly mean, in red, rises and falls with the growing season. The black line is adjusted for the mean seasonal cycle.
Kevin Trenberth, CC BY-ND based on NOAA data

Carbon removal is usually discussed in terms of mass, which is measured in megatons – millions of metric tons – of carbon dioxide per year, not parts per million by volume. The mass of the atmosphere is about 5.5×10¹⁵ metric tons, but carbon dioxide (molecular weight 42) is heavier than air (molecular weight about 29), with 1 part per million volume of carbon dioxide being about 7.8 billion metric tons.

According to the World Resources Institute, the cost of capturing air directly varies between US$250 and $600 per metric ton of carbon dioxide, depending on the technology, energy source and scale of deployment. Even if the cost fell to $100 per metric ton, the cost of reducing atmospheric concentrations of carbon dioxide to 1 part per million is about $780 billion.

Keep in mind that the concentration of carbon dioxide in the atmosphere has increased from about 280 parts per million before the industrial era to about 420 today, and is currently increasing at a rate of more than 2 parts per million per year.

According to WRI calculations, the restoration of trees on one-third to two-thirds of suitable acres is projected to be able to remove about 7.4 gigatonnes of carbon dioxide without displacing agricultural land by 2050. It will be more than any other route. This may sound like a lot, but 7 gigatonnes of carbon dioxide is 7 billion metric tons, and so it is less than 1 part per million by volume. The cost is estimated to be up to $50 per metric ton. So even with trees, the cost of removing 1 part per million volume could be as much as $390 billion.

Geoengineering is also expensive.

So for hundreds of billions of dollars, the best possibility is a tiny dent in carbon dioxide concentration of 1 part per million by volume.

This arithmetic highlights the tremendous need to cut emissions. There is no viable solution.

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