• Ian Sutton


Splitting iceberg caused by climate change and global warming

Credit: Pexels

On April 22nd President Biden and his climate change team committed to very ambitious goals for greenhouse gas reduction. The following statement is from the official White House release.

. . . the New Target Aims at 50-52 Percent Reduction in U.S. Greenhouse Gas Pollution from 2005 Levels in 2030.

The principal greenhouse gas is carbon dioxide, CO2. (Methane is actually a more powerful greenhouse gas, but is not considered in this analysis because it is emitted in relatively small quantities.) In the base year of 2005 to which the statement refers the United States emitted 5.9 gigatons (5,900 billion tons) of CO2. Therefore, to achieve the administration’s goal, this amount has to fall to 2.9 gigatons. Hence the White House statement can be written as,

. . . the New Target is for U.S. CO2 emissions to be 2.9 gigatons or less by the year 2030.

Given the size of this commitment, and the speed with which it has to be implemented, we are justified in asking, “Is the target realistic, or is it just another instance of ‘greenwashing’ ”? In other words is the government making a commitment that is conveniently far enough into the future that they don’t have to worry about accountability were the targets not to be met?

There are reasons for skepticism. The following chart is the 'Keeling Curve'; it shows the concentration of carbon dioxide (CO2) in the atmosphere as measured since the year 1958.

Overlaid on the curve are the occurrences of major government conferences (the acronym COP stands for Conference of the Parties) and the dates of IPCC reports (IPCC stands for Intergovernmental Panel on Climate Change). The lesson is plain: CO2 concentrations have continued their inexorable upward trajectory — the conferences, reports and government commitments have had little or no impact in the past. Why should it be different this time?

Historical Trend

The target that the White Hose has set for itself is ambitious, but it may not be quite as ambitious as it sounds. The following chart is from the U.S. Energy Information Agency (EIA).

The black line on the chart shows that, in the year 2005, the starting point for the White House pledge, CO2 emissions in the United States were the 5.9 gigatons. By the year 2020 that value had declined to 5.2 gigatons. In other words, although the overall world concentration of CO2 in the atmosphere has climbed steadily, as shown by the Keeling Curve, CO2 emissions in the United States have declined slightly at a rate of about 0.05 gigatons annually. That is not a big number, but at least the trend is favorable.


Most of the decline in CO2 emissions can be attributed to a reduced consumption of coal, as shown in the next chart, also from the EIA. It shows coal use in the United States from 1950 to the present.

Inspection of the chart yields three conclusions.

  1. Most coal is used for electrical power generation.

  2. Peak consumption occurred in the year 2005 (thus making it a rather convenient for the White House starting point.)

  3. Consumption of coal since the year 2005 has dropped by almost 50% (the power sector switched to natural gas).

If consumption of coal continues to fall at its present rate then, by the year 2030 (the target date) very little coal will be consumed (in the United States — other nations are still building new coal-fired facilities.) Coal is being replaced by natural gas (which has a lower CO2 emissions per unit of energy generated than coal) and by renewable fuels, mostly solar and wind. Based on the historical data, we can expect CO2 emissions to fall to around 4.5 gigatons per year simply by reducing the use of coal.

This still leaves us a long way from the target of 2.9 gigatons. Further reductions of 1.6 gigatons per annum are needed.

Other Sectors

The next chart is also from the EIA. It shows energy emissions by sector.

Going back to the year 2005, when total CO2 emissions were 5.9 gigatons, we see the split between the end-use sectors is:

  • Transportation: 2.0

  • Industrial: 1.9

  • Residential and Commercial: 2.0

The previous section showed that about 1.6 gigatons of emissions reductions are needed before the year 2030. In order to achieve the goal, each of these sectors will have to switch roughly 30% of its energy supply from fossil fuels to renewable energy sources. The new energy sources will be mostly solar and wind. (Nuclear is not a realistic option since there is no way in which the enormous number of facilities needed could be financed and built in just nine years.)

Transforming 30% of the energy infrastructure in just nine years is a formidable challenge — one that will require an huge commitment of resources, money and human skills. It is also a risky project — there are bound to be many surprises that will slow down the pace of change.

We will look into some of the details of implementing the change in future posts.

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