Are Global Carbon Emissions Increasing or Decreasing?

The annual Carbon Budget report found that, although fossil fuel emissions remained steady in 2015, the level of atmospheric carbon reached a record high, says atmospheric sciences professor Atul Jain. Photo by L. Brian Stauffer

Editor’s note: On Nov. 14, the Global Carbon Project published the Global Carbon Budget 2016, giving world leaders access to data on atmospheric carbon concentrations, emissions and trends. Illinois atmospheric scientist Atul Jain was among the many scientists worldwide who contributed data to the report. Jain talked about the carbon budget and this year’s findings with News Bureau physical sciences editor Liz Ahlberg Touchstone.

What carbon emissions trends were seen in the 2016 report?

Global carbon emissions from fossil fuel and industry are nearly unchanged for the third year in a row. For 2015, the emissions were 36.3 billion tons, approximately the same as in 2014 and are projected to rise only about 0.2 percent in 2016. This is unprecedented compared with the average growth of 1.8 percent per year that we saw from 2006–2015 and more than 3 percent per year during the early 2000s.

However, CO2 emissions from deforestation and other land-use changes were estimated at 4.8 billion tons in 2015 – about a billion tons higher than the average of the previous decade – because of increasing forest fires due to El Niño conditions and clearing of forests. Land-use change emissions for 2016 are not reported yet, but fire activities related to land management so far this year suggest a return to average or below-average conditions.

What was the likely cause of this slowdown in the rise of carbon emissions from fossil fuel burning?

The slowdown in the growth of CO2 emissions from fossil fuel burning is largely a result of a marked slowdown in coal consumption in China, the largest contributor to global emissions (29 percent). This change may be largely due to economic factors, such as weaker global demand for steel. The growth of solar and wind energy in order to control climate change may have also played some role.

The United States, the second largest polluter of CO2 emissions (15 percent), has also played a role in the global fossil fuel emissions slowdown. U.S. fossil fuel emissions decreased by 2.6 percent in 2015, with coal decreasing and oil and gas increasing.

If emissions are holding steady, does that mean the level of atmospheric carbon stays steady as well?

The Global Carbon Budget analysis shows that, in spite of a slowdown in growth rates of CO2 emissions from fossil fuels, the growth in atmospheric CO2 concentration was a record high in 2015, and could be a record high again in 2016.

This is mainly because total CO2 sources (fossil fuel plus land use changes) were much higher than total net CO2 sinks (ocean sink plus land sink). Simply put, we are emitting carbon at a much higher rate than the planet can absorb it. Specifically, the new study shows that in 2015, the land sink – vegetation and soil that uptake CO2 – was smaller compared with the previous decade. In fact, we expect that CO2-sinking reservoirs, both ocean and land, will absorb CO2 at much lower rates in the future because of global warming itself. That would mean even more CO2 would stay in the atmosphere, causing a much higher rate of climate change.

What would have to happen to reduce atmospheric carbon levels, if slowing emissions growth is not enough?

The challenge to control atmospheric CO2 concentrations is to identify the most economical and realistic measures to control fossil fuel emissions with continued economic growth. Accomplishing this challenging goal will require innovative, cost-effective and carbon-emission-free technologies that can provide additional tens of terawatts of primary energy in the coming decades. The magnitude of the implied infrastructure transition suggests the need for massive investments in innovative carbon-free energy research.

There are already known technological options that exist today that can be implemented without requiring any new drastic technological breakthroughs, such as solar and wind energy, biomass, nuclear fission, nuclear fusion, fission-fusion hybrids and fossil fuels from which carbon has been sequestered. Other technologies that could help control atmospheric CO2 and climate change include efficiency improvements, geoengineering, hydrogen production, storage and transport, and other advanced technologies.

Another option is carbon sequestration, which has the potential to offset emissions by removing CO2 from the atmosphere. This CO2 removal can be accomplished by taking carbon produced by the global energy system and sequestering it in trees and subsurface reservoirs, such as in depleted natural gas cavities.

Do you predict emissions will increase, decrease or stay steady in 2017? How might these predictions change if President-elect Donald Trump backs out of the Paris Agreement, as he has indicated he would?

Whether a slower growth in emissions will be sustained depends on the use of coal in China and elsewhere, and where new sources of energy will come from. If countries want to accomplish the goal of the Paris Agreement – that is, to avoid a 2 degree warming – emissions need to actually decline, rather than stabilize.

If President-elect Donald Trump withdraws from a global climate change agreement, it would be difficult, not impossible, for the remaining countries to meet the goal of the Paris Agreement. One thing is for sure: Without U.S. participation there will be fewer funds available for the developing countries to combat global warming.

Editor’s note: To contact Atul Jain, call 217-333-2128; email: jain1@illinois.edu.

Liz Ahlberg Touchstone/Physical Sciences Editor/Illinois News Bureau