CO2 and Climate Change

We know that carbon dioxide (CO2) is increasing in the atmosphere from human activities such as burning of fossil fuels and deforestation. This increase is one of the major factors in global warming. There is no longer any scientific debate about this. The most recent report by the Intergovernmental Panel on Climate Change has confirmed this.

In 2007 the concentration of CO2 in the atmosphere is approximately 380 parts per million (ppm). Every year human activities add to that. Some scientists and economists in the climate science world such as David Stern and James Hansen have identified a concentration of 450 ppm as a maximum goal for CO2 that may avoid the most significant damage to the Earth’s ecosystems and economies. There is a great deal of uncertainty about the severity of the effects associated with this or any other target level for CO2.  We have chosen to use it for this simulation, but we could have set it higher or lower.  As you play with the simulation consider how the three scenarios would play out if the bathtub overflowed at a level other than 450 ppm.

Already there is much more CO2 in the atmosphere than at any time in the past 425,000 years. Follow the green line to the right edge of this graph. This is where we are today.

Questions about CO2 and Climate Change

What are CO2  emissions?

 Carbon dioxide (CO2) is a gas that makes up a tiny fraction of the Earth’s atmosphere. It occurs naturally, mostly as a result of breathing, of decay, from the burning of wood and the release of CO2 from the oceans. CO2 emissions also result from the burning of fossil fuels and other human activities.  It is this human-generated CO2 that we are showing in our simulation.

What are CO2 removals?

Carbon sinks remove carbon from the atmosphere. The main carbon sinks responsible for removals are photosynthesis and absorption by the oceans.

The oceans are both a carbon sink and a source of CO2. There is an ongoing exchange of CO2 between the atmosphere and the oceans. The balance depends upon factors including water temperature and the concentrations of CO2 in both the oceans and the atmosphere.

For hundreds of thousands of years emissions and removals remained roughly in balance with the concentration of CO2 in the atmosphere varying between 180 and 300 parts per million (ppm). This was true until humans began to burn fossil fuels during the Industrial Revolution. These additional CO2 emissions are the problem. Currently much more CO2 is being released than can be taken up by plants or absorbed by the ocean. The concentration of CO2 in the atmosphere is now 380 ppm and rising.

Why do removals seem to follow emissions?

Carbon dioxide flows between the atmosphere, biosphere, and oceans in order to maintain a balanced distribution. When the concentration of CO2 in the atmosphere increases, two things happen:

• “CO2 fertilization” occurs. Plants use more CO2 for photosynthesis, growing more leaves and woody material.
• The surface ocean—mixed by wind-driven waves— quickly absorbs CO2, which then diffuses more gradually into the deep ocean.

Both processes have limits. The oceans can only absorb so much CO2 before releasing as much CO2 back to the atmosphere as was taken up. For plants, the limitations on growth from water and other nutrients become important. This is called “sink saturation.”

In the “Allow Increased Emissions” future, removals increase because the rapidly-growing concentration of CO2 in the atmosphere continues to drive uptake. Part of the excess CO2 is absorbed by plants and the oceans.

In the “Reduce CO2 Emissions” future, removals fall because the excess of CO2 in the atmosphere above that in the biosphere and oceans is not so great.

What’s the connection between CO2  and climate change?  

We know that CO2 absorbs heat from the Sun and releases it into the atmosphere. Going back millions of years, when the concentration of CO2 was higher, the Earth was warmer. Eventually CO2 concentration dropped and the world became cooler. Since the 1740s CO2 concentration has increased significantly, and the average temperature on Earth has also increased.

 Why does the CO2 level in the atmosphere continue to rise even when emissions are leveled off?
This scenario corresponds to clicking the middle button in our simulation: “LEVEL OFF CO2 EMISSIONS.” After about 2045 emissions are no longer increasing. At that point removals are also level from year to year. But since emissions are greater than removals, each year more CO2 goes into the atmosphere than is removed. So the amount of CO2 in the atmosphere continues to rise. 

It’s like a bus traveling through the city with people getting on and off. Let’s say that at one stop 5 people get on the bus and 3 get off. At the next stop the same thing happens: 5 people get on and 3 get off. If this pattern continues the bus will get very crowded. The number of people getting on the bus is level: 5 at each stop. But since only three people get off there is an increase of 2 people each time the bus stops. In order to keep the crowding from getting worse, the same number of people have to get off the bus as get on.  And to reduce the crowding, more people have to get off than get on.

In order to keep the concentration of CO2 in the atmosphere at a given level, say 450 ppm, emissions and removals have to be equal.  In order to reduce the concentration of CO2 in the atmosphere, removals have to be greater than emissions.

Climate Crisis

In developing countries such as India, the concerns for climate change parallel the concerns for meeting energy demands for developmental works.

Total emissions in India are the fourth-largest after the US, China and Russia, but its per capita footprint is 1.2 tonnes a year, against 20 tonnes in the US and the world average of 4 tonnes

Consider this. The country’s largest electricity generator National Thermal Power Corporation (NTPC) has also been identified as the third largest polluter among the world’s power generation companies by the Washington-based Center for Global Development.

At the same time, India faces acute power shortage that leaves more than 400 million, mostly rural, people without electricity every day. Nearly 7 million Indians use firewood and animal waste as fuel for cooking. The country needs to expand power generation capacity by 160,000MW over the next decade.

Analysts estimate that if 1.02 lakh family type biogas plants are installed within a year, the move would save 1.4 lakh tonnes of fuel wood and 14 lakh tonnes of organic manure. Biogas fuel can be used for cooking, heating and lighting, space cooling, refrigeration and in dual-fuel or 100% gas engines for motive power. When attached with alternators, it can generate electricity. The government is close to achieving its target of installing 1.02 lakh biogas plants.

Arun Mohanty of Parivesh Unnayan Parishad, an NGO that works towards environmental causes, feels that while development cannot be compromised, justifying environmental damage in the name of progress is inexcusable. The solution is to find a middle path. He says every citizen needs to be aware of the importance of a balanced ecosystem, and shouldn’t wait for the government to take steps.

“Where is the problem if every individual takes the initiative towards a greener environment? Even the educated ones living in the cities are not aware enough. Tell them that the river Ganges is going to dry up in two to three decades and they will laugh it off as a joke,” he says.

That said, energy security is a key to sustaining India’s 8%-plus economic growth.

India’s consumption of petroleum products is around 112mt per annum and it imports 78% of its energy needs.

By the government’s estimates, energy consumption in the country is set to quadruple over the next 25 years, inevitably expanding Indian emission of greenhouse gases.

But the current figures show that the Indian per capita carbon footprint remains a fraction of that of the industrialized world — the average American produces 16 times the emission of the average Indian. This fact empowers the central Indian argument for its right to consume more, not less, energy in the future.

India points out that it contributes 4.6% of the world’s greenhouse gases although its people represent 17% of the world’s population.

India has pledged to ensure its per capita emissions never exceed those of the developed world. It has consistently tackled pressures to set targets for reducing emissions, arguing that it has neither been a significant polluter nor yet able to spread modern energy to millions of its poor.

Power generation across India has been stepped up, with the government promising to extend electricity across rural India over the next five years, but that, too, is a mixed blessing. The old-fashioned coal-fired power plants in India are among the biggest polluters in the country, according to a survey released recently by an American environmental group, Carbon Monitoring for Action.

“The key is to find the rich and the poor, the developed and the developing, and the large and small polluters in a deal, if we want to leave behind a healthy liveable environment for our children,” contemplates Mohanty.