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CCP - FAQs - Climate Change

I read a lot about climate change but who / what institutions are the most authoritative sources on the topic?

There are a huge variety of organisations involved in researching the issue and science of climate change. The most comprehensive and authoritative source is widely considered to be the Nobel Prize-winning Intergovernmental Panel on Climate Change Another accessible and comprehensive source on climate change can be found at the BBC website.

What is the correlation between human activity and the rise in CO₂ levels? Is there a correlation between CO₂ levels and global temperatures?

According to the IPCC, “global atmospheric concentrations of CO₂, CH4 and N2O have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years”.

Although there are other GHGs – including Methane and Nitrous Oxide – that play a role in global warming, the main focus is on carbon dioxide – primarily given off by burning fossil fuels. This has the highest radiative forcing (warming) effect than other GHGs, makes up 77% of total anthropogenic GHG emissions as of 2004 and its rate of growth has increased faster than other GHG emissions (IPCC Working Group 3 report).

IPCC data illustrates that the global atmospheric carbon concentration of carbon dioxide has risen from about 280 parts per million (ppm) before the Industrial Revolution to about 390 ppm today. Research also found that that these atmospheric carbon dioxide concentrations are at levels not seen for at least 600,000 and possibly 25 million years – previous range was 180ppm – 300ppm. Over these time periods the IPCC found that CO₂ concentration levels and global average temperatures are closely linked and have stated that “Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations”.

Furthermore, the climate responds only slowly to CO₂ levels – the time lag occurs because rising air temperatures take time to make themselves felt throughout the immense thermal mass of the oceans, which stay warm long after the cause of the warming has been removed. This means that Earth has not yet felt the full effect of today's level of greenhouse gases.

Therefore, for example, even if we had stabilized GHG emissions at year 2000 levels, the best estimate suggests that we would still have an increase of 0.6°C in global average temperatures by 2090-2099 as compared to 1980-1999 levels.

Why are CO₂ levels rising? Don’t the forests and oceans absorb a great deal of CO₂?

Growth in energy use – and therefore CO₂ emissions emitted by burning fossil fuel - is strongly linked to global economic growth, which is in turn linked to population growth and development. The world is developing extremely quickly particularly in large newly industrializing economies like China and India, which have added to the previous CO₂ emissions from more mature industrialized economies. The world’s population at the same time has been explosive – from approximately 3 billion in the mid-20th century to more than 6 billion today, also increasing the demand for energy.

This is also exacerbated by another factor, particularly in countries in South America and parts of Asia, namely the effect of deforestation on climate change and natural greenhouse gas absorption, particularly as land use changes from natural habitat to either agricultural or industrial use. As emissions continue to rise and the ability of the land biosphere and oceans to absorb CO₂ is diminished, CO₂ concentration levels in the atmosphere will rise even faster.

What is the consensus on the levels at which CO₂ levels should be stabilized?

The IPCC found that reaching a level of 550ppm CO₂ concentration in the atmosphere has a very high probability – between 77% to 99% - that the 2°C rise in global average temperatures will happen.

As a result, in order to not exceed this and to try to global mean temperature increases to 2°C and so likely avoid the worst global warming scenarios, the IPCC has stated that CO₂ emissions must peak within the next 15 years and drop by 50-80% compared to today’s levels by 2050.

Where are the main sources of man-made CO₂ in the atmosphere coming from?

In excess of 60% of man-made global annual CO₂ emissions are created through energy use and production. Of this 60%, over 40% is produced by power generation (from large fixed-point sources) nearly double that of both industry and transport. Within the power generation sector, over 70% of emissions come from coal – for example just one 1GW coal plant emits 5-7 million tonnes of carbon dioxide per year.

Other industrial sources:


Mt CO₂


Source and notes

Industrial Processes



WRI, Climate Analysis Indicator Tool (

Year 2000 data (latest complete data set in CAIT)

1. Industrial Processes is roughly 50:50 other GHG and CO₂.

2. Agriculture and Waste sector emissions consist of non-CO₂ GHG.

3. International bunkers (824 Mt CO₂) is included in Energy.







Land-Use Change & Forestry







Current CO₂ Emissions from Power Sector by Fuel


Mt CO₂


Source and notes




IEA WEO 2006; Year 2004 data.

1. Power and Transport correspond to IEA sectors.

2. Heat includes the IEA sectors: industry, residential and services (includes energy-related, non-transport, agriculture and public-sector emissions), and other (includes international bunkers, own uses and losses).




Power Generation



CO₂ can be captured from a wide range of industries, including major industrial processes that create emissions from a large single-point source. As explained in the following table, these CO₂ emissions are significant and account for nearly 30% of the per annum emissions from power generation.

CO₂ emissions

Million tonnes/year

Cement manufacture
Oil refining
Iron and steel production
Ethanol, Ethylene, Ethylene Oxide
Other industry
(Overall industry)
Power generation


How can these CO₂ emissions be reduced to meet the desired emissions reductions targets?

The emissions cuts that the IPCC have indicated to avert the worst effects of climate change are substantial – 50-80% reductions from today’s levels, and in a world which is continually developing and requiring more energy. There is therefore no one existing ‘magic bullet’ technology or new technology such as nuclear fission that can solve the whole problem of CO₂ emission reductions.

There is a variety of emission reduction strategies that can be pursued now, using existing technologies, that can provide energy but in line with emission levels reductions. These fall under four main banners: energy efficiency and conservation measures, fossil-fuel based switching and CCS measures, renewable energies and nuclear.

Energy Efficiency & Conservation

  • Increased transport efficiency – for example lighter, smaller more efficient cars
  • Reducing miles traveled – for example via the uptake of public transportation, increased video conferencing etc
  • Increased heating efficiency – for example using more efficient boilers, increasing insulation in buildings etc
  • Increased efficiency of electricity production

Renewables & Biostorage 

  • Wind-generated electricity
  • Solar electricity
  • Wind-generated hydrogen fuel
  • Biofuels

Fossil-fuel-based strategies

  • Fuel switching e.g. coal to gas – coal is the most CO₂ intensive of all the fossil fuels
  • Fossil-based electricity with carbon capture & storage (CCS)
  • Coal synfuels with CCS
  • Fossil-based hydrogen fuel with CCS


  • Nuclear-generated electricity

What part can CCS really play in this? Wouldn’t it be better to consider renewable sources and nuclear as more effective options in the long run?

CCS is not the only solution to global climate change but it is one that can reconcile our rising fossil fuel use and energy demand with carbon emission cuts in the short to medium-term, while allowing the developing world to develop. Reducing CO₂ emissions will take a number of solutions that coordinate companies, governments, and consumers.

Fundamentally, there is a huge gap between global energy demand and their potential to reduce CO₂ emissions on the massive scale required and in the timeframe needed to avoid substantial climate change, given that in order to meet the IPCC target emissions should peak at 2015 and decline afterwards. Bridging this gap with CCS – ensuring that carbon dioxide from the burning of fossil fuels is kept away from the atmosphere – is a crucial way of meeting energy needs and having a sudden and major impact on carbon emissions.

Nuclear and renewable generation will play an important part in the energy mix but because of the nature of this generation it will take years to get fully online. Even when new build is online it will not mitigate the emissions of existing fossil-fuel burning plants that are projected to be on line for many years to come.

According to a variety of scenarios considered by the IPCC Special Report on Carbon Dioxide Storage and Capture, CCS could contribute at least 25% of the emissions reductions required to avoid the worst effects of climate change by keeping carbon concentrations at 550ppmv or below.

What are other ways we can reduce CO₂ output? Are there certain CO₂ emissions that cannot be addressed by CCS technology?

The reduction of fossil fuel usage through energy efficiency and lower consumption is a necessary step in combating the worst effects of GHG-induced global warming. The most obvious application for CCS is energy generation and industrial applications such as cement manufacture, refining and gas production, and these methods have clear links to consumption and consumer and industrial demand.

Reducing other CO₂ generating activities like automobile use and aviation is an important step in reducing overall emissions. This is of particular importance since it is far more difficult to reduce or capture emissions from the billion-plus of these small single-point sources than it is from stationary, large-point sources like power plants, refineries and industrial facilities. Eliminate those emissions from these far less numerous sources and you wipe out large volumes of CO₂ at a stroke.




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