Climate research is incredibly complex. Climate is defined as the weather over long period and is therefore based on long-term averages. Weather manifests as temperature, airflow (wind) and the water cycle (clouds), phenomena that influence each other and that are subject to natural variations. Changes in the climate can only be seen over longer periods of time, especially changes that are outside of the normal weather variations.
Scientists agree on the state of the climate. The temperature of the Earth is rising. Of course, scientists do debate with each other, but only about the details. These discussions help to bring research a step further. If, as a layman, you would like to debate about the climate, climate change and everything that goes with it, and you would like to have an informed opinion, you need to thoroughly research it. If you do not want to do that, you can rely on a summary from a reliable authority that has already spent the time.
Is the climate really changing?
The WMO, the World Meteorological Organization, recently put together an overview of weather conditions between 2001 and 2010. The organization concluded that global warming has continued and even speeded up in that time period: it was the warmest decade since we started measuring and it finished with the warmest year measured (2010). The average temperature on the Earth’s surface was 14.54°C in 2010, 0.54°C warmer than the average in 1990-2000. The decade was 0.86°C warmer than the one that preceded it. The WMO is an authority to me, and their conclusion seems to be reasonable and fact-based. The Dutch Environmental Assessment Agency (PBL), which we also consider a reliable institute, recently put all the facts together (Climate Change – Scoping the issues). They concluded that:
- It has been unequivocally determined that, since the industrial revolution, the Earth has been warming, the land and sea ice have been melting and hence, the climate is changing.
Is the change caused by humans?
This question is also not easy to answer, so we have to listen to the experts for this answer as well: the IPCC, the Intergovernmental Panel on Climate Change. In 1988, the United Nations gave the IPCC the task of evaluating the risks of climate change. The panel consists of hundreds of experts from all around the world, from universities, research institutes, businesses, and environmental and other organizations. The IPCC does not conduct their own research; instead they evaluate research that has been published in peer-reviewed journals.
The IPCC provides the informed mainstream opinion, and they are supported by a large coalition of scientific institutes. The Dutch Environmental Assessment Agency (PBL) gives the Dutch input to the IPCC. In the last PBL report, which was a summary of the IPCC report it was reported that:
- It is certain that the concentration of CO2 in the atmosphere has risen by almost 40% since the beginning of the industrial revolution. It is also certain that this increase in CO2 is caused by human activities.
- From physics, we know that greenhouse gases, including CO2, warm the Earth. It is now almost certain that much of the recent warming is caused by the human emission of greenhouse gases. The cooling effect of aerosols (particulates), which likewise come from human activities, works against the warming effect of greenhouse gases.
The degree of cooling is uncertain, but warming dominates the relationship. The IPCC concluded in 2007 that the probability that climate change is largely caused by people is about 90%. The first part of the fifth report has just been released; according to that report the certainty is about 95% (“It is extremely likely that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951 to 2010”).
Assuming that climate change is caused by greenhouse gases in the atmosphere that have been emitted by human activities, we can predict what will happen. The IPCC (and the PBL) think that:
- There is uncertainty about the precise impact of greenhouse gases on the global mean temperature. The likely impact of a doubling of the CO2 concentration on the temperature (the climate sensitivity) is between 1.0 and 2.5 degrees Celsius, and is most likely not greater than 3 degrees Celsius.
- The effects of the warming (globally 0.8 degrees above the pre-industrial temperature, 1.7 degrees warmer in the Netherlands) are already noticeable. Heat waves, droughts, floods, damage to ecosystems, threats to food production and damage to health are all expected to intensify in the future as the global mean temperature increases.
- Without a climate policy, the average temperature in 2010 could rise by 2.6 to 5.8 degrees compared to pre-industrial levels. With a drastic approach to greenhouse gas emissions, this could be limited to 1.1 to 2.6 degrees. Because the costs and benefits of climate policy are difficult to quantify, we usually talk about limiting risks rather than giving precise cost-benefit trade-offs.
These are the most important conclusions drawn by the IPCC and articulated by the PBL. There are scientists with other opinions, but there are fewer and fewer of them and they are relatively negligible. If there was a vote, they would form a very small minority. There are indications that this minority gets disproportionate attention from the press, but they have almost no voice in the scientific debate. But the debate will continue long as people are not willing to recognize the results of well-founded research, preferring to hide behind less well-substantiated research and media interpretations, or even worse, denying the climate problem all together.
Why is there still a climate debate?
The climate is so frantically debated because if the above conclusions are accepted they must lead to radical action. In order to keep climate change manageable, policy makers around the world are aiming for the so-called ‘2 degree’ scenario: a plan to hold the rise in average temperatures within 2°C. There are those who say that we have already gone past this and that we are heading for 3°C, and that if we extract and burn the fossil fuel that is still in the ground the worst case scenario will become reality. For the ‘2 degree’ scenario, the global CO2 emissions in 2050 need to be lower than half of those from 2009 and then continue to fall. This while the demand for energy from emerging economies and the growing world population continues to rise. The task facing politicians and industry is huge as it can have profound consequences for all the world’s people. The effects of climate change will be dramatic; to hold these effects within limits we will need to drastically change our behaviour. The consequences include: more extreme weather, leading to disasters, threats to food security, the disappearance of land through rising sea levels and climate refugees.
Climate scientists agree, we will need to stop our reckless use of fossil fuels. Changing the behaviour of individuals is difficult enough, let alone changing the behaviour of countries and companies of all sizes. It means saying goodbye to old values without really knowing what you will get in return. All change is difficult – it seems as though humans have a natural ‘resistance’ against it. By making agreements, laws and regulations, one can compel change. But the drive to keep things as they are is powerful. Fossil fuels represent an enormous value for international companies and national economies. The climate problem is a global problem and global agreements like Kyoto have proven impossible.
Wieb Miedema, September 2013