by David Warrilow
RMetS Vice- President and Chair of the Climate Science Special Interest Group
Climate change has been recognised by scientists and Governments as being one of the most significant challenges facing the world today. Growth in the human population coupled with industrialisation has resulted in a huge demand for energy. Most of that demand has been met by using fossil fuels (coal, oil and gas) and this has powered human development over the last two to three centuries. Unfortunately, fossil fuel use comes with environmental costs. Sulphur based air pollution, particularly from coal burning, was evident from its early use and is still a major issue in large parts of the developing world. Combustion of fossil fuels also generates nitrogen oxides which are detrimental to health as has been recognised recently across the UK, largely due to vehicle pollution.
The less obvious, but even more detrimental product of fossil fuel burning has been the increase in carbon dioxide (CO₂) in the Earth’s atmosphere (up 40% since the industrial revolution in the 18th Century). CO₂ is essential to life and occurs naturally. CO₂ is a so-called greenhouse gas - it slows the rate of radiative cooling of the Earth and maintains its climate at a moderate level. Indeed, without it the world would be much colder than today and probably uninhabitable. But you can have too much of a good thing. The carbon cycle has been altered by human use of fossil fuels and increased atmospheric CO₂, along with other greenhouse gases, threatens to warm the planet by several degrees over this century. Accompanying changes in weather patterns and increases in extreme weather, threaten the functioning of ecosystems, food production, human health, infrastructure, economic activity and human well-being on a global scale.
How should we respond? There are 4 main options: 1) do nothing and accept the risks, 2) deal with the problem at source – e.g. by cutting back significantly on fossil fuel use, 3) adapting to the changes in the weather and climate – e.g. by making infrastructure more resilient and finally 4) undertake climate engineering – e.g. countering the warming effect by artificially increasing sulphate aerosols in the stratosphere to reflect more sunlight.
Option (1) is often characterised by a wait and see attitude – if it turns out very bad then we will do something. But the difficulty here is that climate change cannot be reversed quickly and possibly not at all. It would likely be too late to act when it had become unacceptably severe. It would also be more expensive to act later. In any case some parts of the world are already seeing the effects of climate change and find it unacceptable now.
Option (2) is the focus of Governments round the world. The simple advice when in a hole is to stop digging! But changing the way we drive our economies is not trivial. It has taken 25 years of diplomacy to get nations to agree to act together to limit greenhouse gas emissions. And yet alternative ways of producing energy now exist – which not only reduce such emissions but also reduce air pollution. Future generations will look back at our era and wonder why we thought it acceptable to treat the atmosphere as a garbage bin.
Option (3) will be necessary whatever else we do – the greater the level of climate change the more we will need to adapt. But adaptation is not easy. Much infrastructure has been designed to cope with historic climates – changing these to cope with quite different climates will require a major effort. And in some cases, adaptation may not be possible or be prohibitively expensive.
Option (4) sounds potentially attractive and there are several imaginative proposals. However, these are likely to be impractical and economically costly to undertake at sufficient scale. Furthermore, there is a risk of unwanted side effects and the challenge of getting international agreement. Finally, such schemes don’t deal with the direct effect of CO₂ such as the acidification of the ocean.
Governments in general have recognised the need to pursue options (2) and (3) together. Some climate change is unavoidable - the global temperature is already 1°C higher than pre-industrial levels. So, adaptation measures are needed already. But it is well recognised that there is a need to limit warming to 2°C (and possibly 1.5°C) so that its risks are contained and are manageable. This will mean reducing net emissions to zero by the second half of the century as agreed in Paris in 2015.
The Royal Meteorological Society is enhancing its work on climate change. If you would like to learn more, a very accessible introduction can be found in the Ladybird Book on Climate Change, authored by HRH The Prince of Wales, Tony Juniper and Emily Shuckburgh, chair of the Society’s Climate Science Communications Group. The book can be purchased here >>
On the 17th January the Society with the Grantham Institute will hold a one-day meeting on climate change at Imperial College, London. Registration details are here >>
In a recent RMetS podcast, we talk about the Special Issue of our "Weather" Journal, which is focused on the subject of Climate Change. We also sit down for an interview with David Warrilow, who was guest editor for this issue and Nigel Arnell who is the author of one of the papers published in it: