5. Climate change impacts

What is dangerous climate change? What is our coping range? ‘Climate change impacts’ assesses the potential effects of climate change on the natural environment as well as on human societies and our economies. Climate change impacts will increase significantly as global temperature rises. Climate change will affect the return period and severity of floods, droughts, heat waves, and storms. Coastal cities and towns will be especially vulnerable as sea-level rise will worsen the effects of floods and storm surges. Water and food security and public health will become the most important problems facing all countries. Climate change also threatens global biodiversity and the well being of billions of people.

3. Evidence for climate change

‘Evidence for climate change’ considers both past and recent climate change through changes in temperature, precipitation, and relative global sea level to show that significant changes in climate have been recorded. These include a 0.85°Celsius (C) increase in average global temperatures over the last 150 years, sea-level rise of over 20 cm, significant shifts in the seasonality and intensities of precipitation, changing weather patterns, and significant retreat of Arctic sea ice and nearly all continental glaciers. The IPCC 2013 report states that the evidence for global warming is unequivocal and that there is very high confidence that this warming is due to human emissions of greenhouse gases.

6. Climate surprises

The assumption of a linear relationship between greenhouse gases and climate change may be wrong. ‘Climate surprises’ examines the possibility that there are thresholds—or tipping points—in the climate system that may occur as we warm the planet. These include the possibility that Greenland and/or the Antarctic could start to irreversibly melt, raising sea level by metres; a change in North Atlantic driven deep-ocean circulation could produce extreme seasonal weather in Europe; dieback of the Amazon rainforest due to deforestation, with concurrent depletion in biodiversity; and, finally, a release of gas hydrates from deep beneath the oceans could occur if the oceans warm up sufficiently, again accelerating climate change.

2. The climate change debate

‘The climate change debate’ describes the combination of factors that led to recognition and acceptance of climate change, including that it was anthropogenic, beginning with climate change science research carried out in the 1950s and early 1960s. The next stages of research into this area came later in the 1980s: the observed upturn in the global temperature data set; the increased knowledge of past climate change; significant advances in global climate modelling; the emergence of global environmental awareness; increased media interest in the confrontational nature of the debate; and finally politicians and economists taking the climate change threat seriously since the late 1990s.

7. Politics of climate change

Climate change can only be solved by having binding international agreements to cut global greenhouse gas emissions. ‘Politics of climate change’ reviews the role of the UNFCC and the regular ‘Conference of the Parties’ (COPs) climate change negotiations beginning with the Kyoto Protocol, which was signed in 1997 by over 190 countries. Failures at COP15 in Copenhagen (2009) due to the introduction by the US and BASIC countries of voluntary pledges set back negotiations. COP18 in Doha (2012) reinstated the Kyoto mechanisms and accounting rules, and encouraged parties to review and, if possible, increase their commitments. It is hoped that a timetable for a binding climate agreement can be finalized at COP21 in Paris in 2015.

1. What is climate change?

‘What is climate change?’ examines the role of greenhouse gases (GHGs) in moderating past global climate; why they have been rising since the industrial revolution; and why they are now considered dangerous pollutants. It considers which countries have produced the most GHGs and how this is changing with rapid global development. The Intergovernmental Panel on Climate Change regularly collates and assesses the most recent key research and evidence for climate change. Its assessments have a profound influence on the negotiators of the United Nations Framework Convention on Climate Change (UNFCCC). As more carbon is emitted into the atmosphere the effects of climate change will increase, which will threaten and challenge human society.

9. Envisioning the future

‘Envisioning the future’ considers some of the deep questions of why humanity seems unable to deal with the question of pollution. The challenge of climate change must be seen within the current dominant political and economic landscape. Only by understanding the fundamental societal and economic causes of carbon emission can we hope to be able to build systems that can rapidly reduce them. In doing so we may also provide solutions to global environmental degradation, poverty, and security. Future policies and international agreements need to provide win-win solutions that deal with the biggest challenges which face humanity in the 21st century.

8. Solutions

‘Solutions’ examines three types of solution to climate change. The first is adaptation, which is simply providing protection for the population, as we already know that there will be climate change even if emissions are radically cut back to 1990 levels. Second is mitigation, which would involve cutting our carbon footprint and thus reversing the trend that currently exists of ever increasing greenhouse gas emissions. Fossil fuels need to be replaced with renewable or alternative energy sources that will not produce greenhouse gas emissions. Third is geoenginnering that involves large-scale extraction of carbon dioxide from the atmosphere or modification of the global climate.

4. Modelling future climate

‘Modelling future climate’ is about understanding the fundamental physical processes of the climate system. Modelling future climate considers the carbon cycle, cooling effects, carbon emissions, and the complex three-dimensional general circulation models that examine and further our understanding of the global climate system and which are used to predict future global climate. Over 40 climate models were used in developing the IPCC projections for the 2013 report. The three main realistic carbon emissions pathways suggest the global mean surface temperature could rise by between 2.8°C and 5.4°C by 2100 and predict an increase in global mean sea level of between 52 cm and 98 cm in this timeframe.