Over the last few weeks one science story has dominated the airwaves and news media, and that is the release of the keenly awaited IPCC report on climate change. Here at Stable Planet, we are particularly interested in this report and thought it would be a good start to our science news blog. We have worked as climate and environmental scientists for many years and have collaborated with some of the scientists who put this report together, and Simon was lucky enough to have co-authored one of the papers cited in the report1. We thought, then we were in a good place to give you a bit of background on what the IPCC is, how the report is built, and the key findings. Next week we are going to take this a little further and start to think what this means for horse owners.
What is the IPCC?
Well, it is a United Nations organisation first established in 1988 and as you may well know, the name stands for Intergovernmental Panel on Climate Change. The panel was formed to give independent advice to governments on the state of our understanding of climate change and likely future outcomes. When the panel was formed and for quite some time after, there was uncertainty and contention about if human induced climate change was real, and what might happen in the future. The role of the panel was to sift through publications by climate scientists to try to achieve a balanced view of what the science was saying, what the risks might be, and what mitigations were necessary. Every six or seven years the IPCC produces assessment reports by different working groups. The report that is in the media at the moment if by Working Group 1. This covers the physical climate science of climate change. It will be followed next year by reports from Working Groups 2 and 3, which cover impacts of climate change and mitigations. We will follow those reports next year, but for now let’s looks a bit more about the Working Group 1 report. The report is broken down into different categories, including a summary for policymakers (and the media), and review of the physical climate science.
The first question that comes to mind is how is it produced?
Well, over the last five years there have been a series of IPCC meetings to start drafting the report. Authors of different chapters are identified and they start working through scientific papers covering the relevant science. Some of these crop up because they make important points, such as potential loss of drinking water where communities depend on water fed from mountain glaciers3. In other cases, there are thousands of papers every year in specific climate journals that may be relevant and need to be sifted. Finally, some papers arise from specific conferences and workshops focussed on a specific question. All of these are then evaluated and brought together to lay out what we know, and importantly, what we don’t know about climate change. Then a draft version is available for comment across the scientific community before the final version is published. The process is pretty thorough and transparent, with reports being published from the meetings that lead up to the final version.
So what does it say?
Well, it says a lot and there is only the briefest summary available here, with a view to things that are important for the equestrian world. The report has 12 chapters and runs to 34949 pages! The report is based on recent and modern observations, comparisons with climate records from the past, simulations using the latest generation of climate models, and an understanding of the key climate processes. The first and most important thing that report says is that the climate change we are seeing is real unequivocally the result of human activity. I am sure you have heard this in the news media but as climate scientists ourselves, we wanted to explain what this means. When we make statements that we are unequivocally sure of something that is based on years and years of analyses. Previous reports have said there was a given probability humans were causing climate change. In the 3th assessment in 2001 the authors 66-100% sure, by the 5th assessment in 2015 they were 95-100% confident. In this 6th assessment the science is absolutely clear, and is worth quoting directly “It is unequivocal that human influence has warmed the global climate system since pre-industrial levels”4.
What that means is we have to take this very, very seriously.
You may, however, be asking how we can be so sure and that is a fair question. The predictions that we will have to make major adjustments to our carbon usage to avoid missing the 1.5°C or even the 2°C target are going to require a lot of work, so it is right that the science is strong. We know a lot about the climate system now both in the past and present and that allows us to make some important statements about the future. A lot of the predictions come from powerful computer models and one of the reasons for confidence is the level of agreement between models. What gives even more confidence is the ability of these models to reconstruct the recent past, for example a comparison of climate models with recorded temperatures since 1850. We also know a lot about natural climate forcing (see Climate Change: the basics here), from volcanic eruptions to solar activity, or the longer term influence of how the Earth’s orbit around the sun influences incoming solar radiation. Combining this information with our observations allows the report to say average global temperatures in the last decade are between 0.8°C and 1.3°C warmer than the recent pre-industrial period (1850-1900). That might not sound particularly scary, but it is for a very good reason. Climate scientists also know a lot about ways in which natural climate change can be driven by changes in one part of the system, they are known as feedback mechanisms. For example, melting glaciers and permafrost release methane and carbon dioxide, and loss of sea ice or glacier ice means less heat is reflected into space. Raising global temperature much more, say over 1.5°C makes these natural feedback mechanisms more likely to take us past tipping points in climate change, meaning reversing things could be harder. Moreover, the report indicates that human induced warming likely drove major changes in global precipitation since the 1950’s. The report also states with certainty that the increase in greenhouse gases has caused changes in temperature extremes that we have seen recently. If we go beyond 2°C, which will happen unless we all make changes, means we will see major loss of glacier ice, contributing to sea level rise. We don’t even need to model that outcome as natural climate change 120,000 years ago led to global average temperatures about 2°C above preindustrial levels, and this drove sea levels that were 4-6 meters higher than now5.
So, all this sounds like scary stuff and there is an awful lot more in the full report, available on the IPCC website here.
One response to all this is that there is nothing we can do, or that it is up to governments and anyway China keeps building coal fired power stations.
At Stable Planet we don’t take that view.
Everyone needs to contribute to getting towards reductions in greenhouse gasses. For sure, a lot of what needs to be done has to be driven by governments and international agreements, but in the end, we as a county produce about 6 tons per capita of CO2 per year6. That is a lot better than the 16 tons per capita for the USA, but remember we need to reach net ZERO by 2050. Some of that can be done by carbon offsetting and some by reduction in CO2 output.
In the next post we will start looking at what needs to be done globally and down to an individual level of the average horse owner.
References
1. Hernández, A. et al. Earth-Science Reviews, Vol. 209, 103286, 10.2020.2.
2. https://www.ipcc.ch/about/history/
3. Imerzeel, W. et al. Nature, Vol. 577, 16.01.2020, p. 364-369.
4. Gulev, S.K. et. al. IPCC AR6, ch3, p. 9. https://www.ipcc.ch
5 Rholing, E. et al. Nature Geoscience 1 1, p. 38–42.