For a long time, it has been argued that in order to understand the potential climate change in the future, we need to understand why and how climate change occurred in the past. We source information on past climates through paleoclimatic reconstruction, which aids our present climate change models and helps give us a better understanding of what could happen in the future (Skinner, 2008). Equally, predictions are and have always been uncertain; the extent of anthropogenic factors of climate change changed throughout history and will undoubtedly change in the future also through for example increased carbon dioxide emissions as a result of fossil fuel combustion. No scientist can predict a ‘for sure’ scenario but can only make an educated guess or prediction (Knutti, 2008).
Although there have been controversies when it comes to climate change, average temperature data shows a clear rise as seen in Figure 1; which shows a sustained increase when looking at the period 1961 – 90. The average rate of warming in this short period appears to be 0.7 °C. Using climate change data from the past gives us an insight into future climate change and allows us to make estimated guesses on what the effects of this could be (Schneider and Mastrandrea, 2013).
Using past data, scientists can produce climate projections, an example can be seen in Figure 2; a projection from the IPCC 2018 Summary for Policymakers report. It shows observed average global temperatures between 1960 and 2017, making this a more up to date piece of data than the previous mentioned graph. Additionally, it also shows us the estimated change with a few different possible scenarios, in particular the effect that the rate of carbon dioxide level reduction will have on future global temperatures in order to limit the warming to 1.5°C as well as non-carbon dioxide radiative forcing which would reduce the possibility of maintaining global warming at 1.5°C. This shows that using environmental and climatic data from the past can help us make educated projections about the future of climate change (Masson-Delmotte et al. 2018).
Whilst using data from the past can be useful to 'predict' climate change scenarios, there are limitations to its use. Past climate change isn’t always a reliable form of predicting the future climate changes; according to Füssel (2007), ‘the effectiveness of pro-active adaptation to climate change often depends on the accuracy of regional climate and impact projections, which are subject to substantial uncertainty’. This means that whilst climate models which are formed using data found as part of paleoclimatic reconstruction provide us with patterns of climate change in the past, they are also limited to the current external factors which were present at a given past date; there’s no doubt that these factors will have changed by now due to industrialisation or deforestation to name a few. Since these processes are fairly recent, it’s hard to tie in with such a long record of climate change where for the most part, anthropogenic factors were very limited. According to Schneider and Mastrandrea (2013), “the changes that force anthropogenic climate change are unprecedented – and thus paleoclimatic conditions are not analogous to future anthropogenic changes”. This explains that anthropogenic factors vary and therefore the way they affect the climate is constantly changing; meaning that these factors will be different now than what they were in the past and what they will be in the future. Since they are such a huge part of climate change especially in the modern age, it is difficult to rely on these models to predict how future climate change will take place.
The above are examples of why we should always follow multiple climate models which focus on different aspects of the atmospheric and climate system in order to get a better idea of alternate outcomes, instead of limiting ourselves to one which may not predict the true outcomes since we don’t have enough data or certainty to focus on one accurate model. An example of uncertainty found within these kind of climate models can be seen in Figure 3, where on the left-hand side, observations, the darker line shows actual observed surface warming, and the grey thicker line around it shows the uncertainty around this piece of data. Ultimately this will affect the projections which in this case are constrained by the observed versus its uncertainty and therefore could result in inaccurate predictions of future surface warming as used in this example (Knutti, 2008).
In conclusion, it is difficult to predict future climate change since there are so many variables that can change the outcome. The climate models that are made are and should be used as guidance of what could happen, rather than a definitive answer of what will happen. Using past environments and events which occurred in the past due to climate change, scientists can now make guesses as to what could happen in the future and to what extent.
DISCLAIMER
This work is an altered piece of work that was originally submitted as an assignment to Queen's University Belfast by the author, all efforts have been made to erase links to the original module in order to avoid plagiarism by other students in the future.
FÜSSEL, H., 2007. Vulnerability: A generally applicable conceptual framework for climate change research. Global Environmental Change, vol. 17, no. 2, pp. 155-167.
KNUTTI, R., 2008. Should we believe model predictions of future climate change? Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 366, no. 1885, pp. 4647-4664.
MASSON-DELMOTTE, T., ZHAI, P., PÖRTNER, H.O., ROBERTS, D., SKEA, J., SHUKLA, P.R., PIRANI, A., MOUFOUMA-OKIA, W., PÉAN, C. and PIDCOCK, R., 2018. IPCC, 2018: Summary for Policymakers. In: Global warming of 1.5 C. An IPCC Special Report on the impacts of global warming of 1.5 C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global. Geneva, Switzerland.
SCHNEIDER, S.H. and MASTRANDREA, M.D., 2007. Paleoclimate relevance to global warming.
SKINNER, L., 2008. Facing future climate change: is the past relevant? Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 366, no. 1885, pp. 4627-4645.
Figures:
(1) SCHNEIDER, S.H. and MASTRANDREA, M.D., 2007. Paleoclimate relevance to global warming, pg. 245.
(2) MASSON-DELMOTTE, T., ZHAI, P., PÖRTNER, H.O., ROBERTS, D., SKEA, J., SHUKLA, P.R., PIRANI, A., MOUFOUMA-OKIA, W., PÉAN, C. and PIDCOCK, R., 2018. IPCC, 2018: Summary for Policymakers. In: Global warming of 1.5 C. An IPCC Special Report on the impacts of global warming of 1.5 C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global. Geneva, Switzerland, pg. 8.
(3) KNUTTI, R., 2008. Should we believe model predictions of future climate change? Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 366, no. 1885, pg. 4650.
