Studies surveyed Millar, R. et al. (2017) Emission budgets and pathways consistent with
limiting warming to 1.5 C, Nature Geophysics, doi: 10.1038 / ngeo3031 Matthews, H.D., et al. (2017) Estimating Carbon Budgets for Ambitious Climate Targets, Current Climate Change Reports, doi: 10.1007 / s40641 -017-0055-0 Goodwin, P., et al. (2018) Pathways to 1.5 C and 2C warming based on
observational and geological constraints, Nature Geophysics, doi: 10.1038 / s41561 -017-0054-8 Schurer, A.P., et al. (2018) Interpretations of the Paris climate target, Nature Geophysics, doi: 10.1038 / s41561 -018-0086-8 Tokarska, K., and Gillett, N. (2018) Cumulative carbon emissions budgets consistent with 1.5 C global warming, Nature Climate Change, doi: 10.1038 / s41558 -018-0118-9 Millar, R., and Friedlingstein, P. (2018) The utility of the historical
record for assessing the transient climate response to cumulative emissions, Philosophical Transactions of the Royal Society A, doi: 10.1098 / rsta.2016.0449 Lowe, J.A., and Bernie, D. (2018) The impact of Earth system feedbacks on carbon budgets and climate response, Philosophical Transactions of the Royal Society A, doi: 10.1098 / rsta.2017.0263 Rogelj, J., et al. (2018) Scenarios towards
limiting global mean temperature increase below 1.5 C, Nature Climate Change, doi: 10.1038 / s41558 -018-0091-3 Kriegler, E., et al. (2018) Pathways
limiting warming to 1.5 °C: A tale of turning around in no time, Philosophical Transactions of the Royal Society A, doi: 10.1098 / rsta.2016.0457
First, they rely on long historical
observational records to calculate the statistical relationship, effectively
limiting the variables that can be downscaled to temperature and precipitation, and the locations to those stations where these long
records were collected.