Global temperature definition affects achievement of long-term climate goals
The Paris Agreement on climate change aims to limit ‘global average temperature’ rise to ‘well below 2 °C’ but reported temperature depends on choices about how to blend air and water temperature data, handle changes in sea ice and account for regions with missing data. Here we use CMIP5 climate mod...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2018-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/aab305 |
| _version_ | 1827870951118733312 |
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| author | Mark Richardson Kevin Cowtan Richard J Millar |
| author_facet | Mark Richardson Kevin Cowtan Richard J Millar |
| author_sort | Mark Richardson |
| collection | DOAJ |
| description | The Paris Agreement on climate change aims to limit ‘global average temperature’ rise to ‘well below 2 °C’ but reported temperature depends on choices about how to blend air and water temperature data, handle changes in sea ice and account for regions with missing data. Here we use CMIP5 climate model simulations to estimate how these choices affect reported warming and carbon budgets consistent with the Paris Agreement. By the 2090s, under a low-emissions scenario, modelled global near-surface air temperature rise is 15% higher (5%–95% range 6%–21%) than that estimated by an approach similar to the HadCRUT4 observational record. The difference reduces to 8% with global data coverage, or 4% with additional removal of a bias associated with changing sea-ice cover. Comparison of observational datasets with different data sources or infilling techniques supports our model results regarding incomplete coverage. From high-emission simulations, we find that a HadCRUT4 like definition means higher carbon budgets and later exceedance of temperature thresholds, relative to global near-surface air temperature. 2 °C warming is delayed by seven years on average, to 2048 (2035–2060), and CO _2 emissions budget for a >50% chance of <2 °C warming increases by 67 GtC (246 GtCO _2 ). |
| first_indexed | 2024-03-12T16:04:04Z |
| format | Article |
| id | doaj.art-dcf3badbda254b8fa05aa9835d9e681c |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T16:04:04Z |
| publishDate | 2018-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-dcf3badbda254b8fa05aa9835d9e681c2023-08-09T14:31:33ZengIOP PublishingEnvironmental Research Letters1748-93262018-01-0113505400410.1088/1748-9326/aab305Global temperature definition affects achievement of long-term climate goalsMark Richardson0https://orcid.org/0000-0001-7063-631XKevin Cowtan1Richard J Millar2https://orcid.org/0000-0002-8349-7758Jet Propulsion Laboratory, California Institute of Technology M/S 233–300, 4800 Oak Grove Drive, Pasadena, CA 91101, United States of America; Author to whom any correspondence should be addressed.Department of Chemistry , University of York, Heslington, York, YO10 5DD, United KingdomEnvironmental Change Institute, Oxford University Centre for the Environment , South Parks Road, Oxford, OX1 3QY, United KingdomThe Paris Agreement on climate change aims to limit ‘global average temperature’ rise to ‘well below 2 °C’ but reported temperature depends on choices about how to blend air and water temperature data, handle changes in sea ice and account for regions with missing data. Here we use CMIP5 climate model simulations to estimate how these choices affect reported warming and carbon budgets consistent with the Paris Agreement. By the 2090s, under a low-emissions scenario, modelled global near-surface air temperature rise is 15% higher (5%–95% range 6%–21%) than that estimated by an approach similar to the HadCRUT4 observational record. The difference reduces to 8% with global data coverage, or 4% with additional removal of a bias associated with changing sea-ice cover. Comparison of observational datasets with different data sources or infilling techniques supports our model results regarding incomplete coverage. From high-emission simulations, we find that a HadCRUT4 like definition means higher carbon budgets and later exceedance of temperature thresholds, relative to global near-surface air temperature. 2 °C warming is delayed by seven years on average, to 2048 (2035–2060), and CO _2 emissions budget for a >50% chance of <2 °C warming increases by 67 GtC (246 GtCO _2 ).https://doi.org/10.1088/1748-9326/aab305climate changecarbon budgetsglobal warmingParis agreementobservational temperature records |
| spellingShingle | Mark Richardson Kevin Cowtan Richard J Millar Global temperature definition affects achievement of long-term climate goals Environmental Research Letters climate change carbon budgets global warming Paris agreement observational temperature records |
| title | Global temperature definition affects achievement of long-term climate goals |
| title_full | Global temperature definition affects achievement of long-term climate goals |
| title_fullStr | Global temperature definition affects achievement of long-term climate goals |
| title_full_unstemmed | Global temperature definition affects achievement of long-term climate goals |
| title_short | Global temperature definition affects achievement of long-term climate goals |
| title_sort | global temperature definition affects achievement of long term climate goals |
| topic | climate change carbon budgets global warming Paris agreement observational temperature records |
| url | https://doi.org/10.1088/1748-9326/aab305 |
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