Detecting climate milestones on the path to climate stabilization
File(s)
Published version
Author(s)
MacDougall, Andrew H
Rogelj, Joeri
Jones, Chris D
Liddicoat, Spencer K
Grassi, Giacomo
Type
Journal Article
Abstract
The era of anthropogenic climate change can be described by defined climate milestones. These milestones mark changes in the historic trajectory of change, and include peak greenhouse gas emissions, peak greenhouse gas concentration, deceleration of warming, net-zero emissions, and a transition to global cooling. However, given internal variability in the Earth system and measurement uncertainty, definitively saying that a milestone has passed requires rigour. Here CMIP6 simulations of peak-and-decline scenarios are used to examine the time needed to robustly detect three climate milestones: (1) the slowdown of global warming; (2) the end of global surface temperature increase; and (3) peak concentration of CO2. It is estimated that it will take 40 to 60 years after a simulated slowdown in warming rate, to robustly detect (>95% change) the signal in the global average temperature record. Detecting when warming has stopped will also be difficult and it takes until the mid 22nd century to have enough data to conclude warming has stopped. Detecting that CO2 concentration has peaked is far easier and a drop in CO2 concentration of 3 ppm is consistent with a greater than 99% chance that CO2 has peaked in all scenarios examined. Thus it is likely that as the rate of CO2 emissions is reduced, and net-zero emissions is approached, interpreting the global temperature record will become difficult—with a high potential to create confusion amongst policy makers and the general public.
Date Issued
2024-07-01
Date Acceptance
2024-06-21
Citation
Environmental Research Letters, 2024, 19 (7)
ISSN
1748-9326
Publisher
IOP Publishing
Journal / Book Title
Environmental Research Letters
Volume
19
Issue
7
Copyright Statement
© 2024 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
License URL
Identifier
10.1088/1748-9326/ad5ab1
Subjects
atmospheric CO2 concentration
climate milestone
EARTH SYSTEM
EMISSIONS
Environmental Sciences
Environmental Sciences & Ecology
global temperature
Life Sciences & Biomedicine
Meteorology & Atmospheric Sciences
MODELS
Physical Sciences
Science & Technology
Publication Status
Published
Article Number
074065
Date Publish Online
2024-07-09