Radiation Transfer Calculations and Assessment of Global Warming by CO<sub>2</sub>

Harde, H.

doi:10.1155/2017/9251034

Cited by 13 publications

(16 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The discussion is focused on ECS but many studies provide also estimated TCR based on the same or similar methods. Some studies are reviews, combine methods or other do not easily fit into any of the categories below 6,[143][144][145][146][147] .…”

Section: Methodsmentioning

confidence: 99%

Beyond equilibrium climate sensitivity

2017

View full text Add to dashboard Cite

Equilibrium climate sensitivity characterizes the Earth' long-term global temperature response to an increased atmospheric carbon dioxide concentration. It has reached almost iconic status as the single number that describes how severe climate change will be. The consensus 'likely' range for climate sensitivity of 1.5-4.5 o C today is the same as given by Jule Charney in 1979, but is now based on quantitative evidence from across the climate system, and through climate history. The quest to constrain climate sensitivity has revealed important insights into the timescales of the climate system response, natural variability, limitations in observations and climate models, but also concerns about the simple concepts underlying climate sensitivity and radiative forcing, which open avenues to better understand and constrain the climate response to forcing. Estimates of the transient climate response are better constrained by observed warming and are more relevant for predicting warming over the next decades. Newer metrics relating global warming directly to the total emitted CO2 show that in order to keep warming to within 2 o C, future CO2 emissions have to remain strongly limited, irrespective of climate sensitivity being at the high or low end.If we increase the amount of CO2 in the Earth's atmosphere and wait for climate to respond, how much warmer would surface temperatures eventually get? What seems like a simple but important question to ask given current and projected human-induced CO2 emissions, is an issue that scientists have struggled with since the first rough estimates were made more than a century ago 1,2 . To answer that question, starting in the 1960s, scientists have used energy balance arguments combined with observed changes in the global energy budget, evaluated comprehensive climate models against observations, and analyzed the relationship between external forcing and climate change over different climate states in the past (see Methods for a list of early publications). The idea of using those different lines of evidence has not changed, but progress in simulating climate, a longer and more accurate observed record of past warming, and better constrained paleoclimate reconstructions now offer more possibilities to evaluate and constrain models. However, recent research has pointed out previously unknown limitations in some of the concepts and assumptions underlying a single constant climate sensitivity 3 . While publications have appeared using various methods, arguably the most important conceptual recent insights is that feedbacks change with equilibration time, an insight that is based on studies in comprehensive climate models. Other recent insights show that the treatment of observations is important 4 . Knowing, to first order, how the global climate will warm in response to increased CO2 is critical: for unabated emissions, it is the difference between a hot and an extremely hot future. The value of halving the uncertainty in that projection may be in the trillions of dollars 5 . Here w...

show abstract

Section: Methodsmentioning

confidence: 99%

Beyond equilibrium climate sensitivity

2017

View full text Add to dashboard Cite

show abstract

“…[152,207,208,215,216,219,221,227] as well as a higher value of 3.0 • C. Similarly, we consider a range of six different values for ECS (1, 2, 3, 4, 5, and 6 • C), which encompasses the IPCC's current "likely" range of 1.5-4.5 • C, but also considers the possibility that the ECS might be lower than 1.5 • C, e.g., refs. [202,[207][208][209]211,212,215,216,[218][219][220]222,226,236,237,260,263,265,266] or that it might be higher than 4.5 • C, e.g., refs. [202,210,262,264,265].…”

Section: Different Climate Sensitivity Definitions and Estimatesmentioning

confidence: 99%

How Much Human-Caused Global Warming Should We Expect with Business-As-Usual (BAU) Climate Policies? A Semi-Empirical Assessment

Connolly¹,

Connolly²,

Carter

et al. 2020

Energies

View full text Add to dashboard Cite

In order to assess the merits of national climate change mitigation policies, it is important to have a reasonable benchmark for how much human-caused global warming would occur over the coming century with “Business-As-Usual” (BAU) conditions. However, currently, policymakers are limited to making assessments by comparing the Global Climate Model (GCM) projections of future climate change under various different “scenarios”, none of which are explicitly defined as BAU. Moreover, all of these estimates are ab initio computer model projections, and policymakers do not currently have equivalent empirically derived estimates for comparison. Therefore, estimates of the total future human-caused global warming from the three main greenhouse gases of concern (CO2, CH4, and N2O) up to 2100 are here derived for BAU conditions. A semi-empirical approach is used that allows direct comparisons between GCM-based estimates and empirically derived estimates. If the climate sensitivity to greenhouse gases implies a Transient Climate Response (TCR) of ≥ 2.5 °C or an Equilibrium Climate Sensitivity (ECS) of ≥ 5.0 °C then the 2015 Paris Agreement’s target of keeping human-caused global warming below 2.0 °C will have been broken by the middle of the century under BAU. However, for a TCR < 1.5 °C or ECS < 2.0 °C, the target would not be broken under BAU until the 22nd century or later. Therefore, the current Intergovernmental Panel on Climate Change (IPCC) “likely” range estimates for TCR of 1.0 to 2.5 °C and ECS of 1.5 to 4.5 °C have not yet established if human-caused global warming is a 21st century problem.

show abstract

“…Figure 12 displays a scatter plot supporting the close correlation of the atmospheric CO 2 concentration with the landocean temperature anomaly (GISS [9]). The latter is controlled by more than 60% by the solar influence and less than 40% by CO 2 as greenhouse gas feedback (Harde [36,37]).…”

Section: Temperature Dependencementioning

confidence: 99%

“…To answer this question we compare the original ∆ 14 CO 2 data of Vermunt and Schauinsland shown in Figure 5, with a hypothetical ∆ 14 CO 2 -distribution, which is found for a fixed δ 13 C-value over the full observation period, thus, assuming no further dilution. This requires first to recalculate the sampling activity A S from (35) and (36) with the known δ 13 C-record, e.g., from Mauna Loa (AR5 [1], Chap6, Figure 6.3c, missing data from 1964-1976 can be extrapolated from this record), and then to simulate the decay curve with new A S activities, which are derived for a constant δ 13 C(1964) = -7.4‰. It directly compares this with the hypothetical ∆ 14 CO 2 decay curve (Brown Crosses).…”

Section: Appendix Bmentioning

confidence: 99%

What Humans Contribute to Atmospheric CO<sub>2</sub>: Comparison of Carbon Cycle Models with Observations

Harde¹

2019

EARTH

Self Cite

View full text Add to dashboard Cite

The Intergovernmental Panel on Climate Change assumes that the inclining atmospheric CO 2 concentration over recent years was almost exclusively determined by anthropogenic emissions, and this increase is made responsible for the rising temperature over the Industrial Era. Due to the far reaching consequences of this assertion, in this contribution we critically scrutinize different carbon cycle models and compare them with observations. We further contrast them with an alternative concept, which also includes temperature dependent natural emission and absorption with an uptake rate scaling proportional with the CO 2 concentration. We show that this approach is in agreement with all observations, and under this premise not really human activities are responsible for the observed CO 2 increase and the expected temperature rise in the atmosphere, but just opposite the temperature itself dominantly controls the CO 2 increase. Therefore, not CO 2 but primarily native impacts are responsible for any observed climate changes.

show abstract

Radiation Transfer Calculations and Assessment of Global Warming by CO₂

Cited by 13 publications

References 64 publications

Beyond equilibrium climate sensitivity

Beyond equilibrium climate sensitivity

How Much Human-Caused Global Warming Should We Expect with Business-As-Usual (BAU) Climate Policies? A Semi-Empirical Assessment

What Humans Contribute to Atmospheric CO<sub>2</sub>: Comparison of Carbon Cycle Models with Observations

Contact Info

Product

Resources

About

Radiation Transfer Calculations and Assessment of Global Warming by CO2

Cited by 13 publications

References 64 publications

Beyond equilibrium climate sensitivity

Beyond equilibrium climate sensitivity

How Much Human-Caused Global Warming Should We Expect with Business-As-Usual (BAU) Climate Policies? A Semi-Empirical Assessment

What Humans Contribute to Atmospheric CO&lt;sub&gt;2&lt;/sub&gt;: Comparison of Carbon Cycle Models with Observations

Contact Info

Product

Resources

About

Radiation Transfer Calculations and Assessment of Global Warming by CO₂

What Humans Contribute to Atmospheric CO<sub>2</sub>: Comparison of Carbon Cycle Models with Observations