Entropy production and the climate

The entropy production rate of the climate is a topic of active study but ongoing confusion, spurred by the yet-unproven hypothesis that the climate system might be organising itself to maximise its entropy production rate and, more broadly, the potential of probing our climate from unorthodox simplifying perspectives. In this thesis, a re-examination of some fundamentals in this topic is offered. Two main suggestions for a climate-relevant global entropy production rate have been established in the literature: one which focuses on non-radiative processes only (labelled 'material') and one which includes all radiative and non-radiative processes (labelled 'planetary'). Another physically-motivated entropy production rate is introduced and investigated here -- the transfer entropy production rate -- which distinguishes radiation according to the role it plays within the system, considering only entropy production due to those transfers of energy which occur within the climate. Various lines of reasoning and evidence point towards the new rate being physically meaningful, which is significant especially as it offers a re-interpretation of the entropy production optimisation hypothesis. Next, the response of entropy production rates to changing climate conditions is investigated and the results used to verify a simple conceptual model capable of predicting the direction of the changes. The transfer and material entropy production rates are found to be significantly more responsive than the planetary rate to the climate's state and they both are able to resolve changes which surface temperature cannot: a simple solar radiation management scenario is found to be able to restore global average surface temperature but not the entropy production rates. Finally, the measurement of the entropy production budget via radiation information in observational and GCM datasets is explored. A new method for accounting for entropy storage in the recently published CERES SYN1deg entropy flux dataset is demonstrated, which makes it possible to estimate the material and transfer entropy production rates from that dataset. This reveals that the transfer and material entropy production rates have increased in line with temperature over the past 20 years and that entropy production rates are higher in years with higher solar absorption. Furthermore, there is a hemispheric asymmetry of entropy production, with more occurring in the Northern hemisphere. The global mean material entropy production rate is 55.3 mW/m^2K and the transfer entropy production rate, 82.0 mW/m^2K in that dataset between March 2000 and February 2018. As a whole, this investigation deepens our understanding of entropy production in the climate and offers new definitions, frameworks and observed patterns to stimulate further research.Open Acces

Reply to Ruhl and Craig: Assessing and governing extreme climate risks needs to be legitimate and democratic

[No abstract available

Reply to Bhowmik et al.: Democratic climate action and studying extreme climate risks are not in tension

[no abstract available

Symmetric rearrangement of groundwater-fed streams

Yi, Robert, et al. “Symmetric Rearrangement of Groundwater-Fed Streams.” Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science, vol. 473, no. 2207, Nov. 2017, p. 20170539

Niche adaptation by expansion and reprogramming of general transcription factors

Experimental analysis of TFB family proteins in a halophilic archaeon reveals complex environment-dependent fitness contributions. Gene conversion events among these proteins can generate novel niche adaptation capabilities, a process that may have contributed to archaeal adaptation to extreme environments

Prediction of the radiative heat transfer in small and large scale oxy-coal furnaces

Predicting thermal radiation for oxy-coal combustion highlights the importance of the radiation models for the spectral properties of gases and particles. This study numerically investigates radiation behaviours in small and large scale furnaces through refined radiative property models, using the full-spectrum correlated k (FSCK) model and Mie theory based data, compared with the conventional use of the weighted sum of grey gases (WSGG) model and the constant values of the particle radiation properties. Both oxy-coal combustion and air-fired combustion have been investigated numerically and compared with combustion plant experimental data. Reasonable agreements are obtained between the predicted results and the measured data. Employing the refined radiative property models achieves closer predicted heat transfer properties to the measured data from both furnaces. The gas-phase component of the radiation energy source term obtained from the FSCK property model is higher within the flame region than the values obtained by using the conventional methods. The impact of using non-grey radiation behaviour of gases through the FSCK is enhanced in the large scale furnace as the predicted gas radiation source term is approximately 2-3 times that obtained when using the WSGG, while the same term is in much closer agreement between the FSCK and the WSGG for the pilot-scale furnace. The predicted total radiation source term (from both gases and particles) is lower in the flame region after using the refined models, which results in a hotter flame (approximately 50-150 K higher in this study) compared with results obtained from conventional methods. In addition, the predicted surface incident radiation reduces by using the refined radiative property models for both furnaces, in which the difference is relevant with the difference in the predicted radiation properties between the two modelling techniques. Numerical uncertainties resulting from the influences of combustion model, turbulent particle dispersion and turbulence modelling on the radiation behaviours are discussed

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570